U.S. Department of lranspoftation Federal Aviation Administration Advisory Circular Subject: Date: 11/25/88 AC No: 00-54 PILOT WINDSHEAR GUIDE Initiated by: AFS- 200 Change:
1 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.
2 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 w&l1 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.
a~%% D, C. Beaudette Acting Director, Flight StandardsService
11/25/88 APPENDIX 1, PILOT WINDSHEAR GUIDE AC 00-54 Appendix 1
AC 00-54 11]25/88 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 This document. Pilot Windshear Guide.
and its companion documents, Windshear Overview For Management. Example Wind- Y shear Training Program,*Windshear Substantiating Data, and v?deo presenta- tlons “A Windshear Avoided" and "Windshear What the Crew Can Do” were=- pared 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 herein and in the companion materials was derived from information originally developed for the Boeing 727, and provides a base-line training program with additional recommendations. -developed and approved by Boeing,-Douglas or Lockheed for their respective aircraft, regarding how that program might be adapted for use in specific commercial transport aircraft manufactured by Boeing [727, 737, 747, 757, and 7673, Douglas [DC-g, MD-80, and DC-101 and Lockheed [L-1011]. ANY USE
OF THIS PILOT WINDSHEAR GUIDE AND ITS COMPANION VIDEO PRESENTATIONS "A 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 DO", AND SUCH ENTITY BY SUCH USE, ADAPTATION AND/OR USE AFTER ADAPTATION
ASSUMES SUCH RISK AND WAIVES AND RE-
LEASES ALL CLAIMS IT MAY HAVE AGAINST
THE BOEING COMPANY, MCDONNELL DOUGLAS
CORPORATION, LOCKHEED CORPORATION, UNITED AIRLINES, AVIATION WEATHER ASSOCIATES, HELLIWELL, INC., THEIR
DIVISIONS, SUBSIDIARIES, AFFILIATES
AND THEIR OFFICERS, DIRECTORS, SUBCON-
TRACTORS AND EMPLOYEES FROM ANY LIA-
BILITY WHATSOEVER, WHETHER BASED ON
CONTRACT (INCLUDING BUT NOT LIMITED
TO EXPRESS AND IMPLIED WARRANTY
CLAIMS), TORT (INCLUDING BUT NOT LIM-
ITED TO NEGLIGENCE AND STRICT LIABIL-
ITY CLAIMS) OR OTHERWISE, ARISING FROM
SUCH USE, ADAPTATION AND/OR USE OF SUCH ADAPTATION. ANY SUCH ENTITY (IN-
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 AVOIDED" AND "WINDSHEAR - WHAT THE CREW CAN DO" OR ADAPTS AND/OR
USES AN ADAPTATION THEREOF WITH RE-
SPECT TO SUCH OTHER AIRCRAFT, CONDI-
TIONS OR TRAINING PROGRAM THEREBY
AGREES TO INDEMNIFY AND HOLD HARMLESS
THE BOEING COMPANY, MCDONNELL DOUGLAS
CORPORATION, LOCKHEED CORPORATION,
UNITED AIRLINES, AVIATION WEATHER ASSOCIATES, HELLIWELL, INC., THEIR
DIVISIONS, SUBSIDIARIES AND AFFILIATES
AND THEIR OFFICERS, DIRECTORS, AGENTS,
SUBCONTRACTORS AND EMPLOYEES FROM ANY
LIABILITY WHATSOEVER, WHETHER BASED ON
CONTRACT, (INCLUDING BUT NOT LIMITED
TO EXPRESS AND IMPLIED WARRANTY
CLAIMS), TORT (INCLUDING BUT NOT LIM-
ITED TO NEGLIGENCE AND STRICT LIABIL-
ITY CLAIMS) OR OTHERWISE, ARISING FROM
SUCH USE, 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.
ii
Appendix 1
PILOT WINDSHEAR GUIDE
TABLE OF CONTENTS
SECTION DESCRIPTION PAGE
2.0
2.1
2.2
2.3
2.3.1
2.3.2
2.3.3
2.3.4
2.3.5
2.4
2.4.1
2.4.2
2.4.3
2.4.3.1
2.4.3.2
2.4.4
2.4.5 INTRODUCTION .eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee OBJECTIVES eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee WINDSHEAR WEATHER l eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee LESSONS LEARNED FROM WINDSHEAR ENCOUNTERS l eeeeeeeeeeeeeeeeee ENCOUNTER DURING TAKEOFF - AFTER LIFTOFF l eeeeemeeeeeeee ENCOUNTER DURING TAKEOFF - ON RUNWAY l eeeeeeeeeeeeeeeeee ENCOUNTER ON APPROACH l eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee WINDSHEAR EFFECTS ON AIRPLANES AND SYSTEMS l eeeeeeeeeeee DEVELOPMENT OF WIND MODELS l eeeeeeeeeeeeeeeeeeeeeeeeeeee MODEL OF FLIGHT CREW ACTIONS l eeeeeeeeeeeeeeeeeeeeeeeeeeeeeee EVALUATE THE WEATHER l eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee AVOID KNOWN WINDSHEAR l eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee CONSIDER PRECAUTIONS l eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee TAKEOFF PRECAUTIONS l eeeeeeeeeeeeeeeeeeeeeeeeeeeeee APPROACH PRECAUTIONS l eeeeeeeeeeeeeeeeeeeeeeeeeeeee FOLLOW ESTABLISHED STANDARD OPERATING TECHNIQUES l eeeeee WINDSHEAR RECOVERY TECHNIQUES l eeemeeeeeeeeeeeeeeeeeeeee 2e4e5e1/3 ENCOUNTER DURING TAKEOFF - AFTER LIFTOFF AND ENCOUNTER ON APPROACH l eeeeeeeeeeeeeeeeeeeeeeeeeeee 2e4e 5.2 ENCOUNTER DURING TAKEOFF - ON RUNWAY l eeeeeeeeeeeee 2e5 SUmARY eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee 1 1 2 14 15 19, 22 24 28 29 30 35 38 38 41 43 45 45 49 56 iii
U/25/88 AC 00-54 Appendix 1
2.0 INTRODUCTION During the period from 1964 to 1986, at least 32 accidents and incidents have occurred in which windshear was identified as a contributing factor.
These accidents and incidents resulted in over 600 fatalities and nearly 250 injuries. There is evidence to suggest that if undocumented "close calls" and general aviation statistics were included, these figures would be much higher.
Due to the serious nature of this problem, the National Research Council was commissioned to study the windshear issue. One finding of the Council was a general lack of effective pilot training programs for windshear. The Council made recomnendations regarding further efforts needed to improve the training of pilots to recognize, avoid, and cope with inadvertent windshear encounters. As a result of these recommendations, the Federal Aviation Administration sponsored development of a comprehensive Windshear Training Aid.
The Pilot Windshear Guide is one of several parts of the Windshear Training Aid. The other components are the Windshear Overview for Management, Windshear Substantiating Data, Example Windshear Training Program, and two Training Videos.
The educational material and training recommendations provided in the Windshear Training Aid were developed through an extensive review process to achieve a wide air transport industry consensus. The goal of the Training Aid is to reduce windshear related accidents and incidents by modifying flight crew behavior through education and training.
2.1 OBJECTIVES The objective of the Pilot Windshear Guide is to summarize and communicate key windshear information relevant to flight crews. It is intended to be provided to pilots during windshear ground training and to be retained as a windshear information reference for future use.
Avoidance is emphasized as the best defense against the hazards of low altitude windshear. Information to assist in recognizing and avoiding windshear is provided. However, precautions and techniques for improving chances of surviving an inadvertent windshear encounter are also discussed. Specifically, the Pilot Windshear Guide presents key findings regarding:
1) Windshear weather, particularly microbursts, and clues which may indicate its presence,
2) Effects of windshear on airplanes,
3) Windshear recognition cockpit, an d avoidance, from the
4) Precautions to take when windshear is suspected,
5)
6) Standard operating techniques lated to windshear, and Recovery techn iques to an inadve &rtent windshea rebe used in encounter. r Page 1
AC 00-54 Appendix 1 11/25/88
2.2 WINDSHEAR WEATHER Wind variations at low-altitude have long been recognized as a serious hazard to airplanes during takeoff and approach. These wind variations can result from a large variety of meteorological conditions such as: topographical conditions, temperature inversions, sea breezes, frontal systems, strong surface winds, and the most violent forms of wind change--the thunderstorm and rain shower.
Throughout this document several terms are used when discussing low altitude wind variations. These terms are defined as follows:
Wi ndshear - Any rapid di rection or velocity.
change in wind Severe Windshear - A rapid change in wind direction or velocity causing airspeed changes greater than 15 knots or vertical speed changes greater than 500 feet per minute.
Increas ing Hea dwind Shear in whit h headw ind i ncreases airspeed increase.
- Wi ndshear cau sing an Decreasing Headwind Shear - Windshear in which headwind decreases causing an airspeed loss.
Decreasing Tailwind Shear - Windshear in which tailwind decreases causing an airspeed increase.
Increasing Tailwind Shear - Windshear in which tailwind increases causing an airspeed loss.
Examination of airplane accident and incident reports from 1959 - 1983 identified 51 windshear-related events. These events are summarized in Figure 1.
In order to avoid further windshear encounters, pilots must learn to recognize conditions producing windshear. As Figure 1 indicates, 2 out of every 3 windshear events were related to convective storms. For this reason, the primary focus of the Pilot Windshear Guide is directed toward windshear associated with convective weather conditions: thunderstorms, and in particular the most hazardous form of windshear, the microburst.
Weather System Number of Windshear Events* Convective Storms (Thunderstorms, Rain/ Snow Showers) Front Strong Surface Winds Unstable (Turbulent ) Air Strong Winds on Top of Temperature Inversion Sea Breeze Front Mountain Wave Unknown Total *Event - accident or incident 33 7 2 2 1 0 0 6 51 Figure 7. Windshear events by weather system (7 959 to 7 983).
Appendix 1 o The Thunderstorm There are two basic types of thunderstorms: airmass and frontal. Airmass thunderstorms appear to be randomly distributed in‘unstable air and develop from localized heating at the earth's surface (Figure 2). The heated air rises and cools to form cumulus clouds. As the cumulus stage continues to develop, precipitation forms in higher portions of the cloud and falls. Precipitation signals the beginning of the mature stage and presence of a downdraft. After approximately an hour, the heated updraft creating the thunderstorm is cut off by rainfall. Heat is removed and the thunderstorm dissipates. Many thunderstorms produce an associated cold air gust front as a result of the downflow and outrush of rain-cooled air. These gust fronts are usually very turbulent and can create a serious threat to airplanes during takeoff and approach.
Cumulus Stage Mature Stage Dissipating Stage Localized Surface Heating t Surface = Airflow/Circulation Cooling Figure 2. Airmass thunderstorm life cycle.
AC 00-54 Appendix 1 11/25/88 Frontal thunderstorms are usually associated with weather systems like fronts, converging winds, and troughs aloft. Frontal thunderstorms form in squall lines, last several hours, generate heavy rain and possibly hail, and produce strong gusty winds and possibly tornadoes. The principal distinction in formation of these more severe thunderstorms is the presence ofrge horizontal wind changes (speed and direction) at different altitudes in the thunderstorm. This causes the severe thunderstorm to be vertically tilted (Figure 3). Precipitation falls away from the heated updraft permitting a much longer storm development period. Resulting airflows within the storm accelerate to much higher vertical velocities which ultimately result in higher horizontal wind velocities at the surface.
Airfic Circr Surface Heating LHeavy Rain and Hail Figure 3. Severe frontal thunderstorm anatomy.
U/25/88 The downward moving column of air, or downdraft, of a typical thunderstorm is fairly large, about 1 to 5 miles in diameter. Resultant outflows may produce large changes in wind speed.
Though wind changes near the surface occur across an area sufficiently large to lessen the effect, thunderstorms always present a potential hazard to airplanes. Regardless of whether a thunderstorm contains windshear however, the possibility of heavy rain, hail, extreme turbulence, AC 00-54 Appendix 1 and tornadoes *make it critical that pilots avoid thunderstorms. Figure 4 shows average annual worldwide thunderstorm days.
Certain areas can readily be seen to have a high potential for windshear because of the high level of convective activity. Due to the lower frequency of air traffic in the highest threat areas (the tropics), fewer accidents have been reported in these regions.
Figure Average annual worldwide thunderstorm threat occurs in the tropics.
days. Note that the highest windshear Page 5
AC 00-54 Appendix 1 1x/25/88 Examination of the worldwide windshearassociated accidents and incidents in Figure 5 shows that the majority of these have occurred in the United States. The greater number of accidents results from the combination of high convective activity and high air traffic density. Many more windshearassociated accidents and incidents have probably occurred worldwide but have not been recorded as such.
I q3y y D\enverA st. LOUIS 6 b Ckcago Tucson b Dallas . Chkanooga dago Pago Figure 5.
A Microburst-related accident/incident Worldwide microburst-related airpiane accidents/incidents. High frequency of air traffic in North America combined with a high number of thunderstorm days leads to concentration of windshear-related accidentslincidents in United States.