Advisory of Transportation U.S. Department Circular Federal Aviation Administration Subject: Date: 11/25/88 AC No: 00-54 PILOT WINDSHEAR GUIDE Initiated by: AFS- 200 Change:
PURPOSE. This advisory circular communicates key windshear information relevant to flightcrews. Appendix 1 of this advisory circular is the Pilot Windshear Guide, which is only one section of the two-volume Windshear Training Aid.
RELATED READING MATERIAL. The other components of the Windshear Training Aid are the Windshear Overview for Management, Windshear Substantiating Data, Example Windshear Training Program, and two training videos. These additional publications may be purchased from the National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161, telephone (703) 487-4650. A multimedia package, including video tapes, slides, and the Windshear Training Aid, may be purchased from the National Audiovisual Center, 8700 Edgeworth Drive, Capitol Heights, MD 20743-3701, telephone (301) 763-1896.
3. BACKGROUND. In 1985, the Federal Aviation Administration (FAA) contracted with a consortium of aviation specialists from the Boeing Company, United Air Lines, McDonnell Douglas, Lockheed California, Aviation Weather Associates, and Heliwell, Inc., to study windshear. As a result, the Windshear Training Aid was developed. The Windshear Training Aid presents an effective means of training flightcrews to minimize the windshear threat through avoidance, cockpit recognition, and recovery techniques. In order to make the Pilot Windshear Guide section of the Windshear Training Aid available to a wide aviation audience, the guide is reprinted as appendix 1 to this advisory circular.
4. UPDATING PROCEDURE. In order to ensure that the Pilot Windshear Guide is kept up-to-date, the FAA will host meetings for the purpose of reviewing new information on the subject of windshear. These meetings will be held approximately every 18 months and will be announced in the Federal Register.
Technical assistance will be solicited from representatives of the original contract team, as well as from other qualified industry sources, in proposing and evaluating changes. As improvements and changes to the Pilot Windshear Guide occur, they will be distributed as a change to this advisory circular.
DCBcauditle D. C. Beaudette Acting Director, Flight Standards Service
Appendix 1 APPENDIX 1. PILOT WINDSHEAR GUIDE
Appendix 1 Pilot Windshear Guide-- Disclaimer and Indemity Notice The following disclaimer is required by virtue of the contract between the Federal Aviation Administration and the Boeing Commercial Airplane Company.
DISCLAIMER AND INDEMNITY NOTICE and its companion documents, Windshear stantiating "A Windshear Avoided" andỗạWindshear What the Crew Can Do" were prepared pursuant to Federal Aviation Administration Prime Contract DFTAOl- 86-C-00005 with The Boeing Company as a training aid for flight in windshear conditions. The information contained erein and in the companion material:
was derived from information originally developed for the Boeing 727, and with additional recommendating, Doug- veloped and approved by Boeing, provides a base-line training program las or Lockheed for their respective might be adapted for use in specific adapted for use in specific commercial transport aircraft manufac-
OF THIS PILOT WINDSHEAR GUIDE AND ITS COMPANION VIDEO PRESENTATIONS ỊA WIND- SHEAR AVOIDED" AND "WINDSHEAR - WHAT THE CREW CAN DO" FOR ANY PURPOSE RE-
LATED TO AIRCRAFT OR CONDITIONS OTHER
THAN THOSE SPECIFIED ABOVE IS NOT
AUTHORIZED AND MAY RESULT IN IMPROPER
AIRCRAFT OPERATION, LOSS OF AIRCRAFT
CONTROL, INJURY AND LOSS OF AIRCRAFT AND LIFE. ANY USE, ADAPTATION AND/OR
USE AFTER ADAPTATION OF THE MATERIAL
IN THIS PILOT WINDSHEAR GUIDE AND ITS
COMPANION VIDEO PRESENTATIONS A WIND- SHEAR AVOIDED" AND "WINDSHEAR - WHAT THE CREW CAN DO" BY ANY ENTITY FOR ANY
PURPOSE RELATED TO AIRCRAFT, CONDI-
TIONS OR TO TRAINING PROGRAMS OTHER
THAN THOSE SPECIFIED ABOVE SHALL BE
COMPLETELY AT THE RISK OF THE ENTITY
RESPONSIBLE FOR USING, ADAPTING AND/OR
USING THE ADAPTATION OF THIS PILOT
WINDSHEAR GUIDE AND ITS COMPANION VID- EO PRESENTATIONS "A WINDSHEAR AVOIDED" AND "WINDSHEAR - WHAT THE CREW CAN
ADAPTATION AND/OR USE AFTER ADAPTATYON SUCH ENTITY BY SUCH USE, †1
ASSUMES SUCH RISK AND WAIVES AND RE-
LEASES ALL CLAIMS IT MAY HAVE AGAINST
THE BOEING COMPANY, MCDONNELL DOUGLAS ASSOCIATE SUSSIARES. CORPORATION, LOCKHEED AVIATION CORPORATION, WEATHER THEIR
THN TOES NO THAN ES THE NY CON AFFILIATES
BILITY WHATSOEVER, WHETHER BASED
CONTRACT (INCLUDING BUT NOT LIMITED
TO EXPRESS AND IMPLIED WARRANT
CLAIMS), TORT (INCLUDING BUT NOT LIM
ITED TO NEGLIGENCE AND STRICT LIABIL-
ITY CLAIMS) OR OTHERWISE, ARISING FROM SUCH ADAPTATION. ANY SUCH ENTITY (IN- ADAPTATION AND/OR USE OF
CLUDING WITHOUT LIMITATION ANY MANU-
FACTURER OF OTHER AIRCRAFT OR OPERATOR
WITH ANOTHER TRAINING PROGRAM BUT NOT
THE UNITED STATES GOVERNMENT) WHICH
USES THIS PILOT WINDSHEAR GUIDE AND
ITS COMPANION VIDEO PRESENTATIONS A WINDSHEAR WHAT THE CREW CAN DO" OR ADAPTS AND/OR AVOIDED" Ạ&WINDSHEAR
USES AN ADAPTATION THEREOF WITH RE-
SIONS OR TRAINING PROGRAM THEREBY TRAINING PROGRAM
AGREES TO INDEMNIFY AND HOLD HARMLESS THE BOEING COMPANY, McDONNELL DOUGLAS
CORPORATION, CORPORATION,
DIVISIONS, SUBSIDIARIES AND AFILTATES
SUBCONTRACTOES ANO PILOTES FROM MAY
LIABILITY WHATSOEVER, WHETHER BASED ON (INCLUDING BUT NOT LIMITED
CLAIMS), TORT (INCLUDING BUT NOT LIM-
ITED TO NEGLIGENCE AND STRICT LIABIL-
ITY CLAIMS) OR OTHERWISE, ARISING FROM
ADAPTATION AND/OR USE OF SUCH ADAPTATION.
Notwithstanding any other provision of this contract to the contrary, the FAA shall accept the items delivered hereunder with the disclaimer affixed by Contractor and agrees not to remove such disclaimer for any reason whatsoever.
Appendix 1
PILOT WINDSHEAR GUIDE
TABLE OF CONTENTS
SECTION DESCRIPTION PAGE
2.0 INTRODUCTION
2.1 OBJECTIVES 1
2.2 WINDSHEAR WEATHER 2
2.3 LESSONS LEARNED FROM WINDSHEAR ENCOUNTERS 14
2.3.1 ENCOUNTER DURING TAKEOFF - AFTER LIFTOFF 15
2.3.2 ENCOUNTER DURING TAKEOFF - ON RUNWAY 19
2.3.3 ENCOUNTER ON APPROACH 22
2.3.4 WINDSHEAR EFFECTS ON AIRPLANES AND SYSTEMS 24
2.3.5 DEVELOPMENT OF WIND MODELS 28
2.4 MODEL OF FLIGHT CREW ACTIONS 29
2.4.1 EVALUATE THE WEATHER 30
2.4.2 AVOID KNOWN WINDSHEAR 35
2.4.3 CONSIDER PRECAUTIONS 38
2.4.3.1 TAKEOFF PRECAUTIONS 38
2.4.3.2 APPROACH PRECAUTIONS 41
2.4.4 FOLLOW ESTABLISHED STANDARD OPERATING TECHNIQUES 43
2.4.5 WINDSHEAR RECOVERY TECHNIQUES 45
2.4.5.1/3 ENCOUNTER DURING TAKEOFF - AFTER LIFTOFF AND
ENCOUNTER ON APPROACH ...45
2.4.5.2 ENCOUNTER DURING TAKEOFF - ON RUNWAY49
2.5 SUMMARY56
iii
Appendix 1
2.0 INTRODUCTION Aid is to reduce windshear related accidents and incidents by modifying During the period from 1964 to 1986, flight crew behavior through education at least 32 accidents and incidents and training.
have occurred in which windshear was identified as a contributing These accidents and incidents resulted 2.1 OBJECTIVES in over 600 fatalities and nearly 250 The objective of the Pilot Windshear injuries. There is evidence to sug- Guide is to summarize and communicate gest that if undocumented "close key windshear information relevant to calls and general aviation statistics flight crews. It is intended to be were included, these figures would be provided to pilots during windshear much higher. ground training and to be retained as a windshear information reference for serious nature of this future use.
problem, the National Research Council was commissioned to study the wind- Avoidance is emphasized as the best shear issue. One finding of the Coun- defense against the hazards of low algeneral lack of effective titude windshear. Information to astraining programs The Council made recommenda- shear is provided. sist in recognizing and avoiding wind- However improving precautions regarding further efforts needed tions and techniques for to improve the training of pilots to chances of surviving an inadvertent recogniZe windshear avoid, and cope with inad- windshear encounter are also disencounters. cussed. Specifically, the Pilot Windresult of these recommendations, the shear Guide presents key findings re- Federal Aviation Administration garding:
sored development of a comprehensive Windshear Training Aid. 1) Windshear weather, particularly microbursts, and clues which may The Pilot Windshear Guide is one of indicate its presence, several parts of the Windshear Training Aid. The other components are the 2) Effects of windshear on airplanes, Windshear Overview for Management, Windshear Substantiating Data, Example 3) Windshear recognition from the Windshear Training Program, and two cockpit, and avoidance, Training Videos.
4) Precautions to take when windshear The educational material and training is suspected, recommendations provided in the Wind- Training Aid were developed 5) Standard operating techniques rethrough an extensive review process to lated to windshear, and achieve a wide air transport industry consensus. The goal of the Training 6) Recovery techniques to be used in an inadvertent windshear encounter.
Appendix 1
2.2 WINDSHEAR WEATHER Decreasing Headwind Shear - Windshear in which headwind decreases causing an Wind variations at low-altitude have airspeed loss.
Tong been recognized as a serious hazard to airplanes during takeoff and Decreasing Tailwind Shear - Windshear approach. These wind variations can in which tailwind decreases causing an result from a large variety of meteor- airspeed increase.
ological conditions such as: topographical conditions, temperature in- Increasing Tailwind Shear - Windshear versions, sea breezes, frontal sys- in which tailwind increases causing an tems, strong surface winds, and the airspeed loss.
most violent forms of wind change--the thunderstorm and rain shower. Examination of airplane accident and incident reports from 1959 1983 Throughout this document several terms identified 51 windshear-related are used when discussing low altitude events. These events are summarized wind variations. in Figure 1.
fined as follows:
In order to avoid further windshear Windshear - Any rapid change in wind encounters, pilots must learn to direction or velocity. recognize conditions producing windshear. As Figure 1 indicates, 2 out Severe Windshear - A rapid change in of every 3 windshear events were rewind direction or velocity causing lated to convective storms. For this airspeed changes greater than 15 knots reason, the primary focus of the Pilot or vertical speed changes greater than Windshear Guide is directed toward 500 feet per minute. windshear associated with convective weather conditions: thunderstorms, Increasing Headwind Shear - Windshear and in particular the most hazardous in which headwind increases causing an form of windshear, the microburst.
airspeed increase.
Weather System Windshear Events* Number of Convective Storms 33 (Thunderstorms, Rain/ Snow Showers) Front Strong Surface Winds 2 Unstable (Turbulent) Air 2 Strong Winds on Top of Temperature Inversion Sea Breeze Front Mountain Wave Unknown Total 51 *Event - accident or incident Figure 1. Windshear events by weather system (1959 to 1983).
Appendix 1 o The Thunderstorm beginning of the mature stage and presence of a downdraft. After ap- There are two basic types of thunder- proximately an hour, the heated upstorms: airmass and frontal. Airmass draft creating the thunderstorm is cut thunderstorms appear to be randomly off by rainfall. Heat is removed and distributed in unstable air and devel- the thunderstorm dissipates. Many op from localized heating at the thunderstorms produce an associated earth's surface (Figure 2). The heat- cold air gust front as a result of the ed air rises and cools to form cumulus downflow and outrush of rain-cooled clouds. As the cumulus stage contin- air. These gust fronts are usually ues to develop, precipitation forms in very turbulent and can create a serihigher portions of the cloud and ous threat to airplanes during takeoff falls. Precipitation signals the and approach.
Cumulus Stage Mature Stage Dissipating Stage
- Gust Front 5x85 Rain Light Rain Surface Heating Localized T = Airflow/Circulation Cooling Surface Figure 2. Airmass thunderstorm life cycle.
Appendix 1 Frontal thunderstorms are usually as- (speed and direction) at different sociated with weather systems like altitudes in the thunderstorm. This fronts, converging winds, and troughs causes the severe thunderstorm to be aloft. Frontal thunderstorms form in vertically tilted (Figure 3). Precipsquall lines, last several hours, itation falls away from the heated upgenerate heavy rain and possibly hail. draft permitting a much longer storm and produce strong gusty winds and development period. Resulting airpossibly tornadoes. The principal flows within the storm accelerate to distinction in formation of these more much higher vertical velocities which severe thunderstorms is the presence ultimately result in higher horizontal of Targe horizontal wind changes wind velocities at the surface.
Anvil Wind Updraft Downdraft / Airflow Circulation 53355 Surface Heating - Heavy Rain and Hail Figure 3. Severe frontal thunderstorm anatomy.
Appendix 1 The downward moving column of air, or downdratt, of a typical thunderstorm is fairly large, about 1 to 5 miles ir and tornadoes make it critical that pilots avoid thunderstorms. Figure 4 shows average annual worldwide thunderdiameter. Resultant outflows may pro- storm days.
duce large changes in wind speed.
Certain areas can readily be seen to Though wind changes near the surface have a high potential for windshear occur across an area sufficiently Decause of the high level of conveclarge to lessen the effect, thunder- tive activity. Due to the lower frestorms always present a potential haz- quency of air traffic in the highest ard tO airplanes. Regardless of threat areas (the tropics), fewer acwhether a thunderstorm contains wind- cidents have been reported in these shear however, the possibility of regions.
heavy rain, hail, extreme turbulence, Figure 4. Average annual worldwide thunderstorm days. Note that the highest windshear threat occurs in the tropics.
Appendix 1 Examination of the worldwide windshear- high convective activity and high air associated accidents and incidents in traffic density. Many more windshear- Figure 5 shows that the majority of associated accidents and incidents these have occurred in the United have probably occurred worldwide but States. The greater number of acci- have not been recorded as such.
dents results from the combination of var
• Edmonton Detroil . *New York City * Chicago Tucson • Chihuahua • New Orleans Mexico City Pago Pago A Microburst-related accident/incident Figure 5. Worldwide microburst-related airplane accidents/incidents. High frequency of air traffic in North America combined with a high number of thunderstorm days leads to concentration of windshear-related accidents/incidents in United States.