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 pilots
  lack of knowledge of Wind Shear
• Low-Level Wind Shear Terminology
• A Comparative Study of Pilots 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 Pilots 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 Pilots 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 guessIf you
  dont 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. Dont 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
  didnt 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 didnt 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