Aviation Wind Shear

1. Aviation Wind Shear by Bob Jackson, MIC Seattle CWSU

2. Introduction • Pilots do not always understand how the NWS uses particular terms, and when a term can/cannot be used in the preparation of forecasts. • This presentation will show common mis-understandings of ‘WS’ terminology and applications.

3. Main Goals: • Help forecasters realize short-comings in terminology of Wind-shear • Improve awareness and understanding of proper application of Wind Shear in TAFs

4. This Presentation Discusses: • How the pilots perceive WS • How many meteorologists perceive WS

5. How Pilots perceive WS • “Forecasters tend to believe that pilots know more about weather than they actually do.” (R. Jackson) • Two Studies by R. Jackson demonstrate pilot’s lack of knowledge of Wind Shear: • “Low-Level Wind Shear Terminology” • “A Comparative Study of Pilot’s Understanding of Low-Level Wind Shear Terminology”

6. “Low-Level Wind Shear Terminology” • Survey taken by Certified Flight Instructors in Washington State in 1991. • Presented at the “Fourth International Conference on Aviation Weather Systems” June 24-28 1991, in Paris, France • Printed in Post-Print Proceedings Volume, pp13-15 by AMS and French Met. Society.

7. “Low-Level Wind Shear Terminology” • It was suggested that pilots in Washington may not be as aware of WS terminology because of less convective activity than in other states, • So a second survey was taken in Texas.

8. “A Comparative Study of Pilot’s Understanding of Low-Level Wind Shear Terminology” • Results of same survey taken by Certified Flight Instructors in Texas, July 1991. • The results of both states were very similar.

9. “A Comparative Study of Pilot’s understanding of Low-Level Wind Shear Terminology” • Delivered to AMS/NWS Aviation Weather Conference, Kansas City, Dec 1991, and printed in post-print volume. • Meteorologists at the conference also took survey.

10. The Survey • Participants were asked not to guess…”If you don’t know, please indicate in appropriate space.”

11. How WS is Perceived Question 1 • Is there a difference between ‘WS’ and ‘Micro-burst’? X

12. Difference between WS & Micro-burst?

13. How WS is Perceived Question 2 • “You are on approach and are told that there is a LLWA in effect. • Would you expect micro-burst activity in the area? X

14. Does LLWA Indicate Micro-burst?

15. How WS is Perceived Question 3 • If you see WS mentioned in the TAF, • Would you expect Micro-burst activity in the area? X

16. Does WS = Micro-burst?

17. How WS is Perceived Question 4 • Does ‘WS’ in the TAF and ‘LLWA’ given by tower mean the same thing? X

18. Does ‘WS’ = ‘LLWA’?

19. How WS is Perceived Question 5 • Is the recovery procedure the same for WS as it is for the micro-burst? X

20. Recovery Procedures

21. How WS is Perceived Question 6 • If micro-burst is expected to occur in terminal area, • How would it be indicated in the TAF? • A. WS • B. +TRW VRB50G55 • C. Don’t know / Unsure X

22. Micro-burst in TAF?

23. How WS is Perceived Question 7 • Is turbulence always experienced when encountering a micro-burst? X

24. Does Micro-burst = Turbulence?

25. How WS is Perceived Discussion - 1 • The majority knew WS and Micro-burst were different (Question 1) • Less than 1/3 of the pilots knew recovery procedure was different for each phenomenon

26. How WS is Perceived Discussion - 2 • Only 2% of Pilots and • Only 14% of the Meteorologists • Answered all of the questions correctly.

27. How WS is Perceived Discussion - 3 • Nearly 80% of pilots did not know how micro-bursts are identified in TAFs, • Nearly 60% of responding “aviation experts” didn’t know.

28. How WS is Perceived Discussion - 4 • Only 1/2 of the meteorologists knew that the term “WS” in a TAF Does not mean that Micro-bursts are expected. • Less than 1/4 of the Pilots knew.

29. How WS is Perceived Discussion - 5 • 13% of Pilots and • 5% of the Meteorologists • answered all questions wrong, or didn’t know.

30. How WS is Perceived Discussion - 6 • If a 70% score was needed for a passing grade, • 90% of the pilots would have failed. • 42% of the meteorologists would have failed. • (Not all of the meteorologists were forecasters.)

31. Why the Confusion? • Most training materials do not differentiate between Convective and Mechanical WS. • The term ‘Wind shear’ has been used interchangeably with Micro-bursts by: • FAA - in training and investigations • NCAR - training materials • NTSB - in accident investigations • MEDIA - reporting aircraft accidents

32. Why the Confusion? • As an example, “The Probable Cause - Wind Shear” , NCAR, 1884 • By NCAR for the FAA • Training Video “Geared toward alerting pilots to Wind-Shear…” • Actually discussed an aircraft accident involving Micro-burst.

33. Why the Confusion? • Described as: “The Wind Shear Factor” , NCAR, 1886 • By NCAR for the FAA • “Training Video geared toward pilots and traffic controllers to Wind-Shear…” • Discussed Micro-bursts.

34. Why the Confusion? • An example of an FAA training material

35. Why the Confusion? • A system designed to detect Micro-bursts is called • The “Low Level Wind Shear Alert system” (LLWAS) • When a Micro-burst is detected, then • A Low Level Wind Shear Alert (LLWA) is issued, warning of a Micro-burst.

36. In Closing • Most pilots and many forecasters do not fully understand the ‘WS’ and Micro-burst elements that can be included in TAFs. • Do You?

37. The End Of Part One