determination of ils critical and sensitive areas

Determination Determination of ILS Critical of ILS Critical and Sensitive and Sensitive

AreasAreas

International Flight Inspection International Flight Inspection SymposiumSymposium

Oklahoma City, OK USA June 2008Oklahoma City, OK USA June 2008

Dale CourtneyDale CourtneyUS FAAUS FAA

Air Traffic OrganizationAir Traffic Organization

IFIS 2008, OKCIFIS 2008, OKC Determination of ILS Critical and Determination of ILS Critical and Sensitive AreasSensitive Areas

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Discussion PointsDiscussion Points

Effects of Multi-Path on ILS Signal-in-Effects of Multi-Path on ILS Signal-in-SpaceSpace

ILS Critical and Sensitive AreasILS Critical and Sensitive Areas ICAO Recognition of Critical and ICAO Recognition of Critical and

Sensitive AreasSensitive Areas Mathematical Model ValidationMathematical Model Validation Simulation ResultsSimulation Results ConclusionsConclusions QuestionsQuestions


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Effects of Multi-Path on ILSEffects of Multi-Path on ILS

ILS Localizer and Glide Path Signal ILS Localizer and Glide Path Signal Quality is Influenced by Multi-PathQuality is Influenced by Multi-Path

Multi-Path Occurs When a Radio Multi-Path Occurs When a Radio Signal Travels by More Than One Signal Travels by More Than One Path to Arrive At the ReceiverPath to Arrive At the Receiver• The Direct Path is From the Transmitter The Direct Path is From the Transmitter

to the Receiverto the Receiver• Additional Paths are Created When the Additional Paths are Created When the

Transmitted Signal Reflects Off Another Transmitted Signal Reflects Off Another Object and Then Arrives at the ReceiverObject and Then Arrives at the Receiver


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Multi-Path Can Be Characterized as Either Multi-Path Can Be Characterized as Either Static or DynamicStatic or Dynamic• Static Multi-Path is Created by Fixed Objects Static Multi-Path is Created by Fixed Objects

Such as Buildings or TerrainSuch as Buildings or Terrain• Dynamic Multi-Path is Created by Transient Dynamic Multi-Path is Created by Transient

Objects Such as Airplanes or VehiclesObjects Such as Airplanes or Vehicles The Amount of Degradation on an ILS The Amount of Degradation on an ILS

Signal due to Multi-Path is a Function of Signal due to Multi-Path is a Function of Location, Size, and Orientation of the Location, Size, and Orientation of the Reflecting ObjectReflecting Object


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ILS Signal Degradation Due to Multi-ILS Signal Degradation Due to Multi-Path is Realized by Structure Path is Realized by Structure Roughness and Alignment/Angle Roughness and Alignment/Angle DeviationDeviation

Effects of Multi-Path due to Static Effects of Multi-Path due to Static Sources Do Not Change Over TimeSources Do Not Change Over Time

Effects of Multi-Path due to Dynamic Effects of Multi-Path due to Dynamic Sources Change with Location of the Sources Change with Location of the ReflectorReflector


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ILS Critical and Sensitive AreasILS Critical and Sensitive Areas

Aircraft and Vehicles Operating Near Aircraft and Vehicles Operating Near Localizer and Glide Path Facilities Localizer and Glide Path Facilities Can Cause Distortion to the ILS Can Cause Distortion to the ILS Signal-in-SpaceSignal-in-Space

Protection Areas Around the Localizer Protection Areas Around the Localizer and Glide Path Facilities Become and Glide Path Facilities Become Necessary to Protect the Integrity of Necessary to Protect the Integrity of the ILS Signal-in-Spacethe ILS Signal-in-Space• Historically Called ILS Critical and Historically Called ILS Critical and

Sensitive AreasSensitive Areas


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ILS Critical and Sensitive AreasILS Critical and Sensitive Areas

Dimensions and Location of ILS Dimensions and Location of ILS Critical and Sensitive Areas Are Critical and Sensitive Areas Are Determined by Both Direct Flight Determined by Both Direct Flight Measurement and Mathematical Measurement and Mathematical ModelingModeling

Movement of Aircraft and Vehicles in Movement of Aircraft and Vehicles in the ILS Critical and Sensitive Areas the ILS Critical and Sensitive Areas Can be Restricted or Operationally Can be Restricted or Operationally Controlled to Protect ILS Signal Controlled to Protect ILS Signal Quality During ILS OperationsQuality During ILS Operations


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ICAO Recognition of CSAICAO Recognition of CSA

The International Civil Aviation The International Civil Aviation Organization (ICAO) Publishes Critical Organization (ICAO) Publishes Critical and Sensitive Area Dimensions and and Sensitive Area Dimensions and Location in Annex 10Location in Annex 10

ICAO’s Navigation Systems Panel ICAO’s Navigation Systems Panel Recognized Published Critical and Recognized Published Critical and Sensitive Areas May Not be Sufficient Sensitive Areas May Not be Sufficient to Protect ILS Signal Quality to Protect ILS Signal Quality Considering Today’s Larger AircraftConsidering Today’s Larger Aircraft


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A Group was Commissioned by the A Group was Commissioned by the Navigation Systems Panel in March 2007 Navigation Systems Panel in March 2007 to Consider Updates to ILS Critical and to Consider Updates to ILS Critical and Sensitive AreasSensitive Areas

The Group Determined Updates to ICAO The Group Determined Updates to ICAO Critical and Sensitive Areas Considering:Critical and Sensitive Areas Considering:• Critical Area is a Dimension About the Localizer Critical Area is a Dimension About the Localizer

or Glide Path Such That Aircraft or Vehicles or Glide Path Such That Aircraft or Vehicles Within the Area Cause Out-of-Tolerance Within the Area Cause Out-of-Tolerance Disturbances to the ILS from the Limit of Disturbances to the ILS from the Limit of Coverage to 2 Nautical Miles from ThresholdCoverage to 2 Nautical Miles from Threshold


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• Sensitive Area is a Dimension About the Sensitive Area is a Dimension About the Localizer or Glide Path Such That Localizer or Glide Path Such That Aircraft or Vehicles Within the Area Aircraft or Vehicles Within the Area Cause Out-of-Tolerance Disturbances to Cause Out-of-Tolerance Disturbances to the ILS from 2 Nautical Miles from the ILS from 2 Nautical Miles from Threshold to the Point the ILS Signal is Threshold to the Point the ILS Signal is No Longer UsedNo Longer Used


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• Critical and Sensitive Area Dimensions Critical and Sensitive Area Dimensions are Determined by the Root Sum Square are Determined by the Root Sum Square Combination of Static and Dynamic Combination of Static and Dynamic Multi-Path ContributionMulti-Path Contribution

Static Multi-Path is Considered to Consume Static Multi-Path is Considered to Consume 60% of Allowable Tolerance60% of Allowable Tolerance

Dynamic Multi-Path is Considered to Dynamic Multi-Path is Considered to Consume 80% of Allowable ToleranceConsume 80% of Allowable Tolerance


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Mathematical Model ValidationMathematical Model Validation

An Extensive Effort Would be Required to An Extensive Effort Would be Required to Completely Define ILS Critical and Completely Define ILS Critical and Sensitive Areas Only by Flight Sensitive Areas Only by Flight Measurement TechniquesMeasurement Techniques

Mathematical Modeling and Simulation Mathematical Modeling and Simulation Techniques Lend Themselves to Better Techniques Lend Themselves to Better Define ILS Critical and Sensitive AreasDefine ILS Critical and Sensitive Areas• Simulation Must be Well Validated by Simulation Must be Well Validated by

Comparison with Ground and Flight Comparison with Ground and Flight Measurement for a Variety of SituationsMeasurement for a Variety of Situations


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Mathematical Model ValidationMathematical Model Validation

Efforts Conducted in Europe and the Efforts Conducted in Europe and the United States to Validate Simulation United States to Validate Simulation TechniquesTechniques• Locations of Interest Were Determined Locations of Interest Were Determined

by Simulationby Simulation• Ground and Flight Measurements of an Ground and Flight Measurements of an

Actual Aircraft in the Determined Actual Aircraft in the Determined Position were CollectedPosition were Collected

• Results were Compared to Validate Results were Compared to Validate Simulation TechniquesSimulation Techniques


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Localizer ValidationLocalizer Validation


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Glide Path ValidationGlide Path Validation


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B747 Impact to Small Aperture LocalizerB747 Impact to Small Aperture Localizer


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B747 Impact to Large Aperture LocalizerB747 Impact to Large Aperture Localizer


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B757 Impact to Medium Aperture LocalizerB757 Impact to Medium Aperture Localizer


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A380 Impact to Medium Aperture LocalizerA380 Impact to Medium Aperture Localizer

IFIS 2008, OKC Determination of ILS Critical and Sensitive Areas

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Localizer Critical and Sensitive Areas

ZS2

ZS1

XC

Critical Area

Sensitive Area

ZC

1500 m

XTH

YC

Y1

Not to scale Dimensions in meters

r u n w a y

Y2

Y3

XS

300 m

Additional Sensitive Area for non-orthogonal, non-parallel to runway orientation

Note - Y3 and XTH are determined by a site-specific study. Where no specific study has been undertaken, the default value for XTH is zero.

120 m

Rear Sensitive

Additional rear Sensitive Area for orthogonal to runway orientation

IFIS 2008, OKC Determination of ILS Critical and Sensitive Areas

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Glide Path Critical and Sensitive Areas

Critical Area

Not to scale

YC [o,p]

Glide Path Antenna

ZC

YS [o,p]

XC [o,p]

XS [o,p]

45°

Sensitive Area

Runway Threshold

Additional Critical Area for non-parallel aircraft higher than 6 meters

ZS

Ws

Runway

Note –The sensitive area extends on the other side of the runway. If vehicle movements or holding are possible in this area, WS is assessed through a specific study.

50m


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ConclusionsConclusions

Critical and Sensitive Area Critical and Sensitive Area Dimensions are Heavily Influenced Dimensions are Heavily Influenced by:by:• Aircraft Tail Height and SizeAircraft Tail Height and Size• Location and Orientation of ReflectorLocation and Orientation of Reflector• Type of Localizer or Glide Path AntennaType of Localizer or Glide Path Antenna

Validated Mathematical Models Can Validated Mathematical Models Can be Used to More Completely Define be Used to More Completely Define Critical and Sensitive Areas as Critical and Sensitive Areas as Compared to Flight MeasurementCompared to Flight Measurement


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ConclusionsConclusions

Care Should be Exercised When Care Should be Exercised When Using Flight Measurement Using Flight Measurement Techniques Alone to Quantify Effects Techniques Alone to Quantify Effects of an Aircraft or Vehicle on ILS of an Aircraft or Vehicle on ILS Signal-in-Space Performance as Signal-in-Space Performance as Small Changes in Reflector Location Small Changes in Reflector Location and Orientation Can Result in and Orientation Can Result in Varying Levels of Measured Varying Levels of Measured DistortionDistortion


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QUESTIONS?QUESTIONS?

determination of ils critical and sensitive areas

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