1. MICROBURST Defeating a Killer
Old Bold Pilots of Palm Desert
November 15, 2012
John McCarthy, PhD
President
Aviation Weather Associates, Inc
Palm Desert, CA 92211

2. OBJECTIVES OF THIS PRESENTATION
To provide a history of research, development, and technology transfer to address the low-altitude wind shear program for civil and military aviation
To describe cross-cutting processes between scientists, pilots, controllers, government program managers, and academia that led to a successful conclusion

3. THE MAIN PLAYERS University of Chicago (Fujita)
National Center for Atmospheric Research (McCarthy and Wilson)
MIT Lincoln Laboratory (Evans)
Boeing (Mulally, Higgins, and Ekstrand)
United Airlines (Ireland and Simmon)
FAA (Hay, Turnbull, Dziuk, Blake), ATC, Flight Standards
NASA (Enders, Bray, Ehernberger)
ALPA, APA, AF, Navy, ATA, IATA, ICAO

5. Microburst illustration showing pulses of very low altitude outflow (0-150 meters above ground)

6. Dry Microburst Formation
Cloud Base
(As high as 15,000 ft)
1000 ft
Approx
Scale
1000 ft
Virga or
Light Rain
Downdraft
Dry
Air
Outflow Front
Horizontal
Vortex
Cold
Air
Plunge
Outflow
Evaporation of rain below cloud base (virga) causes intense cooling of rainshaft air and subsequent cold air plunge.

7. JAWS Experiment Continued in Earnest….
Time = 0
Only a hint of storm downdraft hitting the surface
JAWS Experiment Continued in Earnest….
Data was collected on >150 microbursts!
On radar, microbursts have these characteristic wind signatures and time evolution:
Time = 2 min
Downdraft and outflow spreading along the ground in opposite directions
Time = 5 min
Wind speed is strengthening in both directions
Time = 7 min
Wind change associated with spreading outflow is greatest at this time
Time = 9 min
Wind speeds are decreasing

9. Fujita’s Conclusion:
Eastern Flight 66 Crash was caused by strong wind shear.
He called this type of wind shear a Downburst or Microburst.

11. Major US Accidents or Incidents
EAL 66, JFK 1975
CAL 426, DEN 1975
AL 121 PHL 1976
EAL 693 ATL 1979
PAA 759 MSY 1982
DL 191 DFW 1985
USA CLT 1994

12. JAWS ran for 90 days during the summer of 1982

13. To understand how they form When they are likely to occur
NCAR scientists conducted detailed research on microbursts:
To understand how they form
When they are likely to occur
To train pilots to avoid them
Schematic Evolution of a Microburst
J. W. Wilson, R. D. Roberts, C. K. Kessinger, and J. McCarthy, 1984, Journal of Applied Meteorology

14. Visual Clues of a Microburst
Small scale rainshaft spreading horizontally along the ground
Vertical curl of dust along leading edge of microburst
Circular Ring of Blowing

16. NATIONAL ACADEMY OF SCIENCES, 1983: LOW-ALTITUDE WIND SHEAR AND ITS HAZARD TO AVIATION: A REVIEW OF THIS NOW NER 20 YEAR OLD DOCUMENT IS QUITE INSTRUCTIVE

17. RECOMMENDATIONS
Need for an integrated wind shear program (detection and training)
Wind shear education program
Improve pilot/controller communications
Develop (complete) wind shear detection system (surface and airborne)

18. 44 95 36 42 8 10 1 7 12 11 14 4

20. Late in 1980’s, NCAR built a new Wind
Shear Display for Air Traffic Controllers
Display lets controllers know when a microburst
is impacting the runways and the intensity of the wind
shear (here: 38 knots). Controllers alert pilots on approach and departure.
Alphanumeric Display
Geographical Situation Display

21. USE OF AIRPORT TERMINAL RADARS
Use of NEXRAD to expand understanding of weather conditions in airport terminal area became important part of the Integrated Terminal Weather System (ITWS)
ASR-9/11 Wind Shear Processor (WSP) became major development for FAA
Total of 75 airports covered by microburst protection radar

23. Hong Kong Operational Windshear Warning System (OWWS) Graphic Display

24. Aviation Weather Associates, Inc.
THE WIND SHEAR TRAINING AID: GOVERNMENT, INDUSTRY, AND RESEARCH WORKING TOGETHER TO DEVELOP A COMPREHENSIVE TRAINING PROGRAM FOR WIND SHEAR MITIGATION
FAA
BOEING
LOCKHEED
DOUGLAS
UNITED AIR LINES
Aviation Weather Associates, Inc.

25. Lessons Learned from Windshear Encounters
Avoid, Avoid, Avoid
Recognition is difficult
Time available for recognition is short (5 to 15 seconds)
Effective crew coordination is essential for windshear recognition and recovery
Flight path must be controlled with pitch attitude (unusual stick forces may result)
Reduced airspeed may have to be accepted to ensure flight path control

26. Guidelines for Unacceptable Flight Plan Degradation
TAKEOFF / APPROACH
1) ±15 knots indicated airspeed
2) ±500 FPM vertical speed
3) ±5° pitch attitude
APPROACH
1) ±1 dot glideslope displacement
2) Unusual throttle position for a
significant period of time

27. Follow Standard Operating Techniques Wind Shear Recovery Techniques
Model of Flight Crew Actions
Evaluate the Weather
Any Signs of Wind Shear? No
Yes
Avoid Known Wind Shear
Is It Safe
To Continue? No
Yes
Consider Precautions
Follow Standard Operating Techniques
Wind Shear Recovery Techniques
Report the Encounter

28. WIND SHEAR TRAINING AID USAGE
Required by FAA FARs in U.S., after 1991
Became part of ICAO requirements
Essentially required of all airline pilots throughout the world
Adapted for high-end GA aircraft by FAA contract to Flight Safety Foundation
Relatively little connectivity to small GA aircraft; risk is much smaller

29. AIRBORNE WIND SHEAR SYSTEMS
In-situ (reactive) alerting systems developed, implemented, and mandated
Wind shear recovery guidance and control systems developed and exist on essentially all new (glass cockpit) aircraft
Generation of airborne forward-looking (predictive) required or widely available and implimented

31. SO HOW DID WE DO?
We had a goal of decreasing the frequency of domestic wind shear accidents from about one each 1-2 years, to one each 20 years
The Jury is still out, but the record would suggest strongly that we may have arrived at a much better accident record
We have not had a FAA Part 121 Air Carrier wind shear Microburst accident since 1994

33. CONCLUSIONS
National Academy of Sciences recommendations fully addressed
OBJECTIVE OF REDUCING WIND SHEAR ACCIDENTS MET WITH OUTSTANDING SUCCESS

34. Reducing the Accident Rate A Model for Success: Wind Shear Accidents
727
New York
6/24/75
Involvement necessary
Regulators
Operators
Manufacturers
Wind Shear Accidents
DC-9
Charlotte
7/2/94
727
Denver
8/7/75
727
New Orleans
7/9/82
DC-10
Faro
12/21/92
DC-9
Philadelphia
6/23/76
727
Doha
3/14/79
L1011
Dallas-ft. Worth
8/2/85
707
Pago Pago
1/30/74
Wind Shear Accident Rate
(Notional)
Increasing research and investment in training, airplane systems and infrastructure
Wind Shear Training 1 1 2 3 7
1 NRC study
2 FAA contract for Training Aid
3 Training Aid contract completed
4 First RWS system certified
5 NPRM on training and RWS equipment
6 FAA rule training and RWS equipment
7 Pilot windshear guide
8 RWS and training required
9 First LLWS installed
10 NASA Predictive Windshear System
research start
11 PWS flight trials
12 First PWS STC
13 First PWS delivery as basic 4 5 6 8
The history of windshear accident prevention efforts can be used as a successful example for efforts in other areas.
In the late 1970’s and early 1980’s, there were a rash of accidents due to wind shear. In 1985, industry and government joined forces to attack the problem. Industry developed and employed training and reactive windshear systems. Government agencies focused research on advanced concepts. Regulatory actions reinforced implementation of training and reactive systems. Ground based detection systems were added in the early 1990s. In the late 1990s, predictive wind shear systems are being delivered on new production airplanes.
It is clear from the above chart that no single intervention was completely effective for preventing wind shear accidents. Multiple interventions were necessary, and were phased in over time. From the beginning of actions to completion of implementation will take more than 15 years! Effective implementation for windshear was simplified because windshear accidents primarliy occurred in the US, and the US industry and government were working together to address the challenge.
Similar approaches can be effective to reduce the rate of other accident types as well. It will require industry and government working together to develop consensus on effective interventions and then taking coordinated actions in training, airplane equipment, ground based equipment and regulations.
Airplane Reactive Systems/Displays 9
Terminal Doppler Weather Radar 12 13 10 11
Airplane Predictive
Wind Shear Systems
Goal established
1970 75 80 85 87 88 92 95 98
2000 05 10 15
Year
Industry FAA NASA Other Governments
AT-052d

35. We need to do it again … and we have a process to help us do it
Industry and Government Working Together
Define problems and interventions
Prioritize and develop plan
Data analysis
Aviation system professionals are doing lots of things today
A coordinated effort will enhance the effectiveness of the actions that we’re involved with individually
We think we have a process that will help us do it
Implement the plan
Achieve consensus on
priorities
Industry and government
execute the plan
STR-072b-C