AVIATION WEATHER HAZARDS IN THE WESTERN U.S.

AND THE NWS ROLE IN CORRESPONDING DECISION SUPPORT

Brian CollinsMeteorologist

Southwest AirlinesBrian.Collins@wnco.com

Southwest Aviation Weather Safety WorkshopAlbuquerque, NM

Oct 26, 2011

Topics of Discussion

Quick look at SWA Facts and Figures

SWA Weather Overview

Western Weather Hazards and the corresponding decision making process

NWS Product Suite – Consistency is key

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SWA Facts and Figures 3400+ daily flights from 72 airports 550 Boeing 737 aircraft (300’s, 500’s, 700’s) Average flight length is 653 miles

Shortest: 133 miles (RSW-MCO)

Longest: 2,295 miles (BWI-SAN)

Southwest consumed 1.4 billion gallons of jet fuel in 2010

New 737-800 aircraft expected to begin sevice next Spring (increase passenger capacity from 137 to 175)

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SWA Cities

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Top 10 SWA Airports

CitiesDaily

DeparturesNumber of

GatesNonstop Cities

Served Established

MDW 226 29 55 1985

LAS 222 19 55 1982

PHX 186 24 49 1982

BWI 177 22 46 1993

DEN 155 17 42 2006

HOU 133 17 32 1971

DAL 127 15 15 1971

LAX 113 11 21 1982

OAK 107 13 19 1989

SAN 95 11 18 1982

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SWA Weather Big picture is a major responsibility

Significant involvement in strategic decision making process (i.e., large scale aircraft movement, weather related station decisions)

Involvement in tactical decision making as needed

Rely solely on NWS TAFs for individual flight planning decisions

Twice daily briefings to ops-related groups (Dispatch, Pilots, Maintenance, Ground Operations, Reservations, Crew Scheduling, Executive Office, Customer Service)

Significant participation in various industry workgroups

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Convection in the Western U.S.

Implications and decisions for SWA operations Decisions not always clear cut, sometimes risk/reward thought

process is necessary

○ Traditionally it would be go, go, go until forced to stop…..that has changed

○ Sometimes holding flights upstream can pay off more than sending them all

○ Connections also big part of the puzzle

Factors besides actual weather also influence decisions

○ What is the specific airport?

○ Is it a maintenance and/or crew base? Handle crew timing out?

○ Aircraft availability for swaps on late lines?

○ Potential for taxi/ramp congestion, ATC initiatives (can get planes caught)

○ Late operations - airport curfews, station staffing (able to support sig late ops)

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Convection in the Western U.S.

Getting flight in ahead of significant weather○ Positives

Maintain schedule times Potential to turn & go

before sig weather hits Weather could diminish

prior to impacting station

○ Negatives Aircraft may be in path

of potential damage (hail, strong winds, lightning, dust deposits)

- Cost of damaged aircraft quite high

Crew timing out possible if departures stopped for any length of time

Less control when wx impacts a station (it’s not easy to speed up a departure)

Gridlock can develop if flights come in but are not getting out

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Convection in the Western U.S.

Holding flights (in air or on ground) ahead of sig weatherPositives

○ Protect aircraft from possible damage Multiple aircraft damaged by

hail this year (DAL, OMA, TUS)

Dust has accounted for 6-10 OTS aircraft at PHX in several events this season

○ Can address possible crew timeout issues upstream (position new crew)

○ When held upstream, better control of aircraft into station after weather moves off

Negatives○ Passengers aren’t there

yet!○ Airborne flights have

increased diversion potential with holding limitations based on fuel Distant alternates, minimal

services, unpleasant passenger experience

Cost of diversions quite high Post-divert return to original

destination not a guarantee (dependent on wx)

○ Lost time (also increases delays down line)

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Significant Dust in LBB (Oct 17th, 2011)

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Decision Support from the NWS

Aviation portion of AFD is a huge asset Adds clarification, conveys forecast confidence, and presents potential

“if then” secondary scenarios Provides access to local NWS office expertise on timing and type of

precip, wind variations, ceiling/vis issues Breaking out specific airports (LAS, PHX, LAX) is VERY helpful

TAF Highlights Amend in timely manner when necessary, even if near end of TAF cycle

(Important with regard to planning for fuel load!) Utilization of VCTS and CB in TAF are key and can be very helpful Same notation can have different interpretation in west vs east U.S.

○ East - frequently means potential for T-storms with rain/showers, or timing of storms still somewhat uncertain

○ West - terrain factors play large role, with these terms used often in storm season Frequently depict distant high terrain T-storms AFD usually brings out the potential for actual terminal impacts

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Decision Support from the NWS

NWS products (and consistency among them) are key in being prepared to make operational decisions Multiple products are viewed and utilized for various aspects of

operational planning

TAF is first and foremost among tools, but dispatchers frequently look at other supporting products○ Gridded Forecasts & Zone Forecasts○ AFD○ Convective Products (CCFP, SPC, LAMP, Model Output)○ Special Weather Statements○ Airport Weather Warnings○ Advanced outlook event statements are big help (LBB, PHX)

Can sometimes be significant variation in forecast products (at terminal or within the local airspace)

Inconsistent products can be a source of confusion in flight planning (especially in terms of the fuel load)

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Decision Support from the NWSMixed Messages (Example #1)

AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE TAUNTON MA656 AM EDT MON AUG 8 2011AVIATION /12Z MONDAY

 AFTER 12Z TODAY…SCATTERED SHOWERS AND THUNDERSTORMS SHOULD BEGIN TO FIRE BY LATE MORNING INTO EARLY AFTERNOON WHICH MAY RESULT IN LOCALIZED LOWER CONDITIONS. MAIN HAZARDS WITH ANY TSTMS WILL BE HEAVY RAINFALL.     KBOS TERMINAL...MEDIUM CONFIDENCE IN TAF.  ITS UNCERTAIN HOW QUICKLY LOW CLOUDS BURN OFF LATER THIS MORNING AND AFTERNOON. IN  ADDITION...SCATTERED SHOWERS AND THUNDERSTORMS MAY AFFECT THE TERMINAL AT TIMES TODAY.  VFR CONDITIONS ARE EXPECTED BY TONIGHT.  

ZONE FORECAST PRODUCT FOR SOUTHERN NEW ENGLAND 715 AM EDT MON AUG 8 2011  

INCLUDING THE CITIES OF...BOSTON...CHELSEA...REVERE...WINTHROP   715 AM EDT MON AUG 8 2011

TODAY: MOSTLY CLOUDY. A CHANCE OF SHOWERS WITH ISOLATED THUNDERSTORMS THIS MORNING...THEN NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS THIS AFTERNOON. AREAS OF FOG THIS MORNING. LOCALLY  HEAVY RAINFALL POSSIBLE THIS AFTERNOON. HIGHS IN THE UPPER 70S. NORTHEAST WINDS 5 TO 10 MPH. CHANCE OF RAIN 60 PERCENT.

KBOS 081122Z 0812/0918 02004KT 4SM BR FEW008 SCT060

      FM081500 04007KT P6SM SCT012 BKN070

      FM082300 33006KT P6SM BKN050

FM091500 08007KT P6SM SCT050

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Decision Support from the NWS

Mixed Messages (Example #2)AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE NEW ORLEANS LA  1214 PM CDT TUE SEP 27 2011   AVIATION  STRONG OUTFLOW BOUNDARY GENERATED FROM OVERNIGHT MESOSCALE  CONVECTIVE SYSTEM IN CENTRAL MISSISSIPPI CURRENTLY PASSING THROUGH  SE LOUISIANA AND OFF THE MISSISSIPPI COAST. MORNING SOUNDING  SHOWED HIGH INSTABILITY SUPPORTIVE OF CONDITIONALLY STRONG  THUNDERSTORMS AS TEMPERATURES EXCEED 88F. MAY NEED TO INCLUDE  BRIEF TEMPO GROUPS AT A FEW TERMINALS FOR ANTICIPATED CONVECTION  BUT WILL TRY TO SHOW DISCRETION TO MOST LIKELY LOCATIONS...LEAVING  OUT OTHERS WITH LESS THAN 30 PERCENT EXPECTATIONS.

KMSY 271729Z 2718/2818 00000KT P6SM FEW040 SCT250

TEMPO 2719/2722 VRB20G40KT 1SM +TSRA BKN025CB

FM280600 25005KT P6SM SCT015

TEMPO 2809/2813 5SM BR BKN012

NWS New Orleans/Baton Rouge, LA

Point Forecast: New Orleans International Airport LA  (29.97°N 90.25°W):

This Afternoon: Mostly sunny, with a high near 91. West wind around 10 mph.

Tonight: Partly cloudy, with a low around 74. West wind around 10 mph.

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Summary & Thanks Going the Extra Mile

Allowing us to be included in conference calls initiated for media or emergency management on significant weather events….very helpful.

Accepting our calls for brief discussions as conditions warrant…..is a huge help.

Additional Helpful Actions Familiarity with your airports operating criteria and local

minimums Working closely with your CWSU to ensure forecast consistency

and awareness of traffic flow status Web sites have become excellent sources for keeping up with

current weather events and looking ahead to upcoming events

Overall increased attention to aviation weather has been very recognizable!

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