eurocontrol experimental centre collaborative … · 2008-08-21 · improving airport operations...

EUROPEAN ORGANISATIONFOR THE SAFETY OF AIR NAVIGATION

EUROCONTROL EXPERIMENTAL CENTRE

COLLABORATIVE DECISION MAKING

IMPROVING AIRPORT OPERATIONS THROUGH CDMZAVENTEM 2001 PROJECT

EEC Report No. 371

Project: SCS-M-22

Revision: 1.0

Issued: March 2002

The information contained in this document is the property of the EUROCONTROL Agency and no part should be reproducedin any form without the Agency�s permission.

The views expressed herein do not necessarily reflect the official views or policy of the Agency.

EUROCONTROL

REPORT DOCUMENTATION PAGE

Reference:EEC Report No.371

Security Classification:Unclassified

Originator:EEC - PFE(Performance, Flow Management, Economics & Efficiency)

Originator (Corporate Author) Name/Location:EUROCONTROL Experimental CentreCentre de Bois des BordesB.P.15F - 91222 Brétigny-sur-Orge CEDEXFRANCETelephone : +33 (0)1 69 88 75 00

Sponsor:PFE

Sponsor (Contract Authority) Name/Location:EUROCONTROL AgencyRue de la Fusée, 96B -1130 BRUXELLESTelephone : +32 2 729 9011

TITLE: Collaborative Decision MakingImproving Airport Operations Through CDM:

Zaventem 2001 ProjectRevision 1.0

AuthorsOlivier DELAIN

Jean-Pierre FLORENT

Date03/2002

Pagesxiv+74

Figures16

Tables12

Appendix1

References7

Project

SCS-M-22

Task No. Sponsor

SCS-M-22

Period

2001

Distribution Statement:(a) Controlled by: Head of PFE(b) Special Limitations: None(c) Copy to NTIS: YES / NO

Descriptors (keywords):

Collaborative Decision Making, Zaventem Airport Implementations, CDM New Concepts, MilestonesApproach, Target Off Block Time (TOBT), Collaborative Procedures, Pre-Notice Start Up Clearance(ESUC), Slot Adaptation Proposal, CDM Key Performance Indicators, Taxi Time Prediction.

Abstract:

The project objective is to improve Brussels airport operations through improved co-operation betweenairport actors (in 2001 represented by Brussels International Airport Authorities, Belgocontrol, Sabenaand Eurocontrol Experimental Centre). Project phases included a state-of-the-art of the situation, thedetection of information gaps and problems, finding of co-operative solutions, then, looking for theirimplementations. New CDM concepts, reused in Barcelona project, encompass the description of aCDM milestones approach and distribution of TOBT (Target Off Block Time). A design of a CDMCollaborative Procedures (pre-notice start-up clearance) is developed. This document also addressespotential further-on challenges.

This document has been collated by mechanical means. Should there be missing pages, please report to:

EUROCONTROL Experimental CentrePublications Office

Centre de Bois des BordesB.P. 15

91222 - BRETIGNY-SUR-ORGE CEDEXFrance

Improving Airport Operations through CDM: Zaventem 2001 Project

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FOREWORD

Airports are the natural environments for collaborative decision making, where most actors that contribute tothe ATM1 picture are represented and interact : airport authorities, ATC2, aircraft operators, ground handling,the CFMU3, passengers.

If much attention has been given so far to reduce ATFM4 delays in Europe with great benefits for theEuropean Community, few concerted efforts have been spent on analysing source of delays at airports,problems and means to alleviate them.

The compelling problem of reducing uncertainty at airport and improving efficiency is constantly growing.Improving the efficiency of an airport site requires a common understanding of problems and collaborativesolutions as well as enablers to improve the situation.

Until now, despite of individual actors� efforts, efficiency has been based on improving individual operationsrather than considering airport users as a team.

However, unless common objectives are targeted, and problems are addressed at a common level, the sumof individual actors� initiatives do not ensure a comprehensive, shared and optimised use of availableresources. Actors may have different and maybe competing objectives but the best use of the availablecapacity and resources will only be attained once quantifiable benefits are proven, and reluctance, defensiveattitudes and disincentives to co-operate are progressively smoothed out.

The main CDM5 challenges are depicted below:

1. The organisational challenge: CDM as a Team

Successful performance often involves interaction amongst several individuals who must work as a team. Acritical feature of teams is that individuals must co-ordinate their decisions and activities by sharinginformation and resources to attain shared goals. Clearly, efforts to improve team performance must focusattention on the performance of individuals.

However, individuals are depending on other team members to provide information and for co-ordination ofactivities. Communication, team orientation, team leadership, monitoring, feedback, backup and co-ordination are critical CDM components.

CDM requires actors to have positive attitudes towards each other, to have received adequate direction andsupport to accomplish common goals, know their own tasks and those of other members with whom theyinteract. These requirements will allow actors to co-ordinate their activities by sharing experience, monitoringthe co-ordination, synchronising operations, communicating and providing feedback and backup assistancewhen needed. The difficult challenge is to move from individual actors with specific role assignments andspecific tasks to a team where interaction, co-ordination and collaborative procedures and decisions arerequired to achieve common goals and outcomes.

Throughout experience gathered, two CDM principles must be respected:

� The sharing of new information or improved QoS6 must be paid back with quantifiable benefits for theoriginator;

� As a corollary, incentives for sharing new information or improving quality of service shall be found inorder to eliminate penalties and to give rewards to entities that contribute to a better situation.

For such, it is recommended that obstacles that would prevent the notification of any information to anentity due to foreseen penalties should be studied as well as means and new procedure to remove suchdisincentives.

1 Air Traffic Management.2 Air Traffic Control.3 Central Flow Management Unit (Eurocontrol).4 Air Traffic Flow Management.5 Collaborative Decision Making.6 Quality Of Service.


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2. The Data Quality Challenge: Sharing Reliable Figures for Arrival and Departure Times

Experience gathered so far through airport CDM show that an important source of benefits for reducingdelays as a whole in Europe and achieving the best use of scarce resources relies on improving the reliabilityand predictability of a very reduced set of data in the airport.

As airports are the physical nodes of the European air traffic network, the implementation of a commonapproach, the assessment of benefits that are expected through field trials should transcend the localcontext of particular sites in a subsequent phase to reach a European dimension.

Accuracy, timeliness, reliability and predictability of arrival and departure data (e.g. ETA, EIBT, EOBT,ETOT7) as well as their connectivity are crucial elements for all users, including CFMU.

Whilst initiatives exist for enhancing landing time accuracy and predictability, two main enablers should beaddressed at the European level to target two different links:

� From in-block time to off-block time: implementation of a milestones approach for accuracy andpredictability of OBT8. The project addressed the notion of CDM turn-around process as a set ofprocedures and milestones that punctuates the usual turn-around process. Starting from outstation,these milestones are key information that improves the awareness of all actors at the inbound station,triggers updates of downstream information and helps in identifying potential delays of the aircraft,allowing collaborative decisions to be made. We developed in co-operation with Sabena, BIAC9 andBelgocontrol the milestones approach that have been repeated in the Barcelona CDM project. Thesustained approach is documented in this report. Field trials in 2002 in both Brussels and Barcelona(with slight implementation differences) will help us to isolate generic concepts that could apply inEurope, along with well-identified benefits.

� From arrival to in-block and from off-block to take-off: predicting a reliable taxi-time10 even with alimited timing horizon would be the subsequent step that would bring huge benefits. The problemof variability of taxi time is a problem shared by the vast majority of European airports (from 5 to 45minutes in Brussels for taxi-out). If individual airport taxi-planners exist (taxi time established throughstatistics that take into account different variables), the challenge to build a European taxi-time toolwould help in predicting the next minutes situation at an airport. New collaborative procedures could thenbe imagined between actors (CFMU, ATC, airlines, handlers and airports).

At current, several individual initiatives have been launched in Europe11, based upon:

� Statistical approaches combining static and dynamic data, whose formula are based on real-dataarchives; of course, the quality of the outcome is directly related to the accuracy of off-block timeprediction12.

� Topological approaches (for complex airports) that integrate algorithms to predict the taxiway pathuntil runway and determine the taxi time.

7 ETA: Estimated Time of Arrival, EIBT: Estimated In Bound Time, EOBT: Estimated Off Block Time, ETOT: EstimatedTake Off Time.8 Off Block Time.9 Brussels International Airport Company (airport authorities).10 At Brussels, the predictability of taxi-out time is at stake since its variability that depends on various conditions (RWYconfiguration, weather, stand/gate, in/out hub wave etc.) may reach 5 minutes up to 45 minutes. By comparison, atCDG airport, the problem of taxi time variability and predictability is both for taxi-in and taxi-out.11 In the United States (Boston Logan airport), research has been launched towards dynamic prediction of taxi-time andthe efficient use of dynamic data (queuing systems).12 The layout of airports means that taxi times for different gate positions on the same airport can vary vastly. The taxitime is not only affected by the physical location of the gate but also for instance by the meteorological conditions andthe type of aircraft taxiing.


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3. The Implementation Challenge Measurement is central to the evaluation and elaboration of theories. It is necessary that concepts and keyperformance could be implemented to bring a sound analysis of benefits gathered through the approach. IfBrussels and now Barcelona projects promote the approach with slight differences, the assessment ofbenefits gathered through these projects and new ones in 2002 will pave the way for isolating generic CDMconcepts and recommendations as well as to build a CDM business case for Europe,

4. Tracking and removing CDM Disincentives

A lot of information required to improve actors� business processes already exists, but is not distributedbecause there is insufficient reason to do so, for operational or economic reasons, or because there areclear disincentives in terms of penalties suffered.

For instance, in order to escape from the so-called �double-penalty mechanism�, aircraft operators use tomaintain an internal off-block time that may be different from the data sent to ATC and the CFMU (EOBT) incertain situations. Even if the problem is well identified from all parties, a kind of dialogue of the deaf is stillapplying between actors that result in a sub-use of the available capacity and resources (runways, taxiways),non-respect of ATFM slot adherence, overdeliveries etc.

We invented the notion of Target Off-Block Time (TOBT) that was linked to the need expressed by ATC,airport authorities and Sabena to share the aircraft operator/handler view on internal off-block time. Sabenahad agreed to share the Target Off Block Time with ATC, airport authorities and proposed to monitor itsquality. Once quality (accuracy and timeliness) is attained, aircraft operator benefits will be obtained througha reduction of stand/gate changes, implementation of new procedure (pre-departure management, etc.).

Generally speaking, all disincentives for sharing information between actors (ATC, airport, airlines, handlers,CFMU) must be tracked, underlying reasons must be identified, the impact quantified and co-operativeagreed solutions raised.

5. Establishing CDM Key Performance Indicators

Data quality is a key enabler for any CDM process. Without definitions of data quality CDM procedures willnot lead to any improvement, and may even lead to deterioration of the situation, as operators would expectthat decisions were based on data of high quality, when this was not the case.

We have developed a set of CDM key performance indicators that support our milestones approach. Nextfuture trials will allow to build a data quality framework, whose elements (accuracy, timeliness, etc.) will becalibrated and refined through experiments.

A CDM quality charter, materialised through service level agreements between actors and associatedmonitoring will ensue from trials. A subsequent step would consist in extending it to Europe.

6. A Common European Need for Predicting Taxi-Time

Planning under uncertainty is the enemy of efficiency and sharing unreliable information is useless, thatresult in heavy European delays materialised through a close loop of cause and effect influences betweenactors. Very few have been performed so far about linking effects and computing an associated cost.

Indispensable enablers for departure management lie on the capacity at an airport to share between actorsmore reliable data with a limited time-horizon about four critical moments: arrival time, in-block time, off-block time and take-off time. In this document, a great emphasis has been placed on off-block time reliability.In that sense, any prediction based on unreliable data is useless, so that the first CDM challenge is put ondata quality.

The quality of in-block time prediction and take-off time lies on computing a reliable taxi-time (taxi-in and taxi-out). The problem of taxi-time variability is common to airports13 but the responsibility for itsprediction/computation is unclear. For instance, it is the aircraft operator responsibility to comply with its 13 Taxi-out and/or taxi-in.


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CTOT14 that lies on taxi-time assessment. However, aircraft operators cannot predict their taxi-time thatdepends on a number of external factors.

The computation of a reliable taxi-time at European airports will bring high benefits. A first step has beencovered through the introduction of CFMU flexible taxi time (gathered through statistics at some airports), butmore dynamic approach is obviously required.

Individual research has started15 in Europe; however a mine of benefits would be brought if Europeanresearch was shared to build a common European Taxi-Time Tool, whose performance would be obviouslylinked to the quality of individual real-time airport parameters.

7. A Need for European CDM Unifiers and Perspective

United States experience brings the thought that one major success CDM factor relied on the commonality oftools. In Europe, individual initiatives at local airports have been launched but a European perspective will berequired to address inter-airports CDM. The definition of external interfaces, data quality required andpotential tools/enablers would help in widening the CDM European map. The next future CFMU ETFMS16

could provide the means for the CDM-net capability in Europe.

14 Ref. CFMU ATFM User Manual, V7.0. CTOT: Calculated Take-Off Time, provided by the CFMU for regulated flights.15 For instance at CENA (Centre d�Etudes de la Navigation Aerienne) in France.16 Enhanced Traffic Flow Management System (CFMU).


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TABLE OF CONTENTSLIST OF FIGURES........................................................................................................................................................XI

LIST OF TABLES..........................................................................................................................................................XI

REFERENCES ............................................................................................................................................................. XII

ACRONYMS................................................................................................................................................................XIII

1 GENERAL ..................................................................................................................................................................... 1

1.1 BACKGROUND............................................................................................................................................... 11.2 BRUSSELS CDM PROJECT ........................................................................................................................... 11.3 DOCUMENT PURPOSE.................................................................................................................................. 11.4 STRUCTURE OF THE DOCUMENT ............................................................................................................. 1

2 BRUSSELS INITIAL PHASE...................................................................................................................................... 3

3 IMPROVING OPERATIONS THROUGH CDM...................................................................................................... 4

3.1 METHODOLOGY............................................................................................................................................ 43.2 BRUSSELS FINDINGS ................................................................................................................................... 5

3.2.1 Connectivity between Arrivals and Departures........................................................................ 53.2.2 Departure Punctuality and Delay Causes ................................................................................ 53.2.3 Turnaround Analysis: Planning Vs Actual Rotations............................................................... 63.2.4 Predictability and accuracy of Taxi-out Time in Brussels........................................................ 73.2.5 Consequences of Departures / Arrivals Uncertainty ................................................................ 9

3.3 IMPROVING THE CAPABILITY TO CATEGORISE PROBLEMS............................................................. 93.3.1 Tracing Operations .................................................................................................................. 93.3.2 Sensors and Monitoring ......................................................................................................... 103.3.3 Assessing impact deviations ................................................................................................... 103.3.4 Monitoring surface operations ............................................................................................... 10

4 DETERMINING CDM SHORT-TERM OBJECTIVES ......................................................................................... 12

4.1 OBJECTIVE 1: REDUCE THE NUMBER OF STANDS/GATES CHANGES............................................ 124.2 OBJECTIVE 2: IMPROVE ACCURACY OF CFMU SLOTS...................................................................... 134.3 OBJECTIVE 3: IMPROVE TAXI-OUT ACCURACY AND PREDICTABILITY ...................................... 134.4 OBJECTIVE 4: MOVE TOWARDS A COLLABORATIVE STRATEGIC PLANNING............................ 134.5 OBJECTIVE 5: MOVE TOWARDS A COLLABORATIVE DISRUPTION RECOVERY......................... 134.6 OBJECTIVE 6: COMMON AWARENESS OF PAX/BAX FOR INBOUND FLIGHTS............................. 14

5 DESIGNING CDM SOLUTIONS.............................................................................................................................. 15

5.1 INTRODUCTION........................................................................................................................................... 155.2 INITIAL CDM ENABLERS........................................................................................................................... 155.3 THE MILESTONES APPROACH ................................................................................................................. 16

5.3.1 Overall Framework ................................................................................................................ 175.3.2 Outstation Milestones ............................................................................................................. 195.3.3 En-route Milestones................................................................................................................ 225.3.4 Surface Milestones.................................................................................................................. 245.3.5 The Target Off Block Time ..................................................................................................... 285.3.6 Alarms and Indicators ............................................................................................................ 295.3.7 CDB gate Statuses ................................................................................................................. 29

5.4 PRE-NOTICE START UP CLEARANCE PROCEDURE ............................................................................ 305.4.1 Objective................................................................................................................................. 305.4.2 Current Departure Operations ............................................................................................... 305.4.3 Problems and issues ............................................................................................................... 315.4.4 Description of the proposal .................................................................................................... 325.4.5 Potential improvements for the CFMU .................................................................................. 33


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6 CDM KEY PERFORMANCE INDICATORS ......................................................................................................... 37

6.1 MILESTONES AND RECORDED DATA.................................................................................................... 376.2 INITIAL IDENTIFICATION OF KPIS .......................................................................................................... 39

7 PREDICTING TAXI TIME AT AIRPORTS: A CHALLENGE FOR EUROPE................................................. 43

7.1 RESPONSIBILITIES...................................................................................................................................... 437.2 INITIAL THOUGHTS.................................................................................................................................... 43

7.2.1 Calibration of Ttravel_time .......................................................................................................... 447.2.2 Calibration of TQueue ............................................................................................................... 44

7.3 EXPECTED BENEFITS................................................................................................................................. 46

8 A GLOBAL PICTURE ............................................................................................................................................... 47

8.1 THE FOUR CRITICAL MOMENTS ............................................................................................................. 478.2 TOWARDS DATA QUALITY STANDARDISATION............................................................................... 488.3 LINKING CDM-AIRPORT AND CDM-EN-ROUTE................................................................................... 49

TRADUCTION EN LANGUE FRANCAISE .............................................................................................................. 5 1

1 GÉNÉRALITÉS .......................................................................................................................................................... 55

1.1 CONTEXTE GÉNÉRAL ................................................................................................................................ 55

2 DÉTERMINER LES OBJECTIFS À COURT TERME DE LA CDM .................................................................. 56

2.1 OBJECTIF 1 : RÉDUIRE LA FRÉQUENCE DES RÉATTRIBUTIONS DE POSTE DESTATIONNEMENT/PORTE D'EMBARQUEMENT........................................................... 56

2.2 OBJECTIF 2 : AMÉLIORER LA PRÉCISION DES CRÉNEAUX DU CFMU ........................................... 572.3 OBJECTIF 3 : AMÉLIORER LA PRÉCISION ET LA PRÉDICTIBILITÉ DU TEMPS DE ROULAGE AU

DÉPART ................................................................................................................................ 572.4 OBJECTIF 4 : S'ORIENTER VERS UNE PLANIFICATION STRATÉGIQUE COOPÉRATIVE.............. 572.5 OBJECTIF 5 : S'ORIENTER VERS UN PROCESSUS COOPÉRATIF DE GESTION DES

PERTURBATIONS DE TRAFIC .......................................................................................... 582.6 OBJECTIF 6 : DIFFUSER LES DONNÉES PAX/BAX CONCERNANT LES VOLS À L'ARRIVÉE ....... 58

3 CONCEVOIR DES SOLUTIONS CDM ................................................................................................................... 59

3.1 INTRODUCTION........................................................................................................................................... 593.2 ÉLÉMENTS IMPULSEURS INITIAUX DE LA CDM................................................................................. 593.3 L'APPROCHE FONDÉE SUR DES JALONS ............................................................................................... 60

3.3.1 Cadre général......................................................................................................................... 613.3.2 L'heure cible de départ de l'aire de stationnement................................................................. 623.3.3 Alarmes et indicateurs ............................................................................................................ 63

3.4 PROCÉDURE DE PRÉAVIS D'AUTORISATION DE MISE EN ROUTE DES MOTEURS ..................... 643.4.1 Problèmes et questions soulevés............................................................................................. 643.4.2 Description de la proposition ................................................................................................. 643.4.3 Améliorations potentielles pour le CFMU.............................................................................. 66

4 INDICATEURS DE PERFORMANCES ESSENTIELS POUR LA CDM............................................................ 70

ANNEX A: ZAVENTEM BRUSSELS AIRPORT ...................................................................................................... 71


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LIST OF FIGURES

FIGURE 1: CONNECTIVITY BETWEEN ARRIVALS AND DEPARTURES (SOURCE:BIAC) ................................ 5FIGURE 2: PLANNED VERSUS ROTATIONS (SOURCE: BIAC)................................................................................ 6FIGURE 3: ACTUAL AND PLANNED ROTATIONS (ZOOMING).............................................................................. 7FIGURE 4 : MEAN TAXI OUT TIME IN BRUSSELS � SAMPLE 8978 FLIGHTS...................................................... 8FIGURE 5: EXAMPLE OF BAD PREDICTABILITY OF TAXI-OUT TIME IN BRUSSELS....................................... 8FIGURE 6: HIGH LEVEL VIEW OF SURFACE MANAGEMENT OPERATIONS.................................................... 11FIGURE 7: STAND/GATE PLANNING UNDER UNCERTAINTY............................................................................. 12FIGURE 8 : MILESTONES APPROAC.......................................................................................................................... 18FIGURE 9 : TARGET OFF BLOCK TIME AND SURFACE MILESTONES .............................................................. 25FIGURE 10 : PROPOSED PRE-NOTICE START-UP CLEARANCE........................................................................... 33FIGURE 11: SLOT IMPROVEMENT WINDOW .......................................................................................................... 34FIGURE 12: SLOT ADAPTATION PROPOSAL........................................................................................................... 36FIGURE 13: TAXI-TIME OUT VARIABILITY AND DEPARTURES CONGESTION EFFECT............................... 45FIGURE 14: TAXI-TIME OUT VARIABILITY AND ARRIVALS CONGESTION EFFECT .................................... 45FIGURE 15: THE GLOBAL PICTURE .......................................................................................................................... 48FIGURE 16: BRUSSELS AIRPORT MAP ..................................................................................................................... 71

LIST OF TABLES

TABLE 1 : SABENA DEPARTURE PUNCTUALITY AT BRUSSELS AIRPORT ....................................................... 6TABLE 2 : OUTSTATION MILESTONES .................................................................................................................... 19TABLE 3 : EN-ROUTE MILESTONES.......................................................................................................................... 22TABLE 4 : SURFACE MILESTONES............................................................................................................................ 24TABLE 5 : MILESTONES AND RECORDED DATA................................................................................................... 38TABLE 6 : BRUSSELS CDM INITIAL KEY PERFORMANCE INDICATORS 1/3 ................................................... 40TABLE 7 : BRUSSELS AIRPORT FIGURES ................................................................................................................ 71TABLE 8 : BRUSSELS AIRPORT MOVEMENTS ....................................................................................................... 72TABLE 9 : BELGIUM SLOT ADHERENCE (JUNE 2001)........................................................................................... 73TABLE 10 : BELGIUM DEPARTURE ANALYSIS (JUNE 2001)................................................................................ 73TABLE 11 : BELGIUM - OVERALL DELAY ANALYSIS (JUNE 2001) .................................................................... 74TABLE 12 : BRUSSELS AIRPORT ANALYSIS (CODA - MAY 2001)....................................................................... 74


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REFERENCES

[ATFM User Manual] ATFM Users Manual, Edition 7.0, 12 Feb. 2001

[ATFM Priorities] Study of ATFM Priorities, EUROCONTROL, September 1998 (authors: OlivierDelain, Patrick Ky, Juan Revuelta, Bernard Kinchin, Mike Rose, Erwin Von DenSteinen)

[CDM Expert Group] Report of Ad-Hoc Expert Group, EUROCONTROL, May 1999, Issue 1.0(authors: Olivier Delain, Peter Martin)

[CDM Applications] Note EEC 9/99, �Application of Collaborative Decision Making� (authors: PeterMartin, Olivier Delain , Nicolas Bouge, Serge Vial, Allison Hudgell, Hugo deJonge)

[FASTER Study] Future ATFM-AO-Airport Synergies Towards Enhanced opeRations), EECReport No 332 (authors: Peter martin, A. Hudgell, S.Vial, N.Bouge)

[ATFM Improvement] Study for ATFM improvement, (2000), IGACEM/SOFREAVIA/ EEC (authors:,Philippe Jaquard, Patrick Ky, Olivier Delain, Stephanie Stoltz)

[A-CDM-D Evaluation] Air CDM Demonstrator Evaluation Report (2000) Eurocontrol / CEC DGXIII,authors: Olivier Delain, Fadi Fakhoury, Jean-Pierre Florent


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ACRONYMS

ACC Area Control CentreA-CDM-D Air CDM DemonstratorAIMS Aeronautical Information Management System (Sabena)AIP Aeronautical Information PublicationAO Aircraft OperatorAIBT Actual In Block TimeAOBT Actual Off Block TimeATOT Actual Take Off TimeATC Air Traffic ControlATFM Air Traffic Flow ManagementATM Air Traffic ManagementBIAC Brussels International Airport CompanyCDM Collaborative Decision MakingCENA Centre d�Etudes de la Navigation AérienneCFMU Central Flow Management UnitCTA Calculated Time of ArrivalCTOT Calculated Take Off Time (CFMU parameter)DC Doors ClosedEEC Eurocontrol Experimental CentreEIBT Estimated In Block TimeEOBT Estimated Off Block TimeESUC Estimated Start Up ClearanceETA Estimated Time of ArrivalETD Estimated Time of DepartureETFMS Enhanced Traffic Flow Management SystemETOT Estimated Take Off TimeETT Estimated Taxi TimeFDO First Door OpenedFMP Flow Management PositionFSA First System ActivationGC Gate ClosedIATA International Air Transport AssociationKPI Key Performance IndicatorMVT Movement MessageOBT Off-Block TimeOCC Operations Control CentrePFE Performance, Flow Management, Economics and EfficiencyQoS Quality Of ServiceREA Ready MessageRFI Request for ImprovementRWY RunwaySB Start BoardingS/G Stand and GateSIP Slot Improvement ProposalSIT Slot Issue TimeSIW Slot Improvement WindowSPA Slot Proposal AcceptanceSRJ Slot Rejection ProposalSRM Slot Revision MessageSTD Standard Time of DepartureSUC Start Up ClearanceSUR Start Up RequestSWM SIP Wanted MessageTIS Time to Insert into the SequenceTOBT Target Off Block TimeTRS Time to Remove from the SequenceTWR TowerUML Unified Modelling Language


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1 GENERAL

1.1 BACKGROUND

Many individual initiatives towards improved co-operation, communication and information sharing arecurrently undertaken in the European ATM community. The Eurocontrol Experimental Centre is involved inCollaborative Decision Making since 1998 through many studies ([ATFM Priorities] (1998), [CDM ExpertGroup] (1999), [FASTER Study] (1999), [CDM Applications] (1999), [ATFM improvement] (2000), [A-CDM-DEvaluation] (2000)) that have opened the perspectives for Collaborative Decision Making.

In 2001, two projects aiming at experimenting concrete CDM in airports (Brussels and Barcelona) have beenset up by the EEC/PFE (Performance, Flow Management, Economics and Efficiency) Business Area. Thesetwo separate projects have been conducted in collaboration with local actors represented by:

� Brussels International Airport Company (BIAC), Sabena (considered as an aircraft operator and handlingagent), Belgocontrol (ATC) in Brussels;

� Barcelona�s Airport (AENA), Iberia, Spanair, Eurohandling (handling agent), Barcelona�s FMP17, TWRand ACC (Area Control Centre (AENA)) in Barcelona.

This report addresses experience gathered through the Brussels CDM project, identifies current intermediateresults and highlights further challenges and subsequent project steps.

1.2 BRUSSELS CDM PROJECT

The main objective of this project, initiated on December 15, 2000, is to improve Brussels airport operationsthrough improved co-operation between actors.

Two different directions have been proposed:

� CDM operational aspects: The objective was to establish a state-of-the-art of the situation, detectinginformation gaps and problems where co-operative solutions were required, then, look for theirimplementation.

� CDM modelling aspects18: The objective was linked to the need for CDM to demonstrate benefits. AsCollaborative Decision Making can be described as a closed loop of cause-and-effect influences that canbe materialised through a multitude of cross-functional actors� interactions, we proposed to launchcause-impact oriented modelling activities in order to support the comparison of different strategies andto quantify benefits.

1.3 DOCUMENT PURPOSE

The purpose of this document is to give the current status, results and initiatives of the CDM project inBrussels as well as to open further perspectives.

We grant all actors for their participation and high professionalism for the definition of common targetobjectives and findings of CDM collaborative solutions. In particular, we have a deep respect for the workdone by Sabena staff.

1.4 STRUCTURE OF THE DOCUMENT

� Section 2 addresses the initial project phase,� Section 3 provides the description of findings and associated main CDM challenges at Brussels airport;� Section 4 describes the common short-term CDM objectives agreed by Brussels� actors ;

17 Flow Management Position.18 This part of the project will be addressed in a separate document.


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� Section 5 addresses the enablers and initial solutions that have been designed in collaboration withBrussels� actors. It also provides an initial description of a new CDM procedure (pre-notice start upclearance).

� Section 6 describes CDM key performance indicators associated to our approach,� Section 7 gives initial thoughts upon a common problem at European airports: predicting a reliable taxi-

time;� Section 8 provides a high-level synthesis of Brussels� findings and the way forward.� Annex provide figures for Brussels Zaventem airport.


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2 BRUSSELS INITIAL PHASE

Both Barcelona and Brussels CDM projects are directed towards implementation and field trials. Groundedon the sound experience gathered in these two projects, the extension to other airports planned in 2002 andbeyond lead us to build upon this experience. The capitalisation of know-how and the objective to reduceinitial fact-finding phases will bring higher cost-efficiency by allowing teams to concentrate as soon aspossible on detecting problems, finding solutions, implementing them and measuring benefits. Eurocontrol experience shows that CDM projects main success criteria rely on:

� The identification and agreement on clear objectives and targets, � The capacity to demonstrate short term and quantifiable benefits,� Actors (airport, ATC, aircraft operators, handlers) participation (resources (manpower), management,

etc.)

The initial phase relied in a sound understanding of operations, assessment of interactions between actorson a specific site, assessment of information used and exchanged (data, information systems) within aspecific site as well as with an external site or external system.

Building this map was of prime importance since we noticed that actors (e.g. airport authorities, ATC, aircraftoperators, handling agents, etc.) have a limited understanding of each other�s operations and constraints.Participants granted this initiative whose result depends on actors� involvement.

In Brussels, actors� interviews were performed supported by a common template to describe usecases/business processes. This format was based on five main different areas:

� The identification of the business process,� Data information required (inputs) and produced (outputs),� Events that trigger the decision making process,� What happens before a decision (prerequisite), co-ordination actions,� What happens once a decision is taken (data produced, revised, etc.).

Two separate outputs were produced during this phase:

� A document that describes Brussels operations,� An UML (Unified Modelling Language) model of operations, that is a first instance (Brussels instance) of

what could establish a future baseline upon which other instances (for future new sites) could be usedand compared.

The second step of the project aimed to identify common CDM target objectives, specify improvements,design solutions (concepts, collaborative procedures) and associate CDM key performance indicators.19

19 The implementation started a few days before Sabena stopped operations.


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3 IMPROVING OPERATIONS THROUGH CDM

An essential capability relies in providing reliable and predictable figures for estimated times of arrivals anddepartures (ETA-ETD20). These estimates need to be continuously monitored by various actors (airportauthority, ground handling, airline, ATC, etc.) who need accurate information to monitor the resources theymanage. However, it is difficult to achieve not only due to the distribution of data across the various systems,potentially missing links between actors or hardware systems, but also because of several deviations ordisruptions. Assembling an integrated view in the airport is made complicated due to multiplicity and distribution ofinformation systems and actors. Completeness, timeliness and accuracy of information across the abovedisplayed management areas is key to appropriate decisions. Processes therefore must becomecollaborative. In the following, several areas have already been identified as suitable candidates.

Depending upon the way these collaborative processes interact with overall flow, resource capacity usageand punctuality are directly impacted. Flow management is the cause, resource usage and punctuality arethe consequences. But it all relies on improved quality of data.

3.1 METHODOLOGY

Dissatisfaction with the status quo is the starting point of any improvement. But general dissatisfaction isoften too vague. Before useful results can be obtained, the general symptom of dissatisfaction must beconverted into a list of specific problems. The practical expression of �separating the vital from the trivial�principle consists in preparing a list of the problems in order of importance, their frequency, the types ofdefects in order of amount of loss caused, the elements of cost in order of amount, etc.

In practice, no company or department can claim to be fully acquainted with its unsolved problems until:

� it has a list of these problems. Without the list, there is no proof that they have thought it out.� it has arranged this list in order of importance. Without a listing in order of importance, there is difficulty

in securing agreement on the priority of problems to tackle.� it has put a value tag on each unsolved problem - an estimate of how much it would be worth to solve

the problem.

Consequently, the approach taken was first to identify short-term stakeholder objectives through theapproach above and then to identify which enablers would facilitate the realisation of these objectives.

For such, workshops main objective was to ground potential key improvements and the path to attain them,to decide and to take necessary actions to implement the measures decided. During working sessions, animportant success factor was to recognise the importance of QoS (Quality of Service) of informationprovided by one actor to other actors, that should provide in return indirect benefits. For instance,conditions/enablers for reducing the number of stand/gates changes in the last 30 minutes relies in part inthe provision of accurate/reliable data regarding ETAs for inbound flights as well as EOBTs21 for outboundflights.

The implementation and the quantification of results depend on comparing a current baseline (criteria andindicators) and to compare with the results obtained through experiments. These aspects are discussed insection 6 of this document.

20 Estimated Time of Arrival (ETA), Estimated Time of Departure (ETD).21 Estimated Off Block Time.


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3.2 BRUSSELS FINDINGS

Participants initially agreed to focus on the turn-around process; it appeared that common airportinefficiencies were directly related to planning under uncertainty. Some analysis were performed to quantifythe problem and to examine the problem extent:

� Connectivity between arrivals and departures,

� Sabena departure punctuality and delay causes analysis,

� Turnaround analysis: planned versus actual rotation times.

The analysis and figures are depicted in the next sections.

3.2.1 Connectivity between Arrivals and Departures

The diagrams depicted below have been established after analysis of the transaction history of the BrusselsCentral Data Base (CDB)22. It is a graphic representation of the quality of estimates, both for arrivals anddepartures. The vertical axis is the horizon before actual arrival or departure, up to 90 minutes whilst thehorizontal axis is the deviation of the estimate from the actual value.

The difference between both quantity of information and distribution of accuracy across arrival and departureclearly shows that there is no visibility or certainty on departing flights, which lead to compare connectivitybetween arrivals and departures as a �Russian roulette�.

FIGURE 1: CONNECTIVITY BETWEEN ARRIVALS AND DEPARTURES (SOURCE:BIAC)

3.2.2 Departure Punctuality and Delay Causes

The table below shows the analysis of Sabena delay causes, as gathered during the A-CDM-D23 project(1999-2000).

22 Brussels Airport Authority Central Database.23 Air CDM Demonstrator

Departures

Accuracy: Actual - Estimated time (min.)

Timeliness:Horizon (min.)

Arrivals


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This table clearly shows that aircraft operators� delays, measured by |AOBT-STD24|, can mainly be groupedin four main categories:

� Delays due to rotations (late arrivals),

� Delays due to turn around problems (technical, airport facilities, crew, catering, security, etc.),

� ATC delays (local), and

� ATFM.

Delay Cause D>3 (*) Percentage Rank D>15 Percentage RankRotation (Late Arrivals) 1977 25.8% 2 1246 41.5% 1ATC [Local] 2232 29.1% 1 352 11.7% 2Miscellaneous 329 4.3% 6 225 7.5% 4ATC [Flow] 777 10.1% 3 162 5.4% 3Technics 236 3.1% 9 159 5.3% 5Airport Facilities 247 3.2% 8 146 4.9% 6Crew 216 2.8% 10 144 4.8% 7Security 383 5.0% 5 141 4.7% 8Catering 302 3.9% 7 131 4.3% 9Connection Load 404 5.3% 4 88 2.9% 10Passage 207 2.7% 11 64 2.1% 11Others (11 causes) 4.7% 4.9%Flight Sample Analysed 7656 2998Total: 10654 flights

TABLE 1 : SABENA DEPARTURE PUNCTUALITY AT BRUSSELS AIRPORT

(*) D is measured by |AOBT-STD| (actual off block time � standard time of departure)

3.2.3 Turnaround Analysis: Planning Vs Actual Rotations

The figure depicted below shows the relationship between planned and real rotation times.

FIGURE 2: PLANNED VERSUS ROTATIONS (SOURCE: BIAC)

On the x-axis is represented the last planned duration of rotations (in minutes) whilst the y-axis addressesthe real occurred ones. A first statement is to recognise that the stated variance is significant whichdemonstrates that the uncertainty regarding turnaround operations is very high. 24 STD: Standard Time of Departure (schedule).


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FIGURE 3: ACTUAL AND PLANNED ROTATIONS (ZOOMING)

Zooming on figure 2, a clear objective to attain would consist in reducing the uncertainty about rotations.Such uncertainty prevents from efficient ATFM and downstream local operations (ATC and airport). Forinstance the rate of non-CFMU slot compliance stated in Brussels (42.3% in June 2001 (see annex A)) is anindicator that highlight actors� problems (planning difficulties, uncertainty, bad reliability of estimates, badpredictability of taxi time etc.).

This leads us to a notion of quality of data interweaving from arrival until departure. There are four dataquality cornerstones that drive CDM efficiency at a local airport:

� Arrival Time data quality: completeness, accuracy, timeliness and predictability of ETA,

� Taxi-in data Time quality: predictability of a reliable taxi-in time25 with a limited horizon,

� Off-Block Time data quality: one of the main CDM challenges. The milestones approach, initiallydeveloped through this project, is intended to bring high benefits for achieving this objective.

� Taxi-out Time data quality: the variability of taxi-out time is high, that prevents from downstreamdeparture and CFMU efficiency.

3.2.4 Predictability and accuracy of Taxi-out Time in Brussels

As said earlier, the predictability of taxi-out time is an important challenge for departure information.However, computing or predicting a reliable taxi-out time will rely on the previous steps, e.g. upon theaccuracy of the off-block time that lies itself upon a number of different factors.

The following figure depicts observations at Brussels airport regarding taxi-out time. In addition to the meanvariability of taxi-out time, day-to-day taxi-out time standard deviation remains significant (the taxi-out timeranges from 5 minutes to 45 minutes).

25 Predictability of taxi-in time in Brussels is rather good in Brussels, around 5� up to 6�. However it is an important factorfor more complex airports (example: Roissy CDG).


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11

12

13

14

15

16

17

18

19

Taxi Tim e (M inutes)

04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22

Tim e (UTC)

FIGURE 4 : MEAN TAXI OUT TIME IN BRUSSELS � SAMPLE 8978 FLIGHTS

Specific examples of induced effect of taxi-time miscalculation can be highlighted. The following figureillustrates problems, even if the aircraft is ready 56 minutes before its CTOT. In that case, a wrongassessment of taxi-out time with a limited time horizon along with uncertainty about evolving congestion atthe airport has lead to bad decisions:

FIGURE 5: EXAMPLE OF BAD PREDICTABILITY OF TAXI-OUT TIME IN BRUSSELS

� The aircraft being ready, the pilot calls for start-up well in advance, but is asked to call back again 20minutes before its CTOT. Conditions that have been taken into account at this stage regard thetaxiway/runway closeness and the CTOT.

� Calling back as instructed, the pilot receives a number 7 rank in the start-up clearance queue, resultingin an additional unplanned delay of 18 minutes. However, the taxi-time was planned to be 5 minutes.

� Because the start-up was delayed, and due to local airport congestion, the taxi-out time actually lasted29 minutes to be compared with the 5 minutes estimated.

Missed SlotMissed Slot DEPARTURE Punctuality DEPARTURE Punctuality Wrong Taxi out timeWrong Taxi out time

EOBT

High sensitivity to : Hub Effects & Weather

08:25

CTOT

09:15

ATFM Delay = 30� Taxi Time = 20�

08:19

Pilot: Ready !

TWR: Please call at 08:55

08:55

TWR: No 7 for SUC

09:13

SUC

SUC: 18� 08:55 Taxi Out: 29 �

AOBT ATOT

09:42

Ready Take off 1h23�

Taxi-out Estimate: 5�

Life Example


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The result is a non-compliance with the CTOT and a bad departure punctuality that may result inoverdelivery. Of course the problem of taxi time assessment and associated responsibility is at stake, that isaddressed in section 7.

3.2.5 Consequences of Departures / Arrivals Uncertainty

The result of planning turnaround under uncertainty (arrivals and departures) as depicted in the abovesection induces various counterproductive effects:

� For aircraft operators, an absence of discipline, non-respect of rules, rule of tomb, mistrust andinsufficient collaboration lead to additional delays and costs. For instance, the marginal cost induced bya departing aircraft that does not leave the stand without any notice, forcing an arrival aircraft to move toanother stand in the last minutes is very penalising.

� For ATC at local airport, uncertainty about departures and non-respect of rules included in local AIPs26

lead to significant inefficiency to construct a departure sequence. The optimisation of the runway use aswell as associated airport throughput is then affected.

� For ground handling, it leads to inefficient use of resources, both human and technical, raising potentialconflicts in resources allocation and affecting the global throughput.

� For the airport, it leads to inefficient use of resources (boarding bridges, gates (contact/remote), buses,reclaim belts, non Schengen-border control, Schengen-border crossing, screening-security checksmanpower, deterioration of the passenger service.

� For En-route ATC, it may lead to overloads and may thus affect the safety.

� For the CFMU, it leads to global inefficiency, lack of slot adherence, lost slots and thus may causeoverdeliveries, that in-return decreases the available airport capacity, especially when regulations areput in place to protect the airport.

3.3 IMPROVING THE CAPABILITY TO CATEGORISE PROBLEMS

3.3.1 Tracing Operations

The capacity to trace operations is the basic capability upon what any prediction can be based on.For such, monitoring the accuracy and timeliness of significant events that occur during the turnaroundsequence is necessary. This means that the determination of the critical path associated to turnaroundoperations shall be established, and the means to notify alarms in case of operations disruptions is at stake.

The turnaround process outcomes need to be continuously monitored, in particular for the consistency andsynchronisation of operations between arrival/departure aircraft. However it is clear that process monitoringis only one element that checks that the continuity of operations is ensured, and in case of processdisruption, would help in assessing the severity of the situation in order to take an collaborative decision.This induces:

� The assessment of consequences of actors� decisions and strategy in connection with monitoringunplanned events. Consequences of any decision that could delay one operation situated on the criticalpath or that could have a strong influence on their operations should be known to actors as soon as it isdecided in order for them to react. For instance, if an aircraft operator decides that one aircraft has towait for connecting passengers, a recalculation of the EOBT should be performed immediately andcommunicated to other actors.

� The knowledge of external constraints: common awareness of external constraints such as a CFMUslot, weather constraints, etc. - even fluctuating before reaching a final value - influence operations.

26 Aeronautical Information Publication.


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3.3.2 Sensors and Monitoring

The problem of determining whether sensors exist to monitor the situation is of main importance, in particularduring surface management operations. A number of operations depend on mobile personnel, meaning thatmobile wireless applications probably need to be developed for surface management to avoid that holes inthe picture lead to inaccuracies and late detection of problems.

Thus an identification of sensors used for instance along surface operations shall be performed, as well asthe use of the information between the different actors that should be aware of.

3.3.3 Assessing impact deviations

The impact assessment of any deviation (e.g. delay) versus a planning depends on several parameters.Amongst them, information uncertainty (e.g. accuracy and stability/reliability aspects), timeliness (e.g. time atwhich an information is known versus an event) and decisions made by one actor independently of othersare the main parameters that influence the overall impact of any planning deviation. Here we shall considerdirect costs of any planning deviation for one flight as well as cost induced on other flights.

Thus the impact of one flight being delayed can impact other flights (for example linked flights) or other flightsthrough non-timely or excessive resource reservation.

3.3.4 Monitoring surface operations

When the aircraft is on the surface, the business processes involve different actors with different - andmaybe competing � objectives. The emphasis in this phase is put on monitoring the situation throughdifferent sensors or planned events that sequence the ground activities.

In absence of significant disruption, the planned working horizon (e.g. until pushback) for aircraftoperators/handlers is basically about 45 minutes up to 1 hour and depends mainly on the aircrafttype/subtype, if the flight is scheduled at a turnaround station or en-route station, etc.

� Notion of critical path: in most cases � according to the IATA27 ground handling manual, �passengersdeplaning, cabin cleaning and passengers boarding are the most constraining operations. In somecases, if the fuelling equipment has insufficient performance, it may consist in fuelling operations. Withbulk-loaded aircraft, off-loading and loading operations may become critical�. This introduces the notionof critical moments that should be monitored.

� Monitoring versus outcome: it is clear that monitoring internal operations to an actor to show itsdeficiencies is not part of CDM. Operations or business processes should be considered first as blackboxes with well-defined agreed outcomes regarding the quality of data expected. Actors shall find a co-operative commitment on what outcomes shall be monitored.

� Publishing consequences of decisions rather than decisions themselves: when looking at thesurface, one of the aircraft operator�s duties is to provide to other actors an expected off-block time. Thisshould take into account his different constraints; of course this information must be reliable andprovided in a timely manner. These constraints can be materialised by decisions. Under CDM paradigm,it is assumed that sharing a common view on data on the one hand and publication of consequences ofdecisions as soon as they are taken will contribute to the optimisation of available resources. Thesubtlety to consider the publication of the consequences of a decision rather than the decision itself hereis essential. For instance the decision of the aircraft operator for flight � to wait on its hub for 7 connectedpassengers from flight � shall be materialised -if the need arises- by a revision of EOBT(flight �).

As an intermediate result, there is a need for a CDM data quality framework:

� To categorise problems and to support their quantification (baseline; do-nothing case),� To provide the capability to demonstrate benefits of any CDM measure.

27 International Air Transport Association.


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The following figure tries to summarise the surface management operations:

FIGURE 6: HIGH LEVEL VIEW OF SURFACE MANAGEMENT OPERATIONS

Remark: This figure represents a high level view of the logical sequence of events during turnaround operations. � Orange boxes represent the events that may be monitored along surface management operations.� Blue boxes represent the basic business processes that may take place during turnaround operations. � Pale blue boxes represent problems that may occur during operations and that may at least induce a delay (or a

more constraining decision),� Dark-blue boxes represent connections with other flights: connecting passengers and baggage, flight attendants.

Check in PaxCheck in Pax

Check-in disruptions

Check inClosed

Check-inOpen

Start Boarding

Board PaxBoard Pax

Pax Boarding disruptions

Deplane PaxDeplane Pax

Service CabinService Cabin

Service GalleysService Galleys

Position Pax

Bridges

Position Pax

Bridges

Pax Services disruptions

Delay/Anomaly

Embark Pax

Embark Pax

End Boarding

CabinReady

CabinDoorsOpen

Bus Call

Resource Problem

Embarkationcomplete

1

Fuel AirplaneFuel Airplane

Service ToiletsService Toilets

Service PotableWaterService PotableWater

RefuelingStart

RefuelingFinished

Jetwaysdeployed

Unload FWDcompartmentUnload FWDcompartment

Unload AFTcompartmentUnload AFTcompartment

Unload / LoadBulk CompartmentUnload / Load

Bulk Compartment

Airplane Service disruptionsLast bagUnloaded

Load FWDcompartmentLoad FWD

compartment

Cabin DoorsClosed

DoorsClosed 2

Cargo/ Baggage Handling disruptions

Connecting FlightsBax

Connecting FlightsBax

Reactionary Delays

Connecting FlightsPax

Connecting FlightsPax

Reactionary Delays

CDM BRUSSELS 2001 - O.Delain

Other Flights

Board Flightattendants

Board Flightattendants

Other FlightsFlight

AttendantsReady

Reactionary DelaysLate assignment

Cargo DoorsClosed

Other Flights

Cargo DoorsOpen

First bagUnloaded

1st bagLoaded

Last bagLoaded

Load AFTcompartmentLoad AFT

compartment

Pilot InitialChecks

Pilot InitialChecks

Equipment- A/C defectsA/C Change

Other Flights



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4 DETERMINING CDM SHORT-TERM OBJECTIVES

Implementing procedures or sharing information between partners is not a target. What is at stake is toidentify clear and quantifiable short-term objectives along with its enablers. Several workshops wereorganised to isolate different potential common CDM short-term objectives. Six were identified, that aresummarised below.

4.1 OBJECTIVE 1: REDUCE THE NUMBER OF STANDS/GATES CHANGES

The agreed objective is to reduce the number of stands/gates changes 30 minutes before arrival in Brussels.

Figures show that more than 20% of Brussels inbound flights see their stand/gate change in theinterval [ATA�30�; ATA]; (mean: 1.2 28).

The stand/gate planner objective is to optimise the planning, to assign all dock-able flights to gates to complywith aircraft operators� preferences as well as to increase the airport safety level by reducing the number ofvehicle movements on the tarmac.

Problems often arise when the first flight has arrived and entered his rotation as planned, but is submitted tointernal disruptions. In fact, thirty minutes before arrival of the next flight, many reasons can lead the airlineto require more time on the gate. Sometimes it is an anticipated delay from a connecting flight, sometimes itis an unanticipated delay due to events that popped up during ground handling. It can range from boardingproblem to baggage sorting issues.

FIGURE 7: STAND/GATE PLANNING UNDER UNCERTAINTY

The standard stand/gate buffer between arrival/departures for stand and gate management is 15�. A conflictmay arise if a cumulated error between arrival and departure exceeds 15�. Typically, an aircraft arriving inBrussels sees its stand/gate change since the one which should perform its pushback is still at its gate forany reason (disruption / last minutes problem, absence of pushback truck, start up clearance not received,etc.).

28 A mean higher than 1 traduces that in some cases, more than one stand/gate change is operated in the last 30minutes before arrival.

Last minute gate changeLast minute gate change Waste of CapacityWaste of CapacityUncertaintyUncertainty

S/G ManagmentSlack Time 15�

Slack Time 15�

EIBT EOBT EIBT EOBT

AIBT

Disruption (missing pax, connecting px)

AOBT EIBT

2� Reality

AIBT

Gaming Theory ...... Experience may lead to late S/G change

SAB2468SAB1357



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Consequently, a growing pressure is put on parking control manager when his margin is reduced to 5minutes or less. The important question is then to assess the probability for the current flight to leave rightbefore next flight arrival. Taking the wrong guess will automatically trigger a last minute gate change as displayed on Figure 7.

4.2 OBJECTIVE 2: IMPROVE ACCURACY OF CFMU SLOTS

The objective is to improve accuracy of CFMU slots through the introduction of flexible taxi time forZaventem airport: The variability of taxi-out time at Brussels airport prevents from global efficiency,predictability of take-off time and CFMU operations efficiency. The immediate result is a CTOT lack ofadherence29 that can induce overdeliveries. At current, the CFMU taxi-out parameter is set to 20 minutes butits actual value can range from 5 minutes up to 45 minutes. Thus a flexible taxi time based on soundstatistical analysis will help in reducing the gap with the reality, and will result in better slots for aircraftoperators, improve ATFM slot adherence and will participate to improve CFMU efficiency.

4.3 OBJECTIVE 3: IMPROVE TAXI-OUT ACCURACY AND PREDICTABILITY

All actors insisted on the variability of taxi out time that depends on various conditions (peak traffic, weather,etc) that is not taken into account in estimating the take off time. Combined with OBT accuracy, a reliableprediction of taxi-out time (even with a limited term horizon) would allow to determine a good estimate of takeoff time. This could lead for instance to an early detection of CTOT non-adherence as well as potentialconsequences.

4.4 OBJECTIVE 4: MOVE TOWARDS A COLLABORATIVE STRATEGIC PLANNING

There is a need for co-ordination between different individual plans between airport slot co-ordinator, ATCand airport authorities. The planning seems to be established on a 15 minutes timeframe without consideringtaxi time influence or the sectors capacity. Whereas the allocation is based upon 70 movements per hour,sometimes the rate exceeds 90 movements per hour. Moreover, there is no link between airport slot andcalculated take-off.

As a consequence, the airport slot planning should be validated at strategic and pre-tactical level by theairport slot co-ordinator, ATC and airport authorities, supported by a comparison between airport capacityand schedules. The idea is that airport infrastructure and capacity utilisation are the cornerstones fordetermining the number of airport slots that can be allocated.

At a tactical level, there are misuses that can be demonstrated but which do not imply any penalty for thosewho not respect the airport slots. More co-ordination and support is required to ensure that airport slots arerespected.30

4.5 OBJECTIVE 5: MOVE TOWARDS A COLLABORATIVE DISRUPTION RECOVERY

The current statement is that insufficient reliable information is available in case of severe disruption (data,intentions). In case of severe weather constraints for example, it seems that diversion information is difficultto obtain. Regarding outbound flights, updating or deleting flight plans are not done or not timely. Provision oftimely and reliable information would constitute an initial step towards a better organisation and recoveryplan that would benefit to the overall airport.

What would bring significant improvement compared to the existing is a improved awareness regardingdisrupted flights from outstation. In some cases, there is no information (or with bad quality, not updated)available in Brussels about delayed flights from outstations. For those flights, no information may be receiveduntil departure MVT31 message. Means and procedures oriented towards advanced notification of the

29 See annex A (ATFM slot adherence figures). In june 2001, 42.3% of flights at Zaventem airport did not respect CFMUslot adherence.30 It had been envisaged that, by the summer 2002, a project would be implemented oriented towards better detectionof both planned and operational misuses.31 Movement Message



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situation would obviously lead to better stand and gate management. Another idea would be to co-ordinatethe cancellation of flights in case of severe disruption at an airport.

4.6 OBJECTIVE 6: COMMON AWARENESS OF PAX/BAX FOR INBOUND FLIGHTS

The requirement is the notification of passengers information for all inbound flights to the airport, e.g. totalnumber of passengers, and transfer passengers information (number/where do they come from, nextdestination/flight callsign and number per destination/flight callsign). Should passenger information alsobecome available for all outbound flights handled at Brussels, airport authorities (BIAC) could combine thisinfo with a deduced baggage coefficient and thus improve the efficiency and quality of severalresources/equipment and processes far outside the domain of stand and gate allocation. In doing so,different airport processes could become better integrated to the benefit of all parties involved.

The rationale behind this requirement is the best use of resources (boarding bridges, gates (contact/remote),buses, reclaim belts, non-Schengen border control, Schengen border crossing, screening-security checksmanpower (Schengen/non Schengen flights), etc.) whilst improving the passenger comfort and reducingoverall queue time and walking/transfer distance/time. This will contribute to smoother boarding operations,thus contributing to the realisation of this project�s objectives e.g. punctuality.

This requirement should be met by all handlers/airlines32.

In addition, the new BIAC billing system plans that bussing would be charged to BIAC, thus the requirementto eradicate useless bussing is at stake.

32 Pax/Bax information for Sabena flights is accesible through AIMS system.



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5 DESIGNING CDM SOLUTIONS

5.1 INTRODUCTION

Several workshops were organised around chosen objectives. Discussions occurred around incoming flightsand the links between them and outbound flights. The need for Brussels site to gather and share accurateand timely delay information was recognised as a main CDM cornerstone.

It was stated that outstations close to Brussels have a bad performance that is detrimental for Brussels, inparticular a bad reactivity due to very late notification. The future use of CFMU flight progress reports(ETFMS33) will bring significant benefits for Brussels incoming flights. At a global level, it was suggested that,at an airline level, each OCC34 (through automatic tools) should communicate to each site information aboutincoming flight delays rather than a point to point communication between the departure station and thearrival station. Brussels users pointed out that some stations play a fair game about delays notifications whileit seems difficult to obtain information from other outstations.

Actors agreed to work both on the causes and on the symptoms, with all parties involved. Eliminating asignificant percentage of the last minutes changes for passengers would reduce uncertainty andunnecessary walking in the terminal. Regarding departing flights, 24% of all gate changes (in the period[STD35-24h, until ATD36]) occur in the period [STD-90�, until AOBT37].

5.2 INITIAL CDM ENABLERS

The main difficulty agreed by all actors relies in the quality of information regarding departures and arrivals.In order to reduce the number of stands/gates changes, the quality of information regarding arrivals (arrivaltime, in-block time) for inbound flights as well as quality of information for outbound flights (off-block time,take-off time) is of prime importance.

Several proposals/enablers have been detected, that are described in the following sections:

� Arrivals and Departures: implementation of a milestones approach.

� Arrivals:

� Propagation of existing information at outstation (ETD/ETA);� Airport stand and gate view on CFMU operational decisions;� Updates of en-route inbound ETAs and next legs ETDs;

� Departures:

� Determination of a reliable Target Off Block Time (TOBT);� Determination of an accurate taxi-out time;� Establishment of a Pre-notice Start Up Clearance Delivery;

In order to improve the reliability of estimates that are notified from an outstation, Sabena agreed toimplement four enhancements:

� Confirm and/or update EOBTs from outstation 20� before their occurrence and to provide ETA andEIBT for this specific flight;

� Publish revisions of next leg and connecting flights EOBTs at each ETA revision,

� Publish all movement messages to ATC, airport authorities and ground handlers at hub station,

� Publish delays higher than ten minutes to other actors at hub station.

33 Enhanced Traffic Flow Management System (CFMU).34 Operations Control Centre.35 Standard Time of Departure.36 Actual Time of Departure.37 Actual Off Block Time.



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� Links with CFMUAt current, Brussels airport authorities receive no CFMU information; such information for inbound flightswould be of interest, especially CTOT and FSA38 messages. However, since the stability of CTOTinformation is challenged until departure, the initial CTOT (for regulated flights) and its value at TRS39 tohave been suggested as CFMU data for inbound flights that could be sent to Brussels airport authorities.In addition, FSA messages would supplement MVT messages by reducing the completeness gap.Finally, as said before the future distribution of ETFMS flight progress updates would also be of greatinterest.

To summarise, current expectations regarding incoming flights are:

� The distribution of CFMU slots and TRS values for airports. The TRS parameter along with the valueof CFMU slot will indicate that the CFMU slot will no more be subject to modification.

� The distribution of FSA messages;� In a next future ETFMS environment, distribution of CPRs40 and APRs41.

The CFMU might be interested in receiving accurate and reliable estimates of TOBTs and taxi-out times.

5.3 THE MILESTONES APPROACH

Planning can be described as the task the actual and future interactions with the real world to reach definedgoals. It is formally expressed as the search for transformation with operators or actions from a defined stateinto another, which satisfy certain goals. Dealing with rotations, the use of planning as a look-ahead, closedlook control (either reactive or dynamic) assumes that adequate solutions must be found for planning underreal-time demand and planning under uncertainty.

Uncertainty is the enemy of efficiency. Regarding uncertainty and despite unavoidable errors inmeasurement, it is clear that:

� The uncertainty of any prediction increases with an expanding timing horizon,

� Different degrees of certainty exist depending upon actors who provide the information (degree ofcertainty).

Such uncertainty is mainly driven by the inaccuracy of signals, the inaccurate and erroneous prediction offuture events and the uncertainty about future operational conditions, constraints, goals, etc.

Uncertainty, constraints and disruptions that may arrive before and during operations prevent from efficientoperations. Under CDM paradigm, it is assumed that sharing a common view on data on the one hand andpublication of consequences of decisions as soon as possible will contribute to the optimisation of availableresources.

� The notion of critical moments (milestones): This led us to define a notion of critical moments fromoutstation to inbound station that punctuates the usual turn-around process. Starting from outstation,these milestones are key information to:� Improve the awareness of all actors at the inbound station, � Trigger updates of downstream information, and � Help in identifying potential delays of the aircraft, trigger re-planning and allowing collaborative

decisions to be made.

38 First System Activation.39 Time to Remove from the Sequence.40 Correlated Position Reports.41 Aircraft Position Reports.



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� A need to an increased but limited look-ahead horizon: any reactive planning has to be based on apermanent comparison between the state of the real and the planned world at the present time. This canbe called plan monitoring which should result in evaluating a difference between the planned and realsituation with a certain �look ahead unit�. The correlation between an increasing planning horizon and theincreasing uncertainty bears the thought that planning should be done with a limited slidinghorizon42 in order to improve the quality of the best plan by increasing stability and quality of thetransmitted data.

5.3.1 Overall Framework

A list of 19 milestones were defined for arrival and departure flights in order to:

� Increase the awareness of essential information to users,� Define events and triggers for associated information along with their accuracy,� Provide the basis for monitoring the accuracy of data,� Create a framework for airport users decision-making based on a sliding horizon of 30 minutes;� Provide the framework for collaborative procedures and decisions.

The figure introduces the global milestones� approach. We consider:

� Flight arriving at the outbound station: index [N-1],� Flight between outbound station and inbound station: index [N],� Flight departing from hub station: index [N+1].

The following acronyms are used:

� EOBT/TOBT: Estimated Off Block Time, Target Off Block Time;� SIT1: CFMU time for publishing a CTOT (for regulated flights): EOBT�2h;� ETA/ATA: Estimated Time of Arrival, Actual Time of Arrival;� AOBT/AIBT: Actual Off Block Time, Actual In Block Time;� Surface Operations:

� FDO (First Door Opened), � SB (Start Boarding), � GC (Gate Closed), � DC (All Doors Closed), � SUR (Start Up Request), � SUC (Start Up Clearance).

42 Participants committed to set up the sliding window horizon to 30 minutes.



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FIGURE 8 : MILESTONES APPROAC

E O B T [ N + 1 ] - 3 0 �

T O B T [ N + 1 ] i n i t

E T A [ N ] N e x t & C o n n e c t e d E O B T s

E T A [ N ] - 3 0 �

E n R o u t e p h a s e

S u r f a c e [ o u t s t a t i o n ]

S u r f a c e [ B r u s s e l s S t a t i o n ]

E n R o u t e p h a s e

M 1 M 2 M 3 M 5 M 6 M 9 M 1 0 M 1 1 M 1 3 M 1 4 M 1 5 M 1 6 M 1 7 M 1 8 M 1 9

M 4 M 7 M 1 2

M 8

S I T 1 N

S I T 1 N + 1

A T A A I B T N - 1 N - 1

A O B T A T O T N N

F D O S B G C D C S U R S U C A O B T A T O T A T A A I B T N + 1 N + 1

A T A A I B T N N

E T A [ N ]

E O B T [ N ] - 2 0 �

A t E O B T [ N ] - 2 h A t E O B T [ N + 1 ] - 2 h

E O B T [ N ] - 2 0 � A T A - 8 � < E T A < A T A + 1 5 � [ N ]

E T A [ N ] - 3 0 �A T A - 4 < E T A < A T A + 6 � [ N ]

E O B T [ N + 1 ] - 3 0 � A O B T - 5 � < T O B T < A O B T + 5 � [ N ]

A C C U R A C Y



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5.3.2 Outstation Milestones

Milestone Event-Related Time-Related CommonAwareness

Triggers update / confirmation of ..

M1 SIT1[N] EOBT[N] �2h E/CTOT[N]43 -

M2 Touchdown [N-1] ATA [N-1] EOBT[N] - ETA[N] - EIBT[N]

M3 In Block [N-1] AIBT[N-1] EOBT[N] - ETA[N] - EIBT[N]

M4 - EOBT[N]-20� EOBT[N] CTA[N] � EIBT[N] � EOBT[N+1]

M5 Off Block[N] AOBT[N] ETA[N] � EIBT[N] � EOBT[N+1]

M6 Take Off [N] ATOT[N] ETA[N] � EIBT[N] � EOBT[N+1]

TABLE 2 : OUTSTATION MILESTONES

M1 (CFMU SIT1 � Regulated Flights)

� Common Awareness:

SIT1 (Slot Issue Time) is issued by the CFMU at [EOBT �2h]44 when the flight is regulated. Its stability isnaturally challenged during the CFMU true revision process that prevent any efficient S/G planning45 basedon this information that continuously evolves.

However, the CFMU has introduced parameters46 for each aerodrome to prevent late change of CTOT[ATFM User Manual V7.0]:

� The TRS (Time to Remove from the Sequence) prevents a change to a later CTOT when the flight isalready in the departure sequence.

� The TIS (Time to Insert into the Sequence) prevents an improvement into an already organiseddeparture sequence47.

Stand/Gate management should not be overwhelmed with unstable information. This is why we propose thatinitial CFMU information that should be shared by ATC and airport authorities (S/G management) at anairport regarding inbound flights should encompass:

� Regarding regulated flights: initial CFMU slot, slot cancellations, TRS information.� In addition to that, better accuracy regarding inbound flights ETAs should be obtained by common

awareness of FSA48 (First System Activation) messages at receiving airport.

� Information Updates and Triggers:

CTOT at SIT1 can be considered as a pre-tactical information that indicates potential delay for flights. Thisinformation will be updated through the revision process until TRS. No update or triggering mechanisms isthus envisaged.

43 ETOT for non-regulated flights, CTOT for regulated flights.44 In the near future, SIT1 could be issued with a shorter notice.45 Reliable information that is taken into account by S/G management at Brussels airport is the MVT message at take-offfrom outstation.46 These parameters may be adjusted at any time depending on the local aerodrome traffic situation and may varyduring the day.47 The TIS message is not relevant when ATC has sent an REA (Ready) message for the flight.48 The FSA message is an ATC message that is sent automatically when the flight is activated in the ATC system in thefollowing 4 situations. At take-off, giving the actual take-off time at the ADEP, at or shortly before arrival at theboundary of the airspace covered by the ATC system, giving the level and the estimated time over a point, at theboundary, to inform CFMU of flight activation and additional estimates updates for ATFM purpose, to inform CFMU fromre-routings inside FDPA for ATFM purpose.



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� Data Quality:

� For flights not subject to ATFM, the ICAO requirement is that delays in excess of 15 minutes49 should becommunicated50.

� For flights that are subject to ATFM, any changes to the EOBT of more than 15 minutes shall be subjectof a DLA message51.

M2 (Touchdown [N-1] ) and M3 (In Block [N-1] )


The occurrence of touchdown (M2) and/or in-block (M3) information at outstation of an aircraft that will take-off after turn around to fly to inbound station should be shared between actors. Different sources may providethese data (in particular MVT messages).


The occurrence of AIBT and/or ATA should trigger an update of downstream estimates: EOBT[N] , ETOT[N],and ETA [N]. We recommend to update downstream estimates either at ATA[n-1] or AIBT[n-1], unless thedifference between ATA[n-1] and AIBT [n-1] is significant, e.g. (AIBT-ATA) higher than 30 min (exceptionalconditions). The requirement is an update of ETA[n] that takes into account the foreseen constraints, inparticular potential flow management constraints (CTOT).

� Data Quality:

Common Awareness of EOBT[n], ETOT[n] and ETA[n] should be obtained not more than 15 minutes afterATA[n-1].

� For flights not subject to ATFM, the ICAO requirement is that delays in excess of 15 minutes should becommunicated52.

� For flights that are subject to ATFM, any changes to the EOBT of more than 15 minutes shall be subjectof a DLA message.

M4 (EOBT[N] �20�)

Two milestones (EOBT[N] �20�) and (ETA[N] �30�) have been selected to:

� Avoid information gaps regarding delays, disruptions, absence of departure movement message fromoutstation. In certain situations, stand/gate management may have no information on flights until Belgiumradar detection.

Figures gathered through A-CDM-D at Brussels airport indicated a non-distribution of 5% up to 8% ofdeparture movement messages for internal European flights going to Brussels. FSA messages couldhelp in reducing the gap.

� Improve data accuracy: at (EOBT[N] �20�), the accuracy of the estimates can be strongly improved withthe visibility of the local handler over the status of the flight.

49 The rules for non-regulated and regulated flights will be homogeneised on March 1,2002 (15 minutes take off window(CTOT and ETOT), instead of 30 minutes for non regulated flights.50 Paragraph 8.2.1.2, ICAO doc. 444451 ATFM user Manual, V7.0, Feb 12, 2001.52 Paragraph 8.2.1.2, ICAO doc. 4444



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The rationale of this milestone is to increase the completeness, reliability and predictability of outstationinformation. It is based on Sabena agreement to publish accurate information at [EOBT�20�] at _outstation. Inmost cases, aircraft operators have quite reliable and stable information for flights coming from outstation at[EOBT �20�] at _outstation. Such information is not distributed to actors at the destination airport that could useit to optimise their operations. In addition, the completeness aspect must be considered, as departuremovement messages are not always notified to the receiving airport.


[EOBT �20�] at _outstation triggers 1. The computation of a CTA (Computed Time of Arrival)2. An update/ confirmation of EOBTnext_leg.

� CTA[N] computation:CTA[N]= EOBT[N] + Estimate Taxi-out Time[N] + Estimate Flight Duration[N] (for non-regulated flights),CTA[N]= CTOT[N] + Estimate Flight Duration[N] (for regulated flights).

� EOBT[N] is provided by the local handler on the outstation,� Estimate Taxi-out Time[N] is the taxi out time for the concerned aerodrome used by the CFMU,� Estimate Flight Duration[N] is provided by the aircraft operator,� CTOT is provided by the CFMU.

It has been agreed that a corresponding new message containing the EOBT[N] / CTOT[N] should bespecified and manually sent from the outstation to the destination airport.

� Update/ Confirmation of EOBTnext_leg

A distinction shall be made for aircraft operators at their hub station where a number of alternatives arepossible to absorb flight delays. In such cases, final decisions regarding next flight leg are often taken laterespecially when a disruption affects the network. In that case, updating EOBTnext_leg at (EOBT �20�) at

_outstation) seems more difficult excepted if decisions (or if no disruption affects the flight, i.e. planning isrespected) have been taken yet. In other cases, potential alternatives are seldom, and so, updating/confirming EOBTnext_leg should be madepossible with medium/high accuracy. In other terms, an aircraft operator that has no possibility to swapaircraft/destination should propagate its delay to next leg.

� Data Quality (ETA[N]) accuracy in the majority of cases should be bounded by: -8�< ATA[N] -ETA[N] <15�; the uncertaintyencompasses the uncertainty at outstation for take-off and the uncertainty at arrival (vectoring or holding).

M5 (AOBT[N] ) and M6 (ATOT[N] )


Aircraft movement messages are used for manually issued as well as machine-issued departure, arrival enddelay messages. In general, departure and arrival messages are distributed immediately after departure orarrival of an aircraft whereas delay messages are distributed as soon as delay is known. Availability andaccuracy of distributed information does not depend on a type of flight or on difficulties linked to weather,disruption etc. The handlers involved (this could be the airline itself or an independent handling company)distribute the information. Some other information is distributed using ACARS.



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Important and reliable information can be obtained through movement messages. Even in the worst case(short haul flight), the distribution of a movement message after takeoff filled with AOBT, ATOT provides thenecessary information required by the receiver airport. Completeness aspect at take off is important.Previous analysis made for Brussels Airport indicate that:

� AOBT and ATOT are both filled for the vast majority of cases (nearly 90%);� either AOBT or ATOT is filled up to 5% of cases;� no departure movement is sent to Brussels is about 5%;

A movement message is distributed at takeoff. It comprises AOBT, ATOT and a precise ETA. The ETAemitted at takeoff differs on average by three minutes from ATA, e.g. the receiving airport has a first, uniqueand precise estimated time of arrival at takeoff. A second movement message is distributed at AIBT andcomprises ATA and AIBT.


(Departure information) at _outstation triggers:

� The update of ETA inbound_flight

� The update of EIBT inbound_flight

� The update or confirmation of EOBTnext_leg.

� Data Quality

The slack time between the occurrence of departure information (AOBT and ATOT) and the sending of thecorresponding information should be studied.

A detailed analysis should be made along with benefits assessment in case of supplementing existinginformation with FSA messages.

5.3.3 En-route Milestones

If the aircraft is ACARS-equipped, ETA (updates) may be published during in-flight phase. If so, EIBT aswell as EOBTs (next flight and connecting flight(s)) should be updated accordingly.

Milestone Event-Related

Time-Related CommonAwareness

Triggers update / confirmation of ..

M7 ETA[N] � 30� ETA[N] ETA[N] - EIBT[N] - EOBT[N+1]

EOBT(s) [C[N+1]]53

TABLE 3 : EN-ROUTE MILESTONES

M7 (ETA[N] �30�)


This milestone defines a sliding tactical window (decision period) for inbound station that starts 30 minutesbefore the occurrence of aircraft arrival.

There is a change in responsibility for updating ETA around (ETA-30�). Indeed if the aircraft operator isresponsible for providing the best accuracy of ETA until Belgium airspace (between 30� and 20� beforearrival). At this specific event, ATC is in the best place to provide an accurate ETA taking into account thevarious conditions and constraints that may arise, such as vectoring or holding.

53 Updates of eventual connected flights EOBTs.



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The accuracy of ETA is particularly important at this stage since downward decisions are taken, such asstand/gate changes, preparation of arrival sequence, preparation of ramp handling operations, decisions forconnecting passengers, etc.). Uncertainty and ETA non-accuracy at this stage significantly increase risks forbad and last-minutes decisions and internal disruptions.

The objective to decrease the number of stand and gate changes in the last 30� requires high-accuracyregarding departure and arrival times to avoid useless conflicts. At (ETA-30�for inbound_Brussels_flights) andtaken into account a mean taxi-in time in Brussels of 5�, last stand/gates decisions for change would be takenbefore EIBT�30�.

(ETA-30�) Brussels inbound flights triggers:

� The update of ETA [N] by ATC taking into account possible conditions of holding and vectoring. Atcurrent, the look-ahead is about 20 minutes in Brussels, that should be extended to 30 minutes.

� The update of next EOBTs (EOBT for next leg and EOBT for connecting flights). Decisions such as thewaiting or not for connecting passengers should be taken and definitive in the vast majority of cases atthis special event (AO decisions that might take place after the occurrence of this event should bemarginal (disruption case)).

� Data Quality

� ETA accuracy:

A few minutes before (ETA-30�for inbound_Brussels_flights) the ETA accuracy provided by the aircraftoperator should be as follows: ETA�8� <ATA< ETA+15�.When the contact is established with the Belgium airspace, the ETA accuracy should be improved byBelgocontrol taking into account eventual vectoring conditions (at current, no holding conditions are inplace in Brussels ACC):

� in case of no vectoring or light vectoring conditions, the ETA accuracy at Canac capture should be:ETA-1�30�� < ATA <ETA+1�30��

� in case of medium vectoring measure, ETA-2�30��< ATA <ETA+2�30�� in case of strong vectoring measure, ETA-4� < ATA <ETA+6�

� Revision of downward estimates (next leg and connecting flights):(ETA-30�) Brussels inbound flights should also trigger the update of next EOBTs (EOBT for next leg andEOBT for connecting flights. As a reminder, TOBTs predictability will depend on EOBTs accuracy.



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5.3.4 Surface Milestones

The following table summarises the different milestones foreseen on Brussels station.

Milestone Event-Related Time-Related Common Awareness Triggers update / Confirmation of ..

M8 SIT1[N+1] EOBT[N+1] �2h CTOT[N+1] -

M9 Touchdown [N] ATA[N] TOBT(s) [C[N+1]]54

M10 In Block [N] AIBT[N] EOBT[N+1]

M11 First Door Opened [N+1] FDO [N+1] EOBT[N+1]

M12 EOBT[N+1] �30� TOBT [N+1] -

M13 Start Boarding [N+1]

TOBT-20� [N+1]

SBO [N+1]

ESUC55

TOBT [N+1], ETT [N+1]56

TOBT [N+1], ETT [N+1]

M14 Gate Closed [N+1] GC [N+1] -

M15 All Doors Closed [N+1] DC [N+1] -

M16 Start Up Request [N+1] SUR [N+1] -

M17 Start Up Clearance [N+1] SUC [N+1] -

M18 Off Block [N+1] AOBT [N+1] ETA[N+2]

M19 Take Off [N+1] ATOT [N+1] ETA[N+2]

TABLE 4 : SURFACE MILESTONES

The expected accuracy of TOBT at [EOBT �30�] is 5�. Any deviation of TOBT in subsequent milestones mustbe notified, along with a new assessment of TOBT.

The aim of the TOBT information (shared between Belgocontrol, BIAC, Sabena and Ground Handling) is togive a fair, timely, accurate and reliable assessment of off-block time. It is recognised that main benefits ofsharing this target off-block time are expected in case of disruptions (internal or external). In such cases, thedifference between EOBT (shared by ATC, CFMU and parking control) and TOBT may be important.

The underlying reason to avoid double penalties for airlines in a few disrupting situations impedesthe notification of the real EOBT to the CFMU. Thus the need to develop new procedures toencourage aircraft operators to publish the real OBT and to avoid double penalties is at stake andshould be a subsequent step to this project.

A 5� accuracy for TOBT at [TOBT-20�] or �Start Boarding� event is a pre-requisite for ATC (Belgocontrol) to re-establish a pushback procedure / pre-departure sequence that relies on confidence between actors basedon reliable and accurate data from aircraft operators regarding departure.

M8 (EOBT[N+1] �2h)

Same remarks as milestone M1.

M9 (ATA[N]) and M10 (AIBT[N])


The occurrence of touchdown (M9) and/or in-block (M10) information at home station of any aircraft aremade available to all actors (airport authorities, ATC, handlers).

54 Updates of eventual connected flights TOBTs (Target Off Block Times).55 ESUC: Estimated Start Up Clearance; only available if the pre-notice departure clearance is implemented.56 ETT: Estimated Taxi Time.



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At ATA[n], we propose that the TOBTs of connected flights would be updated. At AIBT[n], the EOBT for thenext rotation (EOBT[n+1]) of the aircraft should be checked and updated if necessary.

� Data Quality

At ATA[n], the accuracy of the connected flights TOBTs should be less than 5 minutes.

FIGURE 9 : TARGET OFF BLOCK TIME AND SURFACE MILESTONES

M12 (EOBT[N+1] � 30�)


[EOBT�30�] milestone serves to initialise and publish the target off block time (TOBT), e.g. the estimateready time for aircraft pushback given by the aircraft operator co-ordinated with local handler. Emphasis isput on the need for the aircraft operator to integrate his own strategy to compute a TOBT related to the flight.In relation with the Zaventem rules TOBT means that the aircraft is ready (for pushback or taxi immediatelyafter reception of ATC clearance)


There is no information triggers or updates excepted the initial publication of the TOBT.

� Data Quality

The expected accuracy of TOBT at [EOBT�30�], defined by |AOBT-TOBT|< 5� in a usual case, e.g. withoutCFMU regulation and start-up clearance given in normal conditions.

Landing ClearanceTaxi-in clearanceAircraft In BlockJetways Deployed1st Door OpenCargo Doors OpenedFirst Bag Unloaded (arrival status)Last Bag Unloaded (arrival status)Gate OpenFinal CallCheck in ClosedBus Call (remote)Embarkation Complete (remote)Flight Attendants ReadyCabin ReadyRefuelling StartRefuelling FinishedStart BoardingGate ClosedEnd BoardingFirst Bag Loaded (departure status)Last Bag Loaded (departure status)Cargo Doors ClosedCabin Doors ClosedA/C Doors ClosedPilot ReadyStart Up RequestStart Up ClearanceReady to PushPushbackStart De-icingEnd De-icingTaxi Out ClearanceTake Off Clearance

Target OBT

Belgocontrol

Parking Control

Sabena OCC

GroundHandling

EOBT-30�

Update

EOBT

TOBT

TOBT-20�

Init. TOBT

Confirmed TOBT

Adjust TOBT

TOBT Window

TARGET OFF-BLOCK TIME



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M11 (FDO[N+1] ), M13 (SB[N+1] and/or TOBT-20�), M14 (GC[N+1] ), M15 (DC[N+1])


Sharing ramp handling critical moments will help in assessing the Target Off Block Time (TOBT) as well asproviding the necessary information to monitor the progress of ramp operations and raise alarms57 ifnecessary. At current, Brussels CDB (Central Data Base) manages different statuses: GTO for gate open,BOR for start boarding, FIN for Final call and GTC for gate closed. It has been agreed that �first door open(FDO)�, �all doors closed (DC)�, �start up request (SUR)� and �start up clearance (SUC)� critical momentsshould be shared by all actors.

The reliability of these critical moments is important to ensure information confidence. As an example, thereis a global problem of quality of information to be solved regarding current statuses. Sometimes, timestampsare false or there is a default value. Sometimes the field is filled a long time after the event and is useless.Another problem is the reliability of in-block time for non-DGS equipped positions. This is why it has beendecided that only automated signals (without human interaction) would be taken into account.


Each of critical moments until start boarding and/or TOBT-20� should trigger the update (if necessary) of theTarget Off Block Time (TOBT).

[TOBT-20�] should be the latest time to start the boarding (SB), but if the boarding starts later, the aircraftoperator and / or the handler should guarantee that the TOBT will nevertheless be respected. A later updateof TOBT, outside the accuracy range, will be considered like a non-respect of the expected accuracy.

In order to respect the start-up clearance rule (aircraft ready, all doors closed, pushback truck present, slotadherence58) as well as to set and improve a pre-departure sequence, ATC at local airport should know at[TOBT-20�] an accurate estimated taxi out time (ETT). This would help in sequence planning, in predictingthe clearance delivery time (SUC) or the AOBT59.

� Data Quality:

One objective of this approach is to share an accurate off-block time between local actors. In a first attempt,conditions for going further (collaborative pre-notice start up clearance, re-distribution of such information tothe CFMU, etc.) relies on the quality of TOBT either at [EOBT-30�] and [TOBT-20�]. It is expected that theimplementation of the milestones approach will lead to reliable (accuracy and timeliness) data sharedbetween local actors (in a first stage), leading to better collaborative decisions. Particular attention will bebrought during trials to calibrate.

M16 (SUR[N+1]) and M17 (SUC[N+1])


SUR[n+1] and SUC[n+1] are key moments for the departure process. The pilot should ask for clearancedelivery60 once the aircraft is ready, e.g. doors closed, jetway(s)/airbridge removed and pushback truck inplace. While aircraft operators are responsible for providing SUR[n+1], they cannot accurately predict thetaxi-out time and the time to push61, and thus CTOT compliance. Moreover, requesting start-up clearance 57 Alarms are described in section 5.2.658 For regulated flights.59 The taxi out time should take into account various departure conditions such as TOBT, CFMU slot, runways occupancy,arrival priority, weather conditions.60 E.g. start-up request (air/ground data link and/or delivery frequency).61 At current, as the CFMU taxi time is set to 20 minutes, they have the responsibility of eventual CFMU slot compliance,taking into account a standard taxi time of 20 minutes. In other terms, the difference between actual start-up clearanceand CTOT should not be lower than 20 minutes. Nevertheless, depending on conditions (RWY vicinity, S/G), taxi-time



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does not ensure its next delivery (SUC[n+1)) and pushback clearance delivery, that is to say thatunpredictable start-up and pushback delays may occur that may in turn influence taxi-out time (especiallyduring hub waves). Common awareness of SUR[n+1] and SUC[n+1] will complete the information channeluntil actual off-block time, will allow to monitor the accuracy of TOBT as well as to see if better integration ofaircraft in the sequence has been operated (by comparing the elapsed time between SUR and SUC). TOBTand SUR should be as close as possible. � Information Updates and Triggers:

Computing or assessing a taxi-out time accuracy with a limited time horizon is a complex problem whosesolution in part relies itself off block times estimates� accuracy provided by aircraft operators. Currentassessment of taxi-out time at SUR shows that taxi-time inaccuracy can be significant, augmented by theuncertainty regarding the interval between SUR and SUC (up to 30 minutes)62, that take into account ATFMslot63, traffic load, co-ordination actions etc.

SUR(n+1) and SUC(n+1) should trigger, if necessary , the update of the take-off time (according to taxi-outtime estimate, departure sequence, SID, etc.).

� Data Quality:

It is expected that the difference between TOBT64 (given at [EOBT-30�]) and AOBT should not exceed 5minutes in the vast majority of cases (normal case up to 80% of the flight). The SUR and the SUC eventscome between TOBT and AOBT. In a normal case the SUR event should be close to TOBT and the SUCshould follow. When the pilot receives the SUC he has one minute to react and to move. In addition, theaccuracy of the predicted taxi-out time at SUC should be 5 minutes.

M18 (AOBT[N+1]) and M19 (ATOT[N+1])


AOBT (actual off-block times) and ATOT (actual take-off times) should be distributed to the receiving airportthrough movement messages.


This information should trigger the updates of ETA and EIBT at outstation.

� Data Quality:

The information should be complete and shared with the outstation that will receive the flight. AOBT[n+1] andATOT[n+1] will also be used for data quality purpose to analyse various data such as to real taxi-timecomputation versus planned, gaps with EOBT and/or TOBT, reactivity analysis to the start-up clearance bycomputing |AOBT-SUC|.

could be much lower than 20 minutes.62 This encourages aircraft operators for anticipated start-up requests.63 Regulated flights have precedence over non-regulated flights for start-up clearance delivery.64 TOBT stability is a key issue. Only one AO TOBT update should be allowed between (TOBT-20) and (TOBT) withoutspecific procedure. A second update during this time period should be considered as a new (TOBT-20�).



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5.3.5 The Target Off Block Time

Important effort has been dedicated during the project around EOBT accuracy provided by the aircraftoperator. A reliable off-block time is one of the main cornerstones upon which ATC, CFMU and AirportAuthorities can base their own operations.

However, it is clear that in certain situations, there are disincentives for aircraft operators to revisetheir real off block time, in particular when the flight is submitted to regulation that can be translatedin the so-called �double penalty�. The statement is that inconsistencies expand into various systems(CFMU and ATC) and results in:

� Stand/gate inefficiencies,� Non-adherence to CFMU slots, overdeliveries or sub-use of the available capacity,� Departure sequence inaccuracy.

One important step was obtained through aircraft operator�s agreement to publish their internal off block time(commitment between OCC and handling part) in order to improve the accuracy and reliability of departureinformation.

The Target OBT corresponds to Sabena internal off block time, shared between aircraft operator, airportauthorities and ATC on Brussels site. It corresponds to a ready status, e.g. all doors closed, jetway/airbridgeremoved and pushback truck in place (for aircraft at contact stands).

The sharing of Sabena real target OBT will obviously increase confidence between partners about realexpected ready times. Of course its notification will not decrease the disruptions that may arise or constraintsthat challenge a departure but will give the utmost fair view on their operations. Along with the notification ofsurface milestones, this constitutes a major CDM step towards confidence and mutual understanding ofconstraints.

What is proposed was the continuous notification of this information to CDB. For each flight, the commonawareness part consists in notifying a specific field (TOBT) in a time window bounded by two specificmoments:

� At [EOBT�30�], the TOBT will be initialised by the aircraft operator (in co-ordination with handlingagents), shared between airport authorities, aircraft operator, ground handling and air traffic control.

� Implementation of surface milestones: it has been agreed that the aircraft operator will share additionalsurface milestones in addition to those that are managed in Brussels CDB (see above):� First door opened,� Aircraft all doors closed,� Start up request,� Start up clearance.

Flight statuses on the surface are automatic statuses that are gathered automatically without humaninteraction, that are subject to errors.

The monitoring of these events will allow the update/confirmation of TOBT and to raise alarms if necessary.The quality (completeness, accuracy, reliability) of this information will be monitored.

� At [TOBT-20�], the TOBT should be stable excepted if a disruption occurs. Of course any deviationshould be notified as soon as it is known to enable other parties to react.

� Requested accuracy: a TOBT 5 minutes accuracy should be observed in the vast majority of cases at[EOBT-30�], to be confirmed during experiments.

The reliability of this information is a pre-requisite for Belgocontrol for this information to be used in a furtherstep. This information should be used as a basis for a pre-start up clearance provided an 5� accuracy ofTOBT at [TOBT-20�]. Elements for establishing a pre-notice start up clearance are given in section 5.4.



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5.3.6 Alarms and Indicators

In the previous sections, we have stressed the need for turnaround process monitoring, in particular for theconsistency and synchronisation of operations for an arrival aircraft. However it is clear that processmonitoring is only one element that checks that the continuity of operations is ensured, and in case ofprocess disruption, would help in assessing the severity of the situation in order to take an eventual decision.

� Completeness of outstation departure information: absence of information regarding incoming flightsneeds clearly to be eradicated. Completeness of information will be ensured through movementmessages, supplemented by CFMU FSA (First System Activation) messages. In a next-future ETFMSenvironment, CPRs (Correlated Position Reports) and APRs (Aircraft Position Reports) will be used tocheck non-departed flights. Despite of existing and future measures to improve departure completenessinformation from outstation, we suggest to raise an alarm if no information about take-off is received atinbound station 30 minutes before the estimated time of arrival at outstation65.

� TOBT consistency checks: a number of discussions occurred in Brussels about the necessity tomonitor the consistency of TOBT.

� [TOBT-20�] versus �start boarding� event: the question of raising an alarm at [TOBT-20�] if theboarding has not yet started have been addressed in Brussels. Confidence is given to the aircraftoperator in co-ordination with the local handler to guarantee the reliability of the TOBT 20 minutesbefore its occurrence (5 minutes accuracy). In a few cases, the fact that the boarding has not started20 minutes before TOBT may not challenge it (depends on aircraft occupancy rate). However, wethink that, in the vast majority of cases, an absence of boarding event at TOBT-20� should trigger analarm and a confirmation from the aircraft operator that the TOBT compliance will be respected.

� TOBT versus �all doors closed� event: the occurrence of �all doors closed� event should neveroccur after TOBT (non-respect of TOBT accuracy), that should trigger an alarm for co-ordinationpurpose.

� The Aircraft Ready status: monitoring the TOBT that is an estimate against a real aircraft readystatus is necessary. However, if �all doors closed� event is an automated signal, jetways/airbridgeremoved and pushback truck in place (for aircraft at contact stands) are not detected automatically. Itis suggested that liaison between red-caps and CDB/AMS through mobile wireless applicationshould be studied to set up such indicator. This indicator could then be used to compare the targetoff block time with a reliable actual ready time.

5.3.7 CDB gate Statuses

Current CDB gate statuses (gate open, final call, start boarding, gate closed) will be supplemented by FDO(first door open), DC (all doors closed), SUR (start up request) and SUC (start up clearance).

It is important that the ATC tower has an accurate view on an actual ready status of the aircraft, e.g. when alldoors are closed, the pushback truck is in place and jetways/airbridge are removed. For such, the pilotshould not request for start up if these conditions are not fulfilled. However, automatic means for providingsuch information do not exist66. The automatic signal �all doors closed� will (in a first attempt) provideadditional information about the aircraft ready status. Start up request should never occur if �all doors closed�signal is not triggered.

65 At current, this is performed manually (phone call to the outstation) 66 The use of a PDA (Personal Digital Assistant) by handler, linked to the CDB, could be of interest in the future.



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5.4 PRE-NOTICE START UP CLEARANCE PROCEDURE

5.4.1 Objective

ATS67 is watching over the use of total available capacity. With current working methods and systems thereappears to be an important amount of hidden or 'frozen' capacity. With the use of new tools and workingmethods this hidden capacity can be made available. For instance with adequate arrival managementtheoretically all available slots with reference to the runway can be assigned. However, with mixed trafficmode, the departures have to be pre-sequenced in between, which means that a number of time slots needto be reserved for them and can not be assigned to arrivals. To preserve capacity these departure slotsshould be adhered to as closely as possible, because each time such a preserved slot is missed, it iscompletely lost and the flight has to be repositioned later in between the arrival sequence.

The conclusion is that, with timely availability of accurate real EOBT values from the side of theairline operators, a stable mixed arrival and departure pre-sequence can be created by appropriatetraffic sequencing tools.

As a result the total amount of delay for arrivals will decrease accordingly. The spread of this re-gainedarrival and departure capacity (and decreased delay) for all participating airline operators is in proportion totheir relative number of flights on the airport.

For such, a pre-notice start-up clearance procedure can be envisaged based on the milestones approachdescribed in the document and the common awareness of TOBT amongst airport users. The objective of thisprocess is to improve global operations� efficiency. As stated, the lack of information (completeness,accuracy and reliability) regarding critical departure information affects all actors on the airport:

� At stand/gate level, the absence of reliable departure information generates a significant number ofstand/gates conflicts between arrival and departing aircraft;

� At ground handling level, it prevents from an optimised use of resources (human and physical).Excessive booking of resources and late gate changes significantly affect their operations.

� At air traffic control level, the absence of departure sequence stability reduces the airport throughput andaugments the number of lost runway slots;

� At CFMU level, departure uncertainty (augmented by the uncertainty regarding taxi-out time) can bematerialised through the lack of slot adherence and thus induces subsequent overdeliveries.

� At an aircraft operator level, induced effects and cost of departure uncertainty over other aircraftoperators (last stand/gate changes, lost ATC slot, etc.) can be significant.

� Lastly, at passenger level, late gate changes and departure uncertainty do not contribute to enhance theairport image.

5.4.2 Current Departure Operations

The main sequence of events is as follows:� Flight plans have to be submitted according to AIP68 regulations. They may be submitted through ARO,

but (handling) companies scan end FPL69 directly to FDPS70.� AFPS makes preliminary FPL checks and dispatches the FPL to all ATC sections involved and to the

CFMU for slot allocation. The CFMU evaluates traffic load, implements restrictions and accordinglydeparture slots71 2 hours in advance, based on the EOBT provided throughout the flight plan and taxi-outtime72. The FPL status is then �Pre-active�. CANAC flow management cell may enter �ready�73 requestsas asked by TWR delivery position.

67 Air Traffic Services.68 Aeronautical Information Publication.69 Flight Plan.70 Flight Data Processing System (in Belgium, AFPS). Scheduled flights are submitted well in advance as repetitive FPL asto allow CFMU to make traffic load evalutions.71 If necessary. Flights are then regulated. CTOT = EOBT + delay + Taxi Time72 May be flexible or not, depends on the European airport.



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� At [EOBT-40�] the flight plan status changes to �Proposed� (strips appear from [EOBT-40�]. The AMSdelivery position is responsible for start-up. He/she has access to pre-active FPL list; in reply to inquiringpilots he/she can forward them with their slot, expected departure runway and SID74. His/her normalscreen deals with proposed FPL.

� When the aircraft is ready to leave its departure stand, the pilot requests permission to start-up (eithervia ACARS or radio), in accordance with AIP AD2 EBBR 24 § 7: �pilots will cal �Brussels delivery� onlywhen they will be ready for start up in accordance with their slot if any, for pushback and/or ready for taxiimmediately after reception of ATC clearance. ATC clearance issued upon this initial call is based on theassumption that, from the time of readiness, an average 20 minutes lapse is needed for start-up,pushback, taxi and take-off manoeuvres. Consequently, any call made deliberately well in advance ormade without reasonable assurance to be ready in time will result in jeopardising the departuresequence and causing delays for the operators�.

� Depending on slots or traffic situation constraints75, the delivery position issues a start-up clearance(SUC) or puts the flight into stand-by mode.

� The start-up clearance is issued in due time by data link and/or by voice. Its acknowledgement brings theflight in �Start Up� mode. The pilot is then instructed to contact the Ground North / Ground South(depending on the aircraft position) for pushback and/or taxi. This is the point at which the aircraft entersthe sequencing system76.

� Flights that are ready for taxiing receive taxi instructions in respect with the moving traffic in vicinity. Taxiinstructions are given in respect of the departure sequence, taking into account traffic from the otherground sector.

� Arriving at holding point, the pilot is instructed to contact or to standby on TWR frequency.� In respect of landing traffic (in case of arrivals/departures on RWY 25R), TWR air controller instructs

departing aircraft in sequence to line up runway and hold. He/she issues take off clearance in respect ofthe preceding departure, co-ordinates as necessary with approach, approves crossings of the runway byaircraft and vehicles.

5.4.3 Problems and issues

Different problems can be highlighted:

� Taxi-out time is not predicted with sufficient accuracy in Brussels. At current, the TWR controllerevaluates the taxi out time and the waiting period in block once the pilot calls for start-up clearance.Depending on the real-time situation and constraints applying to the airport and due to increasingcontroller workload, the error on taxi out estimate can be significant, up to losing CFMU slots (scarceresource). As an example, we found intervals of more than 30 minutes between the CTOT and theATOT, despite of an interval of more than 45 minutes between start-up request and CTOT. This is notacceptable and shows that the current procedure does not give satisfaction to the users. In order to havea reliable predicted taxi time (plus waiting block time) with a limited time horizon (30 minutes), a toolmight be useful to enhance its predictability. In addition, the provision of a decision-aid tool77 wouldreduce the TWR controller workload.

� The reliability of information is not sufficient, especially regarding EOBTs that is the basis for ATC andCFMU slot allocation. In addition, anticipated start up requests may worsen the situation.

� Poor information reliability and predictability prevent from efficient early sequencing and CTOT non-adherence, and may induce over-deliveries. As an example, 42.3 % of regulated flights departing fromBelgium did not adhere to their slots in June 200178.

73 The CFMU �REA� message can only be sent by ATC. But aircraft operators may ask ATC to send it in two situations:the flight is ready to depart (maximum 30 minutes before), or the flight can accept an improvement with a noticeshorter than usual.74 Standard Information Departure.75 Congested sectors, maximum of 10 aircraft waiting simultaneously at the holding point.76 Flights on remote or nose-out stands make their start-up and call �ground north� or �ground south� when they areready for taxi.77 See Section 7.78 Reference (ATFM/IFPS Operations Statistical Analysis (06/01)). See Table 9.



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5.4.4 Description of the proposal

5.4.4.1 Assumptions

This section has to be considered as an initial draft of a collaborative pre-departure sequence, based on theelements described throughout this document. In particular, it relies on:

� Sharing an initial Target Off Block Time (TOBT) amongst airport users at [EOBT-30�] that reflects a fairview on the ready time for the aircraft;

� The confirmation by aircraft operators/handlers79 to ATC and airport authorities of a reliable80 target offblock time 20 minutes before its occurrence. Implementing the TOBT with success (accuracy andtimeliness) should assure the airport users that the aircraft is ready for push back at TOBT81.

� The establishment of a taxi-out time82 per flight with a limited time window. This issue is addressed insection 7 of this document.

5.4.4.2 Estimated Start Up Clearance

The timely provision of such information would help in minimising uncertainty regarding departure processthat could bring high benefits. The approach that is described below relies on the previous steps, e.g. theimplementation of an ESUC83 that is reliable and shared between actors. This is why the objective tominimise uncertainty regarding departure process is a key objective that could bring high benefits.

It is proposed that, provided a accuracy and reliability conditions to be determined collaboratively, anestimate of the start-up clearance delivery (ESUC) should be provided at [TOBT-20min.]:

� The reliability (timeliness and accuracy) of the TOBT is a sine qua non condition for implementing thisprocedure.

� The issue of TOBT revision on aircraft operator request (one revision or more) between [TOBT-20�] and[TOBT] shall be addressed and a specific rule shall be established84.

Remark: In past years, Belgocontrol had established a pre-departure process based on data provided byaircraft operators. Due to unreliable data regarding off block time, Belgocontrol renounced to suchprocedure.

� The ESUC should be returned to aircraft operators and airport authorities by ATC at [TOBT-20�] with theobjective to cope with the TOBT to the maximum extent. ESUC expected accuracy should be as follows :|ASUC-ESUC| < 5 minutes;

� ESUC should never precede TOBT (ESUC > TOBT). The ESUC is just an estimate of start up clearancedelivery time that means that ESUC may be different from ASUC for any reason (constraints applying toATC). In any case after TOBT, a delivery of SUC (start-up clearance) from TWR should triggerpushback. The expected reactivity from the pilot (e.g. pushback) to start up clearance delivery should notexceed one minute in nominal conditions.

� In principle, the start-up clearance may be delivered to the pilot at any time after TOBT, possiblyreducing the dialogue between pilot and controller (pilot start-up request might be discarded as theaircraft should be ready to start-up from TOBT). Controller workload would then be reduced.

� Once the start-up clearance delivered, unless restrictive constraints (pushing traffic for instance), thedifference between start-up clearance and pushback clearance should not exceed one minute (nominalconditions)85.

79 A large majority of aircraft operators and handlers should participate in order to bring large benefits.80 Of course last minutes disruption may occur; however, in the vast majority of cases (say 80%), the TOBT establishedat [TOBT-20�] should not be challenged. Lessons should be learnt from trials.81 As proposed earlier in this document, this information should be initialised 30� before EOBT with an accuracy of 5�around AOBT during favourable conditions (off peak). However, the target off-block time is an estimate that does notprovide the actual time when the aircraft leaves the block and freezes the stand/gate.82 Established either manually in a first attempt. It is expected that a decision-aid tool could provide an accuratecomputation of taxi-time in the future. 83 Estimated Start Up Clearance Delivery84 A revision of the TOBT should only be possible at a later time.


EE

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� ESUC delivery should take into account CTOT constraint. However, an important issue is the capacityto establish a predicted taxi-out time86 (that should include the waiting block time after TOBT to cope withthe ETOT87) beforehand (e.g. at [TOBT �20�]). The common awareness and reliability of the TOBT andtaxi-out time per flight are a pre-requisite so that the CFMU could use such data for improving itsoperations for the benefit of the European Community. For instance, the computation of a realistic taxi-out time should allow to compute an estimated take-off time with a 30�-45� time horizon and so forecastCTOT non-adherence88:

� Local rules, for instance flights prioritisation by ATC TWR89 should be established to solve smalldeviations from CTOT.

� If a solution to CTOT non-adherence cannot be found, collaborative solutions should be envisagedbetween ATC, FMPs and the CFMU. In any case, the estimated take off time should becommunicated to the CFMU and should be updated (if necessary) until start up clearance delivery.

� At current, the start-up clearance delivery time is displayed on the departure screen. It is proposed thatthe ESUC would be displayed on the same screen beforehand the ASUC (such proposal would notinduce any change in the current display system). The display of ESUC data would allow the operator tosee and to control the value as well as to adapt it to the real time constraints (that is not the case today).

5.

Ththreslose

85 86 87 88 89Tco

C Report No.371 33

FIGURE 10 : PROPOSED PRE-NOTICE START-UP CLEARANCE

4.5 Potential improvements for the CFMU

e distribution to the CFMU of an accurate predicted take-off time should bring significant benefits. Onceese the TOBT and taxi out time per flight are shared between the airport users along with qualityquirements, the CFMU could then use it to improve the calculation of the regulations and the allocatedts. Some premises of potential new procedures are described below that relate to pre-departurequence, taking into account that:

Causes and deviation extent shall be recorded and analysed.See section 7.No waiting bays are implemented in Brussels, so that the aircraft waits at the block if needed.For regulated flights.aking into account hard constraints (wake vortices, route constraints, minimum departure interval) and softnstraints.

TOBTTOBT-20�EOBT-30�

AIRLINE, PILOT HANDLING AGENTS RESPONSIBILITY

CTOT Window

TOBT accuracy < 5

ATC RESPONSIBILITY

PILOT READY PUSHBACK PRESENT

TWR/ PLANNER: PREPARE SEQUENCE

PUSHBACK

TOBT ESUC ASUC

TAXI

TAKEOFF

TOBT UPDATE WINDOW

TWR : START-UP CLEARANCE

AOBT : Push-back ATOT

< 5� < 1�

CTOT

SUR



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� The pre-departure sequence is established for departing flights;� TIS/TRS are airport-dependent CFMU parameters that set the last time at which the CFMU can revise a

CTOT (TRS) or improve the slot (TIS).

5.4.5.1 Slot Improvement Window

When a flight receives a slot from CFMU (regulation), the aircraft operator may operate different strategiesbetween about boarding passengers: boarding as soon as possible or late boarding according the fact thathe waits for an improvement of the slot or not.

� Boarding as soon as possible: the immediate consequence is that passengers will wait in the aircraftrather than in the airport. The pilot waits for start-up delivery and for an eventual slot allocationimprovement according to CFMU possibilities. The messages exchanged between CFMU, AOC90 andTWR are:� Request for direct improvement;� Request for conditional improvement;� Ready Message: the REA message can only be sent by ATC to CFMU TACT. But aircraft operators

may ask ATC to send it in two specific situations:� The flight is ready to depart before EOBT (maximum 30 minutes before);� The flight accepts an improvement with a notice shorter than usual (minimum line-up)91.

� If an improvement is possible, the CFMU will send an SRM.

� Late boarding; the passengers stay in the waiting hall and the boarding starts later to comply with theCTOT. The flight does not wait for any improvement of its slot.

We propose to set-up a Slot Improvement Window from [TOBT-30�] up to [TOBT-20�]. The idea is that a pre-departure sequence can be established once data stability is performed (in particular CTOT).

Once reliable TOBT and predicted taxi-out time per flight would be made available to the CFMU, the CFMUmight automatically re-calculate the slot during this interval (if necessary), complying with the real-timeconditions on the airport considered. CTOT would be frozen at [TOBT-20�]. The pre-departure sequenceshould then start at [TOBT-20�].

Slot ImprovementCFMU

New CTOT CTOT SIP Window

TOBTTOBT-30� -20� TOBT

AIBT AOBT ATOT

A.O.C

Taxi Time

Pilot ��..SUR

Tower ESUC ASUC ��.

Waitingblock

FIGURE 11: SLOT IMPROVEMENT WINDOW

90 Airline Operations Centre91 The minimum line-up is the duration needed by the flight to go from its present position to the take-off;



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Potential benefits are as follows:

� The CFMU delay can be reduced,� The AO manages its operations (boarding),� The CFMU should be confident in the estimates provided,� The ESUC could be issued in a steady manner for all airport users,� The TWR could include the flight in a fixed pre-departure sequence at [TOBT-20�],� The handlers could plan the ramp operations for the next flight,

� Stand and Gate Management decision-making could be improved.

5.4.5.2 Slot Adaptation Proposal

At current, multiple delays may accumulate that result in losing valued CFMU slots. CFMU calculates slotsaccording to EOBTs provided by aircraft operators along with a taxi-out time that can be either permanent(e.g. 20 minutes for Brussels at current) or variable.

� As a rule, the aircraft operator shall notify the CFMU with a new EOBT when the difference between thenew EOBT and the previous one exceeds 15 minutes.

� In addition to EOBT uncertainty, taxi-out time variability can worsen the situation. Depending onconditions, taxi out time can increase from an average period of 15 minutes (CFMU parameter) up to 30minutes and more according to the demand arrival and departure on the departure runway, weatherconstraints, etc.

When the two uncertainty effects (EOBT and taxi-out) are added, the stated difference between actual takeoff time compared to what was expected can exceed 30 minutes. Even if procedures are implemented, theimmediate result is an important number of regulated flights that do not adhere to their CTOT.The provision of TOBT and Taxi out Time estimates before [TOBT-20�] would result in an early prediction ofnon-adherence to CTOT as well as its potential consequences (for instance overdeliveries in the sectorsclose to the airport).

As a result, the CFMU could find collaborative solutions to try to comply with real-time conditions at theairport considered. In that case, the benefit would not be an improvement of the delay but an automaticadjustment (if possible) to the real airport conditions 20� beforehand the event TOBT.

Forecast benefits of future implementation include:

� The slot would not be lost in the majority of cases,� This procedure decreases the workload of the TWR controller,� The aircraft operators would have a better accurate time to start the boarding.

Deviations of more than 5 minutes (compared to previous value) should be communicated. The assessmentof non-adherence to CTOT (and consequences) should be established and solved collaboratively:

� A first attempt should consist in adapting the slot to comply with real time conditions (slot adaptation)through automatic adjustment if the consequences of deviations are acceptable by ATC, FMP andthe CFMU.

� If consequences of CTOT deviation are important, existing CFMU measures92 may apply incollaboration with ATC and FMP. However, depending on conditions, more collaborative measuresshould be envisaged such as slot swapping between flights. Collaborative en-route measures93

could also be envisaged to make up for the time lost.

92 Flight Suspension93 FAM (Future ATFM measures) project (EEC).



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FIGURE 12: SLOT ADAPTATION PROPOSAL

Stabilisation of data after [TOBT -20�] would be an improvement for the CFMU in order to avoid the currentaircraft operator gambling that are free to file and/or amend any flight plan up to very last minute. In case ofheavy demand, and because of that freedom, flows tend to shift and to move from one place to anotherdepending on the regulations and on the inherent delays, increase the number of overdeliveries and re-routings, resulting in some kind of vicious circle.

EOBT Delay

TOBT-30� TOBT-20� TOBTA.O.Chandlers

ESUC SUC Taxi Time Tower

Delay

Delays:

AOC

+

ATC

+

CFMU

=

CTOT

Delay Taxi.time 15�

CFMU

AOBT ATOT

At TOBT -30�, CFMU receives TOBT, Taxi-Out Time DataAt TOBT -20�, CFMU would compute a new CTOT.

TOBT Taxi Time NEW CTOT Slot Adaptation?

TOBT+ T.T+ SLOT= SAP

SAP



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6 CDM KEY PERFORMANCE INDICATORS

Providing information and better quality induce costs that should be balanced by higher benefits. Giving anaccess to information with an expected quality that would benefit to the addressee (for example betterresources management planning) should be directly reflected through quantitative measurable improvementfor the entity providing the information (return of investment). This can be envisaged as a contract betweenparties where the collaboration (in that case, access/distribution of information with an expected quality)should bring benefits to both sender and receiver of information. Consequently, obtaining an agreement onKPIs is important and raises several issues:

� Definition of QoS (Quality of Service), that deals with distribution, access to information, responsibility,accountability and use of information. This should be materialised through Service Level Agreementsbetween actors.

� Definition and monitoring of the expected quality of information that is materialised by establishingmetrics (for instance precision, accuracy, reliability, timeliness etc.) and associated indicators.

� Assessment of benefits on both sides achieved through measurements. This assumes a baselineagainst which to compare, and the monitoring of quality of information in addition to benefits�assessment.

6.1 MILESTONES AND RECORDED DATA

The success of implementations will be measured as an initial baseline against which to compare (do-nothing case of the cost-benefit analysis terminology).

Following proposed implementations, a set of data should be recorded at each milestone that will set up ourdata quality framework.

The following table indicates the data to be recorded.



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M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M11 M12 M13 M14 M15 M16 M17 M18 M19

ETA(n-1) � �

ATA(n-1) �

EIBT(n-1) � � �

AIBT(n-1) �

EOBT(n) � � � � �

AOBT(n) �

ETOT(n) � � � � � �

CTOT(n) � � � � � �

ETT(n) � � � � � �

ATOT(n) �

EET(n) � � � � � � � �

ETA(n) � � � � � � � �

ATA(n) �

EIBT(n) � � � � � � � � �

AIBT(n) �

S&G(n+1) � � � � � � � � � � �

FDO �

SB �

GC �

DC �

SUR �

ESUC � � � � �

SUC �

EOBT(n+1) � � � � � � � � � � � � � � � � � �

TOBT(n+1) � � � � � � �

AOBT(n+1) �

ETOT(n+1) � � � � � � � � � � � � � � � � � � �

CTOT(n+1) � � � � � � � � � � � �

ETT(n+1) � � � � � � � � � �

ATOT(n+1) �

ETA(n+1) � � � � � � � � � � � �

Remark: each update of TOBT, EOBT, ETOT, CTOT will be recorded (timestamp, source)

TABLE 5 : MILESTONES AND RECORDED DATA

M1: CFMU SIT1 [N] M11: First Door Opened [N+1]M2: ATA [N-1] M12: EOBT-30� [N+1]M3: AIBT [N-1] M13: Start Boarding [N+1] / TOBT-20�[N+1]M4: EOBT�20� [N] M14: Gate Closed [N+1]M5: AOBT [N] M15: All Doors Closed [N+1]M6: ATOT [N] M16: Start Up Request [N+1]M7: ETA-30� [N] M17: Start Up Clearance [N+1]M8: CFMU SIT1 [N+1] M18: AOBT [N+1]M9: ATA [N+1] M19: ATOT [N+1]M10: AIBT [N+1]

Index [N-1]: flight arriving at outstation,Index [N]: flight from outstation to home station,Index [N+1]: flight departing from hub station.



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6.2 INITIAL IDENTIFICATION OF KPIs

Global target objectives at an airport can be classified under capacity and resources, efficiency andpunctuality categories along with stakeholders� objectives that could be improved through CollaborativeDecision Making.

� The global objective of aircraft operators is to meet their programmed operating schedule. The majorimpact of delays on aircraft operators is direct extra costs and the costs or reduced profits caused bysystem disruptions (missed connections and impact on hub operations).

� Handlers objectives are to optimise the allocation and use of available resources whilst satisfying withthe service level agreements regarding departure punctuality and turn-around times. The best use ofavailable resources depends in part on arrival data quality.

� The objective of airport authorities is to comply with their airport operation plan and maximising thethroughput. The major impacts of delays on airport authorities are mainly the loss of image/reputationand a reduced cost/benefit ratio in the management of airport resources as a result of the changes in theplanned assignment of resources. From an airport authority perspective, the minimisation of the impacton airport resource planning is a main challenge. For such, both departure and arrival punctuality areimportant since they influence the use of airport resources (stands, gates, etc.).

� ATC authorities global objectives at local airport are to ensure safety whilst making the best use of theavailable resources (runways and taxiways).

� CFMU objectives are �to protect air traffic services from overloading while at the same time enablingaircraft operators to carry out their flight operations as planned with the minimum penalty. This isachieved by making best use of the available air traffic control and airport capacities�. For achievingtheir mission, the provision from other actors of high quality of data (arrivals, off block time and taxi time)are the cornerstone for their efficiency. In particular, ATFM slot adherence and EOBT accuracy areimportant indicators.

The following table is intended to provide an initial basis for CDM key performance indicators that supportsthe approach recommended in the document.

Data quality has been split between outstation (external world) en-route and hub-station data quality. Hubstation data quality has been refined in different categories that correspond to actors� separate views andoverall performance.

In order to distinguish when the measure is performed, we have adopted the following rules:

� |AIBT10 � ATA 9| means �AIBT is measured at milestone M10 and ATA at milestone M9�.� |AOBT5 � EOBT 1..5| means �AOBT at milestone M5 will be compared with EOBTs at milestones M1,M2,

M3, M4, M5�.



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REF Indicators Metrics RefinementOUTSTATION

94 Measure ETA accuracy For non regulated fligh|ETA1..6 � ATA9| [Mean, Max, Min, �] and per ADEP, per AO95 Measure CTA accuracy For regulated flight |CTA1..6 � ATA9| [Mean, Max, Min��] and per ADEP, per AO

Measure EOBT accuracy |AOBT5- EOBT1..5| [Mean, Max, Min,��] and per ADEP, per AOMeasure ETOT accuracy |ATOT6 - ETOT1..6| [Mean, Max, Min,��] and per ADEP, per AOMeasure Taxi out Time CFMU changesif any

Taxi out Time 1..6 [Mean, Max, Min,��] and per ADEP

Measure Taxi out Time accuracy |(ATOT6 � AOBT5) � CFMU Taxi Time| [Mean, Max, Min,��] and per ADEPMeasure completeness of expectedinformation at [EOBT�20�]

Percentage of flights for which no information isreceived at [EOBT-20�]

[Mean, Max, Min,��] and per ADEP, per handler, per flight

96 Measure ETA accuracy at M4 |ATA7-ETA4| [Mean, Max, Min,��] and per ADEP, per AO.Measure number of flights without MVTat EOBT-20�

Percentage of flights for which no NVT messageis received at [EOBT-20�]

Ratio (number of flights / total number of flights)

Measure EET stability and accuracy EET change2..6 and accuracy 2..6 Estimated elapsed time (flight duration)EN ROUTE

97 Measure ETA accuracy at M7 |ATA7 - ETA7| [Mean, Max, Min, �] and per ADEP, per AOMeasure EET stability and accuracy EET change and accuracy During en route phase until M7

HOME STATIONAirline/handlerMeasure real Taxi-in Time |AIBT10 � ATA9|Measure EOBT accuracy |EOBT2..17 � AOBT18| [Mean, �] Number of EOBT changes after M7 per AO, per flightMeasure TOBT accuracy |TOBT12..16 � AOBT18| [Mean, �] per AO, per flight

TOBT-20� > EOBT => wrong EOBTMeasure decision time period |TOBT12 � EOBT12 � 30�| [Mean, �] per AO, per flightMeasure real Taxi out Time |ATOT19 � AOBT18|Measure estimated Taxi out Timechanges

|ETOT8..19 � EOBT8..19| [Mean, �] per flight

TABLE 6 : BRUSSELS CDM INITIAL KEY PERFORMANCE INDICATORS 1/3

94 Computation: ETA1..6 = EOBT1..6 + Taxi out time1..6 + flight duration95 Computation: CTA1..6 = CTOT1..6 + flight duration96 Expected accuracy: ATA9 � 15�< ETA4 <ATA9 + 15�97 Expected accuracy: ATA9 � 4�< ETA7 <ATA9 + 6�



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REF Indicators Metrics RefinementMeasure TOBT changes after TOBT � 20� |TOBT13..16 � TOBT13| [Mean, �] per AO, per flight, and details.

98 Measure TOBT accuracy at M12 TOBT12 |AOBT18-TOBT12|Measure TOBT respect range of accuracy |TOBT 12..16 � TOBT 12| < 6� Without delay (CFMU, airport, Tower..) per AO, per flightOverall Ground PerformanceS&G allocation changes S&G2..10 Number of changes after M7 / flightFirst door open performance |FDO11 � AIBT10| [Mean, �] per AO, per flightStart boarding performance |SB13 � AIBT10| [Mean, �] per AO, per flightGate closed performance |GC14 � AIBT10| [Mean, �] per AO, per flightDoors closed performance |DC15 � AIBT10| [Mean, �] per AO, per flightStart-up request pilot reactivity ASUR16 � DC15 [Mean, �] per AO, per flight (negative value = anticipation)

99 Clearance delivery time |ASUC17 � ASUR16| [Mean, �]Start-up pilot reactivity |AOBT18 � ASUC17| [Mean, �] per AO, per flight nb of aircraft / |AOBT18 � ASUC17| > 1�Estimated turn-around duration |EOBT2..17 � AIBT10| [Mean, �] per AO, per flightActual turn-around duration |ASUR16 � AIBT10| [Mean, �] per AO, per flightATC TowerEstimated Taxi out Time accuracy At M12, M14, M16, M17, M18Measure ESUC accuracy |ASUC17 � ESUC13..17| [Mean, �], percentage of flights / |ASUC-ESUC| <5�

100 Measure ESUC respect range of accuracy ATOT19 � ESUC13..17 > Taxi out Time ESUC13..17 > TOBTRunway Capacity: number of departuresand/or arrivals hr versus capacity (foreach RWY configuration)

|declared RWY capacity � number ofdepartures and/or arrivals (for each RWYconfiguration)

Capacity gap (difference), [Mean, Max, Min, �]

CFMUMeasure ATFM slot adherence |ATOT19 � CTOT18| [Mean, �] per AO, per flightMeasure taxi out time variability |CTOT18 � AOBT18| Comparison actual vs with Taxi out Time CFMUMeasure CTOT stability Number of changes between CTOT13..19 [Mean, �] number of CTOT changes per flight

TABLE 6 : BRUSSELS CDM INITIAL KEY PERFORMANCE INDICATORS 2/3

98 Expected accuracy: AOBT18 � 5�< TOBT12<AOBT18 + 5� without constraint or delay : TOBT, SUR, SUC in sequence.99 Clearance Delivery Time (*). This does not represent the ATC performance but the multiple constraints that apply to issue the clearance delivery: eventual CTOT, airporttaxiway/runway congestion, etc100 ATOT19 � Taxi out Time > ESUC > ATOT19 � Taxi out Time � 5�



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REF Indicators Metrics RefinementOverall PunctualityDeparture / EOBT: estimated out of block |AOBT18 � EOBT8| [Mean, �] per AO, per flight

Departure / EOBT: take off |ATOT19 � ETOT8| [Mean, �] per AO, per flightDeparture / TOBT: target out of block |AOBT18 � TOBT12| [Mean, �] per AO, per flight

101 SUR versus TOBT |ASUR17 � TOBT12| [Mean, �] per AO, per flightESUC versus ASUC |ESUC13 � ASUC17| [Mean, �]

102 TOBT accuracy Occurrence of doors closed event after TOBT Number and Percentage of flights for which doors closed signal occursafter TOBT

TOBT accuracy Occurrence of start boarding event afterTOBT-20�

Number and Percentage of flights for which start boarding signal occursafter TOBT

TOBT Stability Number of TOBT changes in [TOBT-20�;TOBT]

[Mean, ��, and details. Percentages of flights for which an internaldisruption is stated after TOBT

Taxi out delaysStand and Gate ManagementStability of Stand/Gate planning Number of S/G changes in [ATA-30; ATA] [Mean, ��Stability of Stand/Gate planning Number of S/G changes in [ATA-10; ATA] [Mean, ��Stability of Stand/Gate planning Number of S/G changes in [ATA; AIBT] [Mean, ��S/G change induced effects Number of domino changes induced by a S/G

change in [ATA-30; ATA]Number of occurrences: [Mean, Max, Min, �]

Number of domino changes induced by a S/Gchange in [ATA-10; ATA]

Number of occurrences: [Mean, Max, Min, �]

Number of domino changes induced by a S/Gchange in [ATA; AIBT]

Number of occurrences: [Mean, Max, Min, �]

Contact Stands Occupation Occupancy Rate Percentage of use (per contact stand)Remote Stands Occupation Occupancy Rate Percentage of use (per remote stand)Contact Stand Turnaround Time peraircraft type

|AOBT(dep.)-AIBT(arr.)| [Mean, ��

Planned vs Real Contact Stand Use |Actual Contact Stand Occupation � LastPlanned Contact Stand Occupation |

[Mean, ��per contact stand, per flight

TABLE 6: BRUSSELS CDM INITIAL KEY PERFORMANCE INDICATORS 3/3

101 No call (SUR) before DC and push back truck present : SUR > TOBT15102 Should never happen. For instance, �aircraft doors closed� should never happen after TOBT.



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7 PREDICTING TAXI TIME AT AIRPORTS: A CHALLENGE FOR EUROPE

According to our analysis, the absence of taxi-time reliability is a major handicap to airline operations. Thefigures gathered with Sabena show significant discrepancy between estimates and actual times for outboundflights. An unforeseen turn of events augment this uncertainty. This has a non-negligible effect on aircraftoperators punctuality and thus on airport (in particular Stand/Gate Management). As a consequence,ensuring compliance with CFMU slot window is not an idle task.

Better taxi time prediction would also profit to airport operations for planning purpose. The basic assumptionis the more accurate the information is the best you can plan your operations. This is particularly true forStand/Gate Management Purpose.

As an example, the length of delays in the United States has increased by 16 percent to 18 per cent from1995 to 1999, 82% of that increase being time spent sitting on the runways, waiting for take off or taxi to thegate. The consequence is that airlines are masking the extent of delays by lengthening scheduled flighttimes. That way, even if a flight takes longer than it did in the past is not officially recorded as delayed.Longer flight times added 130 million minutes of travel time for air passengers from 1998 to 1999(Washington Post � July 25,2000).

7.1 RESPONSIBILITIES

The problem of responsibility regarding the taxi out is important. If the responsibility of the aircraft operator inco-ordination with the local handler is to plan, share and update when appropriate103 an off-block time, theresponsibility for assessing a taxi-out time may depends on specific conditions and organisations (airport,ATC, or local handler in case of de-icing procedure).

The CFMU ATFM user manual104 specifies that �the AO is responsible for complying with a CTOT. �Toachieve this, AOs are to plan the departure of a flight so that the aircraft will be ready for start up in sufficienttime to comply with a CTOT taking into account of standard taxiing time (unless advise of change of thestandard taxi time) and any congestion known to them on the airfield.� Thus, the responsibility of complyingwith the CFMU slot105 being placed on aircraft operators, they would also need to calculate an estimated taxi-time. However they cannot compute a reliable taxi-time on their own.

Predicting a reliable taxi-time is a CDM process that relies on the reliability of off-block time predictability.

7.2 INITIAL THOUGHTS

Clearly predicting a reliable taxi-out time relies on:

� Aircraft Operators ability to publish reliable TOBTs 30 minutes before EOBT with sufficient accuracy.� Accurate TOBTs will allow ATC to predict reliable start up and pushback time, based on TOBTs.A statistical and topological approach help in determining the taxi-time. The approach to model the taxi-outprocess is to capture the observed statistical behaviour of the departure process106.� An approximate of taxi-out time of a particular aircraft (from pushback to takeoff) is determined first by

the departure congestion at pushback, that is the number of departing107 aircraft that are already on theairport surface but have not taken-off yet.

� Thus, the taxi-out time can be envisaged as the sum of a travel time (from the gate until the holdingpoint) plus a queue time (from holding point to take off) that correspond to eventual congestion, adverseconditions, etc.

T�taxi_out �� T��travel_time + T queue 108.

103 according to CFMU rules.104 CFMU ATFM User Manual, V7.0, edition Feb. 2001105 for regulated flights106 Initial work exist in the USA (Logan Airport) and Europe.107 Of course it is a simple approach that does not take into account the arrival process at the moment. 108 Ref. R.Shumsky (real-time forecasts of aircraft departure queues), N.Pujet, E.Feron, B.Delcaire (input-outputmodeling of the departure process of congested airports).



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When departure congestion is low, an unimpeded distribution of taxi-out times can be observed for anaircraft pushing back from a particular gate. In such situations (off peak hours), aircraft can reach their activerunways in a different order from their pushback sequence because the departure traffic is thenunconstrained.

7.2.1 Calibration of Ttravel_time

The determination of taxi-out times at off-peak hours will give a good indication of Ttravel_time since they usuallycorrespond to periods with little or no runway queue.

First, to capture the differences in travel time due to different gate locations, each gate ideally has to beassigned with an individual probability distribution.

Two steps are foreseen:

� Step 1: The initial step is to build a graph through historical data, with taxi-out time (minutes) in x-axisand probability of occurrence (0.05; 0.10; 0.15; 0.20 etc) in y-axis (Gaussian distribution).

� Step 2: Then the model can be refined by determining taxi-out times per gate or pool of gatesassignment (e.g. what is the distribution of taxi time per gate or pool of gates). Historical data will beused to calibrate the model. The result will show for each runway configuration the distribution of traveltime from the terminals to the departure runways.

In other terms, under a runway configuration ��the aircraft assigned to gate �� uses the taxiway ��and takes�� minutes to go to the departure runway. This would be achieved under light, moderate, and heavy trafficconditions as defined above.

It is intended that Gaussian or log normal distribution be used to model the travel time. For complex airportfor which different paths may exist to go from stand until holding point, a prediction of this path based onactual aircraft positions on taxiways might be performed.

7.2.2 Calibration of TQueue

Once reaching the runway, an aircraft usually enters a runway queue and its position in the queue becomefixed. The airport throughput seems primarily limited by this bottleneck effect at the runways. Runwayconfiguration and weather appear to be the primary factors that determine the behaviour of the runwayqueue. This includes the maximum runway throughput, the approach to throughput saturation that highlydepends on rising departure congestion.

Several parameters should be taken into account, amongst them:

� Determination of index ND: work performed at Boston Logan airport shows that each departing aircraftcan be assigned an index ND which counts the number of aircraft that take off whilst a particular flight istaxiing out on the airport surface. If an expected event affects this aircraft, as this aircraft may be passed by another departing aircraft, NDwill grow-up since a larger number of aircraft will take off will it stays in the queue.The effect of ND on the observed distribution of taxi-out time should be studied. It is intended that theobserved distribution will increase both in mean and variance as ND increases.



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FIGURE 13: TAXI-TIME OUT VARIABILITY AND DEPARTURES CONGESTION EFFECT

The analysis should be detailed along two axes: clement and inclement weather conditions and/or alongdifferent runway orientations.

� Determination of index NA: The taxi-out time may also depend on arrival congestion, e.g. departurecongestion may tend to increase as arrival congestion increases. The same analysis as the oneperformed for ND should be undertaken. For such we name NA the index of arrival congestion,measured as the number of arriving aircraft that are taxiing on the runways when a departing aircraftpushes back from the gate. An analysis should show if the increasing taxi-out times at Brussels Nationalairport is clearly related or not to levels of arrival congestion. Building praphics would help us in determining if the influence of arrivals is limited or not.

Potential influence of arrival congestion on taxi-out timeDistribution

Taxi-out Time 15mn 20mn 25mn 30mn 35mn 40mn 45mn

0.14

0.12

0.10

0.08

0.06

0.04

0.02

NA < 77 < NA < 15NA > 15

In that case, limited influence arrival congestion on taxi

FIGURE 14: TAXI-TIME OUT VARIABILITY AND ARRIVALS CONGESTION EFFECT

Potential effect of ND on taxi-out distributionDistribution

Taxi-out Time 15mn 20mn 25mn 30mn 35mn 40mn 45mn

0.14

0.12

0.10

0.08

0.06

0.04

0.02

ND < 7

7 < ND < 15

ND > 15



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7.3 EXPECTED BENEFITS

Significant benefits are expected from better take-off time reliability. In particular, the awareness of apredictable take-off time would help in predicting air situation. Combined with an accurate climbing profilecomputation, the confidence in predicting overdeliveries for eventual close regulations that protect the airportwould increase significantly.

The impact of overdeliveries is pernicious, as it can induce declarations of capacity under the relevant leveljust in order to protect controllers from facing too high peaks of traffic. It is considered a major weakness ofthe current system.

As such, the direct adverse effect of experiencing overdeliveries is the proclivity of FMPs to integrate anadded margin of safety when declaring their capacity. Thus, arguably, the same factors that contribute tooverdeliveries also contribute, in varying degrees, to under-utilisation. In addition, they imply that in anotherpart of the airspace, capacity is underused.

Predicting overdeliveries, even with a limited time horizon should trigger a new CDM process toavoid them. The ability of the airport users to reduce such overdeliveries should then encourage En-Route ATC to reduce over-protections and so, reduce underused ATC and increase airport capacity .

In other words, the capability for airport users to monitor, control, and give confidence in reducing theirnumber through enhanced predictability and collaborative measures will in return provide high benefitsthrough a reduction of ATC over-protections.



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8 A GLOBAL PICTURE

8.1 THE FOUR CRITICAL MOMENTS

As said earlier, implementing procedures or sharing information between partners is not a CDM target. Whatis at stake is to increase quality of data (completeness, accuracy, timeliness, reliability) for the benefit of theoverall ATM community.

Situation on the ground can be seen as a series of filters whose quality outcome of an upstream filterinfluences downstream ones. Four high level critical moments rhythm CDM airport operations:

� ETA (Estimated Time of Arrival): predicting a reliable and complete picture of inbound traffic is a sinequa non condition for downstream operations at an airport. If significant progress has been made sinceyears, reliable information is required from outstation to reach a high quality level;

� EIBT (Estimated In Block Time): estimating in-block time according to taxi-in time is a minor problem inBrussels compared to taxi-out compelling problem, because the variability of taxi-in time is low.

� TOBT (Target Off Block Time): the most difficult challenge for which we have developed the milestonesapproach and associated KPIs109. The reliability of the TOBT will encourage new CDM procedures (suchas pre-notice departure clearance) and reliable predictability of actual off block time.

� ETOT (Take Off Time): Advance predictability of off block time will bring tremendous benefits to keyusers by providing an essential input to a future tool of taxi-time prediction. The ultimate objective ofpredicting and sharing a reliable estimate of take-off time will enable an advance prediction ofoverdeliveries as well as early detection of CTOT non-compliance. Then collaborative CDM measurescould be put in place to reduce these overdeliveries and uncertainty about peaks that would in turnencourage FMPs to reduce capacity margin, contributing to increase airport capacity. Such approachcould then be linked with CDM ATFM measures.

The main CDM challenge is then to increase the quality of these data (completeness, accuracy, timelinessand predictability) and to reduce uncertainty.

The interdependency of data quality is also an important challenge since a bad quality observed about onedata influences downstream data quality. For instance, off-block accuracy and reliability directly influencesthe predictability of taxi-time, especially during hub waves. Predicting taxi-out time then directly relates to thequality of off-block times (inputs).

Thus the quality of data obtained for one critical moment can be considered as an outcome for downstreamdata quality, and so, the data quality associated to successive critical moments (arrival/in-block/off-block/take-off) has to be considered as a quality chain.

Main part of the effort spent on data quality relates to arrivals. Arrival managers, early ATC tracks detection,MVT and FSA messages participate in arrivals (touchdown) quality enhancement. Next future ETFMS(Enhanced Traffic Flow Management System) will provide additional benefits through CPRs and APRs.

The next complex and difficult challenge in Brussels is put on obtaining accurate and reliable off-blocktimes110.

This project has put an important emphasis on this challenge through our milestones� approach agreed by allactors and we hope that further implementation in 2002 (baseline, implementation of measures, comparison,calibration of CDM KPIs) will bring important benefits.

109 Key Performance Indicators.110 Accurate Taxi-in time in Brussels are obtained in the vast majority of cases (around 5�30 in Brussels).



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FIGURE 15: THE GLOBAL PICTURE

The last but not least difficult challenge would consist in a prediction of taxi-out time with a limited time-horizon that relies in part on upstream data quality. It is intended that complying with this objective will bringhigh benefits for all actors (CFMU, airport authorities, aircraft operators, ATC, FMPs), leading toimprovement for the passenger.

8.2 TOWARDS DATA QUALITY STANDARDISATION

Clearly, any flexibility in the system can be envisaged between actors once confidence in data quality isobtained (such as slot shifting, slot swapping [ATM Priorities]). On local airports, it is intended that CDMframework and data quality compliance will provide the necessary basis upon which any collaborativeprocedure can be specified and implemented. This is the case for the pre-notice departure clearancedescribed here that would be implemented once sufficient data quality about off-block data is obtained.

There is a need to identify, understand, categorise and quantify problems for sharing reliable information, ata local level but also at European level. For instance, all actors in Europe stand firm about the complexEOBT data accuracy and there is a huge need to solve such problems through shared understanding andagreed CDM procedures for the benefits of the overall community.

As enhancing quality has a cost, this should be balanced through clear and identified benefits. Clearly, thereis no interest for one actor to publish new data or enhancing quality if benefits for his operations are notclearly identified. Moreover, the dilution of committed efforts for better quality and objectives such as�enhancing the global situation� are not convincing for companies that would invest money for unclear returnon investments. Regarding aircraft operators, a possible but sensible idea would consist in examining areward system (through procedures, integration of preferences, etc. to be studied) for those that would investin the quality field, under the provision of data with an expected quality, (European indicators would have tobe carefully studied). The general assumption there is that companies that provide bad data quality might nothave the same service compared to those who invest and provide high data quality.

CDM

Handlers

ATC Airport

AOs CFMU FMPs

TA IBT OBT TOT

En-Route

CDM

Arrival In-Block Off-Block Take-Off

OBT

Off-Block

TOT

Take-Off

En-Route

CDM



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8.3 LINKING CDM-AIRPORT AND CDM-EN-ROUTE

The concepts of Airport-CDM and En-Route CDM are the main cornerstones of a future gate-to-gateimplementation in Europe that are closely interconnected.

CDM at airport is obviously directed towards real-time operations whilst current ATFM efforts are directedtowards pro-active planning. However, European projects (such as CEC NOAA111 project) have paved theway for En-Route CDM and developed real-time CDM measures. Such concepts have been re-visited112 thatprovide the link between two �CDM-Airports�.

Further studies will be required to define a consistent CDM bridge that involve all concerned actors in theloop (ATFM, ATC, airport authorities, aircraft operators and passengers), which will provide a first gate-to-gate CDM.

111 New Optimisation Approaches to ATFM.112 Eurocontrol Project FAM (Future ATFM Measures).



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Améliorer les opérations aéroportuaires par le recours à la CDM: Projet Zaventem 2001

Rapport CEE No.371 51

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TRADUCTION EN LANGUE FRANCAISE

AVANT-PROPOS

Les aéroports constituent des environnements naturellement propices à la prise de décision encollaboration, en ce sens que la plupart des acteurs du processus ATM113 y sont représentés et fonctionnenten interaction : autorités aéroportuaires, ATC114, exploitants d'aéronefs, services d'escale, CFMU115 etpassagers.Si une attention considérable a été accordée jusqu'ici à la diminution des retards ATFM116 en Europe, avecdes retombées bénéfiques substantielles pour la communauté européenne, peu d'efforts concertés ont, enrevanche, été consacrés à l'analyse des retards aux aéroports, aux problèmes engendrés par ces dernierset aux moyens d'y remédier. La nécessité de réduire les incertitudes aux aéroports et d'accroître l'efficacité se fait chaque jour plusimpérieuse. Améliorer l'efficacité d'un aéroport suppose une perception commune des problèmes et la miseau point de solutions coopératives, étayées par des éléments impulseurs appropriés. À ce jour, malgré les efforts déployés par les différents acteurs, le concept d'efficacité demeure axé surl'amélioration des diverses opérations, considérées isolément, au lieu d'envisager l'activité des utilisateursdes aéroports comme celle d'une équipe. Or, à moins de cibler des objectifs communs et d'aborder les problèmes collectivement, la somme desinitiatives individuelles est insuffisante pour permettre une exploitation partagée et optimisée de l'ensembledes ressources disponibles. Les acteurs peuvent poursuivre des objectifs différents, voire antagoniques,mais il ne sera véritablement possible d'assurer la meilleure utilisation de la capacité et des moyensdisponibles qu'à partir du moment où l'on aura fait la preuve d'avantages quantifiables et que l'on seraparvenu à vaincre progressivement les réticences, les attitudes de méfiance ou les entraves à lacoopération.

Les principaux défis que pose la CDM117 sont illustrés ci-après :

1. Le défi organisationnel : la CDM en tant que processus d'équipe

La qualité des performances repose souvent sur l'interaction entre individus appelés à travailler en équipe.Une des caractéristiques principales de toute équipe réside dans le fait que les individus qui la composentdoivent coordonner leurs décisions et leurs actions en partageant informations et ressources pour atteindredes buts communs. Tous les efforts visant à améliorer les performances d'une équipe doivent, à l'évidence,être axés sur les performances des individus. Toutefois, ces mêmes individus sont tributaires des autres membres de l'équipe pour obtenir desinformations et coordonner leur action. Communication, orientation, leadership, suivi, information en retour,appui et coordination constituent autant d'éléments fondamentaux de la CDM. La CDM supposent que les acteurs adoptent une attitude positive envers les autres, aient reçu desinstructions et un soutien adéquats pour atteindre des objectifs communs et sachent en quoi consiste leurmission ainsi que celle des autres membres avec lesquels ils doivent interagir. Le respect de ces exigencespermettra aux acteurs de coordonner leurs activités par le jeu du partage des expériences, du suivi de lacoordination, de la synchronisation des opérations, de la communication et de la fourniture d'une informationen retour ainsi que d'une assistance en tant que de besoin. L'ampleur du défi réside dans le passage dustade de l'acteur individuel, remplissant un rôle et des tâches spécifiques, à celui de l'équipe, où uneinteraction, une coordination ainsi que des procédures et des décisions en collaboration sont nécessairespour atteindre des buts et des résultats communs.

L'expérience acquise à ce jour montre que deux principes CDM doivent être respectés : 113 Gestion de la circulation aérienne114 Contrôle de la circulation aérienne115 Organisme central de gestion des courants de trafic aérien (Eurocontrol)116 Gestion des courants de trafic aérien117 Prise de décision en collaboration


52 Rapport CEE No.371

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� le partage d'informations nouvelles ou l'amélioration de la QoS118 doit être payé(e) en retour par desavantages quantifiables pour son initiateur ;

� corollairement, des incitations à partager des informations nouvelles ou à améliorer la qualité du servicedoivent être trouvées pour éliminer les pénalités et récompenser les entités qui �uvrent à uneamélioration de la situation.Pour ce faire, il est recommandé d'analyser les obstacles mis à la notification de toute information à uneautre entité en raison de possibles pénalités et d'étudier les moyens ainsi qu'une procédure nouvellepropres à éliminer de telles entraves.

2. Le défi de la qualité des données : partager des informations fiables sur les heures d'arrivée et dedépart

Il ressort de l'expérience de la CDM menée à ce jour dans les aéroports que l'un des principaux élémentscontribuant à la diminution générale des retards en Europe et à l'utilisation optimale des maigres ressourcesdisponibles consiste en l'amélioration de la fiabilité et de la prédictibilité d'un ensemble très restreint dedonnées aux aéroports. Les aéroports constituant les n�uds physiques du réseau du trafic aérien en Europe, la mise en �uvred'une approche commune et l'évaluation des avantages escomptés dans le cadre d'essais en conditionsréelles devraient transcender le contexte local de quelques sites donnés pour prendre, à terme, unedimension européenne.La précision, la ponctualité, la fiabilité et la prédictibilité des données d'arrivée et de départ (ETA, EIBT,EOBT, ETOT119) de même que leur connectivité sont autant d'éléments essentiels pour tous les usagers, ycompris le CFMU. Bien que des initiatives aient déjà été prises pour améliorer la précision et la prédictibilité des heuresd'atterrissage, deux éléments impulseurs fondamentaux mériteraient d'être pris en considération à l'échelleeuropéenne afin de cibler deux liens distincts :

� De la pose à l'enlèvement des cales : mise en �uvre d'une approche reposant sur des jalonspour améliorer la précision et la prédictibilité de l'OBT120. La démarche du projet a consisté àenvisager la notion de processus CDM d'escale sous l'angle d'un ensemble de procédures et de jalonsponctuant le déroulement usuel des opérations d'escale. À partir de la station de départ, ces jalonsfournissent des renseignements clés qui permettent d'affiner l'information contextuelle de tous lesacteurs à la station d'arrivée, déclenchent l'actualisation des informations en aval et contribuent à cernerles retards potentiels des aéronefs, de manière à permettre la prise de décisions en collaboration.Élaborée en association avec la Sabena, BIAC121 et Belgocontrol, l'approche retenue a été réutiliséedans le cadre du projet CDM Barcelone. La démarche suivie est documentée dans le présent rapport.Des essais en conditions réelles auront lieu à Bruxelles et à Barcelone en 2002 (moyennant de légèresdifférences sur le plan de la mise en �uvre), qui nous permettront de dégager des concepts génériquesse prêtant à une application à l'échelle européenne et d'en recenser clairement les avantages.

� De l'arrivée à la pose des cales et de l'enlèvement des cales au décollage : prévoir de manièrefiable le temps de circulation au sol122, même avec un horizon temporel restreint, constituerait laprochaine étape porteuse d'avantages considérables. La variabilité du temps de circulation au solest un problème commun à la plupart des aéroports européens (de 5 à 45 minutes pour le roulage audépart à Bruxelles). Bien qu'il existe déjà des dispositifs de planification des opérations de roulage surcertains aéroports (temps de circulation au sol calculés sur la base de statistiques intégrant différentesvariables), le défi consiste à mettre au point un outil à vocation européenne permettant de prévoir lasituation à quelques minutes sur n'importe quel aéroport. De nouvelles procédures interactivespourraient alors être imaginées entre les différents acteurs (CFMU, ATC, compagnies aériennes,services d'escale et aéroports).

118 Qualité de service119 ETA : heure estimée d'arrivée ; EIBT : heure estimée d'arrivée sur l'aire de stationnement ; EOBT : heure estimée dedépart de l'aire de stationnement ; ETOT : heure estimée de décollage120 Heure départ de l'aire de stationnement121 Brussels International Airport Company (autorités aéroportuaires)122 L'enjeu, à Bruxelles, porte sur la prédictibilité du temps de roulage départ. Ce dernier peut, selon les conditions(configuration des pistes, météo, poste/porte, vague des arrivées/départs sur la plateforme de correspondance, etc.)varier de 5 à 45 minutes. À titre de comparaison, à CDG, le problème de la variabilité et de la prédictibilité du temps deroulage concerne tant les arrivées que les départs.



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À l'heure actuelle, plusieurs initiatives ont été lancées en Europe123, qui reposent sur :

� des méthodes statistiques, combinant données statiques et dynamiques et dont les formules fontintervenir des données d'archive réelles � la qualité des résultats est évidemment en rapport directavec la précision de l'heure estimée de départ de l'aire de stationnement124 ;

� des méthodes topographiques (pour les aéroports de configuration complexe), intégrant desalgorithmes de prévision du circuit de roulage et de détermination du temps de circulation au sol.

3. Le défi de la mise en �uvre L'activité de mesure est au c�ur du processus d'évaluation et d'élaboration de théories. Il est nécessaireque des concepts et des critères de performance essentiels soient mis en �uvre pour analyser correctementles avantages intrinsèques de l'approche retenue. Si les projets de Bruxelles et Barcelone appliquentl'approche avec de légères différences, l'évaluation des avantages découlant tant de ces deux projets quede ceux qui seront menés en 2002 ouvrira la voie à la mise au point de concepts CDM génériques ainsi quede recommandations en la matière, et permettra de constituer un argumentaire CDM pour l'Europe.

4. Cerner et éliminer les obstacles à la CDM

Bon nombre des informations requises pour améliorer les processus mis en �uvre par les acteurs sont déjàdisponibles mais ne sont pas divulguées, faute de motif suffisant sur le plan opérationnel ou économique ouen raison d'évidentes contre incitations en termes de pénalités subies. Ainsi, pour échapper au mécanisme de "double pénalisation", les exploitants d'aéronefs ont pour habitudede maintenir une OBT interne qui peut, dans certaines situations, différer de celle qui a été communiquée àl'ATC et au CFMU (EOBT). Bien que le problème soit clairement reconnu par l'ensemble des parties, unesorte de dialogue de sourds s'est instauré entre les acteurs, qui se traduit par une sous-utilisation de lacapacité et des moyens disponibles (pistes et voies de circulation), le non-respect des créneaux ATFM, dessurcharges de secteur, etc.

Nous avons mis au point le concept d'heure cible de départ de l'aire de stationnement (TOBT) en réponse aubesoin exprimé par l'ATC, les autorités aéroportuaires et la Sabena de connaître les vues des exploitants etconsignataires d'aéronefs sur l'OBT interne. La Sabena a accepté de communiquer la TOBT à l'ATC et auxautorités aéroportuaires, et a proposé d'en contrôler la qualité. L'obtention du niveau de qualité requis (entermes de précision et de ponctualité) se traduira, pour l'exploitant d'aéronefs, par des changements moinsfréquents de poste de stationnement ou de porte d'embarquement et la mise en �uvre de nouvellesprocédures (gestion des pré départs, etc.). D'une manière générale, il y a lieu de cerner tous les freins au partage des informations entre les acteurs(ATC, aéroports, compagnies aériennes, agents de service d'escale, CFMU), d'en analyser les raisons sous-jacentes, de chiffrer leurs incidences et de mettre au point des solutions coopératives.

5. Instaurer des indicateurs de performances essentiels pour la CDM

La qualité des données est un élément impulseur fondamental de tout processus CDM. En l'absence dedéfinitions de la qualité des données, les procédures CDM n'apporteront aucune amélioration et pourraientmême susciter une aggravation de la situation, dans la mesure où les exploitants attendraient des décisionsfondées sur des informations hautement fiables, alors que tel ne serait pas le cas.

Nous avons mis au point un ensemble d'indicateurs de performances essentiels à l'appui de notre approchepar jalons. De prochains essais permettront d'élaborer un cadre de qualité des données, dont les éléments(précision, ponctualité, etc.) seront étalonnés et affinés au travers d'expérimentations. Une charte de qualité CDM, matérialisée par des accords de niveau de service entre les différents acteurs etpar une procédure de suivi connexe, sera ensuite établie. La démarche suivante consistera à donner à cettecharte une dimension européenne.

123 Aux États-Unis (aéroport de Boston Logan), des travaux de recherche ont été entrepris, qui portent sur le calculdynamique du temps de roulage et l'utilisation efficace de données dynamiques (dispositifs de mise en file d'attente).124 Selon la configuration de l'aéroport, le temps de roulage peut varier considérablement d'une porte d'embarquement àl'autre. D'autres facteurs que l'emplacement physique de la porte d'embarquement peuvent influer sur le temps deroulage, comme les conditions météorologiques et le mode de circulation au sol de l'aéronef.



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6. Nécessité commune, à l'échelle européenne, de prévoir le temps de circulation au sol

Planifier dans l'incertitude est contre-productif et partager des informations non fiables, inutile : il en résultedes retards très importants à l'échelle européenne, matérialisés par une boucle fermée d'influences decause à effet entre les acteurs. Peu de démarches ont été entreprises à ce jour pour mettre ces effets enrelation et en calculer le coût.

Un élément impulseur indispensable pour une bonne gestion des départs réside dans la capacité, pour lesacteurs du dispositif aéroportuaire, de partager des données plus fiables et assorties d'un horizon temporelrestreint concernant quatre moments critiques : arrivée, arrivée sur l'aire de stationnement, départ de l'airede stationnement et décollage. Dans le présent document, une attention particulière a été accordée à lafiabilité de l'heure de départ de l'aire de stationnement. Toute prévision fondée sur des données non fiablesétant, par essence, sans valeur, le premier défi de la CDM portera donc sur la qualité des informations.

La qualité des prévisions de l'heure d'arrivée sur l'aire de stationnement et de l'heure de décollage reposesur la détermination la plus exacte possible du temps de circulation au sol (roulage à l'arrivée et au départ).Or, si la variabilité du temps de roulage est un problème commun aux aéroports125, la responsabilité del'établissement des prévisions/calculs en la matière n'est pas établie avec certitude. Ainsi, il incombe àl'exploitant d'aéronefs de se conformer à sa CTOT126, qui repose sur une estimation du temps de roulage.Mais les exploitants d'aéronefs ne sont pas en mesure de prévoir ce temps de roulage, car ce dernier esttributaire d'un certain nombre de facteurs extérieurs.

La détermination d'un temps de roulage fiable sur les aéroports européens sera porteuse d'avantagesconsidérables. Une première étape a été franchie avec l'introduction, par le CFMU, du concept de temps deroulage flexible (déterminé à partir de données statistiques d'aéroports), mais une approche plus dynamiques'impose d'évidence.

Des travaux de recherche isolés ont été entrepris127 en Europe ; toutefois, il serait infiniment plusavantageux d'engager un effort de recherche conjoint pour mettre au point un outil européen commun dedétermination du temps de roulage, dont les performances seraient bien évidemment liées à la qualité desparamètres temps réel de chaque aéroport.

7. Nécessité d'une approche unificatrice de la CDM dans une perspective européenne

L'expérience acquise aux États-Unis montre que l'un des principaux facteurs de réussite de la CDM résidedans l'uniformisation des outils. En Europe, des initiatives ont été lancées à l'échelon aéroportuaire localmais une perspective européenne s'impose dans le contexte de la CDM entre aéroports. La définitiond'interfaces externes, de niveaux de qualité des données et d'outils/d'éléments impulseurs potentielscontribuera à élargir le cadre de la CDM en Europe. Le futur ETFMS128 du CFMU pourrait servir defondement à la mise en place d'un réseau CDM européen.

125 Roulage au départ et/ou à l'arrivée126 Réf. : Manuel CFMU des utilisateurs ATFM, V7.0 : CTOT : heure calculée de décollage, communiquée par le CFMUpour les vols régulés.127 En France notamment, au Centre d'études de la navigation aérienne (CENA)128 Système amélioré de gestion tactique des courants de trafic



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1 GENERALITES

1.1 CONTEXTE GÉNÉRAL

De nombreux travaux indépendants sont actuellement menés, au sein de la communauté ATM européenne,qui ont pour objet d'améliorer la coopération, la communication et le partage de l'information. Le Centreexpérimental Eurocontrol (CEE) s'intéresse au concept de prise de décision en collaboration (CDM) depuis1998 et a déjà réalisé de multiples études exploratoires sur la question ([ATFM Priorities] (1998), [CDMExpert Group] (1999), [FASTER Study] (1999), [CDM Applications] (1999), [ATFM improvement] (2000), [A-CDM-D Evaluation] (2000)).

En 2001, deux projets visant à expérimenter concrètement la CDM sur deux aéroports (Bruxelles etBarcelone) ont été mis au point par le domaine PFE (Performance, Flow Management, Economics andEfficiency) du CEE. Ces deux projets, distincts, ont été menés en collaboration avec des acteurs locaux :

� Brussels International Airport Company (BIAC), Sabena (en tant qu'exploitant d'aéronefs et agent deservice d'escale) et Belgocontrol (ATC), pour Bruxelles ;

� Aéroport de Barcelone (AENA), Iberia, Spanair, Eurohandling (agent de service d'escale) ainsi queFMP129, TWR et CCR Barcelone (AENA), pour Barcelone.

Le présent rapport relate l'expérience acquise dans le cadre du projet CDM Bruxelles, dresse un bilanintermédiaire et met en évidence les prochains défis et étapes ultérieures du projet.

129 Poste de gestion des courants de trafic



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2 DETERMINER LES OBJECTIFS A COURT TERME DE LA CDM

La mise en �uvre de procédures ou le partage de l'information entre partenaires ne constitue pas unobjectif. Le véritable enjeu consiste à recenser des objectifs à court terme précis et chiffrables, ainsi que leséléments permettant de les atteindre. Plusieurs ateliers ont été consacrés à la définition d'objectifs à courtterme communs pour la CDM. Six objectifs ont ainsi été définis, qui sont résumés ci-après.

2.1 OBJECTIF 1 : RÉDUIRE LA FRÉQUENCE DES RÉATTRIBUTIONS DE POSTE DESTATIONNEMENT/PORTE D'EMBARQUEMENT

L'objectif convenu est de réduire la fréquence des réattributions de poste de stationnement/ported'embarquement dans les 30 minutes précédant l'arrivée à Bruxelles.

Les chiffres font apparaître que plus de 20 % des vols à l'arrivée sur Bruxelles se voient réattribuerun nouveau poste de stationnement ou une nouvelle porte d'embarquement dans l'intervalle [ATA�30�; ATA]; (moyenne : 1,2130).

L'objectif du planificateur est d'optimiser la gestion des postes de stationnement/portes d'embarquement,d'attribuer ces derniers en tenant des compte des préférences des exploitants d'aéronefs et d'accroître lasécurité sur la zone aéroportuaire en réduisant le nombre de mouvements de véhicules sur le tarmac.

Des problèmes surgissent fréquemment lorsqu'un aéronef a atterri et entamé sa rotation comme prévu, maisfait ensuite l'objet de perturbations internes. De fait, dans les trente minutes précédant l'arrivée du volsuivant, de nombreuses raisons peuvent conduire une compagnie aérienne à devoir rester plus longtempsque prévu sur l'aire de stationnement. Ce délai supplémentaire peut être imputable au retard escompté d'unecorrespondance ou à un événement imprévu pendant les opérations d'escale : cela peut aller d'une incidentà l'embarquement des passagers à des problèmes de tri des bagages.

FIGURE 1 : PLANIFIER LES POSTES DE STATIONNEMENT/PORTES D'EMBARQUEMENT DANSL'INCERTITUDE

130 Une moyenne supérieure à 1 traduit le fait que, dans certains cas, plus d'un changement de poste/porte intervientdans les trente minutes précédant l'arrivée.

Last minute gate changeLast minute gate change Waste of CapacityWaste of CapacityUncertaintyUncertainty

S/G ManagmentSlack Time 15�

Slack Time 15�

EIBT EOBT EIBT EOBT

AIBT

Disruption (missing pax, connecting px)

AOBT EIBT

2� Reality

AIBT

Gaming Theory ...... Experience may lead to late S/G change

SAB2468SAB1357



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En matière de gestion des postes/portes, le délai tampon standard entre les arrivées et les départs est de 15minutes. Un conflit peut surgir lorsqu'une erreur cumulée entre l'arrivée et le départ excède ce délai.Exemple le plus fréquent, un vol à l'arrivée sur Bruxelles se voit attribuer un nouveau poste de stationnementou une nouvelle porte d'embarquement parce que l'aéronef qui devrait effectuer à ce moment là saman�uvre de refoulement est demeuré sur place pour une raison quelconque (perturbation, problème dedernière minute, absence du tracteur, autorisation de mise en route non reçue, etc.).

Le gestionnaire des aires de stationnement se voit ainsi soumis à une pression croissante lorsque sa margede man�uvre est réduite à 5 minutes, voire moins. L'enjeu consiste alors à évaluer la probabilité quel'aéronef au sol quitte son emplacement juste avant l'arrivée du vol suivant. Une mauvaise estimation en la matière entraînera automatiquement un changement de porte de dernièreminute, comme illustré à la Figure 16.

2.2 OBJECTIF 2 : AMÉLIORER LA PRÉCISION DES CRÉNEAUX DU CFMU

L'objectif est d'améliorer la précision des créneaux du CFMU par l'introduction du concept de temps decirculation flexible à l'aéroport de Zaventem. La variabilité du temps de roulage au départ sur l'aéroport deBruxelles nuit à l'efficacité générale, à la prédictibilité de l'heure de décollage et au bon déroulement desopérations du CFMU. La conséquence immédiate en est le non-respect de la CTOT131, qui peut entraînerdes surcharges de secteur. À l'heure actuelle, le paramètre de temps de roulage au départ a été fixé par leCFMU à 20 minutes, mais la valeur réelle peut osciller de 5 à 45 minutes. L'instauration d'un temps deroulage flexible, fondé sur une analyse statistique pertinente, permettra de réduire l'écart par rapport à laréalité, d'attribuer de meilleurs créneaux aux exploitants d'aéronefs, de mieux garantir le respect descréneaux ATFM et de contribuer à une plus grande efficacité du CFMU.

2.3 OBJECTIF 3 : AMÉLIORER LA PRÉCISION ET LA PRÉDICTIBILITÉ DU TEMPS DEROULAGE AU DÉPART

Tous les acteurs ont souligné le fait que le temps de roulage au départ est tributaire de divers facteurs (traficde pointe, conditions météorologiques, etc.) qui ne sont pas pris en considération dans la détermination del'heure de décollage. Associée à une OBT précise, une prévision fiable du temps de roulage au départ(même avec un horizon temporel limité) permettrait d'obtenir une estimation correcte de l'heure dedécollage, ce qui pourrait notamment conduire à une détection précoce du non-respect de la CTOT et deses incidences potentielles.

2.4 OBJECTIF 4 : S'ORIENTER VERS UNE PLANIFICATION STRATÉGIQUE COOPÉRATIVE

Une coordination des différents plans entre le gestionnaire de créneaux d'aéroport, l'ATC et les autoritésaéroportuaires est requise. La planification semble actuellement reposer sur un horizon temporel limité à 15minutes, sans tenir compte de l'influence du temps de roulage, ni de la capacité des secteurs. Alors que lemécanisme d'allocation se fonde sur un chiffre de 70 mouvements par heure, il arrive que le taux horaireeffectif soit supérieur à 90 mouvements. Qui plus est, il n'y a pas de lien entre le créneau d'aéroport etl'heure calculée de décollage.

Par conséquent, il conviendrait que la planification des créneaux soit validée conjointement, aux échelonsstratégique et prétactique, par le gestionnaire des créneaux d'aéroport, l'ATC et les autorités aéroportuaires,et étayée par une comparaison entre la capacité aéroportuaire et les horaires de vol, le principe étant quel'infrastructure aéroportuaire et l'utilisation de la capacité constituent les pierres angulaires de ladétermination du nombre de créneaux d'aéroport pouvant être alloués.

À l'échelon tactique, on relève des abus qui peuvent être prouvés, mais qui n'entraînent cependant aucunepénalité pour ceux qui ne se conforment pas aux créneaux d'aéroport. Une coordination et un appui plussoutenus sont nécessaires pour garantir le respect des créneaux d'aéroport132.

131 Cf. Annexe A (Statistiques concernant le respect des créneaux ATFM) : en juin 2001, 42,3 % des vols au départ deBruxelles n'ont pas respecté le créneau alloué par le CFMU.132 Il a été prévu de mettre en �uvre, d'ici à l'été 2002, un projet axé sur une meilleure détection des abus commis àl'échelon tant de la planification que de l'exploitation.



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2.5 OBJECTIF 5 : S'ORIENTER VERS UN PROCESSUS COOPÉRATIF DE GESTION DESPERTURBATIONS DE TRAFIC

L'opinion qui prévaut actuellement est que l'on ne dispose pas d'un nombre suffisant d'informations fiablesen cas de perturbation grave du trafic (données, intentions). En cas de mauvaises conditionsmétéorologiques par exemple, les informations relatives aux réacheminements semblent difficiles à obtenir.En ce qui concerne les vols au départ, l'actualisation ou la suppression des plans de vol ne se fait pas oualors tardivement. La fourniture en temps opportun d'informations fiables constituerait un premier pas versune optimisation de l'organisation et des procédures de reprise, avantageuse pour l'ensemble des acteursaéroportuaires.

Un progrès sensible par rapport à la situation actuelle serait une meilleure diffusion des informationsconcernant les perturbations affectant les vols à l'arrivée. Dans certains cas, Bruxelles ne dispose d'aucuneinformation (sinon des données incomplètes et périmées) sur les vols retardés en provenance de la stationde départ. Pour ces vols, aucun renseignement ne peut être obtenu avant l'envoi du message MVT133.L'instauration de mécanismes et de procédures de notification anticipée permettrait à l'évidence d'améliorerla gestion des postes de stationnement et des portes d'embarquement. Une autre mesure utile consisterait àcoordonner l'annulation des vols en cas de perturbation grave du trafic sur un aéroport.

2.6 OBJECTIF 6 : DIFFUSER LES DONNÉES PAX/BAX CONCERNANT LES VOLS ÀL'ARRIVÉE

Le besoin exprimé ici porte sur la notification des informations concernant les passagers de tous les vols àl'arrivée : nombre total de passagers et renseignements concernant les passagers en transit(nombre/origine, prochain(e) destination/indicatif de vol et nombre par destination/indicatif de vol). Dansl'hypothèse où des renseignement concernant les passagers seraient également disponibles pour tous lesvols au départ pris en charge à Bruxelles, les autorités aéroportuaires (BIAC) pourraient déduire de cetteinformation un coefficient de bagages et, partant, accroître l'efficacité et la qualité de plusieursressources/équipements/processus qui se situent largement en dehors du domaine de l'attribution despostes de stationnement et portes d'embarquement. Une telle démarche permettrait de mieux intégrerdifférents processus d'aéroport au bénéfice de toutes les parties concernées.

Le bien-fondé de ce besoin réside dans l'optimisation de l'exploitation des ressources (passerellesd'embarquement, portes (à accès direct ou déporté), bus, tapis convoyeurs de bagages, contrôles frontaliersnon-Schengen, accès à la zone Schengen, contrôles filtrants de sécurité (vols Schengen/non-Schengen),etc.) et l'amélioration corollaire du confort des passagers ainsi que la réduction générale des files d'attente etde la longueur/durée des déplacements/transferts. Les opérations d'embarquement s'en trouveront facilitées,ce qui contribuera à la réalisation de l'objectif du présent projet, à savoir la ponctualité.

Ce besoin devrait être satisfait par l'ensemble des agents d'escale/compagnies aériennes134.

En outre, le nouveau système de facturation de BIAC prévoit que cette dernière prend à sa charge lesdéplacements en bus, d'où l'intérêt manifeste pour cette dernière de supprimer les mouvements superflus.

133 Message de mouvement134 Les informations PAX/BAX concernant les vols Sabena sont accessibles via le système AIMS.



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3 CONCEVOIR DES SOLUTIONS CDM

3.1 INTRODUCTION

Plusieurs ateliers ont été organisés sur le thème des objectifs retenus. Les échanges de vues ontnotamment porté sur les vols à l'arrivée ainsi que sur les liens entre ces derniers et les vols au départ. Lanécessité, pour le site de Bruxelles, de recueillir et de partager des informations ponctuelles et précises surles retards a été reconnue comme l'une des pierres angulaires de la CDM.

Il a été fait observer que les stations de départ proches de Bruxelles affichent des performances médiocres,préjudiciables au bon fonctionnement Bruxelles : on citera en particulier une mauvaise réactivité pour causede notification très tardive. Le recours futur aux rapports de progression de vol du CFMU (ETFMS135) aurades retombées bénéfiques sur la gestion des vols arrivant à Bruxelles. Il a été proposé, à titre de mesuregénérale, que les OCC136 des compagnies relaient (automatiquement), vers les différents sites, lesinformations concernant les retards des vols à l'arrivée, en lieu et place d'une communication de point àpoint entre les stations de départ et d'arrivée. Les utilisateurs du site de Bruxelles ont indiqué que sicertaines stations jouent franc jeu en matière de notification des retards, d'autres se monteraient plutôtréticentes à cet égard.

Les acteurs sont convenus d'étudier les causes et les symptômes avec toutes les parties concernées.L'élimination d'un pourcentage considérable de changements de dernière minute pour les passagers aurapour effet de réduire le facteur d'incertitude et les déplacements superflus dans le terminal. En ce qui concerne les vols au départ, 24% des changements de porte d'embarquement (opérés au coursde la période [STD137 � 24h jusqu'à à l'ATD138]) ont effectivement lieu entre [STD � 90' et l'AOBT139].

3.2 ÉLÉMENTS IMPULSEURS INITIAUX DE LA CDM

De l'avis unanime des acteurs, la principale pierre d'achoppement est la qualité des données relatives auxdéparts et aux arrivées. Or, il est d'une importance capitale de disposer d'informations fiables tant sur lesvols à l'arrivée (heure d'arrivée sur l'aéroport, heure d'arrivée sur l'aire de stationnement) que sur les vols audépart (heure de départ de l'aire de stationnement, heure de décollage), si l'on veut réduire la fréquence deschangements de poste de stationnement ou de porte d'embarquement.

Plusieurs propositions/éléments facilitateurs ont été recensés, dont on trouvera la description dans lessections ci-après :

� Arrivées et départs : mise en �uvre d'une approche ponctuée de jalons.

� Arrivées :

� diffusion des informations disponibles à la station de départ (ETD/ETA) ;� point de vue de la gestion des postes/portes d'aéroport sur les décisions opérationnelles du CFMU ;� mise à jour des ETA en route et des ETD pour les prochaines étapes de vol.

� Départs :

� détermination d'une heure cible de départ de l'aire de stationnement (TOBT) fiable ;� détermination d'un temps de roulage départ précis ;� instauration d'un préavis d'autorisation de mise en route des moteurs.

135 Système amélioré de gestion tactique des courants de trafic (CFMU)136 Centres de contrôle d'exploitation137 Heure départ standard138 Heure de départ effective139 Heure effective de départ de l'aire de stationnement



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Afin d'améliorer la fiabilité des estimations en provenance d'une station de départ, la Sabena a acceptéde mettre en �uvre quatre nouvelles mesures :

� confirmer et/ou actualiser les EOBT de la station de départ 20' avant et communiquer l'ETA ainsi quel'EIBT des vols concernés ;

� publier, à chaque révision de l'ETA, des EOBT révisées pour l'étape de vol suivante ou les vols decorrespondance ;

� communiquer tous les messages de mouvement à l'ATC, aux autorités aéroportuaires et auxservices d'escale de la plateforme de correspondance ;

� communiquer tous les retards supérieurs à 10 minutes aux autres acteurs de la plateforme decorrespondance.

� Liens avec le CFMUÀ l'heure actuelle, les autorités aéroportuaires de Bruxelles ne reçoivent aucune information du CFMU.Or, certaines données concernant les vols à l'arrivée, notamment les messages CTOT et FSA140,présenteraient un intérêt manifeste. La stabilité de l'information CTOT étant toutefois sujette à cautionjusqu'au départ, la CTOT initiale (pour les vols régulés) et sa valeur à la TRS141 ont été proposéescomme données CFMU pouvant être communiquées aux autorités aéroportuaires de Bruxelles pour cequi est des vols à l'arrivée. Par ailleurs, les messages FSA compléteront utilement les messages MVT,dans un souci d'exhaustivité. Enfin, il convient de rappeler que la diffusion des comptes rendusactualisés de progression de vol qui seront établis par le futur ETFMS revêt également un intérêtconsidérable.

En résumé, les attentes actuelles en ce qui concerne les vols à l'arrivée sont les suivantes :

� communication des créneaux CFMU et des valeurs TRS aux aéroports ; le paramètre TRS, combinéà la valeur du créneau CFMU, indiquera que ledit créneau ne sera plus modifié ;

� communication des messages FSA ;� dans le contexte du futur ETFMS : communication des CPR142 et APR143.

De son côté, le CFMU pourrait être intéressé par la réception d'estimations fiables sur les TOBT et lestemps de roulage au départ.

3.3 L'APPROCHE FONDÉE SUR DES JALONS

La planification peut se définir comme la tâche consistant à cerner les interactions actuelles et futures avecle monde réel pour atteindre des objectifs déterminés. Au plan formel, elle revêt l'aspect d'une rechercheciblée visant à faire passer les choses d'un état défini à un autre par le jeu d'opérateurs ou d'actions.Appliqué aux opérations de rotation, le recours à la planification en tant qu'outil de suivi étroit et prospectif(réactif ou dynamique) se fonde sur le principe que des solutions adéquates doivent être trouvées pourpermettre à la fois une planification sur la base de la demande en temps réel et une planification dans uncontexte d'incertitude.

L'incertitude est l'ennemie de l'efficacité. À propos de l'incertitude, et malgré d'inévitables erreurs de mesure,on peut formuler les affirmations suivantes :

� le degré d'incertitude d'une prévision augmente proportionnellement à l'horizon temporel ;

� il existe différents degrés de certitude, selon les acteurs qui fournissent l'information (degré de certitude).

L'incertitude est principalement entretenue par l'imprécision des signaux, l'imprécision ou l'inexactitude desprévisions et le caractère aléatoire de l'évolution du contexte opérationnel, des contraintes, des objectifs, etc.

140 Première activation du système141 Heure de retrait de la séquence142 Comptes rendus de position corrélés143 Comptes rendus de position d'aéronef



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Les incertitudes, contraintes et perturbations qui peuvent surgir avant et pendant les opérations nuisent audéroulement efficace de ces dernières. Le paradigme CDM se fonde sur le double postulat que laconnaissance partagée des données et la communication aussi rapide que possible des conséquences desdécisions prises contribueront à l'optimisation des ressources disponibles.

� Le concept de "moments critiques" (jalons) : Ce constat nous a amenés à définir une série de"moments critiques" entre les stations d'arrivée et de départ, dont l'occurrence vient ponctuer ledéroulement normal des opérations d'escale. À partir de la station de départ, ces jalons fournissent desrenseignements clés qui :� permettent d'affiner l'information contextuelle de tous les acteurs à la station d'arrivée ;� déclenchent l'actualisation des informations en aval ;� contribuent à cerner les retards potentiels des aéronefs, déclenchent le mécanisme de

replanification et permettent la prise de décisions en collaboration.

� Étendre l'horizon prospectif tout en le maintenant dans de justes proportions : Tout processus deplanification réactive doit se fonder sur une comparaison permanente entre l'état du réel etl'environnement tel que planifié au moment considéré. On peut parler ici de suivi de planification, dontl'aboutissement est évaluer la différence entre la situation planifiée et la situation réelle par l'applicationd'un certain "élément prospectif". La corrélation entre la portée de l'horizon temporel et la croissance dufacteur d'incertitude nous amène à penser que la planification devrait s'opérer sur la base d'unhorizon temporel limité et glissant144, de manière à affiner la qualité des plans grâce à une stabilité etune qualité accrues des données transmises.

3.3.1 Cadre général

Dix-neuf jalons ont été recensés pour les vols à l'arrivée et au départ, qui visent à :

� favoriser une meilleure connaissance des informations essentielles pour les utilisateurs ;� définir précisément une série d'événements et d'éléments déclencheurs d'informations connexes ;� étayer le suivi de la précision des données ;� mettre en place, pour les utilisateurs des aéroports, un cadre décisionnel fondé sur un horizon temporel

glissant de 30 minutes ;� permettre l'adoption de procédures et de décisions en collaboration.

Dans le cadre de notre approche globale, nous considérons :

� le vol à l'arrivée à la station de départ : index [N-1] ;� le vol entre la station de départ et la station d'arrivée : index [N],� le vol au départ de la plateforme de correspondance: index [N+1].

Les abréviations suivantes sont utilisées :

� EOBT/TOBT: heure estimée de départ de l'aire de stationnement, heure cible de départ de l'aire destationnement ;

� SIT1: heure de publication d'une CTOT par le CFMU (pour les vols régulés) : EOBT�2h;� ETA/ATA: heure estimée d'arrivée, heure effective d'arrivée ;� AOBT/AIBT: heure effective de départ de l'aire de stationnement, heure effective d'arrivée sur l'aire de

stationnement ;� Opérations au sol :

� FDO (ouverture de la première porte de l'aéronef)� SB (début de l'embarquement)� GC (fermeture de la porte d'embarquement)� DC (fermeture de toutes les portes de l'aéronef)� SUR (demande d'autorisation de mise en route des moteurs)� SUC (autorisation de mise en route des moteurs)

144 Les participants se sont engagés à mettre en �uvre un horizon temporel glissant de 30 minutes.



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3.3.2 L'heure cible de départ de l'aire de stationnement

Un attention particulière a été accordée, dans le cadre du projet, à la précision de l'EOBT communiquée parl'exploitant d'aéronefs. La fiabilité de l'heure de départ de l'aire de stationnement revêt en effet uneimportance capitale pour l'ATC, le CFMU et les autorités aéroportuaires.

Or, il apparaît d'évidence que, dans certaines situations, les exploitants d'aéronefs n'ont aucunintérêt à modifier leur heure effective de départ de l'aire de stationnement, en particulier lorsque levol considéré est soumis à une mesure de régulation, ce qui peut alors se traduire par une "doublepénalisation". Ces incohérences se répercutent dans différents systèmes (CFMU et ATC), avec commeconséquences :

� une gestion inefficace des postes de stationnement et portes d'embarquement ;� le non-respect des créneaux CFMU, des surcharges de secteur ou la sous-utilisation de la capacité

disponible ;� un séquencement imprécis des départs.

Un pas important a été franchi en obtenant des exploitant d'aéronefs qu'ils publient leurs heures internes dedépart de l'aire de stationnement (engagement entre les OCC et les agents d'escale), de manière àaméliorer la précision et la fiabilité des informations concernant les départs.

L'OBT cible correspond à l'heure interne de départ de l'aire de stationnement de la Sabena, information quese partagent l'exploitant d'aéronefs, les autorités aéroportuaires et l'ATC du site de Bruxelles. Ellecorrespond au statut "prêt au départ" : portes d'aéronef closes, passerelle retirée et tracteur en place pourla man�uvre de refoulement (pour les aéronefs stationnant sur des postes adjacents au terminal).Le partage de l'OBT cible effective de la Sabena renforcera de toute évidence la confiance entre lespartenaires quant à la détermination du moment où un vol sera effectivement prêt. Certes, la notification decette information sera sans effet sur les perturbations et contraintes susceptibles d'entraver les départs, maiselle permettra d'obtenir l'image la plus fidèle possible des opérations de la compagnie aérienne. Associée àla notification des jalons "sol", la communication de cette information constitue une étape majeure de la CDMvers un renforcement de la confiance et une compréhension mutuelle des contraintes.

La procédure proposée portait sur la notification en continu de cette information à la CDB. Pour chaque vol,le volet informationnel commun consiste en la notification d'un champ spécifique (TOBT) dans unefourchette de temps délimitée par deux moments spécifiques :

� À [EOBT-30'], la TOBT sera initialisée par l'exploitant d'aéronefs (en coordination avec les agentsd'escale) et exploitée conjointement par les autorités aéroportuaires, l'exploitant d'aéronefs, les servicesd'escale et le contrôle de la circulation aérienne.

� Mise en �uvre des jalons "sol" : il a été convenu que l'exploitant d'aéronefs communiquera certainesinformations chronologiques complémentaires à celles qui sont gérées par la CDB de Bruxelles (voirplus haut) :� ouverture de la première porte de l'aéronef ;� fermeture de toutes les portes de l'aéronef ;� demande d'autorisation de mise en route des moteurs ;� autorisation de mise en route des moteurs.

Générés automatiquement, sans contrôle humain, les statuts des vols au sol ne sont pas exempts d'erreurs.

Le suivi des événements précités permettra d'actualiser/de confirmer la TOBT et de déclencher des alarmesau besoin. La qualité des informations (exhaustivité, précision, fiabilité) sera contrôlée.

� À [TOBT-20'], la TOBT devrait être stable, sauf perturbation. Tout écart devrait naturellement êtresignalé d'emblée de façon à permettre aux autres acteurs de réagir en conséquence.

� Précision exigée de la TOBT : une précision de 5 minutes devrait être observée dans la vaste majoritédes cas à [EOBT-30'] ; à confirmer pendant l'expérimentation.



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Pour Belgocontrol, la fiabilité des données conditionne leur exploitation dans une phase ultérieure. Celles-cidevraient servir à l'établissement d'un préavis d'autorisation de mise en route des moteurs sur la base d'uneTOBT offrant une précision de 5' à [TOBT-20']. Les éléments requis pour l'établissement d'un préavisd'autorisation de mise en route des moteurs sont énumérés à la section 12.4.2

3.3.3 Alarmes et indicateurs

Dans les précédentes sections, nous avons souligné la nécessité d'un suivi du processus d'escale, enparticulier pour ce qui est de la cohérence et de la synchronisation des opérations entourant les vols àl'arrivée. Il est clair cependant que ce suivi n'est qu'un mécanisme parmi d'autres qui permet de contrôler lebon déroulement des opérations et, en cas de perturbation, d'évaluer la gravité de la situation pour suite àdonner.

� Exhaustivité des informations de vol en provenance de la station de départ : L'absenced'informations concernant les vols à l'arrivée doit être clairement éliminée. L'exhaustivité de l'informationsera assurée au moyen des messages de mouvement, complétés par les messages FSA (premièreactivation du système) du CFMU. Dans le futur environnement ETFMS, il sera fait usage des CPR(comptes rendus de position corrélés) et des APR (comptes rendus de position d'aéronef) pour contrôlerles départs effectifs. Nonobstant les mesures en place et envisagées pour améliorer les informations enprovenance de la station de départ, nous proposons qu'une alarme soit déclenchée si aucunrenseignement concernant le décollage n'est parvenu à la station d'arrivée 30 minutes avant l'heureestimée d'arrivée145.

� Contrôles de cohérence de la TOBT : la nécessité d'un suivi de la cohérence de la TOBT a étédébattue en plusieurs occasions à Bruxelles.

� [TOBT-20']>< événement "début de l'embarquement" : l'opportunité de déclencher une alarme à[TOBT-20'] si l'embarquement n'a pas encore commencé a été abordée à Bruxelles. L'exploitantd'aéronefs, agissant de concert avec l'agent d'escale, a la confiance des autres acteurs qu'ilgarantira la fiabilité de la TOBT 20 minutes avant son occurrence (avec une précision de 5 minutes).Dans quelques rares cas, le fait que l'embarquement n'ait pas encore débuté 20 minutes avant laTOBT peut ne pas remettre en cause cette dernière (cela dépend du taux de remplissage del'aéronef). Toutefois, nous sommes d'avis que, dans la vaste majorité des cas, la non-occurrence decet événement à TOBT-20' devrait déclencher une alarme et la confirmation, de la part del'exploitant d'aéronefs, que la TOBT sera respectée.

� TOBT >< événement "fermeture de toutes les portes de l'aéronef" : cet événement ne devraitjamais intervenir après la TOBT (non-respect de la précision de la TOBT devant entraîner unealarme aux fins de coordination).

� Statut "aéronef prêt" : la TOBT, en tant que valeur estimée du statut "aéronef prêt", doit faire l'objetd'un suivi. On notera cependant que si la fermeture de toutes les portes de l'aéronef génère unsignal automatique, l'enlèvement des passerelles d'embarquement et la mise en place du tracteurpour la man�uvre de refoulement (pour les aéronefs stationnant sur des postes adjacents auterminal) ne sont pas automatiquement détectées. Il est suggéré d'envisager une liaison mobile sansfil entre les "red caps" et la CDB/l'AMS pour fournir un tel indicateur. Ce dernier pourrait alors êtreutilisé pour comparer l'heure cible de départ de l'aire de stationnement avec une heure fiabled'acquisition effective du statut "prêt".

145 À l'heure actuelle, cette opération s'effectue manuellement (communication téléphonique avec la station de départ).



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3.4 PROCÉDURE DE PRÉAVIS D'AUTORISATION DE MISE EN ROUTE DES MOTEURS

3.4.1 Problèmes et questions soulevés

Différents problèmes peuvent être mis en évidence :

� Le temps de roulage au départ n'est pas calculé avec une précision suffisante à Bruxelles. À l'heureactuelle, le contrôleur TWR évalue le temps de roulage au départ et le temps d'attente sur l'aire à partirdu moment où le pilote demande l'autorisation de mise en route des moteurs. Selon les conditions etcontraintes prévalant sur l'aéroport, et compte tenu de l'augmentation croissante de la charge de travaildes contrôleurs, le taux d'erreur peut être considérable et entraîner la perte de créneaux CFMU(ressource limitée). À titre d'exemple, nous avons enregistré des intervalles supérieurs à 30 minutesentre la CTOT et l'ATOT et ce, malgré un délai de plus de 45 minutes entre la demande d'autorisation demise en route des moteurs et la CTOT. Une telle situation est inacceptable et démontre que laprocédure actuelle ne donne pas satisfaction aux utilisateurs. Un outil pourrait être utilement développépour améliorer la fiabilité des prévisions du temps de roulage (et du temps d'attente sur l'aire) avec unhorizon temporel limité (30 minutes). L'adoption d'un outil d'aide à la décision146 permettrait, de surcroît,d'alléger la charge de travail du contrôleur TWR.

� La fiabilité de l'information est insuffisante, en particulier pour ce qui est des EOBT, sur lesquelles sefonde le processus d'allocation des créneaux ATC et CFMU. À cela s'ajoutent les demandes anticipéesde mise en route des moteurs, qui peuvent rendre la situation plus compliquée encore.

� Le faible taux de fiabilité et de prédictibilité de l'information empêche une mise en séquence efficace àun stade précoce, conduit au non-respect de la CTOT et peut engendrer des surcharges de secteur. Àtitre d'exemple, 42,3% des vols régulés au départ de la Belgique n'ont pas respecté leur créneau en juin2001147.

3.4.2 Description de la proposition

3.4.2.1 Hypothèses

La présente section doit être considérée comme un premier projet de séquence pré-départ coopérative,fondée sur les éléments décrits dans l'ensemble du document. Elle repose plus spécifiquement sur :

� la notification d'une TOBT initiale à tous les acteurs aéroportuaires à [EOBT-30'], cette valeur cibleconstituant une indication objective de l'heure à laquelle l'aéronef sera prêt ;

� la confirmation, adressée à l'ATC et aux autorités aéroportuaires par les exploitants d'aéronefs/agentsd'escale148, de la fiabilité149 de l'heure de départ de l'aire de stationnement à 20 minutes de sonoccurrence. Le fait d'appliquer avec succès la TOBT (précision et ponctualité) devrait donner l'assuranceaux acteurs aéroportuaires que l'aéronef est prêt à effectuer sa man�uvre de refoulement à l'heurecible150 ;

� la détermination, pour chaque vol, d'un temps de roulage au départ151 avec un horizon temporel limité.Cet aspect est abordé à la section 7 de la version anglaise du présent document.

146 Cf. section 7147 Réf. : (ATFM/IFPS Operations Statistical Analysis (06/01)). Cf. tableau 9148 Une participation aussi large que possible des exploitants d'aéronefs et agents d'escale est nécessaire pour obtenirdes résultats probants.149 Il est clair que des perturbations de dernière peuvent toujours se produire ; toutefois, dans la vaste majorité des cas(nous dirons 80 %), la TOBT arrêtée à [TOBT-20'] ne devrait pas être remise en cause. Il conviendrait de tirer lesenseignements des expérimentations.150 Ainsi qu'il est proposé plus haut dans le document, cette information devrait être initialisée 30' avant l'EOBT, avecune précision de l'ordre de 5' par rapport à l'AOBT en conditions favorables (hors pointe). Toutefois, l'heure cible dedépart de l'aire de stationnement est une estimation qui ne fournit pas l'heure effective de départ de l'aire et entraînedonc un "gel" du poste de stationnement ou de la porte d'embarquement.151 Cette détermination peut s'opérer manuellement dans un premier temps. Un outil d'aide à la décision devraitpermettre de calculer précisément le temps de roulage dans l'avenir.



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3.4.2.2 Heure estimée de délivrance de l'autorisation de mise en route des moteurs

La fourniture en temps opportun d'une telle information contribuerait à une diminution des incertitudesinhérentes au processus de gestion des départs, ce qui présenterait un grand intérêt. L'approche décrite ci-dessous se fonde sur les étapes précédentes, à savoir la mise en �uvre d'une ESUC152 fiable, notifiée àl'ensemble des acteurs. C'est la raison pour laquelle l'objectif de réduire au minimum les incertitudesinhérentes au processus des départs constitue un objectif clé, porteur d'avantages considérables.

Il est proposé que, sous réserve de conditions de précision et de fiabilité à déterminer collectivement, uneheure estimée de délivrance de l'autorisation de mise en route des moteurs (ESUC) soit notifiée à [TOBT-20'] :

� La fiabilité (ponctualité et précision) de la TOBT est un préalable indispensable à la mise en �uvre decette nouvelle procédure.

� La question de la révision de la TOBT sur demande de l'exploitant d'aéronefs (révision unique ourépétée) entre [TOBT-20'] et [TOBT] sera examinée et une règle spécifique instituée153.

Remarque : Belgocontrol a expérimenté par le passé une procédure prédépart reposant sur la fourniturede données par les exploitants d'aéronefs. Vu le manque de fiabilité de l'heure de départ de l'aire destationnement, Belgocontrol a renoncé à poursuivre l'expérience.

� L'ATC devrait communiquer l'ESUC aux exploitants d'aéronefs et aux autorités aéroportuaires à [TOBT-20'], afin que la TOBT puisse être respectée au maximum. La précision attendue de l'ESUC devrait êtrela suivante : |ASUC-ESUC| < 5 minutes;

� L'ESUC ne devrait jamais précéder la TOBT (ESUC > TOBT). L'ESUC n'est qu'une estimation de l'heurede délivrance de l'autorisation de mise en route des moteurs, ce qui signifie qu'elle peut différer del'ASUC pour une raison ou l'autre (contraintes de l'ATC). Quoi qu'il en soit, passée la TOBT, ladélivrance de la SUC (autorisation de mise en route) par la TWR devrait déclencher la man�uvre derefoulement. Le délai de réaction du pilote (amorce de la man�uvre de refoulement), à compter de ladélivrance de l'autorisation de mise en route, ne devrait pas dépasser une minute en conditionsnormales.

� En principe, l'autorisation de mise en route peut être délivrée au pilote à n'importe quel moment après laTOBT, ce qui serait de nature à limiter les échanges entre le pilote et le contrôleur (la demanded'autorisation de mise en route du pilote pourrait être supprimée dans la mesure où l'aéronef devrait êtreprêt pour la mise en route des moteurs à compter de la TOBT). La charge de travail du contrôleur s'entrouverait de ce fait allégée.

� Une fois l'autorisation de mise en route délivrée, et sauf contraintes restrictives (pression du trafic, parexemple), le délai entre l'autorisation de mise en route et l'autorisation de refoulement ne devraitexcéder une minute (en conditions normales)154.

� La notification de l'ESUC devrait tenir compte de la contrainte CTOT. Mais se pose ici un problèmecapital, à savoir la capacité d'établir préalablement (à [TOBT-20'], par exemple) une prévision du tempsde roulage départ155 (qui devrait inclure le temps d'attente sur l'aire après la TOBT, pour tenir compte del'ETOT156). La connaissance partagée et la fiabilité de la TOBT et du temps de roulage départ doiventêtre choses acquises afin que le CFMU puisse exploiter ce type d'informations pour améliorer sespropres opérations au bénéfice de la communauté européenne. À titre d'illustration, l'établissement d'untemps de roulage départ réaliste devrait permettre de calculer une heure estimée de décollage avec unhorizon temporel de 30 à 45 minutes et, partant, d'anticiper le non-respect de la CTOT157.

152 Heure estimée de délivrance de l'autorisation de mise en route des moteurs153 Une révision de la TOBT ne devrait être possible qu'ultérieurement.154 L'origine et l'ampleur des écarts seront consignées et analysées.155 Cf. section 7156 Il n'existe pas de plateformes d'attente à Bruxelles, de sorte que l'aéronef demeure sur l'aire de stationnement si lasituation l'exige.157 Pour les vols régulés


66

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� Des règles locales, comme par exemple l'ordonnancement des vols par ordre de priorité par l'ATCTWR158, devraient être instaurées pour résorber les écarts mineurs par rapport à la CTOT.

� S'il n'est pas possible de remédier au non-respect d'une CTOT, des solutions concertées devraientenvisagées entre l'ATC, les FMP et le CFMU. Dans tous les cas, l'heure estimée de décollagedevrait être communiquée au CFMU et faire l'objet d'une actualisation (si nécessaire) jusqu'à ladélivrance de l'autorisation de mise en route des moteurs.

� Aujourd'hui, l'heure de délivrance de l'autorisation de mise en route est affichée sur l'écran des départs.Il est proposé de faire apparaître l'ESUC sur le même écran, préalablement à l'ASUC (cette innovationne nécessiterait aucune modification du système d'affichage actuel). L'affichage de l'ESUC permettrait àl'exploitant de noter et contrôler la valeur pour ensuite l'adapter aux contraintes temps réel (ce qui n'estpas le cas aujourd'hui).

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Rapport CEE No.371

FIGURE 2 : PROPOSITION DE PRÉAVIS D'AUTORISATION DE MISE EN ROUTE DES MOTEURS

Améliorations potentielles pour le CFMU

mmunication, au CFMU, de données prévisionnelles précises du temps de roulage départ devrait êtreuse d'avantages considérables. La TOBT et le temps de roulage départ ayant été notifiés à tous lesrs aéroportuaires en respectant les critères de qualité requis, le CFMU pourrait exploiter cetteation pour affiner le calcul des régulations et des créneaux alloués. Des amorces de procédures

elles sont décrites ci-après, qui ont trait à la séquence prédépart et tiennent compte du fait que :

séquence prédépart est établie pour les vols au départ ; TIS et la TRS sont des paramètres dépendants des aéroports, qui définissent le moment à partiruquel le CFMU ne peut plus modifier une CTOT (TRS) ou améliorer un créneau (TIS).

.1 Fenêtre d'amélioration du créneau

u'un vol reçoit un créneau du CFMU (régulation), l'exploitant d'aéronefs peut mettre en �uvreentes stratégies d'embarquement des passagers : embarquement aussi prompt que possible ourquement tardif, selon qu'il escompte ou non une amélioration de son créneau.

r la base des contraintes majeures (turbulences de sillage, routes obligatoires, intervalle minimum de départ) etres

TOBTTOBT-20�EOBT-30�

AIRLINE, PILOT HANDLING AGENTS RESPONSIBILITY

CTOT Window

TOBT accuracy < 5

ATC RESPONSIBILITY

PILOT READY PUSHBACK PRESENT

TWR/ PLANNER: PREPARE SEQUENCE

PUSHBACK

TOBT ESUC ASUC

TAXI

TAKEOFF

TOBT UPDATE WINDOW

TWR : START-UP CLEARANCE

AOBT : Push-back ATOT

< 5� < 1�

CTOT

SUR



EUROCONTROL

� Embarquement aussi prompt que possible : la conséquence immédiate en est que les passagerspatienteront dans l'aéronef plutôt que dans l'aéroport. Le pilote attend l'autorisation de mise en route desmoteurs ainsi qu'une amélioration éventuelle de son créneau, selon les possibilités du CFMU. Lesmessages échangés entre le CFMU, l'AOC159 et la TWR sont les suivants :� demande d'amélioration directe ;� demande d'amélioration conditionnelle ;

� message "prêt" : seul l'ATC est habilité à envoyer le message REA au CFMU TACT, mais lesexploitants d'aéronefs peuvent demander à l'ATC de l'envoyer dans deux cas spécifiques :

� le vol est prêt au départ avant l'EOBT (maximum 30 minutes avant) ;� le vol accepte une amélioration avec un préavis inférieur à la normale (délai d'alignement

minimum)160 ;� si une amélioration est possible, le CFMU enverra un SRM.

� Embarquement tardif : les passagers patientent dans le hall d'attente et l'embarquement débute plustard de manière à respecter la CTOT. Le vol n'escompte aucune amélioration de son créneau.

Nous proposons d'instituer une fenêtre d'amélioration du créneau située entre [TOBT-30'] et [TOBT-20']. Leprincipe est que la séquence prédépart ne peut être établie qu'une fois la stabilité des données acquise (enparticulier la CTOT).

À partir du moment où il serait en possession d'une TOBT et d'un temps de roulage départ fiables, le CFMUpourrait recalculer automatiquement le créneau pendant l'intervalle précité (le cas échéant), en tenantdûment compte des conditions prévalant sur l'aéroport considéré. La CTOT serait "gelée" à [TOBT-20'], laséquence prédépart s'amorçant à partir de ce moment-là.

Slot ImprovementCFMU

New CTOT CTOT SIP Window

TOBTTOBT-30� -20� TOBT

AIBT AOBT ATOT

A.O.C

Taxi Time

Pilot ��..SUR

Tower ESUC ASUC ��.

Waitingblock

FIGURE 3: FENÊTRE D'AMÉLIORATION DU CRÉNEAU

Les avantages potentiels sont les suivants :

� le retard CFMU peut être réduit ;� l'exploitant d'aéronefs gère ses opérations (embarquement) ;� le CFMU devrait avoir confiance dans les estimations fournies ;� l'ESUC pourrait être communiquée de manière uniforme à tous les acteurs aéroportuaires ;� la TWR pourrait inclure le vol dans une séquence prédépart fixe à [TOBT-20'] ;� les agents d'escale pourraient planifier les opérations de prise en charge du vol suivant ;� la gestion des postes de stationnement et portes d'embarquement s'en trouverait facilitée.

159 Centre d'exploitation de la compagnie aérienne160 Le délai d'alignement minimum correspond au temps requis par l'aéronef pour se présenter au décollage à partir desa position initiale.



EUROCONTROL

3.4.3.2 Proposition d'adaptation du créneau

Actuellement, de multiples retards peuvent s'accumuler, qui se traduisent par la perte de précieux créneauxCFMU. Le CFMU calcule les créneaux sur la base des EOBT transmises par les exploitants d'aéronefs,auxquelles il ajoute un temps de roulage départ qui peut être fixe (par ex. 20 minutes pour Bruxelles,actuellement) ou variable.

� En principe, l'exploitant d'aéronefs communiquera une nouvelle EOBT au CFMU lorsque la différenceentre la nouvelle heure et la précédente dépasse 15 minutes.

� À l'incertitude de l'EOBT vient s'ajouter la variabilité du temps de roulage départ. Selon les conditions(demande au niveau des arrivées/départs sur la piste de décollage, contraintes météorologiques, etc.),le temps de roulage départ peut passer de 15 minutes - paramètre moyen du CFMU - à 30 minutes,voire plus.

Le cumul des deux facteurs d'incertitude (EOBT et temps de roulage départ) peut se traduire par unedifférence de plus de 30 minutes entre l'heure effective et l'heure estimée du décollage. Même si desprocédures sont mises en �uvre, cela entraîne, comme résultat immédiat, qu'un nombre considérable devols régulés ne respectent pas leur CTOT.

La fourniture d'estimations de la TOBT et du temps de roulage départ avant [TOBT-20'] permettrait de cernerplus tôt le risque de non-respect de la CTOT et ses conséquences éventuelles (surcharge des secteursproches de l'aéroport).

Le CFMU pourrait donc imaginer des solutions coopératives pour tenter de tenir compte des conditionstemps réel sur l'aéroport considéré. L'avantage obtenu serait non pas une amélioration du retard mais uneadaptation automatique (si possible) aux conditions prévalant sur l'aéroport 20' avant la TOBT.

Les retombées attendues de la mise en �uvre de la proposition sont notamment les suivantes :

� le créneau ne serait plus perdu dans la majorité des cas ;� la charge de travail du contrôleur TWR serait allégée ;� les exploitants d'aéronefs disposeraient de paramètres horaires plus précis pour entamer les opérations

d'embarquement.

FIGURE 4: PROPOSITION D'ADAPTATION DU CRÉNEAU

EOBT Delay

TOBT-30� TOBT-20� TOBTA.O.Chandlers

ESUC SUC Taxi Time Tower

Delay

Delays:

AOC

+

ATC

+

CFMU

=

CTOT

Delay Taxi.time 15�

CFMU

AOBT ATOT

At TOBT -30�, CFMU receives TOBT, Taxi-Out Time DataAt TOBT -20�, CFMU would compute a new CTOT.

TOBT Taxi Time NEW CTOT Slot Adaptation?

TOBT+ T.T+ SLOT= SAP

SAP



EUROCONTROL

Les écarts de plus de 5 minutes (par rapport à la valeur précédente) devraient être communiqués.L'appréciation du non-respect de la CTOT (et de ses conséquences) devrait s'effectuer en collaboration :

� dans l'hypothèse où les conséquences des écarts seraient jugées acceptables par l'ATC, le FMP etle CFMU, la démarche initiale devrait consister à adapter le créneau aux conditions temps réel(adaptation du créneau) par le jeu d'un mécanisme d'ajustement automatique ;

� si, au contraire, les conséquences de ces écarts sont jugées trop importantes, le CFMU pourraitappliquer des mesures existantes161, en concertation avec l'ATC et le FMP. Selon les situations,des mesures plus coopératives devraient être envisagées, comme la permutation de créneaux. Desmesures coopératives en route162 seraient également envisageables pour rattraper le temps perdu.

La stabilisation des données après [TOBT-20'] serait un plus pour le CFMU, en ce sens qu'elle mettrait unterme aux pratiques actuelles des exploitants d'aéronefs, qui sont libres de déposer et/ou de modifiern'importe quel plan de vol jusqu'à la dernière minute. En cas de demande soutenue, et en raison de cetteliberté laissée aux exploitants, les courants ont tendance à se déplacer d'un endroit à l'autre en fonction desmesures de régulation et des retards inhérents, ce qui accroît les surcharges de secteur et lesréacheminements et engendre une sorte de cercle vicieux.

161 Suspension d'un vol

162 Projet FAM (Future ATFM Measures) du CEE



EUROCONTROL

4 INDICATEURS DE PERFORMANCES ESSENTIELS POUR LA CDM

Offrir une information de meilleure qualité implique des coûts qui doivent être compensés par des avantagesaccrus. Le fait de communiquer des données d'une qualité déterminée, qui puissent être avantageusementexploitées par leurs destinataires (meilleure planification de la gestion des ressources, par exemple), devraitavoir pour contrepartie directe des retombées bénéfiques mesurables, quantitativement, pour l'entité quifournit l'information (rendement de l'investissement). Cette collaboration mutuellement profitable peuts'envisager sous la forme d'un contrat entre les parties (portant, dans ce cas précis, sur la mise à disposition/ diffusion d'informations d'une qualité définie). La recherche d'un consensus sur des indicateurs deperformances essentiels (KPI) revêt une importance particulière dans ce contexte et fait intervenir plusieurséléments :

� la définition de la qualité de service, qui couvre la diffusion de l'information, l'accès à cettedernière, les responsabilités diverses et l'utilisation des données ; elle devrait se concrétiser pardes accords de niveau de service entre les acteurs ;

� la définition et le suivi de la qualité de l'information, qui passe par l'établissement de critères demesure (précision, exactitude, fiabilité, ponctualité, etc.) et d'indicateurs connexes ;

� l'évaluation des avantages mutuels par le jeu de mesures : cette activité implique une base decomparaison ainsi que le suivi de la qualité des informations en sus de l'évaluation des avantages.



EUROCONTROL

ANNEX A: Zaventem Brussels Airport

Brussels Airport is operated by Brussels International Airport Company (BIAC), which was created byBelgian law through a merger of BATC with the ground operations departments of the RLW/RVA.

206 L

23 8

232230R

205 L

207

21 1 L

21 7 L

22 9 L

23 3 L

205R

209211R

215217R

227

231233R 23

7L33 4

338

34 234 4

346

348350

352356

33 1

33 7

34 1

34 7

351353

30 1 302

303R

303L

304R304L

30 53063 07

308

309

421

422423

424

431

432

433

441442

443444

107105

102

10099

104103

106

101

5 08 504

5 02

206R

216R

138

208

132

137136

135

131130

129127

128

126124

123121

117118

204

133210R210 L

228R228L

230L

234R234L

236120

125

119

134

122

201

510512514516518520522

APR ON 51

52452652853053 2

APR

ON

53

22 9 R

108

69 469 268 868 668 268 0

90 190290390 4

90590 690 790890991 0

91191291 391491 591 6

91791 891 992092 192 2

92392 4

561

562

5 63 5 6

4 5 65 5 6

65 6

7

APR ON 56

506

684

690

696

69 9

69 869 769569 369 1689

681

68 768 5683

98

9695

94

9392

9189

88

86

85

83

8079

77

76

74

71

7068

73

SD3 8

SD 3

5

SD15

SD32

SD31

SD50SD51

SD54

SD53

SD 55

SD52

SD61

SD62

SD60SD100

SD90

SD500

SD27SD26

SD25

SD24

SD2

2

SD21

SD 23

SD36

SD34

SD33

SD3 9

SD 37

SD20

SD 400

SD40

SD116

SD1

14

SD113 S

D1 1 2

SD111

SD 110

SD1 0 9

SD1 08

SD10 7

SD106

SD105

SD104

SD103

SDT1

SDT2

SDT3

SD102

SD101

SD14

SD 10

SD28

SD29

OLD _S D40

FIGURE 16: BRUSSELS AIRPORT MAP

Brussels AirportCode ICAO/IATA EBBR/BRULocation 50°54'08 N

04°29'09 ETotal Surface 1,245 ha (3,706 acres)Brucargo total surface 109 ha (268 acres)Elevation 56mRunways · 02/20 (2,984m)

· 07L/25R (3,638m)· 07R/25L (3,211m)

Handling Companies Sabena,AviaPartner

ILS Cat II/IIINumber of aircraft stands at maximum aircraft capacity

Contact Remote

Passengers 32 66Cargo - 31

TABLE 7 : BRUSSELS AIRPORT FIGURES



EUROCONTROL

� Main figures:

TABLE 8 : BRUSSELS AIRPORT MOVEMENTS

� The number of movements in 2001 (until September) was exceeding 25,000 flights per month.� 30% of passengers arriving in Brussels are transferring to another destination.� The number of scheduled passenger flights was about 259,000 in 2000 (increase of 100% compared

to 1991 (130,100 in 1991); non-scheduled passenger flights reached 22,200 in 2000 (to becompared with 12,100 in 1991).

� The number of cargo flights is decreasing since 1998 (2000: 23,500 flights versus 26,200 flights in1998).

� The part of general aviation was constantly decreasing until 1996 (13,200 flights); since then, itregularly increases (15,400 flights in 2000).

� The number of military flights was quite constant between 1995 and 1998 (about 9,100 flights). Sincethen, the tendency is a reduction of military flights (5,700 flights in 2000).



EUROCONTROL

� Adherence to ATFM slots (ATFM/IFPS Operations Statistical Analysis (06/01))

Adherence to ATFM slots � Belgium (June 2001)Indicator Value PercentageTotal number of regulated flights 9210Total number of flights outside slot tolerance window Negative (1) Positive (2)

389228491043

42.3% [3892/9210*100]30.9%11.3%

Variation per flights outside ST window Neg (3): Pos (4):

-9.3 min.18.1 min.

Slot Tolerance Index (5) 20705 min.

TABLE 9 : BELGIUM SLOT ADHERENCE (JUNE 2001)

(1) Negative: number and percentage of regulated flights which departed more than 5 minutes before CTOT), i.e.(ATOT<CTOT-5 min.)(2) Positive: number and percentage of regulated flights which departed more than 10 minutes after CTOT), i.e.(ATOT>CTOT+10 min.)(3) Neg: Average number of minutes per flight which departed too early (ATOT-CTOT<0)(4) Pos: Average number of minutes per flight which departed too late (ATOT-CTOT>0)(5) Slot Tolerance index: The total number of minutes outside the tolerance window.

� Departure Tolerance Analysis (ATFM/IFPS Operations Statistical Analysis (06/01))

Departure Tolerance Analysis � Belgium (June 2001)Indicator ValueFlight Plans Counted Not Regulated

17380162637053

Flights outside Departure Tolerance window 458 flights 6.5% [458/7053]Departure Tolerance Variation Neg: -51.8 min. Pos: 48.3 min.

TABLE 10 : BELGIUM DEPARTURE ANALYSIS (JUNE 2001)

Departure Tolerance window is referring to a fictitious time window of ETOT-30� to ETOT+30�. ETOT=EOBT+Taxi Time.Flight Plans: number of departing flightsCounted: the number of flights used for this calculationNot regulated: The number of non-regulated flights amongst the counted flights. Only the flights for which an actualtake-off time is known are used for this overview. ATOTs are obtained via FSA messages with the ADID keyword or fromDEP messages.Outside departure tolerance window: The number of flights of which the ATOT is outside the departure tolerancewindow and the percentage of non-regulated flights.Departure tolerance variation: The average variation in departure time per flights outside the departure tolerancewindow in minutes (ATOT-last received ETOT).



EUROCONTROL

� Overall Delay Analysis (Source: ATFM/IFPS Operations Statistical Analysis (06/01))

Overall Delay Analysis - Belgium (June 2001)IndicatorFlight Plans Counted Regulated

17380162639210

Average per counted flight [minutes] AO delay ATFM delay Activation delay Overall delay

Value5.5 minutes7.0 minutes5.4 minutes17.8 minutes

Percentage30.8%39.2%30.1%

TABLE 11 : BELGIUM - OVERALL DELAY ANALYSIS (JUNE 2001)

- Flight Plans: number of departing flights- Counted: the number of flights used for this calculation. Only the flights for which an actual take-off time is known areused for this overview. ATOTs are obtained via FSA messages with the ADID keyword or from DEP messages.- Regulated: The number regulated flights amongst the counted flights. - Delays:� AO delay: the average delay per counted flight due to airline messages. The delay is derived from messages such asCHG, DLA, SRR, FSR, � (last received ETOT � first ETOT)� ATFM delay: the average delay per counted flight caused by ATFM regulations (last CTOT � last received ETOT).� Activation Delay: the average final departure delay per counted flights for non-regulated flights: ATOT-last receivedETOT, for regulated flights: ATOT � last CTOT.� Overall delay: the total average delay per counted flight (ATOT � last received ETOT)

Source (CODA � May 2001)

Brussels Airport AnalysisBrussels as a departure airport Total number of departing flights Total delayed flights Percentage of delayed flights Total delay Flights delayed > 60 minutes Average delay per delayed flight Average delay per movement Most penalised airport ranked by average delay per movement (*)

13730499636%93139 minutes5318.6 minutes6.8 minutesEuropean rank: 14

Brussels as a destination airport Total number of arriving flights Total delayed flights Percentage of delayed flights Total delay Flights delayed > 60 minutes Average delay per delayed flight Average delay per movement Most penalised airport ranked by average delay per movement (*)

13725536139%122,277 minutes6622.8 minutes8.9 minutesEuropean rank: 4

TABLE 12 : BRUSSELS AIRPORT ANALYSIS (CODA - MAY 2001)

(*):Rank 4 for �most penalised airport ranked by average delay per movement� means that Brussels airport isconsidered as the 4th most penalised European destination airport.

eurocontrol experimental centre collaborative … · 2008-08-21 · improving airport operations...

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