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NASA Conference Publication 10050

Part 2

Airborne

Wind Shear

Detection and

Warning Systems

Second Combined Manufacturers'

and Technologists" Conference

Compiled by

Amos A. Spady, Jr.

and Roland L. Bowles

NASA Langley Research Center

Hampton, Virginia

Herbert Schlickenmaier

Federal Aviation Administration

Washington, D.C.

Proceedings of a conference sponsored by the

National Aeronautics and Space Administration

and the Federal Aviation Administration

and held in Williamsburg, Virginia

October 18-20, 1988

July 1990

U.S. Department of Transportation

Federal Aviation Administration

NASA

National Aeronautics and

,S_q,)ce Admt -,strat,or ,

Langley Research Center

Hampton, Virginia 23665-5225
FOREWORD

The Second Combined Manufacturers' and Technologists' Conference was hosted

jointly by NASA Langley Research Center (LaRC) and the Federal Aviation

Administration (FAA) in Williamsburg, Virginia on October 18-20, 1988. The meeting was

co-chaired by Dr. Roland Bowles of LaRC and Herbert Schlickenmaier of the FAA.

Amos Spady of LaRC and the Science and Technology Corporation coordinated the

meeting.

The purpose of the meeting was to transfer significant ongoing results gained during

the second year of the NASA/FAA joint Airborne Wind Shear Program to the technical

industry and to pose problems of current concern to the combined group. It also

provided a forum for manufacturers to review forward-look technology concepts and for

technologists to gain an understanding of the problems encountered by the manufacturers

during the development of airborne equipment and the FAA certification requirements.

The present document has been compiled to record the essence of the technology

updates and discussions which followed each. Updates are represented here through the

unedited duplication of the vugraphs, which were generously provided by the respective

speakers. When time was available questions were requested in writing. Questions and

answers from the floor are included for all sessions. The written questions were presented

and answered in the final session and are included in the document. Several of the

speakers did not have vugraphs; their talks were transcribed from the recordings of the

sessions, edited by the speaker, and are included. Additionally, the opening overview by

Mr. David Johnson was transcribed and included to provide the reader with an

understanding of the multiple elements included in the Joint Airborne Wind Shear

Program.

iii
TABLE OF CONTENTS

Part 1"

FOREWORD

L OVERVIEW .......................................................

Dave Johnson

2. TECHNICAL PRESENTATIONS - Tuesday, 18 October 1988

Session I. Airborne--Terms of Reference

A. Tools for the Trade ..............................................

Wallace M. Gillman, American Airlines

B. Overview of SAE Committee S-7 ARP 4102/11

"Airborne Wind Shear Systems" . .....................................

Robert L. Ireland, United Airlines

C. Wind Shear Regulatory Activities .....................................

Steve Morrison, FAA

D. Hight Experience with Wind Shear Detection .............................

Terry Zweifel, HoneywellSperry

E. Interface Standards for Integrated Forward-Looking Predictive/Reactive

Wind Shear Systems ...................... "........................

Mark McGlinchey, HoneywellSperry

Session II. Airborne--Hazard Definition

F. Heavy Rain Effects on Airplane Performance .............................

KE. Dunham, Jr., G.M. Bezos, and B.A. Campbell, NASA LaRC,

W.D. Mace, Jr., PRC Kentron, and W.E. Melson, Jr., Wallops Flight Facility

G. A Proposed Definition for a Pitch Attitude Target for the Microburst

Escape Maneuver ................................................

Richard S. Bray, NASA ARC

H. 11 July 1988 Weather and Resulting TDWR Alarms at Denver, Colorado .........

Wayne Sand, NCAR

I. Numerical Simulation of the Denver 11 July 1988 Microburst Storm .............

Fred Proctor, MESO

J. 11 July, Denver Wind Shear Encounters ................................

Robert L. Ireland, United Airlines

K. Questions and Answers for 18 October Sessions I and II .....................

°,.

111

1

9

35

43

57

71

85

103

123

159

179

189

TECIINICAL PRESENTATIONS - Wednesday, 19 October 1988

Session I. Airborne--Sensors

A. Airborne Doppler Radar Detection of Low Altitude Wind Shear ...............

E.M. Bracalente and W.R. Jones, NASA LaRC, and Charles L. Britt, RTI

B. Analysis of Synthetic Aperature Radar (SAR) Data for Wind Shear Radar

Clutter Modelling ................................................

D. Gineris, ERIM, S. Harrah, NASA LaRC, and V. Delnore, PRC

C. Preliminary Airborne Wind Shear Detection Radar Assessment Study ............

C.L. Britt, RTI, and E.M. Bracalente, NASA LaRC

*Published under separate cover.

209

225

243

PRECED:H3 PI_._E _LAhlK NOT FILMED
D. Clutter Filter Design Considerations for Airborne Doppler Radar

Detection of Wind Shear ...........................................

E.G. Bara, Jr., Clemson Universily

E. Airborne Radar Scatterometer Design and Flight Test .......................

W.ag Jones and C.D. Lytle, NASA LaRC

F. Ramifications of the Recent FAA Rule for Wind Shear Systems

on the Development of Forward-Looking Systems ...........................

H. Patrick Adamson, Turbulence Prediction Systems

G. Status of the Delco Systems Operations Forward Looking Wind Shear

Detection Program ...............................................

Brian Gallagher, Delco Systems

H. Infrared Thermal Imaging of Atmospheric Turbulence .......................

David Watt, John McHugh, University of New Hampshire, and

William Pfei_ Kollsman

I. Investigation of Airborne Lidar for Avoidance of Wind Shear Hazards ............

Russell Tar_ Lockheed and Roland Bowles, NASA LaRC

J. 2/zm Lasers for Wind Shear Detection: A Technology Assessment ..............

Mark Storm, Roland Bowles, and Bruce Conway, NASA LaRC

279

295

313

331

349

365

379

Part 2

Session II. Airborne--Flight Management

K. Flight Guidance Research for Recovery From Microburst Wind Shear ............

David A. Hintorg NASA LaRC

L. Analysis and Synthesis of a Wind Shear Detection Algorithm ..................

Kioumars Najmabadi, Boeing

M. Analysis of Guidance Law Performance Using Personal Computers ..............

Z Rene Barrios, HoneywellSperry

N. Crew Interface with Wind Shear Systems ................................

Dave Carbaugh, Boeing

O. An Expert System for Wind Shear Avoidance .............................

Robert Stengel and Alex Stratton, Princeton University

P. The Effect of Wind Shear During Takeoff Roll on Aircraft Stopping Distance ......

Terry Zweife_ HoneywellSperry

Q. Wind Shear Wind Model Simulator Analysis Status .........................

Bernard Ades, DGAC/SFACT/TU-France

R. Wind Shear Predictive Detector Technology Study Status .....................

C. Gandolfi, DGAC/STNA/3E

S. Questions and Answers for 19 October Sessions I and II .....................

393 t"/

417

469

485

511

545

563

591

639

4. TECHNICAL PRESENTATIONS - Thursday, 20 October 1988

Session I. Ground Systems

A. TDWR Program Status ............................................

A.L. Hansen, FAA

B. Low Level Wind Shear Alert System (LLWAS) ...........................

Craig Goff, FA,4

661

671

vi
C. Terminal Doppler Weather Radar 1988 Operational Demonstration

Stapleton International Airport, Denver, Colorado .........................

Wayne Sand, NCAR

D. A Cursory Study of F-Factor Applied to Doppler Radar .....................

Kimberly L. Elmore and Wayne R Sand, NCAR

E. Summer 1988 TDWR Microburst Analysis ...............................

Mark W.. Merritt, M1T Lincoln Laboratory

F. Automatic Detection of Low Altitude Windshear Due to Gust Fronts in the

Terminal Doppler Weather Radar Operational Demonstration .................

Diana Klingle-Wilson, MIT Lincoln Laboratory

Session II. Perspective

G. Some Perspective on the Wind Shear Protection Problem ....................

Sam Saint, Safe Flight

H. Lessons Learned .................................................

William Laynor, NTSB

I. Wind Shear Procedures and Instrumentation .............................

W.W. Melvin, Airline Pilots Association

J. Airbus Wind Shear Warning and Guidance System .........................

1L. Bonafe, Airbus Industries

K. The "Windvan" Pulsed CO 2 Doppler Lidar Wide-Area Wind Sensor .............

Rhidian Lawrence, Spectra Technology

Session III. Topics

L. Low-Cost Airborne Lidar for Wind Shear ...............................

Loren D. Nelson, OPHIR

M. Questions and Answers for All Sessions .................................

683

721

739

753

773

785

797

809

835

843

855

o APPENDIXES

Appendix A. Agenda ................................................

Appendix B. List of Attendees ..........................................

869

875

vii
Session II. Airborne.-Flight Management
Session II. Airborne-Flight Management

Flight Guidance Research for Recovery from Microburst Wind Shear

David A. Hinton, NASA LaRC

393
N91-11696 '

,-ql J

FLIGHT GUIDANCE RESEARCH FOR RECOVERY FROM

MICROBURST WIND SHEAR

David A. Hinton

NASA, Langley Research Center

Hampton, Virginia 23665

ABSTRACT

Research is in progress to develop flight strategy

concepts for avoidance and recovery from microburst wind

shears. The objectives of this study are to evaluate the

performance of various strategies for recovery from wind shear

encountered during the approach-to-landing, examine the

associated piloting factors, and evaluate the payoff of

forward-look sensing. Both batch and piloted simulations are

utilized. The industry-recommended manual recovery technique

is used as a baseline_i strategy. Two advanced strategies were

selected for the piloted tests. The first strategy emulates

the recovery characteristics shown by prior optimal trajectory

analysis, by initially tracking the glideslope, then

commanding a shallow climb. The second strategy generates a

flight path angle schedule that is a function of airplane

energy state and the instantaneous shear strength. All three

strategies are tested with reactive sensing only and with

forward-look sensing.

Piloted simulation tests are in progress. Tentative

results indicate that, using only reactive alerts, there

appears to be little difference in performance between the

various strategies. With forward-look alerts, the advanced

guidance strategies appear to have advantages over the

baseline strategy. Relatively short forward-look alert times,

on the order of 10 or 15 seconds, produce a far greater

recovery benefit than optimizing a recovery from a reactive

alert.

395

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FIRST ORDER FILTER

TIME RESPONSE

s

H(S) - (_S -t- 1)

W X

t

W x

INPUT

K

t

Wx

FILTER'S

OUTPUT

K

mDw_n

!

I

t

1 t

L

Threshold

FILTER'S OUTPUT :

t

_/x =K-K e D_

THRESHOLD CROSSING TIME:

BO_'#NG

435
SECOND ORDER FILTER

TIME RESPONSE

H(s) =

2 S

ton

2

S2 + 2_0)nS + (O n

CASE I : 0<_<1

e- _o_ nt sin 0)11 5 - _ 2t =L

CASE II : _ = 1

W x = 0)2t e-C°nt =L

CASE III: _ > 1

• _ -(_-_-_)oo_ _o -(_÷_-_)oo_

e 8

2 -1 2 -1

=L

NO_'JAFO

436
EXCEEDANCE STATISTICS

x(t) _l H(s) ] y(t)

7 I

l..

y(t)

t

N(y L) = _0_" = y P(y, _) d_

y=L

N (L) = The frequency of crossing the value of L

with positive slope per unit time

P (y, _) = Joint probability density of y (t) and _ (t)

437
EXCEEDANCE STATISTICS

ASSUMING THAT y AND _r ARE STATISTICALLY INDEPENDENT :

P (y, Y) =P (Y)P(Y)

N (y)=p(y) _,p(3_) d_,

IF y IS GAUSSIAN :

P(y) =

1

P(y)=

1

1/2

(.2_ Oy)

1 2

- _(y/ay)

e

THEN

N(y) = 2/CC_y e -_'(y/°y)2

AF,LFLe'JN_"

438
FREQUENCY DOMAIN APPROACH

c_2 = E (y2) -[E (y)]

Y

LET E(y)=0, E(y) =o

THEN

2 m

Cyy=E(y2)=y 2, 2 _g2 -- c_),= E ( ) "_

_y=_ --y_ = I__1__ f+__yyd00 2/I: _

2 1 f + 002 (I)yy do3 (_br = _- - 2_

O0

439
FREQUENCY DOMAIN APPROACH

Noise White (R) _1 shaping HT(S) filter Turbulence_d systemHs(s)

Y

v

(I)yy (03) = R HT (jc0) HT(-j CO)H s (jco) H S(-jco)

FOR THE PRESENT CASE:

HT(S)= _ (y-:s+1) DRYDEN TURBULENCE

s

Hs(S) = ('Cs + 1) 2

FILTER TRANSFER FUNCTION

WHERE

AND

Ls - SCALE LENGTH

Va = AIRSPEED

44O
white I

noise v[

FIRST ORDER FILTER

(HORIZONTAL WIND COMPONENT)

Turbulence_ [

Va

Y=Ls

2G2uy s 2

a'_x (s) - (v2- s2) (_2 s2 - 1)

("US +1)

S

_s+l

l?_rX

v

Wx

¢Wx (s)=

2G2Ts 4

(,y2_ s 2) (2:2s2_1) ([_2s2 _ 1)

02. 1 f+ Wx = _ (1) _¢x (¢o) do) -

o.2. W 1 f+"_ OW x

x = _--_- " ((a) do_ =

_O0

2

Gu Y

_(l+w)

2

o u y[l+y(z+]3)]

_x(VX + 1)(_ +[3)(1 + 7[3)

o/_ - y

N (L) - " e

X

EXPECTED NUMBER OF

THRESHOLD CROSSING

PER UNIT TIME

441
SECOND ORDER FILTER

(HORIZONTAL WIND COMPONENT)

white_ noise l

Ou_/_

s+T CtS

(s+ a)(s+ b)

202 T oc2s2

( s2-v_) (s2-a 2)(s2 -b2 )

J

s

W X

Wx

¢_wx (s)=

2 4

2Ou ycc2 S

(v_-s_)(_- a_)( s_ -b_)

1 f+ o_ 2 0C2

°2wx : _ j _,Wx(o3 ) do) = °u Y

-,_ (7 + a) (7 + b) (a + b)

o2.W 1 +oo [ T(a+b)+ ab x = _" f _ Wx (o3) do3 = 0 2u oc 2 T (T+ a) (7+b) (a +b)

--00

N(L) : X --"

e

2_OQx

EXPECTED NUMBER OF

THRESHOLD CROSSING

PER UNIT TIME

442
white

noise

v

2

(s + 3,)

FIRST ORDER FILTER

(VERTICAL WIND COMPONENT)

Turbulence I a

"-[ (s+a)

"Ca

• (s) =

Wh

_Wh (s) =

(T2-S2) 2 (a2-s 2)

(rz_ _z)2 (a2__ 2)

Wh

S

r

Wh

2 1 f+oo C_Wh = _ cb Wh(m ) d_ =

O0

o_ aCy + 2a)

2 (T + a) 2

2 1 +_

(_.W --_ f

h 2x V_ h (03) do) =

c_ a 2 7(2"/' + 3a)

2

2(y+ a)

N(L) =

• -_--

(_Wh ' e

2x C_Wh

EXPECTED NUMBER OF

THRESHOLD CROSSING

PER UNIT TIME

443
+

• -t.-

u_o

OZ

gg_

_ m

I

t_

t_

II

z

444
TIME DOMAIN APPROACH

white noise

(R) ÷

(t)= A(t) x(t) + B(t) w(t)

y= Cx

×(to) =Xo

WHERE

E[ w(t) w(x)] = R 8(t - x)

E[Xo] :mo

EI(x o- mo) (x o- mo)T]= Qo

THE STATE COVARIANCE MATRIX Q :

(t) = AQ + QA T + BRB T

Q(to) =Qo

STEADY-STATE VALUE OF Q :

AQ + QAT+ BRB T = 0 (LYAPUNOV EQUATION)

THE OUTPUT COVARIANCE MATRIX P :

P =CQC T

_'UEfAV_

445
SECOND ORDER FILTER.

(HORIZONTAL WIND COMPONENT)

white noise _ s + y

(R)

Turbulence._ ! abs

. "_(a + s)(b+ s)

w;,

_(t) = A(t) x(t) + B(t) w(t)

y= Cx

DEFINE :

X -- Wx

x

y ... IIE Jw l _vx olo Wx

w_= oo 1

STATE MODEL :

[ixll ° ' °lIw lEl

Wx o o 1 Vex +

X '_ -AB -A2 -A1 x _u _/_ W

WHERE :

Al=a+b+7

A 2 = ab+ yb+ ya

A s = aby

,8'a_'E'J,,4t,_

446
SECOND ORDER FILTER

( VERTICAL WIND COMPONENT )

w (t) _l

white(R)noise_

s

(S + 7) 2

(as + 1) (bs+ 1)

W h

r

Wh N Wh

w w

1

N (s + V)2 (as +1) (bs+ 1)

_,,, (s',r_ s+ 7¢-7-)

i(t) = A(t) x(t) + B(t) w(t)

y= Cx

DEFINE :

FN

°°

N

X =

°o°

N

°°°°

N

Y=I

W h

STATE MODEL :

0 1 0 0 )

• 0 0 1 0

x = 0 0 0 1 x

A 1 A 2 A 3 A 4

WHERE :

AI= 72

y

I Wh W 1

h

2 2

27+ 7 a+ 7 b

A2 = ab

A 3 =

2

1+27a +27b+ 7

ab

(a + b+27ab )

A4 = - ab

ab

7_d7

0 7-,/7

W

w

°°Ix

8OEJA,'_

447
EXCEEDANCE STATISTICS

(F-FACTOR)

F __

Wx Wh

g Va

1

E(F) = _ E(Wx) - "V'a E(Wh)

2 1 (32 1 2

(3F =_--_ Wx + _ (3 V a Wh

o2: i o2 + I__ o2

2 Wh F g2 Wx Va

o. N(L)- F e-'2"

2_ (3F

448
H(S)-

S

(_S+l) 2

L = THRESHOLD = .15g

2O

Positive slop.e threshold crossings p.er hour as

a function of Dryden Gust intensity for various

filter time constants tau.

_J

v

z

¢-

¢-

°_

£

"o

O

tO

I,==

Q}

E

::3

z

18

16

14

12

10

8

6

4

2

0

%z"

1 0 1 5 _f-'[=2"0

i T IN

/

1 .O0+

1.50o

2.00><

2.51t:3 j 3.00_ 3.50o

. _ _ = = _ = ____ 4.00+

4 RMS6Gust intensity, sigma u8(ft/s). 10

449
S

H(S) =

('rs+l) 2

L =.15g

20

tQ..

t./)

¢..-

"mo_

03

PrO

"O

_O

ttO

0

18

16

14

12

10

8

6

4

2

0

1.5

Ou INCREASING

2"5Filter coefficient Tau 3"5

I

4.5

O'U FPS

4.0 +

6.0 o

8.0 x

10.0o

12.0_

450
S

H(S) =

(3S +1) 2

20

Positive slop.e threshold crossings p.er hour as

a function of Dryden Gust intensity for various

thresholds, L.

,,,4.

..J

z

..c:

$

O.

(/1

t--

(/)

(/}

£

O

t.-

t--

o

(/)

(I)

.>__

Or)

O

O,.

18

16

14

12

10

8

6

4

2

0

L = .07

, L__

• • _ .,',m _ 1.. _"

4 RMS6Gust intensity, sigma 8(ft/s). 10

L

0.07 +

0.09 o

0.11 x

0.13[]

,0.15_

451
S

H(S) -

( 3S +1)2

2O

18

.

A

16

v

z

t-,

t-,,.

$ 14

(f}

,- 12

03

_ 10

0

e- •

_ 8

cO 6

ffl

m 4

0

2

0

0.04 0.06

Positive slope threshold crossings per hour as

a Tunction of thresnold L, for various

Dryden gust intensities, sigma_u.

1 Ou INCREASING

Th rO_,l_81dCoefPl(_tent, 10 (th reOhl_d/g) .

0.14 0.16

au FPS

4.0 +

6.0o

8.0 x

IO.OD

12.0_

452
H(S) -

s

(TS +1) 2

L = THRESHOLD = .15g

20

Detection time as a function of constant shear

intensity for various filter time constants.

,,4,

E

c:

o

o_

a

18

16

14

12

10

8

6

4

2

1.5

1" INCREASING

I I I I

2.5 3S__ear (knot/s1:5 5.5

1"

2.000+

.3.000o

¢.O00x

I

6.5

,4VL_',LL"J,,4¢,GT

453
H(S)= S

(TS+I) 2

L =15g

20

Detection time vs filter time constant tau

for various constant shear levels

18

16

(D

E

t.-

o

E3

14

12

10

8

Wx INCREASING

6

4

2

1.5

i 1

_i_ter time constant (sect'.5

i

4.5

Wx KTS/SEC

3.00+

4'000

500x

6.0Oo

454
s

H(S)-

(3S +1)2

20

Detection time as a function of constant shear

intensity for various thresholds L.

18

16

14

A 12

E

= 10

o

_ 8

D

6

4

2

0

1.5

( I

\

21s

THRESHOLD

,_ INCREASING

1 i

S_ear (knot/4[ 5

I

5.5

L/g

0.15+

0.14<>

0.13x

0.1213

0,11_

0.10o I

6.5

LI'OEING

455
H(S) =

S

(3S +1) 2

20

Detection time vs. threshold level

for various constant shear levels.

A

Q)

E

cO

tO

D

18

16

14

12

10

8

6

4

2

0.04

;REASING

i i i i

0.06 Thr &_8°Id Coef p,_:_ent, lo (thre Ohlo_ _/g)

i

0.14

i

0.16

W x KTS / SEC

1.50+

2.000

2.50x

3.000

3.50_

4.00o

456
s

H (S) -

2

(_S + 1)

ou =8 FTISEC

20

Detection time as a function of shear intensity for second

order filter having varying nuisance alert rates

due to Dryden gust. E = .15 lu = 500, v = 228

o

_fJ

E

FtOo_

15

1:3

18

16

14

12

10

8

6

4

2

2.0

N (LS)ING

2:4 I I I I

_hSear (Knot/se36._ 3.6 4.0

N (L) T

0.50+ 2.17

1.000 2.06

1.50x 1.99

2.000 1.95

3.00_ 1.88

4.000 1.82

_p,D,E'JAI#'___

457
H(S) =

2

_n S

S2+2(wnS+wn 2

= .707

ou = 8 FT / SEC

20

Detection time as a function of shear intensity for second

order filter having varying nuisance alert rates

clue to Dryden gust. E = .15 lu = 500, v = 228

, A

o

o

E.mIc

0

ol

o

a

18

16

14

12

10

8

2

2.0

D

2.4

-_ N(L)

! i

_h8ar (Knot]s3d._ 316 410

N (L) T

0.50+ 2.72

1.00o 2.59

1.50x 2.50

2.000 2.44

3.00_ 2.36

4.00O 2.29

458
H(S)=

S

(TS +I)

O'u = 8 FT/SEC

N(L) = 2 / HR J

20

Detection Time vs. Constant Shear for various

coefficient / threshold combinations that satisfy a

gust rejection requirement, N(L) = 2.0 / hr.

E

i-:

¢-

._o

tj

a

18

16

14

12

10

8

6

4

2

0

1.5

\\

\

"7"

2.5

1 T

3S'_ ear (Knot/sl: 5

5.5

L "[

0.07+ 3.9

0.09 o 3.2

0.11 x 2.6

0.13n 2.3

0.15_ 2.0

3

6.5

,8'J_',&L"/,,_G

459
H 1 =

(Ts + 1)

H2 S

(TS+I) 2

H ab = H(s) = S

(as + 1) (bs + 1)

Hx=

L = THRESHOLD = .15g

O'u = 8 FT/SEC

N(L) = 2 / HR

18

16

14

4

2

2nd ORDER

COMPLEX

= .707

0

i

1.5 2.5

1stORDER T =5.6

2ndORDER / a=1.4 b=2.8

/ 1"=2.0

! i

3S._ear (Knofj4:5 515

TIME1 +

TIME2 o

TCMPL_

,TIMEABo

6.5

Detection time vs. Constant Shear for first and second order filters.

N(L) = 2.0 crossings per hour.

L = 0.15g

,B,O, EJJlV',I$ _

460
O

ILl

09

IJJ

I--

60 _

55

50

45

4O

35

30

25

20

15

10

5

0

I

I

I

t

I

I

I

L--

0

TIME VERSUS SHEAR

PENALTY AREA'S

BOUNDARIES

NEVER ALERT

THRESHOLD

T

2

SHi_AR (KTS/SEC) 6

time15 +

8

461
c_

I

o)

O.

52

5.1

5.0

4.9

4.8

4.7

4.6

4.5.

4.4

,3 ..

o

_<

E3

(

H (s) =

2

co S n

-9

s - + 2_co n s + co2FL

Penalty area as a function of filter damping

ratio zeta.

+

0

X

D_

_O

+

O

X

]

O

+¢

C

,[_ ox 0

,_L)+c>X[_(O"

U

X

0

_r

0.4 0.5 0.6 0.7

Filter damping ratio (Zeta)

N (L) =

_x I =

WX U =

I. =

1: m.

%,

+

O

r

_J

<)

"tO

0.8

2/HR.

2.8 KTS / SEC.

4.0 KTS / SEC.

.14

1

(.on

8',d_,,t_J,,4Y,A_7

462
5.2

5.1

5.0

4.9

4.8

4.7

4.6

4.5

4.4

4.3

H (s) =

2

n

s 2 + 2_o3 n s + co2n

Penalty area as a function of tau.

N. (L)

W'x I

Wx u

L

+

X

+

[]

0

[]

x

(

+

0

£3

X

o

-t

0

-t0

%

X

[]

0

+

)

X

D

0

2.4 2.6

Tau

2.8 3.0

= 2/HR.

= 2.8 KTS / SEC.

= 4.0 KTS / SEC.

= .14

= 1

_n

463
,°

FILTER DESIGN METHOD

SELECT THE ACCEPTABLE

NUISANCE ALERT

RATE t

SELECT MINIMUM VALUE OF WIND SHEAR

THAT SHOULD TRIGGER AN ALERT.

(WIND SHEAR LEVELS BELOW THIS PRESENT

NO POTENTIAL HAZARD TO AIRPLANE)

SELECT THE WIND SHEAR BOUNDARIES

FOR WHICH THE FASTEST DETECTION TIME

IS DESIRED

COMPUTE FILTER'S PARAMETERS FOR

THE FASTEST DETECTION TIME

IS DETECTION TIME

SATISFACTORY?

I NO

I

I

YES

r

MUST ACCEPT

A HIGHER NUISANCE

ALERT RATE t

STOP

_p,d_,,C='lAV'_

4(>4
PROBABILITY DENSITY AND DISTRIBUTION

FOR PEAKS

1 dN(L)

Pp (L) = N(0)- dC

FOR A GAUSSIAN PROCESS:

Pp (L) - L2 exp

G F

(-L2/ 2_ 2 ) RALEIGH DENSITY FUNCTION

Pp(L) : 1- exp (-L2/ 2_ 2)

PROBABILITY DENSITY FUNCTION FOR

PEAKS OF A GAUSSIAN PROCESS

465
PROBABILITY OF NUISANCE ALERT

N (L)

PI(L, AT)

P2(L, AT )

PI= AT n(L)

P2 = 1-P1 =1- AT N(L)

= AVERAGE TIME DENSITY OF EVENTS

= PROBABILITY OF AN EVENT IN AT

= PROBABILITY OF NO EVENT IN AT

PROBABILITY OF NO EVENT IN

t n =nAT

P2 (L, tr0 = - -if- N(L)

n SUCCESSIVE INTERVALS :

FOR LARGE n:

P2 (L, tn) = exp (- t n N(L))

P1 (L, tn) = 1 - exp (- t n N(L)) PROBABILITY OF AN EVENTIN t

FOR A GAUSSIAN PROCESS:

PI(L" tn) = 1- exp (- t n N(0) exp (-

n

NOEJNO

466
l--

n- W

_J0Z

O0

=)Z

la= 0Z0m

k-. mm

o"

)=. m

>..

k.-- m

.=J

0am0

nO=

i

0d

C:,

i

0_, 0d

tO

0

)..=

tO

0

,)-,.

'q'o

,r.,=

0')

0

v,.=

N

0

v..=

jzJJ

J /l

o

v,.=

II

0vz

e"

,.t...-

Od

riiiiiii0

00 I'-- CD tO ._- O3 OJ0

0 _-'_00000000

d I_00ododoo

d

fff

tO

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C)

C) 0

9==.

Ol

0

c)

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0vZ

iiiiii

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J

ii_0

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d

d

000

0000

467
Session II. Airborne-Flight Management

Analysis of Guidance Law Performance Using Personal Computers

J. Rene Barrios, Honeywell/Sperry

469
NASA

N91- 11697

SECOND COMBINED MANUFACTURERS' AND TECHNOLOGY

AIRBORNE WINDSHEAR REVIEW MEETING

OCTOBER 18 - 20, 1988

WILLIAMSBURG, VIRGINIA

ANALYSIS OF GUIDANCE LAW PERFORMANCE

USING PERSONAL COMPUTERS

PRESENTED BY:

J. RENE' BARRIOS

HONEYWELL INC.

SPERRY COMMERCIAL FLIGHT SYSTEMS GROUP

PHOENIX, ARIZONA

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PC-Based Models

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* 3-D Wind Models

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* Takeoff/Roll Dynamics

* Instrument Error Models

484
b

Session II. Airborne-Flight Management

Crew Interface with Wind Shear Systems

Dave Carbaugh, Boeing

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Session II. Airborne-Flight Management

An Expert System for Wind Shear Avoidance

Robert Stengel and Alex Stratton, Princeton University

511
An EXPERT SYSTEM for

WIND SHEAR AVOIDANCE

Robert Stengel and Alex Stratton

PRINCETON UNIVERSITY

Department of

Mechanical and Aerospace Engineering

Princeton, NJ

Presented at:

Second Combined Manufacturer's and Technology

Airborne Wind Shear Review Meeting

October 18-20, 1988

Williamsburg, VA

513
N91-11698

AN EXPERT SYSTEM FOR WIND SHEAR AVOIDANCE

Robert F. Stengel and D. Alexander Stratton

PRINCETON UNIVERSITY

Department of Mechanical and Aerospace Engineering

Princeton, New Jersey 08544

ABSTRACT

Flight in strong wind shears, especially microbursts, poses

a unique and severe hazard to aircraft. The disturbance caused

by the wind field may literally exceed the performance characteristics of the aircraft, making safe transit impossible even with

optimal guidance and control strategies. An unusual degree of

piloting skill may be required to successfully elude danger.

Only the best pilots may be able to cope with strong wind shears,

but even they may be unable to safely penetrate extreme wind

shears. Nevertheless, planes fly in moderate wind shear all the

time; pilots learn to handle crosswinds, gustiness, and moderate

frontal activity. The problem is that microbursts are random,

rare phenomena: pilots do not develop the needed skills for

coping with wind shear through normal experience. The typical

pilot is likely to be confronted with a life-threatening wind

shear only once or twice in an entire flying career; hence, it is

unlikely that he or she can learn all the important signs of wind

shear and maintain a high level of proficiency in the proper control procedures.

On-board computation provides an excellent opportunity to

assist the pilot in surviving encounters with severe wind shears,

but the logic that must be executed in real time is complex and

must have sufficient inputs for framing decisions about appropriate control actions. The computer program(s) and hardware to

perform this task must have attributes of expert systems and control systems, they must account for the limitations of aircraft

performance, and they must operate in real time. At least as

important as its technical specifications, the on-board system

must provide a satisfactory interface with the flight crew, which

bears the ultimate responsibility for assuring safety. This

means not only that the system must deduce near-optimal strategies and tactics for emergency situations but that it must distinguish between truly hazardous conditions and the more likely

alternatives associated with normal aircraft operations.

A program to investigate ways of protecting against the

adverse effects of wind shear during aircraft takeoffs and landings has begun, with current emphasis on developing an expert

system for wind shear avoidance. Our principal objectives are to

_-'_i_.:.,._::.._.:.,_:_ f'_OT FILMED

515
develop methods for assessing the likelihood of wind shear

encounter (based on real-time information in the cockpit), for

deciding what flight path to pursue (e.g., takeoff abort, landing

go-around, or normal climbout or glide slope), and for using the

aircraft's full potential for combating wind shear. This study

requires the definition of both deterministic and statistical

techniques for fusing internal and external information, for

making "go/no-go" decisions, and for generating commands to the

aircraft's autopilot and flight directors for both automatic and

manually controlled flight.

The expert system for pilot aiding is based on the results

of the FAA Windshear Training Aids Program, a two-volume manual

that presents an overview, pilot guide, training program, and

substantiating data provides guidelines for this initial development. The WindShear Safety Advisor expert system currently contains over 140 rules and is coded in the LISP programming language for implementation on a Symbolics 3670 LISP Machine.

516
BACKGROUND

Flight in strong wind shears, especially microbursts, poses a unique and severe hazard to

aircraft. The disturbance caused by the wind field may literally exceed the performance

characteristics of the aircraft, making safe transit impossible even with optimal guidance and

control strategies. An unusual degree of piloting skill may be required to successfully elude

danger. Nevertheless, planes fly in moderate wind shear all the time; pilots learn to handle

crosswinds, gustiness, and moderate frontal activity. The problem is that microbursts are random,

rare phenomena; pilots do not develop the needed skills for coping with wind shear through normal

experience. The typical pilot is likely to be confronted with a life-threatening wind shear only once

or twice during an entire flying career; hence, it is unlikely that he or she can learn all the important

signs of wind shear and maintain a high level of proficiency in the proper control procedures.

On-board computation provides an excellent opportunity to assist the pilot in surviving

encounters with severe wind shears, but the logic that must be executed in real time is complex and

must have sufficient inputs for framing decisions about appropriate control actions. The computer

program(s) and hardware to perform this task must have attributes of expert systems and control

systems, they must account for the limitations of aircraft performance, and they must operate in

real time. At least as important as its technical specifications, the on-board system must provide a

satisfactory interface with the flight crew, which bears the ultimate responsibility for assuring

safety. This means not only that the system must deduce near-optimal strategies and tactics for

emergency situations but that it must distinguish between truly hazardous conditions and the more

likely alternatives associated with normal aircraft operations.

A _ogram to investigate ways of protecting against wind shear has begun at Princeton

University, with current emphasis on developing an expert system for wind shear avoidance. This

program is sponsored by the NASA Langley Research Center under Grant No. NAG- 1-384. Our

principal objectives are to develop methods for assessing the likelihood of wind shear encounter

(based on real-time information in the cockpit), for deciding what flight path to pursue (e.g., abort,

go-around, normal climbout, or glide slope), and for using the aircraft's full potential to combat

wind shear. This study requires the definition of deterministic and statistical techniques for fusing

internal and external information, for making "go/no-go" decisions, and for generating commands

to the aircraft's autopilot and flight directors in automatic and manually controlled flight.

The expert system for pilot aiding is based on results of the Integrated FAA Wind Shear

Program. Its two-volume manual presents an overview, pilot guide, Iraining program, and

substantiating data and provides guidelines for this initial development. The WindShear Safety

.Advisor currently contains over 140 rules and is coded in the LISP programming language for

Implementation on a Symbolics 3670 LISP Machine.

517
BACKGROUND

Hazards of Low-Altitude Wind Shear

Difficulty of Maintaining Pilot Proficiency

Proper Decision-Making and Control Strategy

Enhances the Possibility of Avoidance and

Survival

Meteorological Studies

Sensor Development

Flight Path Optimization

Reactive and Predictive

Feedback Control

FAA Windshear Training Aid

518
FAA WINDSHEAR TRAINING AID

The FAA Windshear Training Aid was prepared with the support of the

Integrated FAA Wind Shear Program. This two-volume manual was written by a

team from the airframe industry that interacted with airlines, government, and

academia. Principal results are expressed in a variety of ways for executive

review, training classes, and public information. One principal goal is to identify

the logical connections between pilot observations and pilot actions when wind

shear is encountered. The functions that a jet transport aircraft crew should

perform are summarized by a flow chart, as shown.

519
WINDSHEAR SAFETY ADVISOR

The WindShear Safety Advisor (WSA) is a computer program that uses

concepts drawn from the world of artificial intelligence (AI) to assess the wind

shear threat and to recommend safe piloting action. The current version is an

interactive but non-real-time program for studying the input information and

logic required to emulate and extend the FAA Windshear Training Aid to

on-board computer systems. In particular, the WSA implements the stated rules

of the Training Aid, and its development is uncovering the unstated (but critical)

implications of the manual. The WSA currently does not address important

human factors issues, such as presentation of information to the pilot and requests

for pilot input or intervention, which would have little significance in

non-real-time simulation. However, our goal is to identify a program structure

that is appropriate for real-time use.

520
ISSUES in MONITORING

and RISK ASSESSMENT

Situational Awareness

Reporting of Threat Indicators

Diversity of lnformation Sources

Relevance to Intended Flight Path

Multiple Reports of Same Phenomenon

Known Limitations to

Target Parameter Selection

Runway length, obstacles

Aircraft performance

System malfunctions

Algorithms for Probability of

Wind Shear Encounter

LOW plus MEDIUM= HIGH?

Bayesian Logic, Fuzzy Sets?

Admonishment of

FAA Pilot Windshear Guide, page 36:

Use of Table I (Microburst Winsdshear Probability Guidelines)

should not replace sound judgement in making avoidance

decisions.

521
ISSUES in MONITORING and RISK ASSESSMENT

The FAA Windshear Training Aid is a significant achievement in the fight

against the hazards of low-altitude wind shear; it identifies the major elements of

observational meteorology that can be linked with dangerous wind shears, and it

gives jet transport flight crews specific actions to take when wind shear encounter

is unavoidable. Nevertheless, it takes a high level of piloting awareness and skill

to evaluate the situation and to execute the implied actions correctly and quickly

enough to avert catastrophe. To the extent that a computer can be fast and

precise, it could assist the flight crew in this dangerous situation.

In seeking to build a computer aid fnr wind shear avoidance, it is necessary

to model the implied logical patterns that the flight crew must use and to quantify

subjective rules for computation. Many factors related to situational awareness,

limitations to effective action, and efficient decision analysis must be considered,

for the computer cannot exert "sound judgment " without having been

programmed to do so.

522
FAA WINDSHEAR TRAINING AID

One Result of the Integrated FAA Wind Shear

Program ,Plan

Volume 1: Overview, Pilot Guide, and Training Program

Volume 2: Substantiating Data

Model of Flight Crew Actions

No

I Evaluate the Weather J_

1

I Avoid Known Windshear

I Consider Precautions 1

1

[ Operating Follow Standard Techniques J

#

Windshear Rec(;very Technique }

JL

r ........ -11

L _ Report _ _ _.the..... Encounter j

523
FAA WINDSHEAR TRAINING AID, continued

Flight crews are given information about the likelihood of dangerous wind

shear when certain observations are made. If the probability of wind shear is

LOW, standard procedures are recommended. If the probability is MEDIUM,

the crew is instructed to consider precautions, including delay or alteration of

terminal operations. If the probability is HIGH, delay or alteration of terminal

operations is recommended, with specifics actions guided by flight phase. If

more than observation suggests dangerous wind shear, the subjective probabilities

should be added, although the guidelines for the risk assessment and the

probability addition are imprecise. For example, two LOWs equal a MEDIUM,

and either two MEDIUMs or a LOW and a MEDIUM equal a HIGH. There is no

guidance regarding spatial or temporal characteristics of the observations; issues

of prox'maity and degree of intensity are left to the pilot's judgment.

Although the strongest suggestion for piloting strategy is "avoid, avoid,

avoid," recommended procedures for recovery or abort following wind shear

encounter are given as functions of flight phase. These strategies are

sub-optimal, but they materially enhance the probability of survival, in

comparison to standard piloting procedures.

524
FAA WINDSHEAR TRAINING AID,

continued

OBSERVATION

PROBABILITY

OF WINDSHEAR

PRESENCE OF CONVECTIVE WEATHER NEAR INTENDED FLIGHT PATH:

- With 1ocalized strong winds (Tower reports or

observed b|owing dust, rings of dust,

tornado-llke features, etc.) ..........................

- With heavy precipitation (Observed or radar

indications of contour, red or attenuation shadow)....

- With ralnshower .......................................

- With ]Ightnlng ........................................

- With vlrga ............................................

- With moderate or greater turbulence (reported or

radar Indlcatlons) ....................................

- With temperature/dew point _pread between

30 and 50 degrees Fahrenheit ..........................

HIGH

HIGH

MEDIUM

MEDIUM

MEDIUM

MEDIUM

MEDIUM

ONBOARD WINDSHEAR DETECTION SYSTEM ALERT (Reported

or observed) .......................................... HIGH

PIREP OF AIRSPEED LOSS OR GAIN:

- 15 knots or greater .................................. HIGH

- Less than 15 knots .................................... MEDIUM

LLWAS ALERT/WIND V_LOCITY CHANGE

- 20 knots or greater ................ ,.................. HIGH

- Less than 20 knots .................................... MEDIUM

FORECAST OF CONVECTIVE WEATHER ............................... LOW

After Liftoff/On Approach Windshear

Recovery Technique

• THRUST

• Apply necessary thrust

•PITCH

• Adjust toward 15 °

• Increase beyond 15 ° if required to

ensure acceptable flight path

• Always respect stick shaker

• CONFIGURATION

• Maintain existing configuration

525
WINDSHEAR SAFETY ADVISOR

FAA Windshear Training Aid

Expansion to Include Implications

and Data Input/Output

Cockpit Simulation

On-Board Data

InertialSensors

Air Data Sensors

Weather Radar

Visual Observations

Look-Ahead Sensors

I_xternal Data

Weather Reports

Tower Reports

LLWAS

PIREPs

SIGMETs

NEXRAD

TDWR

WindShear

Safety

Advisor

Flight

Crew

526
RULE-BASED SYSTEM for CONTROL

An on-board implementation of the WSA would be a Rule-Based Control

(RBC) system having attributes of both expert systems and conventional

eontroUers. In the parlance of AI, the Inference Engine executes the intelligence

of the system, drawing on the Data Base for information (in the form of

parameter values and properties) and on the Rule Base for logical relationships

(in the form of IF...THEN or PREMISE...ACTION statements). In "firing" the

rules, the Inference Engine may require that certain side tasks be accomplished,

such as taking measurements, making estimates, computing control settings, and

transferring commands to control effecters. Continuing the AI jargon, this

procedural, quantitative computation is done in a Side Effects Engine that calls on

both the Data Base and an Algorithm Base for its knowledge. (Measurement and

control are considered side effects of the request for information and the

decision-making process.)

Decision and control functions are readily separated in an RBC system, the

former calling for symbolic computation, the latter for numeric computation.

(In eithe,- case, the digital computer simply moves bits around; however,

interpretations of the logical operations are different.) Not surprisingly, some

computer programming languages are better than others at performing the two

types of tasks, so it is most efficient to use different languages for decision and

control during the development phase. For example, LISP is a good language for

developing logical relationships among strings of symbolic data, while Pascal or

FORTRAN is a good language for numerical computation. Consequently, LISP

is the language of choice for current WSA development.

Once decision and control functions have been defined, they must be

merged (in some sense) in the RBC system. It would be rare indeed for a given

application to need all the subtle features of either development language; thus a

single language can be used at the final step. Development of a real-time version

of an RBC system is thus aided by one or more language translators that

efficiently transform subsets of the development languages into the final code.

Experience with current compilers and computers indicates that procedural

languages like Pascal, FORTRAN, and C produce fast, concise target code for

both decision and control.

527
RULE-BASED SYSTEM for CONTROL

COMMAND

KNOWLEDGE BASE

I RULE BASE

DATA BASE

I ALGORITHM BASE

I USER 1 DISPLAY INTERFACE

INFERENCE

ENGINE

SIDE EFFECTS 1

ENGINE

CONTROL

MEASUREMENTS

Partitioning for

Decision and Control Functions

Integration of Symbolic and Numeric

Computation

528
GRAPHICAL REPRESENTATION of KNOWLEDGE

The elements of decision making needed for the WSA are illustrated by this

simple example. A parameter is a quantity that can have several values as well as

an array of complicated properties (not shown). A rule accepts one or more

parameters as its premise and performs the action of setting another parameter if

the values of its input parameters make the rule true. For the premise to be true,

it may be necessary that all multiple parameters take certain values (represented

by the arc between connecting lines), or it may be sufficient for any parameter to

take a certain value (represented by no arc between channels into the rule).

The example shown illustrates such a rule: Rule 1 says that IF the flight

phase is approach AND the aircraft is below a critical altitude AND a stable

glideslope has not been established, THEN the pilot should perform a go-around.

Rule 2 is the logical exclusion of Rule 1 and need not be implemented; it is here

just for demonstration. Note that the go-around decision proceeds from the rule;

in an array containing a number of such rules, setting parameters by moving

from the bottom up is called forward chaining. Sometimes a result is known and

it is necessary to determine what combination of parameters might have caused

the result. Answering this question requires backward chaining, that is, moving

through the rules from the top down. The WSA requires that both types of

chaining be used at different times.

529
GRAPHICAL REPRESENTATION

of KNOWLEDGE

PARAMETER

_I_I._I NAMEI

>I>I>I

RULE

i

T ACTION Sets Values

ofParameters

NAME RULE 1

//_PREMIS E Values Tests

of Parameters

AND OR

EXAMPLE

APPROACH

RULE

1

60

AROUND

• BELOW

CRITICAL

ALTITUDE

Fo/"_rd

Chaining

i"

RULE t

2

GLIDESLOPE

NOT STABLE

iJ

,=ii.;.

530
STRUCTURE of a RULE

The current version of WSA defines each role as a list in the computer

language called Common LISP. Thus, each rule is expressed as follows:

(name, premise, action, par-act, par-pre, translate)

The meaning of each list element is defined on the chart. The Inference Engine

effectively takes this list apart to find the needed inputs and outputs, performing

an IF...THEN operation on the appropriate parts.

531
NAME

PREMISE

ACTION

PAR-ACT

PAR-PRE

TRANSLATE

STRUCTURE of a RULE

Name of the Rule

Logical Relation of Parameters to

be tested by the Rule

Logical Result of Rule being TRUE

Parameters set by Action

Parameters tested in Premise

Documentation String for

Optional Display

•[Implemented as a Common LISP LIST ]

532
RULE BASES of the WINDSHEAR SAFETY ADVISOR

The current WSA version contains over 140 rules that set over 80

parameters. They are organized in the left-to-right hierarchy shown, addressing

the functions defined by the FAA Windshear Training Aid.

533
RULE BASES of the

WINDSHEAR SAFETY ADVISOR

Executive

Mission Phase

Communication

Wind Shear Alert

Wind Shear Detection

Flight Path Deviation

Risk Assessment

PIREP-LLWAS

ATIS-SIGMET

Generic Weather Risk

Heavy Precipitation

Rainshower

Lightning

Virga

Turbulence

Action

Standard Procedures

Recovery Procedures

Go-Around Procedures

Delay Procedures

Planning

Runway

Airspeed

Flaps

534
STRUCTURE of a PARAMETER

The parameters of the WSA currently are defined as Common LISP

variables. There are different classes of parameters, defined by how and when

their values are determined. A variable has the value current, to which is

appended a property list containing (use, update, expect, translate), defined in the

chart.

535
STRUCTURE of a PARAMETER

Parameter Classifications

INTERNAL

PRESET

STATE

OUTSIDE

Parameter is internal to the Expert System;

Value defined by a Goal-Directed Search

Parameter is set by Initialization

Parameter is set by an Estimator

Parameter is set outside the Expert System

Parameter Properties

CURRENT

USE

UPDATE

EXPECT

TRANSLATE

Current Value of the Parameter

Rules that Use the Parameter

Rules that Set the Parameter

Allowable Values of the Parameter

Description of the Parameter for

Optional Display

[Implemented as a Common LISP VARIABLE ]

536
EXAMPLE PARAMETERS of the WINDSHEAR SAFETY ADVISOR

Names of some of the WSA parameters are shown and are, for the most

part, self-explanatory. Each parameter may represent not only a symbolic or

numerical value but a list that further defines its properties. Therefore, the

Inference Engine can readily identify parameters that have certain attributes, in

turn, aidi_,: the searches associated with monitoring, assessment, planning, and

action.

537
EXAMPLE PARAMETERS of the

WINDSHEAR SAFETY ADVISOR

Communication Rule Base

New-information-received

Incident-reported

Tower-informed-goa

Tower-informed-delay

Precautions-taken

Flight Path Deviation Rule Base

Target-airspeed

Airspeed-deviati0n

Max-airspeed-deviation

Agl-at-max-speed-deviation

Target-vertical-speed

V erti cal- speed-de via tion

Outside Parameters

PIREP

LLWAS

Dispatch-office

ATIS

ASWW

SIGMET

Onboard-radar

Tower-report

TDWR

Wind-profiler

538
LABORATORY for CONTROL and AUTOMATION

Development of the WindShear Safety Advisor is being conducted within

the Princeton University Department of Mechanical and Aerospace Engineedng's

Laboratory for Control and Automation. The laboratory has a broad variety of

computational tools that are appropriate to research in artificial intelligence,

computer-aided design, flight dynamic_ and digital control. A real-time expert

system for fault-tolerant control of a tandem-rotor helicopter has been

implemented in the laboratory using three 80286 MULTIBUS computer boards

for execution. Current WSA development makes use of the LISP Machine, which

employs Common LISP for the expert system and FORTRAN for flight

simulation.

539
LABORATORY for

CONTROL and AUTOMATION

Symbolics 3670 LISP Machine

Silicon Graphics IRIS 3020 Workstation

Macintosh II

IBM PS-2/80

IBM PC-AT (2)

IBM PC/XT (2)

Lab-wide Ethemet Connection (TCP/IP)

Broadband Connection to IBM 3081s

and ETA 10 s

Portable and Fixed MULTIBUS

Computers (5)

Fixed-Base Cockpit Simulator

540
DEVELOPMENT SCREEN for WINDSHEAR SAFETY ADVISOR

A typical LISP Machine display for WSA development is shown. The

program developer uses a mouse to invoke features listed on the menu line and

types information into the User Interaction Pane (or window). Parameters that

change as a result of WSA activity are highlighted in the Parameter Information

Pane, while the overall behavior of the expert system can be followed in the

Result Monitoring Pane. This display is not intended as a prototype cockpit

display but as an engineering tool for concept and program development.

541
DEVELOPMENT SCREEN

for

WINDSHEAR SAFETY ADVISOR

Princeton WindShear Safety Advisor Interface

Flight Plan Get Value Of Make Message Presets ......... L'_lenuLine)

User Interaction Pane Parameter Information Pane

• Messages to program

developer

• Messages to creJ.J._,tower, etc..

• Data and commands from

program developer

Result Monitoring Pane

• Parameters that have changed

values

• Otherparameters of interest

• Executive observations

• Monitored information

• Status assessment

• Planning activity

• Recommended action

• Current airport weather

LISP Machine Implementation

for Concept/Program Development

Interface to FORTRAN

Flight Simulation

542
CONCLUSION

The WindShear Safety Advisor program implements the stated

decision-making logic of the FAA WindshearTraining Aid, as well as a set of

unstated implications that are necessary for practical application. The WSA

expert system contains over 140 roles that set over 80 parameters for terminal

or_rations of jet transport aircraft. Future modifications will account for spatial

and temporal variations of the aircraft and its meteorological environment, as

well as for interfaces with the air traffic control system. The WindShear Safety

Advisor sets the stage for cockpit simulation of logic for wind shear avoidance,

which, in turn, will lead to practical systems for operational aircraft.

543
CONCLUSION

Logic of Wind Shear Avoidance

Computer Aiding for Crew Decisions

Spatial and Temporal Factors

Off-Line and On-Line Simulation

Interfaces with Sensors, Aircraft,

and Crew

544
Session II. Airborne-Flight Management

The Effect of Wind Shear During Takeoff Roll on Aircraft Stopping Distance

Terry Zweifel, HoneyweU/Sperry

545
NASA

SECONDCOMBINEDMANUFACTURERS'AND TECHNOLOGY

AIRBORNEWINDSHEARREVIEW MEETING

OCTOBER 18 - 20, 1988

WILLIAMSBURG, VIRGINIA

THE EFFECT OF WINDSHEARDURING TAKEOFFROLL

ON AIRCRAFT STOPPINGDISTANCE

PRESENTED BY:

TERRY ZMEIFEL

HONEYWELL INC.

SPERRY COMMERCIAL FLIGHT SYSTEMS GROUP

PHOENIX, ARIZONA

547

----'°:',+:_. i:';Gi ° _:_LP/iEb
N91-11699.

THE EFFECT OF WINDSHEAR DURING TAKEOFF ROLL

ON AIRCRAFT STOPPING DISTANCE

Terry Zweifel

Sperry Commerical Flight Systems Group

Honeywell, Inc., Phoenix, Arizona

3 February 1988

ABSTRACT

A simulation of a Boeing 727 aircraft during acceleration

on the runway is used to determine the effect of windshear on

stopping distance. Windshears of various magnitudes, durations, and onset times are simulated to assess the aircraft

performance during an aborted takeoff on five different runway

surfaces. A windshear detection system, active during the

takeoff roll and similar to the Honeywell Windshear Detection

System is simulated to provide a discrete to activate aircraft

braking upon shear detection.

The results of the simulation indicate that several factors affect the distance required to stop the aircraft. Notable among these are gross weight, takeoff flap position, runway characteristics, and pilot reaction time. Of the windshear parameters of duration, onset and magnitude, magnitude

appears to have the most significant effect.

INTRODUCTION

Low-level windshears have proven to be one of the most

significant threats to aircraft safety. Several aircraft

accidents have been directly attributed to the phenomenon,

and, as a result, considerable progress has been made in the

understanding of the atmospheric mechanisms, methodology of

detection, and the control of the aircraft's flight path during a shear encounter.

The research has also resulted in the development of several on-board systems which have been certified by the FAA and

are currently in use. These systems have proven effective in

detecting the presence of a windshear and, in at least two

cases, have been instrumental in the successful escape from an

encountered windshear.

One aspect of the windshear problem which has not been

adequately addressed, however, is the effect of windshear on

the aircraft during takeoff roll: the time between the initial

acceleration of the aircraft on the runway and lift off. Several cases of windshear encounters during the takeoff roll are

known, the most notable being the incident of United Airlines

Flight 663 at Stapleton International Airport on May 31, 1984.

In this instance the aircraft, a Boeing 727, encountered the

549 =' 5"_[.P_LVD
localizer antenna located 1074 feet (327 m) beyond the departure end of the runway. Fortunately, no injuries occurred,

but substantial damage was done to the aircraft.

If a flight crew is aware of a windshear condition prior

to obtaiming the critical engine failure speed, Vl, they may

elect to either abort the takeoff or to continue on through

rotatio, and lift off. V 1 is thus a "go,no-go" speed which is

generally determined by the aircraft's ability to stop within

the remaining runway distance. V 1 is defined as a calibrated

airspeed and thus differs from the actual ground speed of the

aircraft by the magnitude of the wind. Consequently, the

attainment of V 1 in a windshear condition does not necessarily

assure that the aircraft can be safely stopped on the runway

since the ground speed, and hence the kinetic energy of the

aircraft, can be significantly higher than normal. The additional kinetic energy of the aircraft may result in a substantial increase in the required runway to safely stop the aircraft should the flight crew elect to abort the takeoff.

If the windshear is detected after obtaining Vl, the

takeoff must be continued in most cases as the available runway to stop the aircraft is usually insufficient.

This paper addresses the problem of windshear occurring

during takeoff roll by simulating an aircraft in various magnitudes, durations, and onset times of windshears, at different aircraft weights, and on different runway surfaces.

SIMULATION CONFIGURATION

A Boeing 727 aircraft was simulated on an Epson Equity

III+ computer as a three degree of freedom model with an

effective one-quarter second computational rate. Lift and

drag were computed from curve fits of actual aircraft data

with the assumption made that angle of attack, alpha, is constant during the ground roll. Ground effect on lift and drag

were included in the simulation.

Thrust was computed from curve fits of Thrust/Delta versus

_Mach number for a fixed takeoff engine pressure ratio (EPR).

_he engines simulated were Pratt and Whitney JT8D-15 engines

To simulate engine spool down, a simple lag filter was utilized. Engine thrust reversers were not simulated.

The lift and drag effect of ground speedbrakes was simulated with the assumption that the ground speedbrakes achieve

maximum deployment within 1 second.

The aircraft's antiskid system was simulated by assuming

60% efficiency in achievingthe maximum coefficient of friction available for the runway surface.

Five runway surfaces were simulated: (a) dry surface; (b)

wet, grooved asphalt; (c) wet, grooved concrete; (d) wet, textured asphalt; and (e) wet, textured concrete. The dry surface coefficient of friction was applicable to either asphalt

550
or concrete. Coefficients of friction were derived from curve

fits of available data and are shown on Figure 7.

Windshear models available were a linear horizontal shear

and a vortex microburst model. The former was used for the

simulation runs since it allowed more precise control of shear

onset, magnitude, and duration.

The runway altitude was sea level for all cases and the

ambient temperature assumed to be standard day, 59 degrees F

(15 degrees C). The runway was assumed to have zero slope.

No explicit pilot model was necessary as braking is done

by the antiskid system; however, recognition delays were

incorporated to approximate pilot response. For all runs

except those directed at pilot recognition time, the delay

used was 1 second.

AIRCRAFT CONFIGURATION

The simulated flap setting for most takeoffs was 15

degrees, the most common setting for this aircraft. Aircraft

weight could be varied, but, as might be expected, the heavy

weight aircraft was most severely affected by the shears. To

achieve worst case conditions, the aircraft weight was set at

210,000 pounds (95254 Kg). Other runs, not included in this

paper, were conducted at 140,000 pounds (63503 Kg) and 175,000

pounds (79378 Kg).

SIMULATION RUNS

The aircraft was initialized at the end of the runway with

full takeoff power set and brakes applied. At the start of

the run, the brakes were released and the aircraft allowed to

accelerate.

The simulated runway was infinitely long to preclude the

complexity of altering aircraft weight and flap setting to

produce a balanced field length. In this way, the worst case

aircraft weight could be used throughout the runs.

TO provide baseline data in no shear conditions, an

aborted takeoff was performed when the aircraft achieved V I.

Following the recognition delay, the thrust was reduced to

idle, the ground speed brakes deployed, and the antiskid system activated to provide braking. The total runway used thus

provided a baseline value for comparing the effect of a windshear.

RUNWAY SURFACE TYPES

As windshears may or may not be accompanied by rain, it is

important to assess the aircraft's performance on both dry and

wet runways. A wet runway is assumed to have from 0 to .5

inch ( 1.27 cm) of standing water. The type of runway surface

551
can also have significant effects on braking performance.

Consequently, the studies used grooved and textured asphalt

and concrete runways. For convenience, mnemonics were used

for the runway types according to Table i:

Table 1

Mnemonic Runway Surface

DRY

GVD ASPH

GVD CONC

TEX ASPH

TEXCONC

Dry Asphalt or Concrete

Wet, Grooved Asphalt

Wet, Grooved Concrete

Wet, Textured Asphalt

Wet, Textured Concrete

EFFECT OF FLAPS ON STOPPING DISTANCE

The flight crew's selection of takeoff flaps significantly

alters the amount of runway required to stop the aircraft. The

total runway required to accelerate the aircraft to V 1 and

then come to a complete stop using the available takeoff flap

settings for the Boeing 727 is shown on Figure I.

Clearly, the flap setting of 25 degrees provides the minimum

runway usage. This is primarily because V 1 for 25 degrees of

flaps is significantly lower than the others. Consequently,

the aircraft achieves V 1 with lower runway usage and also has

a lower kinetic energy.

However, consideration must be given to aircraft perfor u

mance once airborne in the event the flight crew elects to

continue the takeoff. For the Boeing 727, for example, a flap

setting of 15 degrees is preferred for airborne performance

and consequently, 15 degrees should be used as a compromise

between stopping distance and airborne performance.

As the incremental runway distance between a flap setting

of 5 degrees and 15 degrees is significantly more than that

between flap settings of 15 and 25 degrees, one must conclude

that a flap setting of 5 degrees for takeoff should not be

used if windshear is suspected.

EFFECT OF WINDSHEAR ONSET

To assess the effect of shear onset time on stopping distance, a constant shear of 5 knots per second (2.57 m/sec/sec)

was introduced at specified points as the aircraft accelerated. The shear, once started, was of infinite duration.

Upon detection and recognition of the shear, the takeoff was

552
aborted. As can be seen in Figure 2, the total runway used in

most cases was less than or equal to the distance for the no

shear case. The times on the Figure indicate the time of

shear onset as measured from initial brake release.

In the cases where shear onset occurred slightly before

obtaining V I speed, the total runway usage was increased, but

not dramatically so.

EFFECT OF WINDSHEAR DURATION

The effect of the duration of several shears of different

magnitudes was investigated to determine the increase in total

runway used in coming to a complete stop. In each case, the

onset of the shear was at approximately 10 knots before V 1

speed. Figure 3 illustrates the results. The ordinate axis

yields the total runway used in thousands of feet. The magnitude of the shear used was 5 knots per second. For the dry

runway or wet, grooved runways the additional runway used is

virtually independent of shear duration.

For the wet, textured asphalt or concrete runway, noticeable increases in runway used are evident. However, once the

duration of the shear exceeds 15 seconds, the total runway

used is approximately constant, leading one to conclude that

shear duration is not a prime consideration except on textured

surfaces.

EFFECT OF WINDSHEAR MAGNITUDE

A series of runs was conducted in which the shear onset,

detection, and reaction coincided with attaining V 1. After

onset, the shear was sustained indefinitely. Figure 4 illustrates the results of the simulation runs. The ordinate axis

gives runway distance in thousands of feet.

The data indicate that shear magnitude is not of prime

concern for the dry or wet, grooved surfaces. Significant

increases in total distance used are evident in the wet, rex-

,lured surfaces, however.

EFFECT OF UNDETECTED WINDSHEARS

As of the time of this writing, no on-board system is

available that will detect a shear during takeoff roll,

although one such system is now in the certification process.

Conse_uently, it is left to the flight crew to determine

whether or not a windshear is present during takeoff ro11. The

detection of such shears can be difficult since the aircraft

is accelerating and the shear may be accompanied by turbulence. I_ the simulation runs, the magnitudes of the shears

were intentionally made small to simulate shears that might go

unnoticed by the flight crew. The onset of the shears occurred

approximately I0 knots before v I speed and the shear was then

553
maintained indefinitely. When the aircraft achieved V 1 speed,

it was braked to a full stop and the total runway used noted.

A graph of total runway used versus shear magnitude is shown

on Figure 5. Undetected shear magnitudes of 2 knots per second or less have profound effects on the total runway used,

particularly for the heavy weight aircraft. This is a

consequence of shear causing a low air mass acceleration

which, in turn, causes v I speed to be achieved much further

down the runway than normally.

EFFECT OF PILOT RECOGNITION

To assess the effect of a recognition delay in reacting to

a detected shear condition, simulation runs were made with

reaction delays of 0, I, 2, 3, 4, and 5 seconds. The results

of the runs are shown on Figure 6. In these cases, a 5 knot

per second infinite shear began at V I. The reaction time

represents the number of seconds between detection of the

shear and the pilot reaction of reducing thrust, braking, and

deploying the ground speed brakes. As can be seen, the

effects are dramatic, particularly for the longer delay times.

On the average, about 4% more runway is used for each additional second of delay, regardless of the surface type.

CONCLUSIONS

The data indicate that flap setting, runway surface type,

and pilot recognition time are all prime factors in determining total runway used. A worst case scenario for this aircraft would be heavy gross weight with 5 degree takeoff flaps

on a wet, textured concrete runway. A long recognition time

further aggravates the situation.

Consequently, one may conclude that the largest possible

takeoff flap setting consistent with good airborne performance

should be used. For the 727 aircraft, this is a flap setting

of 15 degrees.

Timely pilot recognition and reaction to a windshear condition on takeoff should and can be reenforced by simulator

training. As mentioned above, approximately 4% more runway is

used for each second of pilot reaction time. It is difficult

to overemphasize the necessity for rapid response to a windshear condition, particularly if the takeoff is to be aborted.

It is interesting that windshears occurring on dry; wet,

grooved asphalt; and wet, grooved concrete runways have such a

small effect on braking performance. With a shear magnitude

of 5 kt/sec occurring at Vl, typical increases in required

distance were of the order of i%.

The effect of ungrooved runway surfaces, however, is significant. A 5 kt/sec shear encountered at V 1 increases the

total runway usage by almost 12% for a wet, textured concrete

surface. The corresponding number for the asphalt runway is

5.4%. It should be noted also, however, that an aircraft on a

554
wet, textured concrete runway requires about 46% more distance

to stop even without a windshear than would be needed if the

runway surface were dry.

The effect of shear onset and shear duration did not

appear to seriously affect the aircraft's braking performance.

Of the detected shears, shear magnitude seemed most significant in terms of braking distance.

Undetected shears resulted in large increases in runway

required - up to 56%. However, it is unlikely that the pilot

would elect to abort in these cases. It is also unlikely that

a low level shear would be sustained for long periods of time;

The simulations did provide an indication of the importance of

shear detection on the runway, however.

It is important to note that the effect of Windshear

Detection System delays were not included in the analysis.

Detection delays due to computation and filtering can add

appreciably to the total runway used in a windshear condition.

The effect of the delays is comparable to the pilot reaction

delays discussed in the paper: for each second of delay time,

up to 4% more runway may be required to stop the aircraft.

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561
Session II. Airborne-Flight Management

Wind Shear Wind Model Simulator Analysis Status

Bernard Aries, DGAC/SFACT/TU

563
WINDSHEAR WIND MODEL SIMULATOR ANALYSIS STATUS

INTRODUCTION

RULEMAKING STUDY ON WINDSHEAR MODELING

NEXT TO COlliE

565
INTRODUCTION

• DGAC MISSION

DGAC ORGANIZATION

SFACT MISSION

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SFACT ENVIRONMENT

566
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w CIVIL AERONAUTICAL MANUFACTURING

• PROVIDE DIFFERENT SERVICES FOR THE BENEFIT OF USERS IN THE FIELDS OF:

AIR NAVIGATION

AIRPORT BASIC E@UIPMENT

TECHNICAL CONTROL AND AERONAUTICAL EDUCATION

567
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)IREET'R)N,S£RVICE:S E'T SERVICES D'LrTAT

DE' (.'AVIATION C_VIL[ OU'TRE-MER

. Antilles / Guyon_

_ R_,unkm

- S4_4-Pi_'te e! MiQuelcm

. II_lyl_$it

Nou_le C4)lt_do_e

I I I

I DIRECTIONS REGIONALES '1 .

IO_ L'AVIATIQN C/VII_[ |

568

ORIGtH.._L PAGE IS

OF POOR QUALITY
SFACT HISSION

• THE AIM OF THIS MISSION IS THE AIRCRAFT SAFETY

m MEANS TO REACH THIS OBJECTIVE ARE:

FLIGHT CREW RULEMAKING, RECRUITING AND PRACTICAL EDUCATION

t GENERAL AVIATION DEVELOPMENT ORIENTATION BY HELPING FLYING CLUBS,

AERONAUTICAL AssocIATIONS

DEFINITION OF AIRCRAFT SAFETY RULES AND SURVEILLANCE OF HOW THEY

ARE PUT INTO OPERATION

TUTELACE OF BUREAU VERITAS AERONAUTICAL ACTIVITY

'569
SERVICE DE

ET DU

SFACT ORCANIZATION

I

LA F0 RM--AT-/oI_--A EIRO-N-A0 T"I-QUE .........

CONTROLE TECHNIQOE

_M. PALAYRET Jr-.

JIM. BOMMIER'I

IM. FRANTZEN|

CHEF DIE SERV_CIE !

I (I I

I

--_M. BOMMIER

"-_M.= V,LLOUTR_SH CHARC;E0¢ U,SS,ON

--IM.COLLOT _ c._oE o¢ .Jss,oN

---_M, SANSOVINI' I___.._ { RE(;CEMCNTArlON PERSONNEL NAVIGANTOU

._'='=_ ..... I I FORMATION ET EXAMEN$

_a'_'UP_I|I"'_=;_I_ _'-"_TLOtl PERSONNEL NAVIGANT

--'_M. BOUFFARD H'PROGRA_"ES M,.,o.s ocs ¢T¢_.rMEs

•--[M. NOBEL }'------'I'AVIATOON GENI¢RALt

--'ILC.sA=I,-mc<L _ SUREAUU,',TA,RI

•--_M:PELTIER l r OCtNCESzr REGIST_ES.

| _ 0U PER$ONNF.L NAVI(}ANT

"--iM'FRANTZEN i I sous- AFFAIRF.SO,Re;CT,ON TF.CNNIOUf._,

--{_ _OI=FIN I__.___ |_ "EGLEMCNTAT,O. 0Es AERONEFS

---{M.LAPASSET ,, _ CE'TIF,CATION Oils AERONEF$

-(M.N'GUYEN _I [ ENrRETIEN DES AERONEF$

-_M:GOUET I

L

I' UT,',SAT,ON O_S A[RONEFS

---'[MDO TRINH _--_ STRT.tSE¢O_'.._N,S

"_M.c.ARPENT,ER _ AFFAIRIES*NTERNATIONAIF$

--{Mme BESSE } { o,vISION.O.,N,ST.AT,V.

HM. QUERE F-'-----'I PER 50N NE L

I- _U,.Loul----I" _,.. o.,...,N. I

IM.CHABAGNOI_-_I ¢.A.. = M,S",ON I

"_MBRUNET _ iNs*_crioN PERSONNEL NAVIGANT 0u J

} t SOU$ "D'RECTION FORMATION AIERONAUTIOUIr I

I

1

I

I

1

1

I

1

I

1

I

1

I

]

1

I

_...______ SERVICE OU MATERIEL O Ir LAI

FORMATION AERONAUT IOuE |

I

; _ __ECOLE$, CENTRES j

I

' 1-N'-$NAT'°N'°' i

I

L__f cE.,., o'EN,RE.,.. I

ET O{ REVISION I

/

570
SFACT ENVIRONMENT

BV L

SFACT/_ 1

STNA/2R

DRAC

DGAC

STPA

STTE

CEV

DCA_

571
mRULEMAKING STUDY ON &#INDSHEAR MODELING

• MAIN OBJECTIVES OF RULEMAKING STUDIES

CARACTERISTICS OF THE STUDY

572
HAINOBJECTIVES oF RULENAKIN_ STUDIES.

I

• CERTIFICATION OF CIVIL AERONAUTICAL MATERIAL IS A FUNCTION OF FRENCH STATE

• NECESSITY TO ELABORATE TECHNICAL RULES (AIRWORTHINESS CODE, QUALIFICATION

NTthNI)iUtDS, MEANS OF CONFORMITY OR INTERPRETATION TEX_S) THAT ARE RECOCNIZED

BOTH BY MANUFACTURERS AND FOREICN AUTHORITIES

• NEED FOR LIVE RULES

• NEED TO OPTIMIZE THE COSTS OF NECESSARY JUSTIFICATION

573
CARACTERISTICSOF THE STUDY

n NOTIFICATION OF THE STUDY BY A CONTRACT BETWEEN DGAC/STPA AND

AEROSPATIALE/CEV SIGNED AT THE END OF YEAR 87

• OBJECTIVE OF THE STUDY IS TO DEFINE AN ACCEPTABLE SET OF WINDSHEAR MODEL FOR

CERTIFICATION PURPOSES (SATISFACTORY MEANS OF COMPLIANCE)

• STRUCTURE OF THE STUDY CONSISTS IN:

• A COMPARATIVE THEORETICALSTUDY BY AEROSPATIALE

• A COMPARATIVE SIMULATOR STUDY BY AEROSPATIALE WITH HELP OF CEV

574
COMPARATIVE THEORETICAL STUDY

1 I

IT CONSISTS OF A CHOICE AMONG DIFFERENT WINDMODELS PRESENTLY AVAILABLE:

* AC 2@-57A AND AC 12e-41

* FAA RD 74-2e6

" HISTORICAL GRADIENTS

" RAE DETERMINIST DOWNBURST

* RAE NON DETERMINIST DO_NBURST

* JAWS B1-85

AFTER EXAMINATION OF:

* BANDE WIDTH

* TURBULENCE STANDARD DEVIATION LEVEL

* FIELD LENGTH COMPARED TO COMPUTER CAPACITY

575
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I
'_ I_:_

VITESSF VP,RIIISLE

VII"ESSE • +140. KT ; IE.-120,.41 ; CHAMP • +4.

, (

12500.

579

_:_ ..... _ PAGE IS

OF POOR QUALITY
140 Kt

IDENTIFICATION

i AC.120-41 AC-120-41 champ 46

SEVERE A BASSE

ALTITUDE

÷÷÷÷

÷÷÷÷

AC-120-41 champ 7

AC-120-41 champ 9 +

AC-120-41 champ 10 + + + ÷

HISTORIOUE CO 426 DEN

HISTORIQUE U,_L 209 ORD

HISTORIQUE EA 66 JFK

HISTORIQUE DAL 191 OFW

HISTORIQUE TWA 524 LGA

18h45 along-path AB

JAWS AUGUST 5, 1982. 18h45' along-path CD

JAWS" AUGUST 5, 1982, 18h45 along-path YZ

I JAWS AUGUST 5. 1982. 18h45 along-path IJ

JAWS" AUGUST 5. 1982, 18h45 along.path KL

i'8h45 along-path GH

+÷÷÷

÷÷÷÷

÷÷÷÷

÷÷÷÷

++÷÷

SEVERE A HAUTi'E.

ALTITUDE

i i

÷ ,i- + ÷

i i

÷

,4-

÷÷÷÷

=,.

•t- ÷ ÷ ÷

÷÷÷÷

HISTORIQUE EA 693 ATL + + +

,i

HISTORIQUE PA 759 MSY + + +

jAWS AUGUST 5, 1982. + ÷

÷

.,I-

°

JAWS AUGUST 5, 1982, . ÷

- JAWS AUGUST 5, 1982. 18h47 along-path AS . + +

18h47 along-path CO

i JAWS

JAws AUGUST 5, 1982. 18h47 along-path KL

- JAWS'AUGUST'5, 1982. 18h47 along-path GH

JAWS' AUGusT 5, 1982, 18h50 along-path AB

JAWS AUGUST 5, 1982,

JAWS AUGUST 5, 1982, 18h47 along-path YZ

AUGUST 5, 1982. 18h47 along-path IJ ÷

• ii ,

JAWS AU_'UST 5, 1982, 18h50 along-path CO

JAWS AUGUST 5. 7982, 18h50 along-path YZ

JAWS AUGUST 5. 1982. 18h50 along-path U

18h50 along-path KL

÷

÷

I JAWS AUGUST 5, 1982, 18h52 along-path CD

! JAws AUGUST 5, 1982, 18h52 along-path YZ

[ JAWS" AUGUST 5, 1982. 1'8hS2' along-path IJ

[ JAWS AUGUST 5. 1982. 18h52 along-path KL

i' JAWS _UGUST 5, 1982, 18h52 along.path GH

d-÷

÷

÷

°

÷ d,,.

JAWS AUGUST 5, 1982.

JAWS AUGUST 5, 1982, 18h50 along-path GH

J

JAWS AUGUST S, 1982, 18h52 along-path AB . ÷ +

severitd insignifiante

sdveritd faible

severite moyenne

580

BASSE ALTITUDE • <= 500 t't

÷

HAUTE ALTITUDE " • 500 ft ÷ +

÷ ÷

,i

,,i , ii

÷ ÷ ÷

÷÷÷4,

$_verite forte

s_ivedta tr&s forte
JAWS

JAWS JUNE 30, 1982, 18h21 along-path MN

JAWS JUNE 30, 1982, 18h21 =long-path PQ

JAWS JUNE 30, 1982. 18h21 aJong-path RS

JAWS JUNE 30, 1982, 18h23 along-path EF

JAWS JUNE 30, 1982. 18h23 =long-I:_th MN

JAWS JUNE 30, 1982, 18h23 along-path PQ

JAWS JUNE 30. 1982, 18h23 along-path RS

JAWS JUNE 30, lg82, 18h26 along-path EF

140

IDENTIFICATION

JUNE 30, 1982, 18h21 along-path EF

JAWS JUNE 30, 1982, 18h26 along-path MN

JAWS JUNE 30, 1982, 18h26 along-path PQ

JUNE 30. 1982, 18h26 along-path RS

SEVERE A BASSE

ALTITUDE

6

SEVERE A HAUTE

ALTITUDE

4-

i

i i

4"

i

,4-4-

i

JAWS . -

JAWS JULY 14. 1982, 14h52 along-path TU . +

JAWS JULY 14. 1982, 14h52 along-path VW + +

JAWS JULY 14, 1982, 14h52 along-path OX + +

JAWS JULY 14, 1982, 14h52 along-path LS +

BASSE ALTITUDE • <= 500 ft

+

.HAUTE ALTITUDE " • 500 ft ÷ +

sdveritd insignifiante + + +

sevedte faible + + + +

severite rnoyenne

581

severite forte

sdverite tres forte
COMPARATIVE SIMULATOR STUDY

I

• ON A COMPUTER

• ON A FBS A300-600 WITHOUT ENVIRONMENT AND CABIN MOTION, DETECTION OF

WINDSHEAR BEING COMPLETED BY OBSERVATION OF TENDANCY BARS OF SPEED VECTOR

• PLUS A STUDY ON A CEV SIMULATOR (CALLED MBS) WITH MOTION AND EXTERNAL

VISUALISATION

582
HB8 SI_JDY

• UTILIZATION OF RIND MODELS

• PRELIMINARY STUDIES

RESULTS

583
UTILIZATION OF WIND MODELS

. __ I !

• HISTORICAL MODELS:

w WIND PROJECTIONS ARE ONLY FUNCTIONS OF DISTANCE ALONG THE

RUNWAY AXIS

* USE OF THESE MODELS IS ONLY POSSIBLE ALONG THE HISTORICAL TRAJECTORY

Z OTH__ (AC 12@-41, JAWS el-85, TEORETICAJ. DOWNBURST)

* WIND PROJECTION ARE ONLY FUNCTIONS OF DISTANCE ALONG THE RUNWAY AXIS AND

HEIGHT ABOVE RUNWAY

* THIS MEANS THAT MORE THAN ONE TRAJECTORY ARE FEASIBLE, ESPECIALLY FOR

TAKE-OFF

I SPECIFIC TRAJECTORIES:

* BETTER THAN NOTION OF FIELDS WOULD BE AIRCRAFT TRAJECTORIES THROUGH THOSI

FIELDS

584
PRELIMINARY STUDIES

I

• OBJECTIVES:

THE AIM IS TO DETERMINE HOW TURBULENCE ON ONE SIDE,.HOW THE MEANS'OF

SIMULATION ONTHE OTHER SIDE, HAVE AN IMPACT ON THE CREW BEHAVIOUR AND ON

THEIR JUDGMENT

w THIS MEANS

- AC@UIRE A PRACTICAL EXPERIENCE ON THE MEANS

- REDUCE THE TOTAL NUMBER OF TESTS BY DEFINING IDEAL CONDITIONS OF TESTING

• CONDITIONS OF TESTING:

FOR DETECTION, NO ALARM IS PROVIDED

FOR ESCAPE, AN ALARM IS DEFINED BY A DISTANCE, IN ORDER TO AVOID TOO LARGE

A DISPERSION OF THE POINTS _IHERE ESCAPES ARE PERFORMED

BEFORE EACH TEST, CONDITIONS ARE SET UP

AFTER EACH TEST, THE CREW FULLFILLS A @UESTIONARY

585
@UESTIONARY ON WIND MODEL @UALIFICATION

-- _ - m _ iii I

1. DETECTION

1.1.

a) With alarm: depending of the piloting informations provided, do you think

the alarm has appeared:

1 - too soon

2 - on time

3 - too late

b) Informations being used for detection: (instruments, external.

visualisation, motion... )

1.2. Entering the gradient (just before applying escape procedure), the

situation has appeared:

A (very critical): immediat danser, necessary reaction to be very urgent;

B (critical) : actual danger, necessary reaction to be urgent;

C alarming) : forecasted danger; the degradation of the performance,

although non critical, is unacceptable

D (abnormal) : but not alarming; the degradation of the performance is

acceptable;

E (normal) : comparable to a current variation of the wind;

586
2._sc_P_

2.1. Piloting capacity during escape:

a) longitudinal: ease of procedure 0 - 17"5

A: very difficult

B: difficult

C: mean difficult

D: little difficult

E: easy

b) lateral: influence of the lateral shear on the longitudinal procedure:

A: very disturbing

B: disturbing

C: little disturbing

D: very little disturbing

E: unexistant

2.2 Global crew workload (data surveillance...)

A: very high

8: high

C: reasonable

D: mean

E: normal

587
2.3. Duration feeling in relation with the concentration effort

A: very long duration

B: long duration

C: mean duration

D: short duration

E: very short duration

2.4. Uncapacity feeling during escape manoeuver (short term)

A: very high, parameters within the critical zone, situation getting

worse

B: high, parameters within the critical zone, stable situation

C: mean, parameters within the critical zone, situation getting better

D: low, abnormal but not critical values o£ vl and V2

E: nul

2.5. Danger feeling durind escape _noeuver (danger being ground proximity or

stall)

A: very high

B: high

c: mean

D: low

E: nul

588
RESULTS

• LIMITS

* AIRCRAFT MODEL

* FLIGHT CONTROLS

* PSYCHOLOGICAL ASPECT

*DIFFERENT WAYS OF PILOTING THE PHENOMENOM

MOVEMENT

4, TURBULENCE

I ENVIRONMENT CONDITIONS IMC/VMC

• EFFECT OF TURBULENCE

INSTRUMENTA[ION

589
NEXTTO COME

• FROM THE STUDY

• FINALIZATION OF AEROSPATIALE RESULTS

• UTILIZATION OF A HUD

• BI-TURBOPROPELLER SIMULATION

• OTHER STUDIES

• DEFINITION OF AN ACCEPTAflLE MEANS OF COMPLIANCE FOR A DETECTION AND GUIDANCE

EWUIPMENT

* OP_ERATIONAL RULES ASSESSMENT WITH AND U_THOUT AUTOMATIC _UIDANCE SYSTEM FOR

A38e/A38@-600/A31@/A32e

590
Session II. Airborne-Flight Management

Wind Shear Predictive Detector Technology Study Status

C. Gandolfi, DGAC/STNA/3E

591
N91-.11700

* "

. Presentation of French Civil Aviation Technical Service

at

(C. GANDOLFI from DGAC/STNA/3E) .

Second Combined Manufacturers' and Technology Airborne

Wind Shear Review Meetinq, Williamsburg October 18-20, 1988

I) Introduction :

Among the different elements to be investigated when

considering the Wind Shear hazard, STNA/3E [I], whose task is

to participate in the development of new technologies and

equipments, focused its effort on airborne and ground sensors

for the detection of low-level wind shear.

The first task, initiated in 1986, consists in the

evaluation of three candidate technics for forward-looking

sensors : LIDAR (Light Detection And Ranging), SODAR (Sound

Wave Detection And Ranging) and RADAR.

No development is presently foreseen for an infrared

based air turbulence advance warning system although some

flight experiments took place in the 70's. A Thomson_CSF

infrared radiometer was then installed on an Air France Boeing

707 to evaluate its capability of detecting clear air

turbulence. The conclusion showed that this technic was

apparently able to detect clouds layers but that additional

experiments were needed; on the other hand, the rarity of the

phenomenon and the difficulty to operate on a commercial

aircraft were also mentionned.

II) LIDAR program :

Laser technology is the only one that

studied for an airborne forward-looking sensor.

is presently

i) The first step of the LIDAR program consisted in a

preliminary contract with the CR©UZET company. This task

initiated in may 1987 was completed by february 1983.

It consisted in the following elements :

*investigation of operational objectives in terms

of functional specifications and system design

requirements : altitude and range of measurez_ent,

speed range, envircn_en_al constraints (weather,

installation .... ) ....

593
r

• .. •-:

• . -- °

..•'-.. • °

*ground experiments with• an existing mock,up

sponsored by military contracts for anemometry

purposes. This equipment is based on a continuous.

laser beam (10,6 _m), with a 75 mm telescope

focusing between I0 and I00 m; the speed sign can

be detected and measures around zero (± 0,25 m/s)

are possible.

*evaluation for both adaptations : ground and

onboard detector.

I.I : Airborne wind shear detection :

General requirements :

The warning criteria recommended by the

CROUZET company proceeds in two steps :

*a pre-alarm advisory for an increasing

headwind of 40 ft/s combined with an upward vertical

component;

*an alarm announce for a tailwind of 40 ft/s

associated with a vertical downdraft.

The proposed technical requirements are the

following ones :

*Radial speeds range from 60 to 240 knots

(assuming aircraft speed between'f20 and 130 knots and a wind

variation of ± 60 knots);

*Velocity resolution : ± 3 knots;

*Look-ahead range of 700 m (I0 s warning

time) with a range resolution _ 300 m;

*Estimation of the vertical wind inferred

from radial speed measurements in two spatially shifted

locations;

*Lateral exploration by a conical scanning

steered at I0 ° from flight path. "Left lateral", "right

lateral", "up ...., down" components would be delivered with an

update rate of approximately 1 s;

*Environmental constraints as defined in

RTCA-DOI60-B.

The resulting information presented to the

pilot would be the radial velocity (Vx) ,an estimation of the

vertical component (Vz) and the lateral shifting of the

perturbation (Vx right and Vx left).

Two technologies are proposed by the CROUZET

company :

_at first, a mock-up based on a continuous

COz laser source (10,6 Dm) with a MTBF (Mean Time Between

Failure) of I000 hours;

*in the future, for operational systems, a

solid-state laser (2,1 Dm) with a MTBF of 5000 hours, an half

size optical diameter, a classical thermal regulation.

594
• Future studies proposals :

*The first idea was to proceed with flight

•experiments of the existing mock-up where a 200 mm telesc6pe

would have been adapted in order to focus at 570 m

(measurement volume between 420 m and 720 m) using Conical

scanning of 1 s and beam steering of i0 °. The aim was to

collect data on Vx laser, Vz laser, the difference between

laser speed and aircraft speed, and spectra. This program

didn't appear efficient enough since the technological options

were not clearly defined at this stage. It seemed necessary to

precisely identify the theoretical environment before carrying

out expensive flight tests.

*Consequently, a second program plan w_s

considered on the basis of flight tests supported by

theoretical tasks and simulations. However, since, the main

technological choices (type of laser, optical diameter .... )

had to be fixed through simulation investigations, it was

decided to delay the experimental phase.

The preliminary theoretical part was

delegated to the ONERA research laboratory [2] because of its

experience in detectors, aircraft simulators, aerodynamics,

and its relationships with meteorologists as well as with

people from the National Flight Test Center "CEV" [3]. Another

point is that an equivalent method combining a theoretical

part carried out by a research center and a realization

through a mock-up designed by a manufacturer proved successful

for the anemometry prototype (cooperation O_IERA/CROUZET).

ONERA program plan :

The contract concerning the OUEEA

participation is presently to be debated but preliminary

guidelines have been identified in terms of an initial study

to start with. It concerns :

*the windshear models :

-implementation of the existing FAA models

-adaptation of new parameters Specific to

laser detection such as variations of the

backscattered signal, absorption, rain and

fog attenuation ....

*simulations with different types of laser

sensors : continuous CO_ source with or

without modulation, pulsed laser, optical

diameter ....

1.2 : Ground-based wind shear detection :

General requirements :

The operational requirements as defined by

CROUZET assume a coverage until I000 ft tha_ is considered to

be the minimum safe altitude to monitor take-off (6 ° ) and

landing (3 ° ) flight paths.

From the various constraints (length and

width of runway, lateral shifting of microburst, warning tirze

of I0 s), a minimum range of 7,5 Km is required for a ground

sensor located at the center of the runaway and alterr_atively

595

ORIOtNAL PAGE IS

OF, POOR QUALITY
scanning departure and arrival flight paths. According to the

cost and availibility of technology, an alternate solution can

consistof two systems focusing at 2400 m (measurement volume

between 40 m and 3400 m). The spatial resolution must be _

better than 300 m for a range of speed of ± 60 knots with a

speed resolution of ± 3 knots.

Among the constraints, the environmental

severity factor must be taken into account : electrical

protection, temperature (-30°C/60°C), humidity, sand and dust,

salt spray .... The foreseen MTBF is 5000 hours.

Another essential aspect is that in order to

be efficient, a ground-based equipment needs an automatic

alert transmission.

Ground-based experiments :

The equipment is based on a continuous laser

source (10,6 pm), with a 75 mm telescope focusing between I0

and 100 m. However, in order to increase the range, some

measurements were done at 200 m ([50m, 350m]).

Preliminary tests were settled in CROUZET

facilities in order to observe building-induced turbulence.

Despite CROUZET conclusions, this experiment didn't prove

demonstrative since the collected values didn't show a

sufficient amplitude dynamic (0 to 4 m/s).

The first set of tests consisted of :

-preliminary measurements with a fixed mirror

and focusing distance of 35 m;

-conical scanning : beam steering at 15 °

orientation and 40 rounds per minute for a

focusing distance of 200 m. The theoretical

graph is a sinusoid whose mean value depends

on the wind component along line of sight.

The amplitude is a function of the

perpendicular component module; the phase is

related to its orientation. Wind field

dispersion distorts the ideal curve.

Several rotation speeds were experimented.

Since the angular shifting of line of sight

cannot be omitted any longer during the

acquisition of instantaneous spectra for one

measurement, the spectrum width increases

with the rotation speed.

-measurements in rain conditions : the

spectrum enlarges because of rapidly changing

speeds of turbulence and rain. in some

experiments, rain drops speed signal was more

powerful than wind speed i_self.

The system was then installed on the military

base of Valence. The frequent proximity of helicopters at low

altitude gave the opportunity to collect data on turbulence

engendered by their rotor blades.

-variation of the focusing distance from 30 m

to 200 m showing the spectrum spreading at

"long distance".

596

OF POOR QUALITY
-measurement volume splitting by putting a

mirror on the line of sight in order to

demonstrate the capability of indicating the

change of sign in velocity.

Future studies proposals :

The pulsed technique is the only valid

candidate for the 7,5 Km range criteria. Furthermore, it

guarantees a spatial resolution propotional to the pulse

length and light celerity. Since ground clutter isn't a

sensitive point, a slight deviation of laser beam (2 ° tilt)

could be used to evaluate phenomenon shifting.

An alternate solution,proposed by CROUZET, is

to use two equipments located at 2400 m from each runway

extremity and monitoring a smaller zone : 40 m to 3400 m. This

system would be based on a continuous laser with adaptative

focusing distance. A 30 cm telescope would be used in order to

conciliate cost constraints and atmospheric turbulence

effects. The spatial resolution rapidly deteriorates with

distance. According to CROUZET, a measurement could be

correctly located for distances up to 1 Km and beyond

detection would still be possible for spread and quite

homogeneous phenomena. The idea consists in frequency coding

of emission. This method was tested and validated for

distances lower than 1 Km but it must be experimented for

greater range since it seriouly decreases the signal to noise

ratio. It could also be a mean of getting rid of undesired

targets (insects, birds .... ).

1.3 : Conclusion :

The efficiency of the LIDAR technic is

obviously mostly limited by attenuation due to rain, fog and

by perturbations engendered by moving point clutter (birds,

insects .... ).

Concerning the laser source itself, the

continuous CO= technology is available but pulsed and solidstate lasers need further development.

In France, airborne LIDAR is also

experimented for vertical wind profiles by the Dynamic

Meteorology Laboratory.

Although CROUZET existing laser anemometry

prototype is well adapted for anemometry purposes, it didn't

appear well suited for a transformation into a wind shear

detector. Furthermore, from preliminary studies, it seems more

efficient to study the option of an airborne LIDAR rather than

a ground-based equipment. That's why, further research work

will be done by the O_[ERA laboratory before proceeding to the

design , integration and validation of an airborne LIDAR in a

flight demonstration program.

2) The second step of

defined but a preliminary study

laboratory (cf i.I).

the LIDAR program is not yet

is to be started with CNERA

597 <_w_'''-'_'_'_ P_.GE IS

[;;,_ F-_CC_ f_UALITY
III) SODAR program :

1) Proqram objectives and methodology :

The SODAR system (developped by the REMTECH

company) analyses the backscattered wave resulting, from

emission of sound pulses. The returned signal will be Doppler

shifted in frequency by an amount proportional to the

backscattering cells representative of wind velocity.

The first generation of SODARs included three

horn fed dishes with one vertical antenna and the two other

ones slightly vertically tilted. The whole thing was enclosed

in an absorbant protecting material. This equipment had been

designed to collect wind field direction and intensity in the

low altitude atmosphere layers for pollution detection

purposes mostly.

The aim of the contract between French Civil

Aviation and Remtech Co. was to examine whether it was

feasible to adapt this type of equipment for ground-based wind

shear detection along take-off and landing flight paths.

The evaluation guidelines concerned :

*environmental problems : surrounding noise,

influence of aircraft noise .... ;

*sound pollution generated by the equipment;

*influence of ground proximity at low tilt :

noise, acoustic rays curvature, ground clutter;

*feasability of a "megasodar" supposed to reach

6 Kms by using a multicellular antenna.

The conclusion of this contract notified in may

1987 was supposed to make a comparison between directivity

patterns calculated in simulations and experimental results in

order to check whether it's valid to extrapolate for a

multicellular antenna.

2) Program evolution :

The feeble performances of the horn fed dish

antenna made it impossible to carry out all the necessary

measurements. Consequently, the realization of a multicellular

antenna mock-up became absolutely necessary. That's why, the

priorities previously defined had to be changed. Furthermore,

the bad wheather conditions of spring 1987 in Paris during the

installation on Roissy airport delayed the experimental phase

that is still going on.

The theoretical part consisted in test antenna

optimization (2,4 m dianeter horn fed dish antenna). At a

given frequency, the only paraneter that can be modified is

the illumination function. In order to evaluate the

characteristics in the far-field, directivity calculations

were done by simulations for various amplitude distributions

with phase locked. Obstacle effects were simulated by

approximated calulations.

598
3) Experimental phase :

It was organized in three parts :

*measurement of the antenna characteristics;

*quantification of physical influences;

*wind measurements.

Directivity measurements showed good agreement

between theoretical and effective patterns for angles lower

than 4 ° and an important discrepancy beyond, resulting in high

sensitivity to ground clutter. It was assumed (and

experimentally confirmed afterwards) that this difference was

caused by the obstacle effect generated by the antenna feed

(horn of 25 cm). Directivity measurements using a piezoelectric tweeter of 8 cm resulted in good agreement with

theory but the improvement for ground clutter is of only 6 dB.

Despite the poor performances of the first

antenna configuration (JBL antenna feed of 25 cm), some

measurements series were recorded with an emission at 4000 Hz

and several tilts were analyzed. It showed the important

influence of temperature and humidity on atmospheric

absorption. These reflectivity fluctuations induce variations

of range from 290 m to 180 m.

Another testing bench with the second antenna

configuration (tweeter + dish antenna) showed that, despite

the ground clutter elimination algorithm, in some cases, wind

measurements were irrelevant. The data processing needed a

manual analysis in order to guarantee good agreement with wind

speeds recorded from an anemometer (from National Meteorology)

located on the airport.

In order to prove "megasodar" feasibility, the

REMTECH company decided to build a small-scale multicellular

antenna mock-up using a rectangular array of tweeters.

The main anticipated advantages are :

*elimination of obstacle effects;

*independant amplitude tuning;

*beam steering by phase shifting among the

different elements;

*increase of power (number of elements).

However, the interaction between elements hasn't

been taken into account and this assumption must be checked by

further experiments.

4) Conclusion :

The small-scale mul ticellular mock-up w_s

designed to reduce complexity by mini:_izing the quantity of

independant elements. Since the major problem concerned th_

vertical plane, the amplitude tuning will only be applied to

the vertical section and there will be less antenna feeds on

the lines than on the columns. Because of their great

dispersion, the tweeters were previously tested and selecte_.

This array is _ade of 392 ele_.ents with a spacing of 8.35 c_:

and distributed into 23 lines and 14 colu2_ns for a surface of

2.5 m x 1.25 m.

599
Theoretical calculations of the estimated range

were done. The multicellular mock-up will be taken up soon in

order to be experimented. The success of this stage is crucial

since the lack of performance of previous antenna

configurations made it impossible to demonstrate the ability

of this technic to detect wind shear.

IV) Ground-based RADAR program :

I) Introduction :

Wave-length is a crucial parameter for radar

detection. With wave-lengths S 5 cm, it's possible to design

small antennas with high angular resolution (<<3°), resulting

in good Vertical resolution for wind profiles and a good

protection against ground clutter. However, an experimental

program carried out by the CRPE [4] in 1985 showed that this

type of radar couldn't correctly measure in clear air

condition. It was theoretically concluded that, in order to

operate in clear air as well as in rain conditions, for a

radar of 4.5 Kw peak power equipped with a 5 m antenna, the

optimal bandwith ranged from 20 to 35 cm.

The laboratory designed a 30 cm radar (4.5 Kw

peak power) for atmospheric research purposes (PROUST system).

With a II m antenna, this equipment proved able to vertically

observe the troposphere up to I0 Kms. Of course, the use of a

5 m antenna will decrease the clear air detection level of 7

dB but a compensation from the turbulent energy gain is

anticipated.

consequently, the UHF radar hold the attention as

a feasible candidate in ground wind shear detection.

2) Program objectives :

An agreement was signed with CNET/CRPE [4] in

order to study the feasability of wind shear detection both in

clear air and rain conditions using a ground-based radar.

The aim is to perfect design criteria for a

specialized radar by theoretical and experimental studies with

the following operational ccnszraints :

*radial measurement of _indshear along

departure and arrival flight paths;

*detection in both clear _ir and rain

conditions;

*range : 600 m to i0 Kns;

*range resolution : S 600 m;

*angular resolution : S 3°;

*speed resolution : 5 i0 -z s-1 ;

*false alarm rate : < 10;%

*moderate cost : _ 3 HF (_ 600,000 $) ;

*peak transmission power : K 5 Kw;

*antenna diameter : _ 5 m.

6OO

,7
3) Program planning:

3.1 Evaluation of 30 cm radars performances at

low horizontal tilt in wind shear conditions :

*Ground clutter calculations,

(July 1988);

*Wind shear models implementation on simulator,

Radar characteristics optimization,

(September 1988);

*Shadow effect generated by aircraft,

Simulation of radar spectra with ground

clutter,

Wind profiles extraction,

(May 1988);

*Experimental evaluation with PROUST radar and

ground clutter and aircraft signatures,

(May 1988);

3.2 Evaluation of feasibility on airport :

*Synthesis of previous tasks,

(November 1988);

*Additional theoretical studies and definition

of an adapted antenna,

(May 1989);

*Measurements of wind shears and/or turbulence

on airport,

(date not fixed);

3.3 Conclusion :

(November 1990);

4) Program evolution :

* Wind shear models (historical, AC!20_41, JAWS

models) were implemented and tested on CNET computer

facilities for simulation. From the discontinuous distribution

of wind speeds, a continuous wind field was produced by using

the techniques described in the JAWS program. Radar spectrum

response within a wind shear field can then be anticipated

gate by gate.

* Ground clutter modelling is based on

gate/ground contact surface and random distribution law of the

obstacles (a hundred obstacles of 107 m _ each for all the

gates).

* Aircraft clutter elimination is the next point

to be studied. Research work concerns :

-antenna optimization (to be studied in 2.2

phase);

-radar processing :

-case of aircraft cn main lobe : saturation,

signal attenunaticn before reception,

elimination algorithm;

-case of aircraft on sideicbe : elimination

algorithm with spectral signature of

aircraft.

601
5) Program continuation.:

5.1 Aircraft clutter elimination : (June 1989)

*New algorithms for elimination;

*Simulation and test of previous methods

elimination;

*Statistic study of aircraft clutter;

of

5.2 Ploemeur Bodou experimentation : (June 1989)

*Definition of experiments and schedule;

*Experiments with antenna tilted at 45°;

*Measurements analysis : experimental results

of clutter elimination methods performances.

5.3 Installation on airport : (September 1989)

*Definition of optimal antenna : sidelobes

attenuation (absorbant material, lattice-work, trench),

antenna feed, radiated pattern;

*Definition of the optimal location for

installation : ground clutter minimization for main lobe and

first sidelobes, ground clutter map, possibility of making a

trench, aircraft return reduction by carefully positionning

antenna lobes in relation to taxiways, departure and arrival

flight paths.

6) Preliminary theoretical results :

6.1 Spectral width :

Among the main causes of increasement of

spectrum width such as distribution of scattering cells

speeds, turbulent field mean quadratic speed, limited width of

beam, sampling rate, non ambiguous distance, wind wheat is the

mos,t contributing one, resulting in radar capability in

providing relevant measurements.

6.2 Measurement Accuracy :

Assumption : in the elementary volume chosen

for simulations (30mx30mx30m), the radial speed is supposed to

be constant.

Simulation showed that for low-altitude

horizontal wind shear structures (inversion layer, thermic

wind) localization can be impossible for several gates. For

vertical wind field distributions, the radar delivers a

precise localization of the phenomenon.

Minimum reflectivity factor (Cn z ) required to

guarantee a good detectability at i0 Kns was evaluated as a

function of wind shear intensity per gate. Wind shear

detection at i0 Kms requires an equivalent reflectivity factor

Z. of - I0 dBz for a wind difference (in a gate of 600 m) of 8

m/s (= 16 knots) and of - 2 dBz for 30 m/s (_ 60 knots). These

results do not depend on antenna aperture that can eventually

modify extreme wind speed measured because of the variation of

the volume observed.

6O2
6.3 Safety requirements :

For the pilot :

*Detect wind shear,

*Identify its type,

*Quantify its intensity,

*Localize it,

*Anticipate its evolution;

For the tower officer :

*Wind speed and direction,

*Anticipation on phenomenon duration,

"15 mn prevision of possible occurence.

(as defined by the CLAWS program).

An alert system combining radar detection and

meteorology analysis is presently foreseen in order to

decrease false alarm rate. At the beginning, human

intervention will be necessary but automatization of the whole

process needs to be developped in a further stage. High

collaboration between radar operators and meteorologists is

necessary to develop and fix a performant wind shear alert

algorithm but meteorological research hasn't begun yet.

6.4 Non atmposheric returns :

High power targets may be all the more detected

as the horizontal tilt of the antenna is low.

shear

cross

by the radar

These spurious echoes are a serious danger for wind

detection since the wind tracers have got a smaller

section. This results in two consequences :

*saturation of radar input level,

*superposition of two signatures of hijhly

different power.

Main bibliographical results on efficient

section influence were summarized. Spectral width increasement

due to ground clutter was experimentally evaluated with PROUST

radar (30 cm) . The main results are the following ones :

*phase stability at short term is crucial; it

should be better than 10 -2 Hz (2 10 -3 m/s) ;

*Doppler jitter highly varies with season

(winter/summer), humidity and wind ground;

*In order to quantify spectral increasement due

to ground clutter, the increasement must be defined from the

amplitude corresponding to the noise, that is the width for a

signal to noise ratio taking while into accGunt the return

statistical dispersion;

*The absolute limits variations due to

multipaths, Fourier transform of a temporal limited function,

echoe structure jitter range from DV = 1 m/s to 2 m/s.

Estimations of signal to clutter ratio show

that it is necessary to decrease ground clutter level of 60 dB

in order to guarantee atmospheric detection for the first

gates. Another point is that these <choes create a Doppler

zone of ± 1 m/s where wind shear de_ctien may be difficult. A

method was developped in _rder <o detect atmospheric echoes

with amplitudes and Doppler shifts lower [han those typical of

fixed echoes. This method makes it possible to detect

atmospheric echoes with ground clutter for a signal to noise

603
ratio of - 30 dB and Doppler shifts of 0.25 m/s. As long as

the analogic signal doesn't saturate amplification and exceed

analogic/numeric converter capa_lilty, wind shear detection

should be provided.

6.5 Fixed echoes elimination :

Angular and temporal filtering methods of

analogic signal were investigated. The methods that are

presently foreseen for the PROUST radar are :

*"distance gate MTI" (Skolnik,1981) : selection

of the main spectrum line and rejection of the central zone

"polluted" by fixed echoes; this technic needs phase stability

to be efficient;

*adjustement of the ground model to the

spectrum; this method is presently tested on the PROUST radar

and makes it possible to discriminate useful and undesired

echoes.

6.6 Preliminary conclusions :

*ground clutter dynamic : it should be

suppressed by improving antenna efficiency and using numerical

filtering methods.

*very law altitudes detection (<<i00 m) at

short distance from GPIP : a technic consisting of gates of

variable length will soon be simulated for evaluation.

IV) Abbreviations :

[I] Aeronautical Navigation Technical Service (cf Annex I)

Service Technique de la Navigation A4rienne

[2] Aerospatial Studies and Research National Office

Office National d'Etudes et de Recherches A4rospatiales

[3] National Flight Test Center

Centre d'Essais en vol (CEV)

[4] CNET : Telecommunication Research National Center

Centre National d'Etudes des T_l_communications

CNRS : Scientific Research National Center

Centre National de Recherche Scientifique

CRPE : Environmental Physics Research Center, laboratory

jointly sponsored by CNET and CNRS.

Centre de Recherche en Physique de l'Environnement

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porte I 5

zrnnox(rn)= 1923.0

Zrnin(rn)=t 340.0

porte 14

zrno=(rn)= 1804.0

zm;n(rn)= 1251.0

porte 13

ZrnOx(rn)=, 1684.0

Zrn;n(rn)=I 162.0

porte 12

Zrnax(rn)== 1564.0

Zrnin(rn)== 1074.0

porte I I

zmox(m)= 1445.0

Zrn;n(rn)= 985.0

porte 10

Zrno"(rn)- 1325.0

zm;n(m),= 896.0

porte9

zrnox(rn)== 1206.0

Zrn;n(rn)== 808.0

porte8

zrnox(m)==108.6.0

zrnln(rn)= 719.0

oltltude du radar(m)-, 10.0

pu;ssonce crete(W) == 4500.

lot 9-;mpu|'siOn(rn;crO-=)= 4.00

Iongueur d"onde(cm)= 30.00

angle de visee(deg) == 80.00

ouverture-antenne(deg). 1.50

gain de I'ontenne(dB)-- 41.7

niveou-lobes-second.(dB)- 20.0

Ze• OdBz

1O0

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zrnox(rn)= 966.0

zrn;n(rn) ==630.0

porte6

zmox(rn)= 847.0

Zrnln(rn) == 542.0

porte5

ZrnOx(rn)- 727.0

Zrnln(rn)= 453.0

porte4

ZrnOx(rn)== 608.0

Zrn;n(rn)= 364.0

porte3

ZrnOx(rn)= 488.0

zm;n(rn)_= 276.0

porte2

ZrnOx(rn)== 368.0

zrn/n(rn)= 187.0

parleI

zrnox(rn)= 249.0

Zrnin(rn)= 98.0

porte0

Zrno,,(rn)= 129.0

Zrn;n(rn) == 10.0

628

modele6

decollage
donc une 6ventuelle variation des valeurs extremes du vent observ6.

in

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cisaillement de vent d'amplitude donnde en ordonnde.On retrouve,

pour un cisaillement de vent nul, ia valeur t!z_orique calcul_e au

§ (I.1.3.a).

629

OF PO_i-_ _]_AL.iTY
cisaillement de vent en prdsencc d'6chos de sol sont fournis en Annexe V. Les principaux

rdsultats de cette simulation en ce qui conceme les 6chos de sol sont r6sum6s dans les figures

•(2,7) et (2,8) ci apr_s.

15

14

13

12

11

10

_9

:8

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z3

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i I I I I I

iodel

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\

1

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Pc/ Pb (ds)

Figure (2,7): variation du rapport puissance chaferpuissance bruit

parfiltre dquivalent FFT, en fonction de la distance (pones I d 15 );

pour deux valeurs de l'angle de visde (or = 3deg et o_= 10 deg );

et pour deux valeurs diffdrentes du niveau des lobes secondaires de"

l"antenne :

20 clB en traits plehzs

30 dB el tiretds

L'ouverture de l'antenne est ici de 0 = 4 deg

-w

Dans cette simulation, on a fait varier l'ouverture de l'antenne (®) ; l'angle de vis6e

(c£) ; et le niveau des lobes secondaires. Le tableau ci-dessous donne l'ensemble des

variations utilis6es •

630
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13

12

11

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3° et 10°

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L

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I

I

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t

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70 80 90 100 110 120

Figure (2,8) • m_me chose que sur la fig.(2,7) mais avec une antenne

d'ouverture 19 = 3 deg.

L'analyse de cette simulation appelle plusieurs remarques.

1°) Le rapport Puissance de l'6cho/Puissance du Bruit (Pc/PB) varie en fonction de la

distance pour chaque ouverture d'antenne et angle de vis6e. Les figures (2.7) et (2.8)

r6sument les variations obtenues dans cliaque porte radar (15 pones de 600m) en fonction de

l'angle de vis6e pour des niveaux de lobes secondaires de -20 et -30 dB et pour deux valeurs

d'ouverture d'antenne : ® = 4 ° (fig. 2.7) et O = 3° (fig. 2.8).

Pour ® = 4 ° le rapport Pc/PB est peu sensible (dans les premieres portes) aux

variations de l'angle de vis6e et au niveau des lobes secondaires. I1 reste _ un niveau de

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-4 --3 -2 .I 0 2 3 4 5

VENT (ntis)

Figure (2,9) • Spectres bruts obtenus d Saint Santin par le radar

PROUST visant d la verticale (rapport SignallBruit en fonction de

la frgquence exprimde en terme de vent vertical)pour les portes

4 d 10 (4500m _ 8100m d'altitude). La situation m&dorologique est

anticyclonique et le ciel sans nudges. Les dchos de sol occupent le

centre du spectre (autour du Doppler nul) darts un domaine spectral

correspondant d +/- 0.6 ads. On voit dgalement appara_tre un signal

"air clair" qui est dans certaines portes entidrement nu2squd par 12cho

de sol

632
22/06/8BII Oil 52_1 395

AL'rl S/B (dB)

81o _-IO _ _

57oC

510C

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Figure (2,10) • Spectres aonosph_riques "air clair" obtenus apr_s

_limination des _chos de sol par la mdthode d'ajustement d_crite dans

le § 1.2.1.6.2.2".

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zmin( .m)== 229.0

porte 13

zmox(rn),= 668.0

zmin(m)= 2 14.0

porte 12

Zmox(m)== 621.0

zmin(rn)== 198.0

porte 1 !

ZrnOX(rn)= 574.0

Zmin(m)= 182.0

porte I 0

Zrnox(m)= 527.0

zrnin(rn)= 166.0

porte 9

zmox(m)= 480.0

zmin(m)= 151.0

porte 8

Zrnax(m)= 433.0 "

zmin(m) = 135.0

altitude du radar(m)

puissance crete(W)

Iorg-impulsion(micro-s) =

Iongueur d'onde(cm)

angle de visee(deg)

ouverture-ont enne(deg)

gainde I'antenne(dB)

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zmox(rn)= 386.0

Zrnin(m)= 119.0

porte 6

zrnox(rn)= 339.0

Zrnln(rn) == 104.0

porte 5

zmox(rn)- 292.0

zmin(m)= 88.0

porte 4

ZrnOx(rn)= 245.0

zmin(rn)= 72.0

porte 3

zrnox(rn)= 198.0

zmln(rn)= 57.0

porte .2

Zmox(m)== I51.0

Zrnin(rn)= 41.0

porte l

ZrnOX(rn)= I04.0

zmin(rn)= 25.0

porte 0

ZrnOx(m)= 57.0

zmin(m)= 10.0

modele 14

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porte 13 l°rg-impulsi°n(rnicr°'s) = 4.00

zrnax(rn)=, 7.41.0

• Iongueur d'o'nde(crn) = 30.00 Zrnin(rn)= 146.0 " "

porte 12" ongle de visee(deg) == 87.00

zrnox(rn)= 689.0 °uverture-ontenne(deg ) =. 2.00

Zrnin(m)= 135.0 goin de I'ontenne(dS) "= 39.2

porte II niveou-lobes-second.(clB) .= 20.0

zrnox(rn)= 637.0

'zrnln(rn)= 125.0

porte 10

Zrnox(rn)= 585.0

zmin(rn)= 114.0

porte 9

zrnox(m)= 532.0

zrnirl(rn)-- 104.0

porte 8

Zrnox(m)= 480.0

zrnin(rn_= 93.0

1O0

50

• O

100

50

O

IO0

50

0

2O

2O

2O

porte 7

zrnox(rn)= 428.0

zmin(rn)= 83.0

porle 6

zrnox(m)= 375.0

Zrnin(rn) = 72.0

porte 5

zmax(m)= 323.0

zrnnin(rn) = 62.0

porte 4

zrnox(rn)= 271.0

Zrnin(m)= 5I.O

porte t 3

zmox(m)= 219.0 ,

•Zrnin(rn)= 4 l.O

porte 2

ZrnOx (m}== 166.0

zrnirt(rn) = 30.0 20 0 -20

100 - ' ....

50O, _ ZrnOx(rn)= porte ! I14.0

20 0 -20 zrnin(rn)= 20.0

100 " ' ' , ,

50O _ Zrnox(m)= porte O 62.0

20 O -20 zmin(rn)= tO.O

vent(rn/,s/

637

rnodele 8

otterrissoge

;7"; ' , ,, •
Questions and Answers for 19 October Sessions I and II

639

P;_:.CL_-',_ BLAT_,_ BlOT FILMED
19 October ._988 Ouestio_ _'nd Answer Session _'" '_'

(tape started in the middle of a sentence) with our three dimensional model, we are

producing complex wind fields from different microburst events and 2) as the

computers are growing _ more powerful, for example, a new computer, a Cray II will

be delivered very soon at NASA. We will be able to run some very high resolution

lines with those three dimensional models and as far as .. I mean, I say I wouldn't

say that anybody working on these problems shouldn't use just model data by

themselves, certainly they should try some of the observational data, but there's certain

advantages with the model data in that we can provide very high resolution data of

the wind fields and also we can provide other things like temperature, humidity, rain,

snow, etc. Does that help?

For example, I mean the model cases that you sound so far are simulating microburst

outflows. One possible source of nuisance alarms to this systems are strong

divergences or velocity grading as seen on the backside of gust fronts and if those gust

fronts aren't generated by the simulator, are you ever going to capture the nuisance

alarms generated by those kinds of phenomena that will be perceived by the system?

A: Well I think looking at a gust front, for example, if you run it through the F factor

calculation and it exceeds, it either goes in a negative direction, which is not

hazardous, or it doesn't last long enough, then it would be filtered out. I would like

Roland to comment on gust front problems and we're trying to look at the microburst

problems as the most severe and answer a question back, earlier you talked about

using some real ground based data and we would like to do that if we can get the

data that has this chaotic information in it, raw data, with resolutions in the order of

50 to 100 meters and I don't think that's available to get from anywhere so we've got

to do it through simulation process.

641
Well, I guess there are different kinds of issues you can address and I'd argue that in

terms of understanding how well your system can do in dealing with some of the sort

of the natural interference and noisiness in the sensing process and meteorological

processes, perhaps you don't need to capture it at the resolution that your using in

your modelling, in fact, you can get a pretty good bound on what the magnitude of the

problem is by looking at a coarser resolution. I think as far as the gust front or other

kinds of shear signatures, you have to face the problem that either .. you can take the

time to detect shears that are hazardous, whether they are from microburst or other

kind of phenomena, but you're still trapped in the situation of either saying, if you

want to detect all the kinds of hazardous shears, then you better simulate them and

assess your performance against the whole spectrum. If you're only interested in

detecting microburst shears, then you still have to look at those other kinds of

phenomena to see that you reject them and so I think it's difficult to assess the true

performance and detectability or false alarmity of your system without considering a

real spectrum of phenomena and what the system is going to do on that entire

combination and I'm not sure you're getting there by simulating specific phenomena

in the absence of all the other kinds of contamination that you're really going to see.

Doing it against flight test data, it's great. But the thing you're going to have to face

up with then is what are you going to use as far as the ground truth data base is

concerned. It's a great approach but there is a serious problem of understanding what

was really out there when you collect the data.

Any other comments on that question.

Did we get everybody's questions, I think I've got them all here. Norm had a

question, Q: Do you have plans to use your radar model microburst model to study

TDWR placement strategies? If not, why not? A: Well, the answer to that is no,

642
we're not going to do that, it's not in our charter, we're looking at the airborne.

Certainly the simulation program could be made available and if FAA wants to

sponsor or somebody sponsor that activity that possibility of the radar simulation model

could be useful, but it's not something we're going to be doing.

Herb, would you can to comment on that? At this point, I don't know of any plans

for using the model in TDWR, Wayne or Jim could talk to it, but for one thing, it's

a smaller domain size than what you're looking at, if I'm not mistaken for a placement

strategy but anyway if you could get a microphone to Jim Evans who will make the

proper response.

Well, we've been involved of course in this, there are a bunch of sites already being

chosen. I think we take the contrarian view, I guess the answer we would say is over

the last four years, we've probably measured close to 1500 microbursts and we believe

that as far as understanding to the knowledge that we think, in terms of radar sensing

we have a fairly good idea of what altitudes we want to look at and we're not

convinced that we're going to learn anything at this point that would improve on the

database from running a simulation. The other side of it is in terms of the ground

clutter and it's predictability, I think the grazing angles we're talking about are very

close to 0 degrees and there's a very large database of ground based measurements

at those kinds of grazing angles and practical experience so again, we don't see that

as being a practical factor. Thanks Jim.

Jim, I was trying to address the other problem of if you put the radar at the end of

the runway, looking up the glad slope, you put it X miles away so you can surveil a

bigger terminal area i....

643
The strategy that the FAA is utilizing which is a proper topic I guess for tomorrow is

been to sight off the airport and in fact work at achieving the kind of timely warning

that we heard a plea from a few minutes ago which was by being able to look a loft,

you would be able to see things coming down and in fact issue warnings well in

advance and in the ease of TDWR the users, the requirement we're working at is to

provide a one minute warning to pilots before they encounter a hazardous wind shear

condition and if you think that's by and large been held up in the major of

experiments today and we'll have a chance to hear about that tomorrow.

Let me go down the list of speakers, Ernie.

This is Ernie Baxa and I have several questions. I will make an attempt to respond

to what I can and then I'm going to refer to Brae and Les Britt, because I think some

of them are model questions.

This first one is from Jim Bull, Q: Azimuth side low clutter can appear at all

velocities of interest, have you computed the clutter to signal ratio for side low clutter

from azimuth side lows for practical antennas say a 28 inch antenna at x-band. A:

The figure that I had shown was a figure to indicate some qualitative aspects of

clutter, to answer the question I guess, succinctly yes, side low clutters included in

model and I think Brae could probably elaborate on it just a little bit.

Yes, we have done some analysis looking at a 30 inch antenna and this information

was shown in an earlier paper this morning but it does indicate the side low levels.

This one is spectrum at a particular range bend, I think it was 4 1/2 kilometers from

the aircraft. The aircraft was at 5 kilometers from touchdown and the main clutter

with a 0 degree tilt was right, this is the main beam clutter right here, it is real spiked

though here with some side lobe energy falling off, now actually there's energy much

lower down if we could extend this scale down, you'd see energy going further and

644
further out but the energy is so low that really beyond when it gets down to this

relative to the peak, it doesn't contribute a lot. When you tilt the antenna up by 2

degrees you can see that the main beam goes from way up at some 50 db here goes

way down to about 5 db but the side lobe energy gets shifted a little bit in frequency

but doesn't, is not changed a lot. Over on this other plot over here, we're pointed off

at an azimuth of 10 degrees, and again, this is the main beam energy coming right

through at this point, when you tilt it down, the side lobe energy, it doesn't change

much but we have looked at the side lobe energy and the clutter to signal ratio and

it does get included in the simulation program.

Jim, do you want to make a comment?

This is Ernie Baxa again, I have a question from Howard Long at Delta Airlines. Q:

How do you expect to automate wind shear detection so that little or no operator time

is required? A: I can't really answer that question directly. What I wanted to say

though is from a signal processing point of view, what our main concern is to provide

what I would call a statistically efficient as well as a computationally efficient statistic

that is also a sufficient from a standpoint of wind shear detection and/or wind shear

prediction and how that is used is really to be communicated to a pilot or to someone

who is going to have to take action is really a different matter from my perspective.

Would you like to comment further on your question or concern. I think that's a

question a lot of folks are certainly interested in and there have been other papers

that have discussed that.

This is Herb Schlickenmaier, FAA, it gets back a bit back to what Dave Carbaugh was

talking about on how one integrates the human factors questions into the systems

design and that's paramount, absolutely. It's not these guys jobs.

645
I certainly don't want to give the impression that I think it's a minimum problem or

a non-problem. A couple of questions from Jim Evans, I will make some comments

but I think Brac and maybe Los might want to comment too. Some of this has

already been talked about in responding to earlier questions. Q: Why doesn't the

clutter spectra show frequency components over the full unambiguous philosophy

range? Clutter velocity is 0 meters per second for clutter well in the front of the

aircraft, 60 meters per second below aircraft and 120 meters per second well behind

the aircraft. This would after .. this should be aliasing I believe, extend over the entire

frequency band. A: I think we've addressed that in answering Jim Bull's question.

Yes it is distributed. Do we need to elaborate on it? It is all relative to aircraft

velocity that was the basically the ground speed, that was the 0 on the Doppler

spectrum.

Next question is also from Jim Evans. Q: Have you considered the loss in sensitivity

due to attenuation of the weather signal by the notch filters in your simulations. This

would be particularly significant with a one pole canceller if you are to achieve 25 db

clutter suppression. A: Yes, the model the analysis that goes with the model that Dr.

Britt, Les Britt from RTI have been working with, does in fact compute the

attenuation of the weather signal. It's not at the present time included in the model

that I have been working with at evaluating filters but it will be and is certainly a

significant matter. The issue here has to do with evaluating how clutter filters affect

the quality of the signal, the information content of the signal or the power level really

of the signal itself. That is an important consideration. What we have clone so far

had to do with estimating the mean and the widths of the spectrum, rather than the

power levels on the sensitivity issue. Does that satisfy that?

646
The last question from Jim Evans, Q: Are the effects of transmitter receiver

instabilities being addressed in your analysis? What is the level of these in current

systems and what is postulated for proposed systems?

A: There's a comment with this magnitron transmitter receivers generates substantive

signal energy frequencies which would be in the past band of the clutter filters you

have described. I want to make one comment and I want to ask Les Britt to make

a comment about what's in the model. Presently I have a student looking at the

effects at phase jitter on the pulse pair instrumentation procedure but basically going

back and accounting for phase jitter looking at a phase jitter spectrum and one of our

thrusts in this analysis was to create a set of specifications that would be appropriate

for a radar system. That work has begun but is not anywhere near completion ..

there's nothing I can really report at the present time except it is a messy problem.

Les might want to say what's in the model at present.

In calculating the I and Q signals, this is the way they're calculated and this does have

a term in that to represent phase error, which is a random phase term that is

generated statistically in the model and changes for every pulse so that's in there.

Now, the number that we've been putting in is a half of .. corresponds to a velocity

or a mass of a half meter per second. This is the number we got from Varian

Associates, talking about some of the stabilities of their transmitters. This is an input

and one of the things that we're trying to determine the effects of, I mean, we're not

building operational hardware, we're doing tradeoff studies that would hopefully come

up with a spec, in other words, we'll determine the effects of phase jitter and then say

the effect of it if it gets bad, so we're kind of working the problem the other way

around. This is a parameter in the simulation. No, well I'll say it again, we're not

building an operational system so the simulation is just a .. it simulates the transmitter

with a certain phase jitter, you know it doesn't matter whether it's a magnitron,

clyston, a solid state or what have you.

647
This is Bracalente. In our flight hardware that we're procuring for the experiment, we

will not be using the magnitron because of this problem. Probably be using a TWT

or a solid state for the low power version and TWT to get up to a couple KW which

has much more stable frequency and phase characteristic.

Did that answer that question?

I would just make one comment, I think you'll find that they make amplitude errors

as well and what wasn't clear and maybe you could put up on the board was whether

this phase error is applied to the clutter signals. Is this formula the formula that's

used to compute the clutter signal. A: Yes, this is as I said in the description of the

simulation, the signal that comes from a particular range bend is a sum of population

of random scatters and the phase term contains a term for transmitter phase error,

a random variable which represents the phase jitter of the transmitter from pulse to

pulse. (new speaker) Ok, so this formula is used for both weather scatters and ground

clutter scatters. A: Yes, that's right.

Carrol Lytle, NASA LaRC. I have a question from Jim Evans, MIT Lincoln Lab. Q:

Have you considered moving your roof top system to a location that is TDWR test

bed measurement site which have frequent microburst activity and the requisite support

sensors to obtain realistic microburst outflow back scatter data. A: As a short answer,

yes we have considered it. Obviously the instrumentation we're talking about is the

aircraft instrumentation and the first priority is to use this on the aircraft. Now we

will be using it on the roof when we're not scheduled on the aircraft. We have

considered what would be involved in taking this to someplace like Denver but we

have made no commitment to engage in a program of that nature. The logistics of

648
sending someone out on site for an extended period. It's something we would fike to

do but we're not committed to it.

Pat, did you have any questions. Is Brian Gallagher, you've got a couple as well.

Dave Watt from the University of New Hampshire said that he will honest send us

back all the written answers, he had to leave early and I would imagine Russ Targ will

do the same.

The first question was from Jim Evans. Q: How does an infrared sensing system

distinguish the cool air outflow of a gust front and that of a microburst. A: Right

now, it doesn't. What we're doing is looking at the data that we can get and trying

to see what we can do about it and when we actually get in the air, we'll be able to

get a little better handle on that.

Second question is also from Jim Evans. This wasn't in the presentation today but a

lot of the work that I'm doing and others in the infrared is doing is based on Pete

Quenes work in the jaws. Q: The penetration of strong microburst outflows between

300 and 800 feet AGL is quite risky and has not been achieved on many microburst

events. That is less than three at the most during the TDWR tests. Have the claim

42 low altitude microburst penetration during jaws been independently, that is by

NCAR scientist confirmed? A: I don't know, I did go back and pull out the report.

The data was taken on the 14 - 15 of July in the B57B. The systems that were up

on that day was the busiest day in the entire jaws project where the 3 radars, the

BS7B, the King Air and so on, those come from the jaws final report. The jaws data

shows 8 microbursts on the 14 and 21 on the 15. Out of the report from Quene and

that's the NASA final report number which I did verify with Kerkowski who was in

charge of that project with NASA Ames. He said there were approaches and

encounters into shear conditions at Stapleton and vicinities in the jaws network and

649
the encounterswere in the lower 100 meters so the answer to your question Jim, I

don't really know. I did when I just got into this go to the NCAR people and others

to try to substantiate where these microbursts were against the fly track and I had

no luck in doing that. The project as I understand it was that the radars would

indicate an area where the B57 should go to look for shears and that's exactly what

they did. So, I guess the question is you need to talk to Quene, but I think the

answer is that the correlation between the air craft track and the radars was not done

on purpose. In other words, they weren't tracking the aircraft with the radar at the

same time all this was going on. It was a very busy day and I couldn't get any

correlation between the work that was clone on the radars and the aircraft. Does that

answer your question.

We tried flying planes in and around the Denver where there's microburst going on

and I would be quite astonished that one would be that successful at flying along 100

meters above the ground through strong microburst and not getting into all kinds of

problems with Air Traffic Control and everybody else in the system and as far as not

knowing whether the airplane went near the radar, it's a little surprising that if this is

a prime data source, I means NCAR people know very well where the microbursts

were in location and as in L, as a function as time and I would presume that the

aircraft people knew very well where it was as a function of time, that's why I'm a

little astonished that nobody knows where the plane was relative to the microburst.

I can tell you, two things I know for use. I talked to Glen Stinet, who was the test

pilot of that plane and asked him if he encountered a lot of microburst. He said he

spend the entire day encountering microburst, going into them. You'll have to .. I

can't answer the question past that and maybe Wayne could help verify it if

somebody's willing to take the time and look at the aircraft track. The big problem

was though was that the aircraft wasn't necessarily in the area where the radars were.

650
It was in and out of the area and was being vectored towards significant areas. That's

the best I can tell you.

I guess I'm really prepared to answer the question in great detail on where the

airplane was relative to the microburst for the B57, but I know in the case of the King

Air, we flew through a great number of microbursts that summer but nothing at 100

meters AGL, I will confirm that because I did virtually all of those and so from King

Air data I'd be surprised if there were any at that altitude, although there were quite

a few at somewhat higher altitudes. The B57, I think had some lower altitude

penetrations but I don't know the number but I'm sure that those data are available,

I know Pat came looking for it and B57 data exists and I'm sure those people knew

where they were. As did the jaws radar people know where the microbursts were so

it's reconstructible data.

Yes, I guess the other point Jim is that that instrument was completely equipped with

data recorders and the shears are very verifiable just from the aircraft data so you

know I think it's a matter .. I took the information I could get and used it.

The other question was from Jim Bull at Boeing. Q: How much rain can your

sensors see through? Isn't there likely to be rain before a microburst in some cases?

A: Thanks to the folks at MIT, I asked them to give us an enroute approach set of

numbers for how wet the microbursts were in both the Huntsville and Denver work

and to make a long story short, it's was about 30 dbz on average for the wet areas

and a little less then that in Denver. But also to show off what the low-tram would

indicate for rain, there's a simple empirical equation for the transmission as a function

of distance in rain and with one inch of rain you can look about 2 1/2 kilometers and

3 inches of rain about 1.18 kilometers. I also took out some of the data we calculated

with the NASA provided models and what I've got here is the temperature profile as

651
sensed by an infrared sensor, ours at two different wavelengths. The temperature

front he model is being sensed by the two different wavelengths. The 15 microns

which is our near channel essentially rides right on top of the temperature in the

model and 13.4 shows the advanced measurement of temperature and starts to go to

very short distance or effective look path right about 3 inches per hour in the model.

So the answer to your question, you could see at least a kilometer at 3 inches per

hour and 2 inches per hour is read on the radar scope so does that answer your

question. Thank you.

Mark Storm did you have any questions. Mark Storm will answer his questions if has

any. Fair enough. Kioumars did you have a question? Dave had a question? Terry

or Renee did you have any questions?

This is Dave Hinton, NASA LaRC, question for Mark. Q: Isn't there a big difference

between following a stick shaker with a training aide versus not reaching stick shaker

when flying the flight path angle? A: I'm not sure exactly what that means. I think

that if you have two guidance strategies that exit the shear at the same altitude one

flys 10 seconds of stick shaker and another one a void stick shaker there is a big

difference. If that what you're .. operationally there is. The only qualification you

have on that is that if the other strategy, the one that does not fly your stick shaker

involves something that is counter intuitive to the crew, we have to face that training

issue for it to be successful. Second question from Joey Sepi Q: With respect to

conclusion No. 1 predicted benefits advanced recovery procedures may not be achieved

or manually flown, how do you generalize your conclusion based on when recovery

procedures to other advanced guidance procedures. Our efforts have shown that your

conclusions are incorrect for at least one other guidance procedure. A: With respect

to that, I underline the words may not, I don't say you that can not realize it, I'm

saying that going from bad simulation to pilot simulations there are many factors that

652
must be taken into account or you may not achieve the benefits, that's what I was

seeing in my results. One of my strategies of flight path angle strategy develops

trajectories that look nearly identical to the trajectory shown in the slide on PC

programs that Barrios did, where it will go to a target altitude level off fly path. Same

type of results. When I flew that in the take off case recovery procedures across all

the shears that I threw at it, it was statistically the same as the other procedures.

There was one shear however, the strongest magnitude shear where that procedure

was statistically better than any of the others. It was very, very tiny, so it depends

on what you throw at it.

From Jim Evans at Lincoln Lab. Q: A very important element in your forward look

reactor alert comparison is the assumed vertical profile in horizontal wind. The

assumed outflow profile is very shallow compared to the assumptions made in the

NASA Airborne Doppler Radar program where in they typically measure horizontal

wind at 400 to 500 meters above the ground, which profiles view is appropriate? A:

I think we answered it as a misconception of the 400 to 500 meter altitude that we've

answered but I would like to mention that the analytic wind shear model I was using

was not pulled out of a hat, that is it was fitted to an output from Fred Proctor's task

program that was based on a sounding in Denver, 30 June 1982 and from that

sounding he generated a series of microbursts with different rain shaft diameters and

this was one of the smaller scale microburst that resulted from that sounding. Q:

How would you result on benefits on forward look sensing have changed if you had

assumed a much thicker outflow depth, that is with the winds down 50% from the

peak level at 500 meters above ground level? A: I can't say for certain without

actually doing it but my belief is not a whole lot for two reasons. One is that my

energy hide analysis which I'm getting more confidence in as I test, the F factor was

assumed constant across the shear regardless of altitude so there was no fall off of

winds in altitude in that case. Secondly, I would expect that the Deltas, that is the

653
difference in performance with or without forward look would be slightly smaller for

sure with stronger altitude but the trends would be the same, very nearly the same.

Howard Long has a question. Q: Do you feel that a forward looking system with

guidance that provides a 5 to 10 second warning could provide equivalent safety to a

reactive system with guidance? A: Good question, I'd like to give a qualified yes to

that. The reason I ought to qualify it is that the exact numbers cannot be determined

at this point. I have not tested in pilot simulations a 5 second warning so I can't say

what would happen there. The second reason is that we would have to test that with

a variety of shears and aircraft types to find out what those minimum numbers would

be and a third very important thing to consider is that in my studies, the pilots know

they're going to hit a wind shear and they react immediately upon an alert. When I

give them a 10 seconds warning, there are times when they receive that warning and

tell me in light of operation, I may not go around just yet because I haven't seen

anything on my .. I have no reason to go around yet, I might think that was a false

alarm. So whether or not they would go around with 5 to 10 seconds warning is really

going to depend on crew training, displays if they can actually see what's in front of

them, etc, so if they actually started to go around with 10 seconds warning, yes, you

can achieve a quick level of safety.

Rob or Alex. Evidently they will answer their questions later in writing as well. Dave,

you said you had a couple of questions. One question.

My one question, I mean I assume that's a misspelling on the Lockheed Alert, it

should be a Look Ahead Alert, less than 11 seconds advanced warning to react a

detection of caution positive energy enunciation or a warning negative energy in

essence and the reactive alert was based on negative energy. That's it.

654
. i

The point I was trying to make as part of the question was that if you did have a

cautionary alert system based on the positive energy, that you could improve 11 second

negative factor by some amount. Yes, but we didn't use a cautionary so I really can't

give you that answer because I don't know. Anybody else?

And can you believe to finish this set up there's a guy by the name of Herb

Sehlickenmaier, is he any where in the building? From Norm Crayble, Q: Is the

FAA's mieroburst policy that the pilot be provided with enough information to permit

him to successfully fly through any microburst within it's capability and thus maintain

airport acceptance rate or to avoid any mierobursts which may pose an unreasonable

threat to safety? A: the policy is avoidance. How one avoids a microburst is the

purpose of the work that Jim Evans is doing and that Wayne is doing and the NASA

team and I are doing which is to provide sufficient information for the flight crew and

for air traffic to make reasonable estimates of the hazard and thus provide avoidance

to the crew in a dynamic environment like a mieroburst that doesn't always happen

as a discreet event, the mountain that isn't going to move in the next time an airplane

comes by so it's not a binary event and the process of information that we're giving

is continuous. Thank you very much folks on the agenda.

e°

.w

655
Session I. Ground Systems
TECHNICAL PRESENTATIONS

Thursday, 20 October 1988
Session I. Ground Systems

TDWR Program Status

A. L. Hansen, FAA

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Low Level Wind Shear Alert System (LLWAS)

Craig Goff, FAA

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Session I. Ground Systems

Terminal Doppler Weather Radar 1988 Odaerational Demonstration

Stapleton International Airport, Denver, Colorado

Wayne Sand, NCAR

6s3

_:,:_;_,o_._ , ,_:_ LA,_K NOT FILMED
i.

TERMINAL DOPPLER WEATHER RADAR

1988 OPERATIONAL DEMONSTRATION

STAPLETON INTERNATIONAL AIRPORT

DENVER, COLORADO

By:

Wayne Sand

National Center for Atmospheric Research

Boulder, Colorado

685

_ _'_" ;:__ _ _ _-.'_!---'-_,.",,_ i_iO'fFILMED
PRESENTATION TOPICS

Surface-based Wind Shear Detection and Warning

Systems: LLWAS and TDWR.

A Strategy for a Warning Message:

Runway-Oriented Alerting.

Microburst Algorithms, Validation and Operational

Displays.

Summer, 1988 Operational Products.

New Directions: Integrated Terminal Weather

Information System- Getting Critical Weather

Information to ATC and the Cockpit.

Conclusions.

687

PRECEDi_4C_ P_'_GE _Lf--_,_;{NOT FILCHED


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114011221 LLWAS WIND DISPLAY

69O
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NW.

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• SW

a

A2

1 •

,10

,,9

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48

A6

-7

A3

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b

F:gure 3. Illustrationof the LLWAS at Denver StapletonInternationalAirport, showing a

generalized array of wind sensors spaced ground airport. Note that spacing is wider than

typical microburst, resulting in many microbursts slipping through the "net." The system

was originally designed to detect gust fronts rather than microbursts. (a) Shows the spacing

prior to 1985, while (b) shows the spacing as enhanced to better detect microbursts. This

improved spacing (b) is available at both Denver Stapleton International Airport and New

Orleans International Airport. (Source: FAA, 1987a)

691
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TDWR Bri_ng Paper

Type of

wind shear

Runway _reshoid

win_

Wino shear

HeadwJnd Location

change (kts)

MBA

MBA

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MBA

MBA

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CF

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693

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1987 DENVER MICROBURST POSITIONS

330 ° 340 • 350 • 0 • I0 • 20 • 30 •

\ /

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695
1987 DENVER MICROBURST POSITIONS

:530 = 340 °" 550 = 0 •

320"

• •

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O_,G,,_,._.L PAGE IS

OF POOR QUALITY




TDWR P RO DU CTS

1988 OPERATIONAL DEMONSTRATION

MICROBURST DETECTION*

- LOCATION

- INTENSITY

GUST FRONT DETECTION*

- LOCATION

- INTENSITY

- DIRECTION AND SPEED OF MOVEMENT

WIND SHIFT PREDICTION

- 20 MINUTE AIRPORT ARRIVAL WARNING

- WIND DIRECTION AND SPEED BEHIND GUST

FRONT

• PRECIPITATION

- STANDARD 6 NWS LEVELS

- HIGH RESOLUTION, LOW ALTITUDE PRODUCT

NEAR AIRPORT

- LOWER RESOLUTION, MEDIUM ALTITUDE

PRODUCT NEAR GATES

* These products will generate microburst and wind shear warnin:

that will be provided to pilots.

7O2
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705 
RECOMMENDATION REGARDING POSSIBLE FLIGHT

OPERATIONS DECISION-MAKING AS A RESULT OF

MICROBURST ALERTS DURING THE TDWR OPERATIONAL

DEMONSTRATION

AVOID KNOWN WIND SHEAR-Guidance from the Windshear

Training AM. Consider the following:

• TDWR Operational Demonstration is expected to clearly

identify microburst wind shear events at Stapleton, with a

high probability of detection and a low false alarm rate.

• When TDWR identifies a microburst, there is a high

probability that a severe wind shear is present.

• The Windshear Training Aid Guideline for recognition of a

high probability of severe wind shear is:

THIS OBSERVATION REQUIRES CRITICAL

ATTENTION. DECISION TO AVOID IS

APPROPRIATE.

• Consider the development of a decision- making bulletin for

Summer 1988 for Denver flight operations.

706
EXCERPT

B-727 FLIGHT MANUAL- HANDBOOK

BULLETIN #

JUN XX, 1988

FROM: DENTK- FLIGHT STANDARDS AND

TRAINING

UA POLICY

During the conduct of this test, as is currently the

case, a "Wind Shear" alert must be given serious

consideration by the flight crew. All pertinent factors

relating to a planned takeoff or approach must be

critically examined before the specific course of action,

e.g., normal procedures, precautions, or avoidance

action is decided upon. (See Flight Handbook

Additional Procedures, Windshear Section)

A "Microburst" alert, however, clearly indicates that

avoidance action is required. A FLIGHT MUST

NOT DEPART NOR CONDUCT AN APPROACH

THROUGH AN AREA WHERE A MICROBURST

ALERT IS IN EFFECT. Delay the takeoff or approach

until the condition no longer exists along your intended

flight path.

707 "
A VARIETY OF R_%NDOM THOUGHTS BY JOHN MCCAIKTI-I%

ON THE OCCASION OF THE REVIEW OF THE MICROBURS _

INCIDENT OF JULY Ii, 1988

Som_ sDec_c comments on the July llth case:

The microburst algorithm did an excellent job in detecting

the onset of the microburst, and apparently pro_-lded an alert

sequence that accurately po_rays the developing intensity, of

the event. Essentially, the system worked at least as we]/as

we could have expected.

Controllers pro_-idedthe fiveflightcrews with the message as

intended. It isunclear that the message impact issui_ciently

c!ear,and a significanteffortisnecessary to address message

knpact, etc.

There was a sigxfificantvariationin flightcrew awareness of

the program, in spite of substantialU AL effortto do so.

It would appear that wind shear recovery procedures were

important aspects of a successfuloutcome.

Flight crews did not provide wind shear PIKEPS, even though

severe encounters occurred.

Human factor, information transfer, and training are the

issues that dominate the action items.

708
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716

OF ?OOR QUALITY
Aircraft Performance in Wind Shear

• Ground based systems currently provide velocity

differentlal (DV)in microbursts.

• We are examining the feasibility of measuring shear

(DV/DR) as a hazard redefinition.

• Critical Question: Should hazard definition from

a ground-based system be a binary (GO/NO GO)

threshold?

STRATEGIC VS TACTICAL DECISION

• Does a shear calculation invite flight crews to

"THREAD THE NEEDLE?"

• Objective: To provide sufficient accuracy of wind

shear hazard to provide "quality" go/no go decision.

• Should ATC be allowed to deny clearance to land or

clearance to take off, once high quality hazard information is provided?

717
Information Transfer:

Human Factor Issues in Wind Shear Hazard Alerts

Assist FAA (Air Traffic Control-Aviation Standards)

in sorting inlormation transfer issues in hazard alert

message delivery.

• Controller procedures

• Flight crew awareness

, terminolog_j

, training issues

718
Airborne Wind Shear in situ Alerting

Validation with wind shear data collected by penetration

aircraft, in conjunction with multiple Doppler weather

radar analysis.

To what extent are the current generation of in situ

sensor systems adequately validated?

MOTTO OF TERMINAL DOPPLER

WEATHER PROGRAM

VALIDATION

VALIDATION

VALIDATION

Does this model apply to airborne alert system ?

If not, why not ?

719
Session I. Ground Systems

A Cursory Study of F-Factor Applied to Doppler Radar

Kimberly L. Elmore and Wayne R. Sand, NCAR

721

PrwCE.D,,,-_, ;:_,AGE _LA,_qK NOT FILMED
A Cursory Study of F-Factor Applied to Doppler Radar

Kimberly L. Ellzzore, Wayne R. Sand

National Center for Atmospheric Research

P.O. Box 3000, Boulder, CO 80307

L.,_.,,_-, .... P,_OT FILMED

723
A Hazard Index: F-Factor

F

,-4

9

TAS'

_?x = wind component Mong flight path,

9 = acceleration due to gravity,

_3 = vertical wind,

TAS = true airspeed.

From Bowles and Targ, 1988

725

PRECEDI_!G PAGE BLANK NOT FILr,,_ED
A Model

y = Asin _--_x ,

nr

D2

To filld the maxinunn difference between shear estimates l_ased

on AV/Ar and those based on the model, evaluate Oy/Ox at

AV_

Oy/Oxl_=° - Ar 2 cos(0)

AV_

Ar 2

x=O:

This is the nlaxinmm ratio between the two estimates.

726
The Least-Squares Fit

The least squares residual is given by:

i/2

R(fl): .f [ftx-Asin(2-_x)]

--1/2

2

fl : slope of least squares line

Least squares line given by y =/3x + o.

Mininfize tile residuM:

112

_'(o1 = 21J.i

-1/_.

--0.

1/2

x2dx-2A .f ,sin(2-_x) dx

--1//2

Solve for fl:

fl/2 7f

A.]_i/2 x sili (-2-'_:r) (l:c

x2 dx

727
Evaluate the numerator using integration by parts with u = x,

dv=sin _--_x ,du=l andv- 7r cos _--_x .

- _ -xcos (2-D -_/2

-1/2

+ sin _-_ z -x/2

(2D) 2 (Tr)(2D) (Tr) = 2 sin - cos

_-_ _ _-_"

For the denonfinator,

1/2

-1/2

x 311/2

3 I-1/2

1

728
The Bottom Line

Solve fi)r _, rearrange terms a_ld substitute in AV and At:

fl-6AV 2 sin (2Xr) - cos (2_, r .

= shear in s -2 over 1 km least - squares line fit to model.

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Concluding Remarks

1. The extremely high correlation coefficients that are obtained

when F or Fx is regressed onto AV/Ar show that the modeled

F-factor and the peak-to-peak divergence are eqltivalent hazard

indices that have different thresholds.

2. Use of A V alone without reference to a length scale severely

limits the potential information content relative to the direct

effect of microburst wind shear on aircraft performance.

3. Use of this model links AV values to some scale length.

U

4. Importance of actual shear distribution and velocity profile is

still unknown.. Simple A V estimats of 15 kts have been shown

to cause aircraft accidents; scaled to 1 nmi, this is olfly about

50% of the F-factor thought to pose a hazard.

5. _ appears to be a significant contribution to the total hazard.

738
Session I. Ground Systems

Summer 1988 TDWR Microburst Analysis

Mark W. Merritt, MIT Lincoln Laboratory

739
SUMMER 1988 TDWR MICROBURST ANALYSIS*

Mark W. Merritt

MIT Lincoln Laboratory

Lexington, MA 02173

ABSTRACT

N91-11701

The Terminal Doppler Weather Radar (TDWR) testbed system was operated

during the months of July-August 1988 in a live operational demonstration

providing microburst (and related weather hazard) protection to the Stapleton

International Airport in Denver, CO. During this time period, the performance of the detection system was carefully monitored in an effort to determine

the reliability of the system. Initial performance analysis indicates that the

microburst detec[ion component of TDWR satisfies the basic performance

goals of 90% probability of detection and 10% probability of false alarm.

An in-depth study of the system performance, based on analysis of both dualDoppler radar observations and surface mesonet measurements, is in progress

to provide a detailed understanding of the observability of microbursts by the

radar, the ability of the algorithms to detect microbursts observed by the radar,

and the timeliness and accuracy of the microburst alarms provided to operational users.

*This work was sponsored by the Federal Aviation Administration. The

United States Government assumes no liability for its contents or use

thereof.

741

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751
Session I. Ground Systems

Automatic Detection of Low Altitude Wind Shear Due to Gust Fronts in the

Terminal Doppler Weather Radar Operational Demonstration

Diana Klingle-Wilson, MIT Lincoln Laboratory

753
Ntil-llroe

Automatic Detection of Low Altitude Wind Shear Due to - - _

Gust Fronts in the Terminal Doppler Weather Radar /'z /_

Operational Demonstration*

Diana Klingle-Wilson

Massachusetts Institute of Technology Lincoln Laboratory

Lexington, MA 02173

ABSTRACT

A gust front is the leading edge of the cold air outflow from a thunderstorm. Wind

shears and turbulence along the gust front may produce potentially hazardous conditions

for an aircraft on takeoff or landing such that runway operations are significantly impacted. The Federal Aviation Administration (FAA) has therefore determined that the

detection of gust fronts in the terminal environment be an integral part of the Terminal

Doppler Weather Radar (TDWR) system. Detection of these shears by the Gust Front

Algorithm permits the generation of warnings that can be issued to pilots on approach

and departure. In addition to the detection capability, the algorithm provides an estimate

of the wind speed and direction following the gust front (termed wind shift) and the

forecasted location of the gust front up to 20 minutes before it impacts terminal operations. This has shown utility as a runway management tool, alerting runway supervisors to

approaching wind shifts and the possible need to change runway configurations.

The formation and characteristics of gust fronts and their signatures in Doppler radar

data will be discussed. A brief description of the algorithm and its products for use by

Air Traffic Control (ATC), along with an assessment of the algorithm's performance

during the 1988 Operational Test and Evaluation, will be presented.

The work described here was sponsored by the Federal Aviation Administration. The

United States Government assumes no liability for its content or use thereof.

755

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770
Session II. Perspective
Session II. Perspective

Some Perspective on the Wind Shear Protection Problem

Sam Saint, Safe Flight

773 "_'_" _'"_ ,_,,_,_,;,_,_ PAGE BLAre]( NOT F]LMED
SAFE FLIGHT

SOME PERSPECTIVE ON THE WIND SHEAR PROTECTION PROBLEM

Sam Saint

Aviation Consultant

Second Combined Manufacturers and Technology

Airborne Wind Shear Review Meeting

Sponsored by NASA/FAA

October 18-20, 1988

Fort Magruder

Williamsburg, Virginia

775

!'.:::f.S:.il, bi..._.3; i ,-_.z _._,.1....._ I'_O]" F_L_E.D
SAFE FLIGHT

What we have accomplished and what yet

remains to be done.

Not everyone yet realizes what a landmark decision FAA

made when they went into the Federal Register with a new

regulation mandating ONBOARD WIND SHEAR PROTECTION.

The FAA action taken last month was absolutely right.

This is clearly the first giant step along the road to total

wind shear protection.

We have come a long way.

Unfortunately, however, there is a residue of misunderstanding about the role of the onboard protection now mandated

by FAA.

That residue of misunderstandingwas put in print in the

AP story of FAA's order "to equip all ... planes with devices

that will help pilots detect and escape from deadly shifts in

the wind." This was the AP story filed on September 22nd, as

reported in the NY Times on September 23rd.

Describing the wind shear disaster at Dallas-Fort Worth

in August of 1985, the AP story said the newly mandated

equipment "tells the pilot when the plane is in the midst of

conditions as dangerous as those at Dallas-Fort Worth in

1985." Then comes this sentence: "By that time, critics of the

equipment suggest, ... it may already be too late ..."

The last paragraph of the AP story (as it appeared in the

NY Times) reads this way:

"Many pilots insist that it is virtually impossible to

escape a powerful microburst like the one that struck the

Delta plane at Dallas-Fort Worth or the one encountered by a

Pan American World Airways jetliner that crashed as it was

taking off from New Orleans in 1982."

The AP story is wrong on two counts.

The assertion that a warning when the plane is "in the

midst of [the microburst] conditions ... may already be too

late," is wrong, as I will show you in moment.

777

F_C_:,_,'_G __..-_.,,_B!.A_',,.;_ NOT cw; _','F_
SAFE FLIGHT

And, the AP story, quoting "many pilots", implies that

use of the mandated equipment would, maybe, not have saved

either the Pan American disaster at New Orleans, or the Delta

tragedy at Dallas-Fort Worth.

This is a totally wrong conclusion, as I think many of

you here in this room already know.

To put it bluntly, there are still some people who

believe the onboard "reactive" systems FAA has now mandated

are simply another "band-aid" solution, to give some protection while we wait for the real solution from the ground-based

and/or airborne "look-ahead" systems they insist we really

want.

We could talk about how these erroneous ideas got

started, but this would not be fruitful today. What we really

want is a clear answer to each of three questions:

One, will the warning the pilot gets from the currently

mandated equipment come too late?

Two, will the warning the pilot gets from the currently

mandated equipment give the pilot the capability of escaping

from microbursts like that at JFK on June 24th, 1975, like New

Orleans on July 9th, 1982, and like Dallas-Fort Worth on

August 2nd, 1985? These three worst wind shear disasters

since 1975 cost 401 lives and many hundreds of millions of

dollars in liability claims. Would the protection now ordered

by FAA have saved those lives and kept those three airlines

out of the courts?

The third question is this: Will the currently mandated

onboard, "reactive" systems become obsolete if and when a

"look-ahead" system is perfected?

I first heard what I believe to be the correct answer to

this third question from Roland Bowles in the hallway at 800

Independence Avenue during a coffee break. Before I talk

about this third question, though, let me give you a solid

answer to the first two questions.

Let me answer both of these question with one concrete

argument. The currently mandated warning will not come too

late, and the mandated equipment, including recovery

guidance, would, beyond question, have kept EA-66, PAA-759,

and DL-191 out of those smoking headlines.

778
SAFE FLIGHT

Give me a moment to back that statement up.

First I need to point out that calling this currently

mandated equipment a "reactive" system is an unfortunate

choice of words. The so called "reactive" systems will give

the pilot an absolute determination that the outside environment is doing something that is outside the limits of normal

turbulence. And this warning will be given many critically

important seconds before the pilot can judge the situation

from his normal instrumentation. Perhaps the most important

of all, the spoken words (Wind Shear! Wind Shear! Wind

Shear!) from the cockpit loudspeaker, going into the Cockpit

Voice Recorder, will take peer p[essure off the pilot's back.

He can act, without hesitation, well before "it is too late."

A closer look at the accident record will make this

clear. Let me give some examples:

EA-66 at JFK on June 24th, 1975 -

The initial warning (based on energy gain) would have

come 20 seconds before these pilots realized what was happening. The warning would have come on the basis of a suddenly increasing headwind, with the airplane 420 feet above

the ground, ballooning above the glide path, with a headwind

of 17 knots and an updraft of 300 feet per minute.

Full power, plus commanded pitch guidance for escape, at

that point on the approach would certainly, beyond any

question, have kept that aircraft out of the approach lights.

What actually happened was disastrously different. The

Captain did not call for go-around power until two seconds

before impact.

Without the mandated protection, I believe this could

have happened to any pilot. It could have happened to me.

The pilot needs the help we are now going to give him.

The mandated warning would have been a "prediction" of

the potential danger that lay ahead. I say again, "reactive"

is a misleading word.

779
SAFE FLIGHT

Continental-426, a takeoff at Denver on

August 7th, 1975 -

This pilot would have been warned when 22 seconds into

his takeoff roll, with a ground speed at that moment of 70

knots. The warning would have come on the basis of an

increasing headwind shear of 7 knots per second, while he '

still had more than 8000 feet to get stopped.

Allegheny,121, an attempted go-around at

Philadelphia on June 23rd, 1976 -

Again, on the basis of a sharply increasing headwind,

this pilot would have been warned and would have started his

go-around while still 270 feet in the air, looking at an

airspeed of 160 knots. With the recovery guidance system to

prevent the disastrous, near zero angle of attack at the

critical part of the escape maneuver, there is just no way

this aircraft would have made a 10-G crash landing in the

middle of the airport.

Continental-63, a takeoff at Tucson on

June 23rd_ 1977 -

This aircraft ran through utility poles and wires 710

feet beyond the end of the runway.

For Continental Flight 63, the computed warning would

have come from the cockpit loudspeaker 26 seconds into the

takeoff roll. The groundspeed at that moment was 90 knots.

There was approximately 4500 feet of runway left in which to

stop.

No problem.

Pan American-759, a takeoff at New Orleans

on July 9th_ 1982 -

In this case, the warning would have come right at lift

off. Thanks to Dr. Fujita's comprehensive analysis of this

record, we can determine that full power, plus commanded pitch

guidance, would have seen this aircraft cross the tree line

that brought it down with a margin of 130 feet.

780
SAFE FLIGHT

UAL-633_ a takeoff at Denver on May 3rd, 1984 -

This takeoff hit the ILS antenna 1074 feet beyond the end

of the runway. There is no way you can come closer to total

disaster and keep on going.

These pilots would have been warned in time to have

coasted to a stop. A hairy near miss would have been turned

into a relaxed operation.

Delta-191 at DFW on August 2nd_ 1985 -

The implication that this disastrous accident could not

have been prevented by the currently mandated wind shear

protection is wide of the mark. Not by any stretch of

imagination can this implication have any validity.

The Flight Data Recorder on this aircraft was recording

42 parameters every second. Dr. Ted Fujita's total analysis

of this accident is available between hard covers. I have

flown a near duplication of this microburst four times in

simulation.

For those Delta pilots, the initial warning would have

come 18 long seconds before they knew the desperate trouble

that lay ahead. This initial warning (based on energy gain)

would have come 35 seconds before initial impact, while the

aircraft was still 770 feet above the ground, with an airspeed

at that moment of 173 knots.

With full power at that point, gear up, and go-around

flaps, there is just no way that Ed Conners and his big flying

machine could have wound up in a smoking heap on millions of

TV tubes.

Let me add a personal word here -

I was an airline pilot for 33 years. If I had been in

command of that L-1011 at DFW -- an aircraft that did not have

the protective technology we now know how to provide -- it is

highly likely that I too would have wound up in that great

fireball against those water tanks.

• 781
SAFE FLIGHT

There is a point we need to clear up with

the aviation community -

Gentlemen, with the prestige of this meeting, with the

prestige of the NASA/FAA Team, we need to tell the world that

the mandated, onboard wind shear protection systems should not

be called "reactive" systems. This word still speaks to some

people of a warning that is "too late".

Again and again, it is seen in the accident record that

these new systems will give pilots enough lead time to change

a potential disaster into a safe escape.

We should tell the aviation community that this currently

mandated equipment is not a "band-aid" solution. We are not

talking about a "crash alarm", as some have suggested. We are

talking about a solid solution of a difficult and very complex

problem.

That leads us to the third question we

asked earlier -

Will the currently mandated equipment become obsolete if

and when the "look-ahead" (Doppler, laser, Lidar, infrared --

airborne or ground-based) systems become available?

Careful examination makes it clear that Roland Bowles at

NASA and Herb Schlickenmaier at FAA have been right all along.

Roland was the first to say this in my hearing: The

"reactive" systems already flying with FAA certification will

not be throw-away technology.

We need to say, with the considerable force of these

important, NASA/FAA sponsored meetings -- we need to tell the

aviation community that the currently mandated equipment forms

a solid foundation to which additional improvements should be

made as they come along.

Nowf a word about what ye t remains to be done -

Four of the eight accidents in the NTSB records, from

EA-66 in 1975 to DL-191 in 1985, were takeoff accidents.

Clearly, we need protection from a microburst encounter

during the takeoff roll. But there is a problem that has not

yet been resolved.

782
SAFE FLIGHT

At least one major airframe manufacturer and two major

airlines have argued that a wind shear warning system must be

deactivated during the critical phase of a takeoff. The fear

is, of course, that an aborted takeoff could be triggered

that might turn into a disaster. The threat of liability

looms like a specter in the background.

I can understand this fear. It is a valid concern. Two

engineering pilots, whose judgment I regard very highly, have

told me that we need to resolve the total runway monitoring

problem before we can allow the wind shear warning system to

be enabled during the most critical part of the takeoff roll.

I agree that this is an unsolved problem that still lies

ahead. Complete runway monitoring will involve many factors

other than a possible microburst encounter. With today's

technology, however, I believe we can solve the runway monitoring problem.

Let me put my Safe Flight hat on for one

final minute -

I want to say I am proud to be a member of the Safe

Flight Instrument Corporation team.

Safe Flight was years ahead of everyone else in arriving

at the correct basic concept for a warning system. Safe

Flight was first to understand that the horizontal and

vertical winds at the outer edge of a microburst should be

measured to provide the earliest possible look at the

"footprint" -- the "signature" -- of the hazard that lies

ahead.

Seven years ago, when I was catapulted into this problem,

Safe Flight stood alone in having a clear understanding of

what we now know to be the way the threat should be measured.

There were many other approaches being pursued. Today, there

is a strong consensus that the basic concept pioneered by Safe

Flight is the correct approach to an onboard warning system.

And this basic concept meets the requirements of FAA's new

rule.

Safe Flight was the first to seriously argue that the

pilot needs computed recovery guidance, and to provide that

guidance.

• ' 783
SAFE FLIGHT

Safe Flight was the first to argue for wind shear protection during the takeoff roll, and to develop that protection.

All through the years of the jet era, _ we have known that

speed targets provided an inadequate signal for the extremely

critical takeoff decision points.

In the course of working toward microburst protection

during the takeoff roll, Safe Flight has invented and now

offers "Runway Rotation Guidance". This is rotation command

based on real world inputs of both ground speed and airspeed.

This, I firmly believe, will eventually replace the totally

inadequate speed targets for marking the last safe abort point

and the point at which rotation should take place.

Thank you for listening.

784
Session II. Perspective

Lessons Learned

William Laynor, NTSB

785
Lessons Learned - William Laynor, NTSB

I'm not real sure what Herb meant when he gave me the title, "Lessons Learned"

here. I thought maybe I was supposed to give a test. It's always a pleasure to follow

Sam, of course, because I've known Sam for a long time. I'm going to take the

opportunity to echo some of the things that he said. I want to really present an

overview of the Safety Board's views and progress made to date and some observations

on the discussions that I've heard during the last couple of days. But before that I

want to mention a probable cause.

About two years ago, out at the SAE Aerospace Technology Conference in Long

Beach, I opened the panel on wind shear. I think a lot of the people here were in

the audience and I read a probable cause. The probable cause that I read was, "loss

of control of the aircraft due to unusually severe turbulence and violent down draft

caused by a thunderstorm of unknown and unpredictable intensity." Since I'm

following Sam, I'll tell this story. Shortly before or after, I can't recall which, I was

preparing this speech, Sam was in my office and I read that probable cause to Sam

and I didn't know exactly which accident he would associate it with. Without blinking

an eye, Sam said "Oh yea, I remember it was back in 1943 and it was Captain So and

So" (I don't know the captain's name but I venture to say he does) and anyhow, it was

July 28, 1943, it was an American Airlines DC3 which encountered a thunder storm

near Bowling Green, Kentucky, while enroute at low altitude between Louisville and

Nashville. The significant part of that accident report (I dug that accident report out

in preparation for that speech) was that back in 1943 there was a very accurate

description of a microburst. It wasn't called a microburst, but the accident described

the constrained high velocity down draft diverging out (that was evident by ground

damage) the trees blown, damage to the ground which was fanned out in a wide range

and it was very evident that unlike somebody said earlier that people didn't recognize

the microburst hazards, they actually did. In fact, there were a couple of

787

r,c._,::u_,,_i PAGE BLAl_,'i( NOT FILMED
recommendations that came out of that report and they were that we needed to

conduct research from the dynamics of thunderstorms, and the development of

accurate methods of forecasting severe developments. Another one was that there had

to be further studies of the behavior of airplanes passing through a verticle downdraft

and into a tail wind. I think most of the people here know that the NTSB tracks

recommendations and the actions being taken to close them out and we grade them

as acceptable actions or unacceptable but I think we've approached the point some

45 years later where we can probably close those recommendations out now.

Obviously progress hasn't been steady during that period of time and even though

there were some people and Bill Melvin was one, some of the NASA people, George

Spectal I think from Huntsville and there's some people from Ames and Captain

Brown from TWA, there were papers that were put out certainly during that period,

in the 60s and before the early 70s. But in the early 70s the whole wind shear

problem started to be recognized by industry and government. Although the Iberia

DC10 accident at Boston Logan in 1973 was actually a funnel system wind shear, not

something that would normally infringe upon the performance capability of the

airplane. It was certainly a wind shear accident and it infringed upon the Captain's

interface with the condition he was going through and that prompted a lot of attention

within the industry. Eastern 66 that Sam referred to came along in 1975 and that

really got people's attention. Ted Fujita and Fernando Carecina among others started

coining words like microburst, downburst, and the whole aviation community became

very intensely interested in the subject. I think that I can honestly say that we have

seen steady progress since 1975 in addressing the problem, although it's certainly been

spurt),. It's been accelerated in 1982 with the Kenner accident and it accelerated again

in 1985 with the Delta Dallas Forth Worth accident. But back in 1975, people

recognized that there was a need for a lot of research. There was a need for

development of ground based detection equipment, there was a need for the

development of airborne detection equipment and there certainly was a need for

788
training so that brings us up to 13 years later. I'm not intending to be critical that

it's taken 13 years, but I think we have to recognize that there's a lot of technological

hurdles that had to be overcome and there's still a lot of them that have to be

overcome. There are budget priorities that we're contending with, we've got problems

other than wind shear. We've got airborne collisions and a whole host of places to

spend money. Government procurement is obviously not necessarily completely

efficient, I guess I should say, and rule making takes time, so we've made progress.

There's no doubt about that and I think the Safety Board views that progress with a

lot of encouragement. The progress has been evident.

We've heard a lot about it here the last couple of days. In 1987 when we had

the enhanced LLWAS test out at Stapleton that certainly was a vast improvement over

what we had seen in LLWAS in the past and we've got to hustle and get that system

in more places. I understand now that it is in New Orleans, but it still has time to go.

The TDWR tests, we've heard an awful lot of in the last past couple of days and

that's been more than encouraging. The NEXRAD terminal and NEXRADS are

coming along. They're under contract and under production I guess. The TDWR

itself (I don't know if the contract has been let yet) is imminent. So that sure is

encouraging. The ASR9; I think perhaps the wind shear community hasn't paid quite

as much attention as it should to the implementation of the ASR9 and the features

that it's going to bring for places where we don't get the Terminal Doppler and how

they integrate it with the LLWAS. I was encouraged this morning when Art Hanson

at least touched upon that pretty much. It was kind of encouraging to think that it

is being thought about someplace. Flight crew training aides were delivered to the

FAA, February 1987, a year and a half ago, almost two years ago. That represented

a very intensive effort by the manufacturers in the community. I agree with Sam that

the rule making that's just been passed is a landmark rule making because we certainly

need that training as well as the reactive, in situ devices that Sam is talking about.

The Safety Board supported that rule making very strongly and we supported the

789
reactive devicesand both the detection and the guidanceaspectsof it. Like we know

that in the preamble there wasa lot of controversial commentsabout the need for the

guidance,but in our view, so long asyou have airplanes flying with speed command,

alpha command and flight directors, we have to do something to improve the crew's

chancesof executing a successfulescapemanuever and that requires this guidance.

The forward looking sensors,the discussionshere were very interesting. There's a lot

of good technologyand we certainly want to seethat program move forward. It seems

to me that there are still a lot of hurdles that need to be overcome. I certainly

disagree that we should have waited until those systemscame along before *we went

into rule making with the presently available devices. And in fact, I've heard some

comments during this discussion from various people here and outside where they've

expressed concern that this rule making that's on the presently available devices is

going to inhibit development or can potentially inhibit development of the forward

looking devices. Why, I certainly hope not. But I thought it was interesting when

Howard Long, at some point yesterday, brought up the question of what happens when

the down draft, a very intensive downdraft, descends on the airplane rather than the

airplane running into it. I think that we've see that in some of the wind shear

incidents we've investigated. I'm not sure about the accidents but I do know we've

investigated incidents where pilots had clear visibility, had no signs of constrained rain

shaft ahead of them and then all of sudden they're deluged in rain and they've got the

wind shear effect. So the forward looking sensors may not always do the trick. One

is not going to substitute for the other in my view.

I want to make a couple of observations on the discussions during the last few

days, Bob Ireland was up here a couple of days ago and was talking about the July

11 incident at Stapleton. That brought about a lot of discussion from the people in

the audience about the controller's and the pilot's performance, which it wasn't

intended by Bob, I'm sure. But I think it pointed out that there is a lesson to be

learned. We have a lot of human factors work to do and I'm not sure that I want to

790
use the words total in the human factors side but we have a lot of work to do where

we get air traffic controllers, pilots and everybody involved and we've been doing this.

When we talk about the controllers job, it's always kind of interesting to me that we

focus in only on the subject at hand, wind shear in this case. The NTSB on the other

hand, we have to focus in on the runway encouraging problems, the operational errors

and everything else. We have to recognize, even though we may not always appear

to, that the controller has one heck of a work load these days. They're limited in

experience, limited from the standpoint that they may be very well trained but it's been

basically a rebuild effort since 1981, they're handling more traffic now they ever did

before and their primary concern, irrespectable of what this group might think, is to

keep those airplanes apart and that's a big job for them. The point I'm trying to

make there is that I don't think we're going to reach the day where you can look to

a controller to be able to understand the performance problems facing a pilot, his

aircraft. I don't think you're going to be able to look to him (even though we'd like

to think he'd have better meteorology training than he has) to do a lot of

interpretation of weather data. So we're going to have to come with the tools that

give him a very objective way in which to make decisions. If we ever put the decision

in the tower and the FAA legal people, the people who decide to suspend operations

as a result of any of these readings, will do so because there's an objective way of

measuring it and there's a no go light there. The controllers subjectivity is not going

to be an issue. Obviously, the July 11 incident pointed out the need to do a little

more work on the message format but that was the purpose of that operational

demonstration program. What we felt was that there was going to have to be more

work done and there is a TDWR LLWAS user group that's certainly going to continue

with that. Bob was asked the question (somewhat leading question) at the end of his

presentation,., would there have been an accident had there not been a TDWR and

the warning devices and I tend to agree with Bob. I hope he's right that there

wouldn't have been but I'm not sure that I agree with him that it's necessarily for the

791
samereason. Thosepilots involved were trained, they had beenthrough the simulator,

they probably instinctively knew a little bit better how to react than pilots who perhaps

had not receivedthe intensive training. But they could also see the ground and in the

accidents that Sam's mentioning (the Eastern JFK Pan Am encounter and Delta

Dallas, and just about every one of those cases) we felt that the pilot's visibility was

just about nil when he entered the rain shaft and he didn't have the altitude

awareness. That's one of the things that really bothered me in Bob assessment when

he said that one of the pilots he'd talked to hadn't realized that he had gotten so low.

We read out the play data recorders from those airplanes and they did get pretty low.

The heavy rain effort itself is .. it's certainly interesting. We strongly support Earl

Dunham's work. I thought he had an interesting presentation. We have to continue

to establish what the stall margins are in heavy rain. We've looked into it in a

theoretical sense after the Delta 191 accident in analysis, but we don't know what the

rain fall rate for sure was in that. But we did look at .. we had a good enough flight

data recorder that we could look at longitude or acceleration and air speed rate and

back out some of the wind defects and then look at the theoretical lift coefficients and

see whether there were any rain effects. We didn't see the 30%, certainly that Earl

was showing here. In fact, we saw very little. Since a lot of the discussion here

concerned views on the compatibility of the ground based systems and the airborne

systems (Wayne Sands brought that up this morning) I frankly, personally, believe that

it's a worthy objective to get those systems compatible. But I'm probably not as much

worried as I've heard some other people indicate *that they have to be perfectly

compatible. I think that these events will be rare enough that the pilots have to be

trained now, irrespectable of which one gives the warning, he's going to hate it and

there certainly are times when you're going to be warned from a ground based system.

You won't see it on an airborne system or look ahead airborne system or even an in

situ system so I don't think it's really achievable that you're going to get complete

compatibility. But that has to be covered by training. Ultimately, I suspect that we

792
ought to be looking at a way for the data link to get the systems talking to each other

so there's really no need for compatibility. A pilot sees a warning and regardless of

whether it comes from the ground based system or the airborne system, he's trained

to do something about it. I hear people talk about using the F factor hazard index

and it's certainly a part of the algorithm to go into any of these systems as detection

modes. I certainly don't agree with that there's any need to give the pilot an F factor

hazard index. He's got enough to think about when he's just coming in and trying

to relate the level. In fact, we take the view that where anything says there's a

microburst, it's "get out',, don't evaluate whether your airplane has performance to try

to penetrate it. Pat Cline was mentioning the false and nuisance alarms after the

presentation by Terry Zwiefiel. I'm certainly hopeful that those problems, if there are

any, can be solved. I thought the data that was put up by Terry where there one

alarm in, I think, 20,000 plus flights, certainly indicated a rarity of the events to the

point that nuisance alarms is not going to be all that critical, but there were a lot of

analogies made to the GPWS. The GPWS was put into service and those people who

say it was put into service prematurely, from the Safety Board's standpoint, we will

argue against that violently, because it undoubtedly started preventing accidents as soon

as it went into service. The evolution of the performance of those systems, you very

seldom hear complaints these days. Some of these guys might take issue with that, but

that's my view.

Again, I've heard discussion that the rule for the reactive devices will inhibit

industry's development of the lo0k ahead system. I certainly hope not. I think that

industry has to continue to strive just like they do from going from black and white

to color radar and the turbulence modes on radar. There are going to be constant

improvements in the systems and all the technologies being discussed here have to be

given a chance. But the systems have to complement each other to the extent that

the reactive systems and the guidance should complement the onboard look ahead

systems. It brings me to where we are and what's still needed. I think Wayne did

793
a pretty good wrap up of what's still needed today. We generally concur with him.

The enhanced LLWAS -- there has to be work there. We're strong advocates of

getting sensors out on the approach and departure path because even with the

expanded array within the airport boundary, we're going to miss some critical events

that could cause accidents and I think that's well recognized in the FAA and like

Craig said, it's a budget and resource problem. I'm sure there's going to be a day,

probably pretty soon, when we're going to look at priorities and whether systems have

to be enhanced and it's going to be weighed whether there's a TDWR there or

whether there isn't, whether there's an ASR9 and a lot can be done, probably, to

combine the ASR9 and LLWAS (without a TDWR to improve the situation where the

TDWR is not going to be installed) I was encouraged this morning to hear Art

Hanson talk about the geographic situation display in the tower because this is the first

meeting I've been to where it's been indicated that that's part of the FAA's plans.

That has been really kind of a concern because I think the test at Denver proved that

that's a very useful piece of equipment. Ultimately, it is the type of display that you

might want to send up to the airplane.

The LLWAS TDWR message format I've mentioned, the use of the ASR9 I've

mentioned and I think the only other thing I didn't hear this morning but I'm sure it

will be coming along is the presentation of the TDWR display on the controller's

BRITE. At the last meeting I attended I also heard that was not part of the FAA's

plan but I certainly hope that becomes part of their plans.

The development of a controller training program as these systems get

implemented is a must. They might not be able to make pilots and meteorologists out

of them but we can at least the controller thinking towards the pilot problems. But

more than that, we also have to continue to develop a data link so that we take some

of the work load off his shoulder.

The 1988 season is over and I think everybody breathes a sigh of relief when the

thunderstorm season ends, but we've got several more years to go where a situation

794
at most of the airports are going to be exactly the same as they were at Dallas Forth

Worth in '85 and in Kenner in '82. So there's no substitute for awareness and training

and that's the only thing we're going to have going for us in the next few years so we

have to concentrate on them.

795
Session II. Perspective

Wind Shear Procedures and Instrumentation

W. W. Melvin, Airline Pilots Association

797

PRECEDING PAGE BLANK NOT F;Lh,'_EL;
737 

N91-11703

W. W. Melvin

Air Line Pilots Association

A recent study by Dr. Anqelo Miete and the Aero-Astronaut_cs

Group of Rice University entitled "Effect of Pitch Rate on Abort

Landing Windshear Encounters" shows that high p_ tch rates

(greater than 3/4 degrees per second) will adverse,'.y affect

flight path performance in strong wind shears close to the ground

(Figures I through 5). This study of a typical ]el transport

aircraft for the landing case is an offshoot of the Optimal

Trajectory Studies by the Rice University group which is funded

in part by NASA Langley under" the directi.on of Dr-. Roland Bowles.

This should call to question the advice in the FAA W).nd Shear

training Aid (WSTA) for pilots to rotate "at a normal rate" [o a

prescribed pitch, a proceOure known as the constant pitch

technique which was also used for tlqe Rice University study.

"Normal rate" is defined and under-stood by pilots to be 2 to 3

degrees per second which is much too fast far the landing case in

a severe shear. In modest wind shears, pitch rate has little

effect upon flight path per-formance. A higher- pitch rate may be

required for initial rotation at takeoff, but for encounters

after takeoff an initial pitch reduction followed by a qradu_)l

pitch increase more closely approximates an optimal tra]ectory.

Borrowing a figure from Dr-. None Barrios' presentation (Figt_re 6)

which is in close agreement with the optimal trajectory studies

at Rice University, it is evident that his altitude profile for

deliberate flight at the stick shaker angle of attack (curve no.

2) is a very poor strategy. One must. question then the advice

from the WSTA to remain at the stick shaker angle of attack after

it is initially encountereo.

A new study by the Rice University group, yet to be published,

should reveal the optimal trajectory after reaching the st. ic:k

shaker angle of attack. ]his study is also an offshoot of the

optimal tr-ajectory studies and is funded by the Aviation Research

and Education Foundation.

Examination of Barrios' curve no. 4 (constant pitch technique)

shows that in this very strong wind shear there comes a time wher_

the pitch can no longer be maintained at the prescribed value of

15 degrees and the flight path becomes negative. Th:.s effect is

also shown in Dick Bray's paper. However, the WSTA tells a pilot

that if at the target pitch and if the flight pat_ is not

satisfactory then the pitch should be increased. This can be art

impossible task which holds out a false hope to pilots.

A correlation is shown in Figure 7 between aircraft performar_e

and the F factor where aircraft performance is des(zri!]ed by a

constant airspeed. Also shown (Figure 8) are some [ _m11 ing

conditions of aircraft performance which reveal some, values far

Pi,_ECEL3iNG PAGE BLANK NOT FILMED

799

ORIGINAL PAGE IS

OFPOOR QUALITY
below the planned alert level of some aircraft warning systems.

As pointed out by Dr. Bowles, in a wind shear an aircraft can in

fact escape a condition exceeding the limiting value by trading

airspeed. Nevertheless, some consideration to these limiting

conditions should be given when designing alert levels and in

prescribing escape procedures, especially recommendations to not

change the high drag landing flap configurations in some cases.

What pilots want in wind shear instrumentation is a device which

assists us. We will know about meteorological and operational

conditions which the machine is not going to know. We do not need

a decision maker, but rather an information device. Some devices,

designed to not have false alarms, in fact do not have false

alarms, but they do not protect against wind shear encounters.

Others which do protect may have nuisance alerts. We accept this

as long as we evaluate the alerts and use our judgement. We also

want alerts on positive performance encounters and when on the

ground.

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808
Session II. Perspective

Airbus Wind Shear Warning and Guidance System

J. L. Bonafe, Airbus Industries

809
AIRBUS WINDSHEAE WARNING

AND GUIDANCE SYSTEM

J. L. BONAFE

Williamsburs, Virsinia

20 October 1988

• 811

P_.'--,'CED;i",IGPAGE E,LA_'_(. NOT FILII_IED
N91-11704

AIRBUS WINDSHEAR WARNING AND GUIDANCE SYSTEM

i. AIRBUS WINDSHEAR PHILOSOPHY

From its first designed airplane, Airbus considered mandatory an help in

the crew's decision-making process to initiate an escape manoeuvre end an

help to successfully realize it.

For doing so forth all the Airbus airplanes are designed since 1975

including alpha-floor function and speed reference control law imbedded

in the SRS box for A 300 end FAC and FCC for A 310, A300/600 and the A

320.

Alpha-Floor function takes into account airplane energy situation

considering angle of attack and observed longitudinal situation in order

to apply immediately the full power without any pilot action.

Speed reference managers airspeed and/or ground speed in order to survive

a maximum in shear situation.

In order to comply with the new FAA regulation: Aerospatiale and Airbus

developed more efficient new systems.

The following part of this presentation is a comparison between 1975 and

newly developed system and explains how the new system does improve the

situation.

2. WINDSHEAR GUIDANCE STRATEGIES

Analog A 300's and digital h 310's and h 300-600's (AFCS standards 5-6-7)

have a very well known and similar SRS guidance law (Basic 1975

situation).

From our experience we confirm thaff this strategy is precise enough to

survive many shears. In some strong shear cases it is however completed

by an OEB procedure for disregarding FD bars at some point.

Safetywise analog and digital systems also do comply with the AC 25.12.

The basic Airbus Windshear guidance is favorable but can be improved.

813
We therefore defined a fully adaptive system that is able to cope with strong shears without any special

procedure at all.

Initially we tried to develop and optimal guidance system but we reached very quickly for impossible

solutions •

First" optimal guidance procedures really are different from one shear to another, in some cases the

system initially even demanding to dive.

Second • guidance is really optimal if we have the full knowledge of the whole shear pattembefore

penetrating it.

Third' which infact is the conclusion of the second point •iq any shear encounter an optimal guidance

system has to bet on the future.

For all these reasons we developed a repetitive and adaptive survival strategy (Figure 2) adapted to all

performance problems in typical shear conditions.

The system is derived from the A 300 SRS System (Figure 3) improved by a vertical speed floor

protection, by a Vmini protection and by a stall protection.

This Control law realizes the survival strategy (Figure 4) whatever be the longitudinal or vertical shear

stressing the aircraft capability in take off or go around conditions.

The Control law implemented in the FCC's SRS take off go around mode is available on flight director,

CWS or command.

In shear conditions and when shear intensity stresses the aircraft's, capability, the SRS law will

progressively adapt its control to a survival strategy •

1 - Basic vote (n°l) will control airspeed (Vsel + 10 Kt) with a vertical speed decreasing to

zero.

2 - Vote n=2then over controls vote n° 1 and commands a slightly positive vertical speed

with an airspeed decreasing down to V stick shaker plus a small A.

3 - Vote n"3then overcontrols vote n=2 and vote n° 1, controls airspeed at Vss + &. The

altitude will be reduced until the shear decreases.

Whatever commanded strategy, pitch attitude demand is limited by a stall protection to avoid

impending any stall situation.

3 - AIRBUS GUIDANCE SITUATIONS

The most severe shears proposed inAC 120.41 windfietd models were simulated in the take off phase

both with the initial A 300 SRS system and with me newly developed windshear guidance system

(called here control of aircratt's energy),

814
Comparing _igures 5 and 6 we conclude that the new system really _oes

improve the situation but that the initial A 300 SRS was already well

effective in its capability to cope with a real encounter.

Figures 7 and 8 emphasize the advantages presented by the new system in

theoretical shear conditions: an adaptive control law maintains the

aircraft inside the operational flight envelope and uses maximum airplane

capability to achieve this.

The control law is implemented in the A 300-600 AFCS since A/C MSN 420 and

for the A 310 it will be in the 89 first part. In principle the control

law is available for retrofit to all aircraft from the digital fleet.

From simulation experience we know that for take off with derated power

or for the landing case a successful escape manoeuvre can be accomplished

if max power or go around decision is promptly decided upon entering the

shear.

This remark just to focus on the absolute need for a tool to trigger the

crew's decision-making process to initiate escape.

Windshear detection can provide this valuable help; but what do we have to

detect what nuisance warning level should we reach to maintain an

acceptable level of crew confidence with regard to the warning.

All those aspects were kept in mind to define an Airbus windshear warning

philosophy from in-flight incldent/accident analyses.

4- AIRBUS WINDSHEAR WARNING

Airbus targets (Figure 9) enhances AC 25.12 aclvices in detection, non-detection and performance

nuisance warnings.

An evident design phy]osophy with regard to warnings was to define a wind severity factor computation

(SF).

d Enerqy Weight _C re- Airspeed x d Wx + g.W z !

ol = -- ol _

SF - r d Wx g

, dt " Airspeed x Wzi

Intuitively this reflects the instantaneous loss of energy due to the gloloal shear (longitudinal & vertical)

ifSF> 0.

Wx = longitudinal wind < 0 IF heaclwind

Wz : vertical wind < 0 IF clown

Cte : function of A/C propulsion and aerodynamics (typical to each airplane)

G : gravity acceleration

815
SF could be filtered and compared to a fixed threshold of 2.5 kts/sec or 0.13 g typically.

This conventionally adopted solutionswas however rapidly abandonned due to a high level of nuisance

warnings.

Wind variations knowledge is in fact the only parameterfor a shear intensity evaluation but can never be

the unique information in a windshear warning without duly taking into accound the aircraft's energy

situation.

Windshear Warning computed without considering actual aircraft energy will lead, in certain cases of

shear encounter, to very early warnings (the crew should identify them like nuisance warning) or will

lead to too late warnings endangering an escape manoeuvre.

A good crew confidence level and a satisfactory escape manoeuvre capability can both be reached by a

winclshear warning as a reasonable compromise between "SF", aircraft's actual energy and a safe

minimal energy.

5 - WIND SHEAR WARNING (WSW) COMPUTATION PRINCIPLE

The WSW is activated when the predicted aircraft's energy is below a predetermined minimal energy

threshold (Figure 10).

This threshold corresponds to still air a floor protection in accordance with Flaps and Slats

position.

a = a + aw

The predicted aircraft's energy depends on C " which is obtained considering filtered angle of attack

(AOA orE[ ) corresponding to the actual aircraft's energy situation increased by equivalent angle of

attack estimates (E.AOA.E) a W.

a w is an estimate of the energy loss foreseable in the close future.

Note than the higher is AOA (a) the lower is the actual aircraft energy and the higher is E.AOA.E (C[W)

the higher will be the future loss of energy,

aw is obtained by a combination of equivalent angles of attack estimates :

.,_- is the E.AOA.E due {o instantaneous tailwind shear

,_,- E.AOA.E of the recent headwind shear. is a memorized

Generally a strong heactwind is precursor of a strong decreasing shear.

,.._ - is an E.AOA.E decrease according to the mean wind observed in order to alleviate

turbulence nuisance warnings

816
a_ - is an E.AOA E related to the observed vertical downward wind.

a, b, c, d, E.AOA.E's cannot be negative

b minus c cannot be negative

aW=a÷d+(b-c) ifa>0

This windshear warning mechanization is schematized on figure 11.

In areas I, IZ and III, E.AOA E's are computed but C ° is identical to AOA since a < 0 (no tail wind

shear)

CI" combines AOA and C,W

In area TV"when vertical wind becomes negative : d • 0

In area V C'W'increases when tailwind shear appears.

In that case WSW threshold is reached. It could have been reached in area IV ifvertical wind intensity

would have been higher. Similarly, it coulcl also have been reached in area V with tailwind shear

depending on shear intensity.

Simulator experience shows that short after lift off below 250 tt it is useful to trigger the WSW

according to the tail shearfor the case of a small margin regarding to 1,2 Vs. For clarification purpose,

this function is not shown on these figures but is should be reminded that from lift off to 250 ft WSW

can occur from (I "or from the _ branch only compared to a smaller threshold if Vc < 1,2 Vs + 5

Kt. v

6 - PERFORMANCE WARNING

6-1 - PERFORMANCE NUISANCE WARNING

We considered both take off and landing cases but we limit intentionna_ly here our evaluation to the

most disturbing case for air traffic and aircraft's utilisation :the lancling case

Nuisance warning probability by approach had _een evaluated _,ysimulating 5C0 automatic landings

in tower wind conclitions Ul:) to 40 Kts according to AC 20.57 A devices (automatic lancing

performance evaluation). Results are plotted figure 12.

Nuisance warning proi_aioility by approach is plotted for Airbus winc_st_ear warning and for t_e

conventional winclsnear warn=ng(properly filtered "SF" by a 4s tag retere0 in section 4)

We remzm_that a conventional winCshear warnir.g leads :¢ a nuisance !evel of 10"3per lancing with a

rec:mmanCecl thresneid of 0.; 3 g _r 2,5 K',S,sec. We also note that the Ai_us wmCsP,e_r warning

:e_cs :: a r:.u|sar:,ceieveict _,0.5 ;er tanding wsth,ts imr.,lememea threshoiC cf 11,5 =.it ;s interest:_gto

remora=or here that the US in serwce observed w=nc_st_ear;rcbaci;ity encounter iS dimout _0"6

817
6-2 - NORMAL PERFORMANCE WARNING

The Airbus WSW will alert the crew after an initial lossof longitudinalairspeed. The closerthe selected

airspeed to 1,3 Vs the smaller this initial loss before the warning is triggered (Figure 13),

Airbus WSW merely alerts the crew but has no activityon throttles or go around, the crew will decide

according to the situation to pursue or to abort when landing otto triggering max power or not at take

off.

a Floor protection is maintained onAirbus being the ultimate protection ifthe crew underestimates the

situation at WSW.

For a windshear encounter case the general situation of Airbus WSW and a FLOOR are plotted on

figure 14. One can notice the remaining energy margin at WSW and at a FLOOR.

In case the pilot wrongly selects too small a speed (1.25 Vs for example) the (ffFLOOR will in same

cases of shear conditions intervene before the warning itself.

7 - AIRBUS WSW AND GUIDANCE IMPLEMENTATION

Since WSW is implemented in each FAC, aural and visual warnings can be tested on ground engines

not running (Figure 15). In a case of shear encounter aural warning is activated and visual windshear

red message displayed on each PFD. Warning can be activated at take off from liftoff to 1000 ft and at

landing from 1000 ft to 50 ft the visual warning will remain for a minimum of 15 s.

The general architecture is given figure 16.

_. JII

818
8. A 320 IMPLEMENTATION

Aerospatidle and Airbus develop now very similar control laws for the A

320 taking advantage of managed speed "autothrottle" function for warning

and guidance in order to further decrease nuisance warning level and

increase safety in the escape manoeuvre initiation.

The A 320 system also takes advantage of the fly by wire concept for the

guidance part.

Fly by wire controls, if necessary, the plane into its maximum lift

capability in the final part of the escape while avoiding any stall

situation.

Certification is expected for 1989 in order to comply with the new FAA

regulation process.

819
1

SRS STRATEGIES

NO SHEAR CONDITIONS

2.

High thrust to

weight ratio

Low thrust to

weight ratio

• SRS controls pitch attitude

max _9 = 18 °

• Climbing slope = cte

• VC increases > V2 + 10 Kts

• SRS controls airspeed

VC = V2 + 10 Kts

(VC = V2 or VEF if VEF>V2) EF case

(Vertical speed > 2,4 % , ,9 < 18 °)

SHEAR CONDITIONS

3

4

Shear does not stress

aircraft capability

Strategy 1 or 2 will control AC

according to shear intensity

and thrust to weight ratio

Shear intensity

stresses aircraft

capability

Control strategy is self adapted to

AC flight parameters •

1 - VC = V2 + 10 Kts control (VZ"--.=0)!

2 - VZ ---0 control (VC"--=VSS + _3)

3-VC=VSS+_V control VZ<0)

i until shear decreases.

Figure2

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Figure 4

822
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CONTROLOFAIRCRAFT'SENERGY

Figure 6

824
A 3 I 0 S / F 20 / 20 150 000 KG 2 5

TAKE-OFF±ISA.SL

5O

20

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Vc

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LONGITUDINAL TAIL SHEAR

Figure 7

825 'uw.'_,'.'.'_::_,::.?,_.GE IS

OF POOR QUALITY
A3 10 - S/ F 2 0/ 2 0 150 000 KG 2 5%

TAKE-OFF ISA-SL

100 T.s

8d"

4O

(Vc - 100) Kt

3O

ft/lO

20

80

40

VOTERS

(Vc- !00) kt

z Ft/iO

VERTICAL DOWN WIND

Figure8

826
AIRBUS WSM SYSTEM TARGETS

Performance

- Detect 106 or < 10-6 simulated cases

- If no detection show the good behaviour of the aircraft

Nuisance

Warning due to active Failure

5.10-6/approach or take off

Lack of warning due to latent Failure

6.10-6/approach or take off

Performance nuisance warning

10-6/approach.

Figure 9

827
L_

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Figure 10

828
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829
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Figure 12

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831

OEtG;NAL PAGE IS

OF POOR QUALITY
I ii

L// /I

MEAN WEIGHT AND CG CASE TCC ON FCC CMD

CONSTANT SPEED APPROACH A300-600

TYPICAL MICROBURST

Figure 14

832
GROUND TEST

1 or 2 FAC ENGAGED

Engine not running, perform Lamp test

sPoi

m

i

]404

loo 

80 -d

OL_

1.5

LAND ICAT 3I FDI DUAL

%1

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\ =_T0oe

Io

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4*

0 0 ¢_ 0 0

...----" Windshear

--- wWindshear

"_ -'_- -- Windshear

Windshear encounter non clean config.

and (from take off to 1000 Ft

or from 1000 Ft to 50 R)

and WSW available

1 or 2 FAC ENGAGED

Aural • Windshear 3 times when WSW gets on either FAC 1 or 2.

Visual • Windshear red on both PFD when WSW gets on either FAC 1 or 2 until WSW condition gets

off both FAC 1 and 2 plus 15 s.

AUDIO AND VISUAL WSW

Figure 15

833
/

/

\ /

x /

,y

/\

/ \

\

\

Figure 16

I

834 "
Session II. Perspective

The "Windvan" Pulsed CO_ Doppler Lidar Wide-Area Wind Sensor

Rhidian Lawrence, Spectra-Technology

835
MOTE 

ND 

USING 

STEMS BY 

ECTRA 

CHNOLOGY 

THE "WINDVAN" PULSED C02 

DOPPLER LIDAR 

W I DE-AREA W I N D SENSOR 

837 
LIDARS FOR REMOTE WIND MEASUREMENT

LASERS TR SWITCH

RECEIVER

TELESCOPE/

SCANNER

TO

.-_.ATMOSPHERE

CONTROL

DOPPLER

PROCESSOR

OUTPUT

1 I

A Doppler lidar transmits a pulse of light into the atmosphere via a telescopescanner. The

Doppler-shifted collected light is photomixed with the light from a reference local oscillator

on the surface of a photodetector, which results in an electronic signal at the Doppler

frequency. The required optical beam switching is achieved by the Transmit Receive (TR)

switch. The frequency content of the RF signal is measured by the Doppler Processor and

normalized to yield the radial velocity of the target. A control computer directs the

operation of the lasers, scanner, processor and output devices.

COMPLETE MOBILE WIND MEASUREMENT SYSTEM DEMONSTRATED

BY NOAA/WPL

OTHER APPLICATIONS

• Doppler Laser Radar

• DIAL Measurements of Pollutant Concentration

SPECTRA TECHNOLOGY, INC. PROVIDES:

• Complete Integrated Systems

• Advanced Lasers

• Other Lidar Components

839
,. '.

PULSED CO 2 DOPPLER LIDAR SPECIFICATIONS

Listed are top-level hardware and performance specifications. A detailed set of specifications

reflecting your particular requirements will be provided on request.

LASERS: The transmitter laser is a 2 J per pulse, 50-Hz PRF injection-controlled TE laser

operating at 10.6 /_. Injection and local oscillator lasers are 5-W cw devices.

TELESCOPE/SCANNER: The transmlt/recelve telescope is a 0.30-rn diameter off-axls

Cassegraln. Beam scanning is accomplished by an AZ-EL mount to'achieve complete

hemispherical scanning. Scan pattern is programmable.

RECEIVER/TR SWITCH: Transport of transmit beam to the atmosphere, received beam

from the atmosphere to the detector and of the local oscillator to the detector achieved by a

ZnSe Brewster plate, ),/4-plate TR switch. Detector is thermoelectrically cooled.

DOPPLER PROCESSOR: Real time digital Doppler processing, Particular algorithms can

be tailored to customer requirements.

CONTROL: Total instrument control by a central computer.

OUTPUT: Per customer requirements. Options include hard copies of tabular and

graphical wind profiles, computer-controlled color displays and magnetic tape.

INSTALLATION: Per customer requirements, laboratory, mobile or airborne.

TIME FOR VERTICAL WIND PROFILE: 30 s

RANGE RESOLUTION: 150 m

MAXIMUM RADIAL WIND SPEED AND ACCURACY: *50 m/s.*0.3 m/s.

PRICE: Subject to your installation requirements. Spectra Technology would be pleased to

quote on your precise requirements.

PERFORMANCE EXPECTATIONS:

A CO 2 Doppler lidar is by its very nature a clear air device with limited propagation

capabilities through, e.g.. fog and clouds. In clear air conditions, the range of the device is

dependent on the prevailing atmospheric aerosol _ontent. Typically. the standard performance

model could be expected to achieve a range in excess of 25 km in the boundary layer and

routinely obtain wind profiles to 10 km altitude {i.e.. the troposphere).

EXTENDED PERFORMANCE MODEL:

For support of high value missions at long range and upper altitude an extended performance

version is recommended. Extended performance is achieved in several ways:

• Increased pulse energy and repetition rate (to 5 J and 100 Hz)

• Increased telescope aperture (to 1 m for 10 dB sensitivity gain)

• Isotopic gas mix (to minimize atmospheric absorption and increase aerosol

reflectivity)

Incorporation of all features results in a sensitivity increase of up to 34) dB. STI would be

pleased to quote on your precise requirements.

84O
WIND SENSING USING A DOPPLER LIDAR

Wind sensing using a Doppler.-Jidar is achieved by

sensing the Doppler content of narrow frequency

laser light backscattered by the ambient atmospheric DOPPLER LIDAR

aerosols. The derived radial wind components along

several directions are used to generate wind vectors,

typically using the Velocity Azimuth Display (VAD)

method described below. Rar_ge resolved information

is obtained by range gating the continuous scattered

return. For a CO 2 laser (10.6 /J) the Doppler

velocity scaling factor is 188 kHz/ms "1.

\ / 8E,M,os,o.o.<co<sc

\ _,/ v. = .,,,<a,w,nd<om.o...,

\-"/ :

k I Vh = horilonlal wind component

= Vt/2 sinp

=h = direction of horizontal

wind component

- III VAO Principle of Operation

• AEROSOLS

,.,,.'LWIND .. -_:..i:i':,_::,; :",_.:_'_.'_<:.._... .......! 4, ._.'...;.._,.....:.,. it .,

._::,.._._p,._::.,;-._,.,:_._ :,_:....

.._;,..'.OOPPLER-SH,_T

,.'_: " BACKSCATTERED ECHO

o.o_."

II/li ""

• i

CONCEPT ,':'"

PULSE OF COHERENT

.LASER RADIATION

In the VAD scan method the zenith angle of the

pointing direction is fixed and and its azimuth is

continuously varied through 2K. A spatially uniform

wind field at a particular altitude yields a sinusoldal

variation of the radial component vs. azimuth. The

amplitude, phase and DC component of this sinusoid

yield the horizontal wind speed, direction and vertical

component of the wind respectively. In a

nonuniform wind field the Fourier components of the

variation yields the required information.

..4

(/3

:E

E

.a¢

I.M

¢3

I--

p-

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<

12

11

10

g

8

7

6

5

4

3

2

°"

S 10 IS 20

iDOL= I

25 30 35 40

WINDSPEED m/sec

12

11

10

9

8

• O()Z RA 3//'6/84" T_Oj_._

o 75° VAD 15:49:33 MS -_.JE,.'1"--

1145 ° VAD 16:37:15 MST _'dl

--_,------

o45° VAD 15:53:02. MST _,_

.r_=

/

WIND DIRECTION DEGREES

An extensive series of measurements at the National Weather Service Forecast office at Stapleton

airport, Denver has demonstrated excellent agreement between Doppler lldar and Rawinsonde

outputs.

DATA: Courtesy National Oceanic and Atmospheric Administration/

Wave Propagation Laboratory

841
EXAMPLES OF DOPPLER LIDAR OUTPUT

(Courtesy of the National Oceanic and Atmospheric Administration/

Wave Propagation Laboratory)

In the PPI display at the right, the velocity in

each range-azimuth cell is color coded according

to the scale at the right. The green-blue scale

indicates flow toward the lidar (located at the

center) and the yellow-red scale flow away from

the lidar. This particular example indicates

west/north westerly flow. Range rings are at

10-kin intervals. Wind measurement to a range

approaching 25 km is indicated.

The dramatic feature at an azimuth of 280 = (as

shown in the photograph on the left) is the

outflow from a down burst. This phenomenon

when it occurs within the landing corridors at

airports can have catastrophic consequences.

The blacked out sector, toward the SSE, is due

to terrain blockage.

The photograph on the right shows scan and

processor flexibility, which allows tailoring of

output to unique requirements. In this example,

a raster scan at a range of 3.2 kin, down a

canyon, shows the nocturnal jet. Note the shear

that occurs at the plateau level above the

canyon.

842

OF POOR QUALITY
Session III. Topics

Low-Cost Airborne Lidar for Wind Shear

Loren D. Nelson, OPHIR

843
!0/14/8S

POlL t

I

PRESENTATION OUTLINE

• OVERVIEW OF PHASE H SBIR CONTRACT

• LIDAR NUMERICAL MODELING RESULTS

• OPHIR LIDAR DESIGN STUDY

• FIELD TESTING AND 1989 TDWR

• CONCLUSION

........ F

Loren D. Nelson, Ph.D., CCM

vice President

7333 West Jefferson Ave., Suite 210

Lakewood, Colorado 80235

Telephone: (303) 986-1512

R_ch and In_mmer4Blion k#r lhe _

_r_ _ ____ i_LA_:_( NOT FILMED

845
FOIL 2

PRIMARY PHASE II TECHNICAL OBJECTIVES

@ ENGINEERING DESIGN OF LIDAR SYSTEM

-- 95%

• CONSTRUCTION OF LIDAR SYSTEM

-- 50%

• LABORATORY TESTING FOR S/N,

HETERODYNE, AND DOPPLER

PERFORMANCE

-- 0%

INITIAL FIELD TESTING

-- 0%

• LARGE SCALE FIELD RESEARCH PROGRAM

-- 10%

• DATA ANALYSIS AND REPORTING

-- 0%

846
OPHIR LIDAR DESIGN

10/14/88

CHI_

FOIL 4

I

CW HETERODYNE SYSTEM

COMPONENT CHARACTERISTICS MANUFACTURER

LASER 5.6 W - 10.6 ttm Line Lite

TELESCOPE DAHL-KIRCHIN f-18 CUSTOM

OPTICS ZINC SELENIDE II-VI Corp

AO MODULATOR 27 MHZ IF Newport EO

DETECTOR HgCdTe BW=50 MHz New England

Res.

SIGNAL

PROCESSOR

HP Spectrum Analyzer HP

.......... F

I

i 847 i
_!-=-.

• I.| "

\

I0

__¢.t

,4

,,-,-lmdl-mrul848 OF POOR QUALITY
1.1 H ::

'] /tlt

¢ ,<.J t., i

J

=, t

i

849

°

ORIG;_,_AL PAGE IS

OF POOR QUALITY
I

Visibility _m)

!

I

100

G s 2o_ t

C. _ _600

_'_:. __..... _ _.<_. _.

850
10/14/118

GPl_

FOIL I0

I

CALIBRATIONTECHNIQUE

4"

TOP VIEV

mL-m_

I J W

SIDE VIEV

_ _Jrrnm

----r--s51

OR;C]_=_L PAGE IS

OF POOR QUALITY
100.00 200.00 300.00 400.00 500.00 600.00 700.00

Wheel Angular Velocity (RPM)

852
FIELD TESTING AND 1989 TDWR

FOIL 15

+

• DATES: MAY 15 - AUGUST 15, 1989

• LOCATION: DENVER STAPELTON AIRPORT

• PARTICIPANTS: NCAR, NOAA, UNIVERSITIES

-- FAA, NSF, DOC sponsorship

LLWAS, Doppler radars and surface networks from

NCAR and NOAA

• STATUS: FIRST DRAFT OF OPHIR FIELD

TEST PLAN COMPLETE

-- Coordination through Jim Moore of NCAR/RAP

I

853
FUTURE PLANS

POlL I '

4'

CONDUCT GROUND FIELD TESTS

• Stapleton Airport

• Summer, 1989

SEEK FOLLOW-ON FUNDING

• Airborne Field Tests

• Ground Long-Term Evaluation

• Interface and Optimization

m

I

854
Questions and Answers for All Sessions

855
Questions and Answers for All Sessions

(answer already in progress) the comparison between Mesonet and radar observations

and how those events break down in terms of strengths, I think they're referring to this

comparison where in the 1988 cases there were two events that which were seen by

a Mesonet which were missed by the radar and likewise, there were two events which

were seen by the radar and missed by the Mezenet. Going back and checked on the

strengths of those, both of these events which were missed by the radar were below

15 meters per second velocity differential and both of these events, also that were seen

by the radar but missed by the Mesonet were also very weak around 12 meters per

second.

Q: For the box with the matrix, where you've got both the 66 observations by the

Mesonet and by the radar, do you have any differentiation as for strength in those?

A." Yes, and those are basically the .. now you're asking what's the distribution of all

the microbursts that you saw between strong and weak? Is that right? And then,

most of the microbursts were seen by both the radar and the Mesonet.

OK, so it's 97 and 77.

A: No, no, these are how well they were detected, this is just saying that for the

stronger events, we detected 97% of them, for the weaker events, we detected 77%.

If you want to get an notion of the distribution, basically there were 259 out of this

sample, there were almost twice as many observations with strong events (.. goes over

15 Imps]) compared to those that were below. These two numbers here give you that

answer. This is showing ..

857

PI::_Ef;_-D[i_!_ p_ _!.._._ NOT FILMED
Q: Yea, I see that but how does the 66 come off of that table?

A: We're looking at two different sample sets. The 66 events are the total number

of microbursts. Each microburst event, each meteorological event counted once and

that's over the 2 months of July and August. Right, and those are only those that fell

within the region covered by both the Mesonet and the radar.

Well, then this chart is not pertinent to my question. Can we go back to the other

chart?

You're asking of these 66, how many were weak and strong?

Of these 66, how many of them were above 15 meters per second in their maximum

and how many of them of were below?

I don't have that number precisely, I would off hand guess roughly half were below

and half were above.

Because earlier today, we heard .. not necessarily today but in the meeting, we heard

some discussion about these weak ones, they can crash some airplanes too and from

the beginning it was obvious that TDWR was going to do very well on the real strong

ones but I would like to know what that split is on those 66 in terms of those that

went above 15 meters per second and those that never went above.

Yes, I can answer that question for you off line, ! think that relates a little bit to Fred

Proctor's other question which is as you change the definition threshold for velocity

differential, how do the statistics change between the numbers of dry versus wet

microbursts and I think that's a little bit related to your question Norm. In general,

looking over the last several years, our observations and looking at the distributions

of strengths of microbursts, you see something like an exponential decaying distribution

858
so that the number of microbursts versus strength. We generally keep track of

microbursts down to the threshold of roughly 10 meters per second and you've seen

thousandsof microbursts, I shouldn't say thousands,at least a thousand microbursts

between 10 and 12 meters per secondvelocity differential. So far, I think we've only

seen two microbursts with a velocity differential rate of 40 meters per second so

there's a very rapid taper and as you raise that threshold Delta V for windshear,

you're willing to accept as a microburst, you're number of events drops off rapidly.

There have been a number of studies looking at a correlation between surface

reflectivity and strength, basicallyyou seeno correlation at all. Whatever ratio a dry

to wet microburst, which is very regionally dependent, the delta V threshold doesn't

appear to make any difference. We haven't seen any correlation between outflow

strength and surface reflectivity level. Does that answeryour question Fred?

Fred Proctor Q: Have you actually looked at the numbers, I mean gone through and

done the statistics on that? A" Both in the JAWS report and in our studies from last

year and this year in Denver, we looked at scattergrams trying to look for a

relationship between surface reflectivity and outflow intensity. Basically, there's no

correlation whatsoever. Q: How about in other parts of the country? Have you

looked at this yet? A: We have observations from Memphis and Huntsville in

Alabama and I think that in the two ye_lrsof observations we made there, I can't

remember if we sawone or two microburstswhich were classifiedas dry. It's certainly

not enough to draw any conclusionsabout correlation of strengthwidth, essentiallywe

saw none in the southeast,and as we go to other parts of the country, Kansas City

and wherever we go from there, that's certainly a studythat we're interested in but the

extent that we've seenlow reflectivity microbursts,I'm not aware of anyonewho's been

able to seethe slightest hint of correlation between their strength and their intensity

in reflectivity research.

859
There were some questions that didn't get typed up, which I perhaps can try and go

through very quickly. The first question is what kind of false alarm break do you feel

to be expectedfor the 6 minute precursor alarm. A: That's an area that hasn't been

looked at very carefully. What we do know is that when we see precursors we see

them several minutes in advance of surface outflow. In terms of taking a setting and

saying, how often do you see these same precursors and you've not seen microbursts.

I'd say that's something we haven't looked at very carefully and certainly the false

alarm rate there is the big thing to be concerned about and I'm afraid I'd be loafed

to judge any kind of statistic to that, that's something that we're just beginning to look

at.

Second is, "what's your opinion about how good the truth is that you compare your

microburst detected by TDWR?"

A" The answer to that is pretty good. In most of these cases, as I mentioned, a

tremendous amount of effort has gone into the development of this ground truth data

base and for several years, we've been going though the processes of developing single

doppler ground truth, that is where experienced people, I mean these are people who

have been doing this for several years, look at the same radar data that's used by the

algorithms, trying to identify where microbursts exist. That's an intermittent process

that get's looked at several times, it gets, refined and corrected. The process that

people from NCAR are now involved with is looking at dual doppler information,

trying to identify ground truth, it's a good deal more objective and should result in

even higher quality ground truth. Assuring quality of that data is something, and as

I mentioned put a very high priority on it and we have a lot of confidence in it. Third

question is are there precursor programs available to be shared with this community?

Yes, in a sense that these algorithms are documented and in fact, part of the Terminal

Doppler Weather Radar System Specification. In fact, that's another part of the

program which has taken up a lot of the effort: formally documenting these

860
algorithms so that they can be implemented by the system contractors. The actual

software implementations that we useto compute thesein the test bed, are in a sense,

available in that it would certainly be possible to make arrangements to use those if

there was someone who was really interested in that. The last question is, do you

have additional source field of reflectivity to improve microburst simulation models?

I'm not sure exactlywhat that means. One of the difficulties we have is .. excuseme,

I think the question he was asking to model the dust and other things that are in the

simulation other than moisture, didn't he mention dust and something else in there ..

yes, if additional source field of reflectivity dust and bugs .. I think that he meant to

add to the reflectivity information the backscatterlevels from bugs and dust. If the

question is, "if we try to figure out what contribution those sources would make

towards reflectivity," the answer is no.

I would like to add that those questionswere submitted by Cliff Schroederof NASA

Langley and he gave them to me, Bracalenteof NASA, so that it gets into the record.

I didn't speak until I had the microphone. Spady is training me. Wayne Sand had

a number of questions but he had fixed outbound. He will get in touch with the

l_eople personally and then give us copies,of the answers. Our last set of questions is

from Mssr. Bonnefay and then we will close.

I have two questions, one/?/one/.9/. Can I start by the/?/. Mr. Bonnefay, that's me.

Is a copy of your presentation available? Yes, it is. I gave a copy to Herb

Schlickermaier yesterday and in this paper, there is not only a presentation of the

guidance but of the wind shear warning and also on wind shear guidance. The second

question, the /.9/one is that one from Mr. Gaines, that's interesting. The direction

change is not really apparent, what is the source of the wind shear warning. I thank

861
you for that question because I consider that it was not at all apparent I switched from

the wind shear warning itself due to the time schedule but I can show you a

viewgraph .. lights out .. this is the principal wind shear warning computation. It's not

a warning taking into account separating factual or how is that a factor. It's a warning

taking into account of the aircraft present energy from the angle of attack which is the

best evaluation of your present energy taking into account sure of the setup and flaps

position and considering the angle of attack would increase the angle of attack by

several equivalent angle of attack estimated coming from the longitudinal wind derived

source longitudinal shear from the memorized head wind increase before the shear

appears it's a little bit predictive. Decreased by the min wind speed, equivalent angle

of attack this is to decrease nuisance warning due to turbulence and wind creates also

the general angle of attack by any equivalent angle of attack due to the vertical wind

combining also those values we can have an efficient wind shear warning which is not

related only to the wind itself. The main result in my finding is that we reach a very

low level of nuisance warning compared to a simple measurement of the separating

factor or the F factor, or the "SF" factor. You have here a comparison between a

conventional wind shear warning nuisance performance warning and zero burst wind

shear warning. We used for search and evaluation the AC 2057A wind model and we

simulated more on the 500 simulation and on the left you have the level of warning

appeared using a conventional system using F factor evaluation and on the right you

have the nuisance warning level reached by the airbus wind shear warning. You can

see on one side 10 to the minus 3 on the other side 10 to the minus 6. It was the

goal which intended to reach because 10 to the minus 6 could be approximate activity,

the wind shear and contour probability. But I can speak longer and longer on the

warning, but see it fit here to stop.

Mr. Bonnefay, have you demonstrated that kind of nuisance performance? Have you

demonstrated it for flight tests? I didn't mean you have to do 10 to 6 cycles .. A: I

862
don't have enough experience in flight for/?/but I can confirm this result. Q: Does

your early data suggest that you will meet that 10 to the minus 6? A: I hope it will

meet but if I don't meet 10 to the minus 6 with such a device I wonder what would

be the level of nuisance warning reached by the left system using just an F factor. It

could be greater for airbus but it will be greater for the other. Something that is

interesting considering just the AC 2057 A model because I reached using this model

the nuisance warning of 10 to the minus 3. If I remember well, Roland, last year you

demonstrate using a very different model or a very different way to the same level and

if I remember also, in Boeing's studies we can consider that the possibility of reaching

a level of 1.2 G is about 10 to the minus 3 also. So, if you are confident with the left

part of this sheet I supposed that we have to also be confident with the right part of

the sheet. Perhaps.

One other questions I would like to ask is have you made any comparison to your

system with an F factor, for instance? Can you give us a comparison to the nuisance

warning we can expect. A: I supposed the answer is in the attached sheet, but it's

difficult to have a good wind and accurate wind modelization for a precise level of

nuisance warning. So I consider the AC 2057 A wind model, why did I consider that

model. It's just because we use it generally for landing or to landing the most

efficient. It's not certain the very accurate sate model. It's not perhaps a very realistic

model but it is a model and I can compare one system and also the system being a

commonly agreed wind shear wind turbulence model. It's what we did and if FAA or

NASA develop a new wind turbulence model it could be interesting to do exactly the

same job using more realistic wind turbulence simulation in order to see if there is

different level of wind shear warning and if we maintain the 10 to the minus 3

difference between an F factor system and an airbus wind shear warning system. We

will do one in the future if the wind shear turbulence model is available.

863
J

Q: There's really no G threshold equivalent to your system? A: It could be, but

look for/?/equivalent, you must have a detection at .24 G, that's to say that when yo u

detect it's really a little bit too late.

Q: Do you have equivalent data to this that shows the probability of a missed alert

with the two different systems? A: About missed alert, I have no probability, what

we demonstrate is that if we don't have an alert the plane can land safely or can go

on the takeoff safely. All we detect and we have to oblige a normal procedure. Or

we don't detect and we have to demonstrate that we can land safely or go on the

takeoff safely but I don't know the possibility to reaching at deliver of those nondetection possibility of an opposite rating. Perhaps you have one.

Q: Maybe I should ask the question a different way? Do you have a feel for what

the difference in relative timings of the alert are between the two system of how

quickly your system will alert the time delay as compared to the conventional system?

A: Yes, it's extremely difficult to report to answer that question due to fact that we

consider the angle of attack, angle of attack represents the present situation of the

plane and if you are in a very low energy situation, if you are flying at 1.3 V-Stall

landing, you will have a very fast warning. It's about the same and sometimes quicker

than the F system. If you are flying 1.5 V-Stall in that case the F system could warn

earlier than airbus system, but if you are flying 1.4 or 1.5 V-Stall, you have a strong

energy margin and you can wait for just a little while in order to prevent false warning

or nuisance warning, so consider if your level of energy is slow because you fly 1.3

V-Stall or perhaps lower because there is an error, you will be warned very soon and

if you have a very high level of energy, you will be warned later than the F system.

This is Howard Long with Delta. Does your system in any way provide you with a

warning on a positive energy shear? A: No. Q: Have you made analysis of of that

864
as compared with the number of wind shears? A: We consider that it was not

absolutely necessary because our plane, our protection devices outflow forward

function, and your outflow forward function, alreadymade protection, if we don't have

the outflow forward function, certainly that we had implemented the alert on the

increaseinertia differ. But, due to the fact that it's perhaps not very good to increase

the number of warnings in the cockpit, we prefer to develop only the red warning,

taking into account there is a after/?! protection with the outflow forward function.

Q: If that information is available, don't you think it could be provided to the pilot?

Q: If you've got the equipment on the airplane that's capable with providing the pilot

with a positive shear data, that is, that you are in a significant increasingperformance

shear, shouldn't that information be available to pilots?

A: Yes, it is, considering the preliminary flight display where you have your speed

scan,your speed also and you can compare your speed answer,nominal 1.3with stall

speedor 1.2 so,you know you are increasingstrongly your speedand adjusting looking

between your speed and your back speed exit. You have it all the time.

Q: Now did I understand from one slide that you already have this system certified?

A: Yes, this systemwas certified last year for the A300 aircraft and certified as the

A310 aircraft sinceApril 1988and it will be certified before the A310 next month and

delivery at the beginning of 1989 and we intend to certify very similar systemmainly

for the warning for the 320 next year for delivery at the end of the year, something

like that.

Just quickly, I might point out that the Boeing systemis also being changedto account

for higher energy levels above the 1.3 V-Stall. We agree, it's a good idea.

865
APPENDIXES

Appendix A. Agenda

Appendix B. List of Attendees

_ =*,:_._.L_;_.,_':_,_,,-' E_L_.._ _,,OI FILMED
APPENDIX A

SECOND COMBINED MANUFACTURERS'

AND TECHNOLOGY AIRBORNE WIND

SHEAR REVIEW MEETING

-AgendaTUESDAY, 18 October 1988

7:45 Registration

8:45 Introduction of Guest Speaker

Herbert Schlickenmaier, FAA

9:00 Welcome

Dav/d Johnson, FAA

9:25 Logistics

Amos Spady, NASA LaRC

SESSION I AIRBORNE - TERMS OF REFERENCE

9:30 Meeting Goals, Session Introduction

Roland Bowles, NASA LaRC

9:45 Tools of the Trade

Wall)" Gillman, American Airlines

10:05 SAE-S7 Wind Shear ARP

Bob Ireland, United Airlines

10:25 Break

10:45 Wind Shear Regulatory Activities

Steve Morrision, FAA

11:05 Flight Experience with Wind Shear Detection

Terry Zweifiel, Honeywell/Sperry

II:25

11:45

Interface Standards for Integrated Predictive/Reactive WindShear Systems

Mark McGlinchey, Honeywell/Sperry

Lunch

869
SESSION II

12:45

12:50

1:10

1:30

1:50

2:10

2:30

3:20

AIRBORNE - IIAZARD DEFINITION

Session Introduction

Amos Spady, NASA LaRC

Heavy Rain Effects on Airplane Performance

Earl Dunham, NASA LaRC

Small Aircraft Performance in Wind Shear

Dick Bray, NASA ARC

11 July, Weather and Resulting TDWR Alarms

Wayne Sand, NCAR

Numerical Simulation of 11 July, Denver Microburst Storm

Fred Procter, MESO

Break

11 July, Denver Wind Shear Encounters

Bob Ireland, United Airlines

Questions and Answers for 18 October sessions

870
WEDNESDAY, 19 October 1988

8:00 Registration

9:15

10:05

10:30

10:45

11:05

11:25

11:45

12:45

SESSION I AIRBORNE. SENSORS

8:30 Session Introduction

Roland Bowles, NASA I.aRC

8:40 Wind Shear Radar Status Review and introduction

E. M. Bracalente, NASA LaRC

8:50 Analysis of Synthetic Aperture Radar (SAR) Data for Wind Shear Radar

S. Harrah, NASA LaRC, V. Deinore, Kentron, and

D. Gineris, ERIM

Preliminary Airborne Wind Shear Detection Radar Assessment Study

C.. L. Britt, RTI, and E. M. Bracalente, NASA LaRC

9:50 Clutter Filter Design Considerations for Airborne Wind Shear

E. Baxa and A. Mackenzie, NASA I.aRC

Airborne Radar Scatterometer Design & Flight Tests

Bill Jones and C.arrol Lyric, NASA I.aRC

Break

Status of IR System Tests

Fat Adamson, TPS

Status of Delco/Hughes IR Efforts

Brian Gallagher, Delco/Hughes

IR Thermal Imaging of Atmospheric Turbulence

Bill Pfeil, Kollsman

Lunch

Investigation of Airborne Lidar for Avoidance of Wind Shear Hazards

Russell Targ, Lockheed

1:05 2.1 Micron Lidar Technology Program Status

Mark Storm, NASA I.aRC

SESSION II AIRBORNE - FLIGHT MANAGEMENT

1:25 Session Introduction

Roland Bowles, NASA LaRC

1:40 Alert Filtering and Time Constants

Kioumars Najmabadi, Boeing

871
2:00

2:20

2:40

3:00

3:20

3:40

4:00

4:15

4:30

Hight Guidance Research

Dave I4_inton, NASA LaRC

Break

Analysis of Guidance Law Performance Using PC Models

Rene Barrios, Honeywell/Sperry

FLight Deck Research

Dave Carbaugh, Boeing

An Expert System for Wind Shear Avoidance

Robert Stengel, Princeton

Effect of Wind Shear During Takeoff Roll on Stopping Distance

Terry Zweifiel, Honeywell/Sperry

Wind Shear Wind Model Simulator Analysis Status

Bernard Ades, DGAC/SFACT/TV

wiad Shear Predictive Detector Technology Study Status

C., Gandolfi, DGACdSTNA/3

Question and Answer Session for 19 October

872
THURSDAY, 20 October 1988

SESSION I GROUND SYSTEMS

8:30

8:40

9:00

9:20

9:40

10:00

10:20

10:40

11:00

11:20

11:40

12:50

1:00

2:00

2:50

3:00

Session Introduction

Herbert Schlickenmaier, FAA

TDWR Program Status

Art Hansen, FAA

LLWAS Program Status

Craig Goff, FAA

1988 TDWR Operational Demonstration in Denver

John McCarthy, NCAR

F-FactorConcept Appliedto SurfaceMeasurements

Wayne Sand,NCAR

Break

Summer' 88 TDWR M/croburstAnalysis

Mark Merritt, Lincoln Labs

Automatic Detection of Low Altitude Wind Shear Related Gust Fronts

Diana Klinge-Wilson, Lincoln Labs

Sam Saint's Five Minutes

Sam Saint, Safe Flight

Lessons Learned

William Laynor, NTSB

Lunch

Introduction of Session

Amos Spady, NASA LaRC

Ten Minute Presentations by those requesting time not available on the

program schedule

Questions and Answers for all sessions

Closing Remarks

Herbert Schlickenmaier, FAA

Roland Bowles, NASA LaRC

Conference Closed

873
APPENDIX B

SECOND COMBINED MANUFACTURERS' AND TECHNOLOGY

AIRBORNE WIND SHEAR REVIEW MEETING

18-20 OCTOBER 1988

List of Attendees

Mr. H. Adamson

Turbulence Prediction Systems

4876 Sterling Drive

Boulder, CO 80301

303/443-8157

Mr. Bernard Ades

DGAC/CFACT/TU

246 rue Lecourbe

75732

Paris France, 75732

Mr. Orville Alitz

Rockwell-International

400 Collins Road

MS 124-111

Cedar Rapids, IA 52498

319/395-3885

Dr. Willard Anderson

NASA Langley Research Center

Chief, GCD

Hampton, VA 23665

804/865-3049

Mr. Charles Anderson

Boeing Chemical Airplanes

M/S 96-06

Box 3707

Seattle, WA 98124-2207

206/237-7281

Dr. E. Arman

FWG Associates, Inc

217 Lakewood Dr

Tullahoma, TN 37388

615/455-1982

Mr. Robert Avjian

Martin Marietta

MS DC 6320

475 School St S.W.

Washington, DC 20024

202/646-5446

Mr. J. Barrios

Honeywell

P.O. Box 21111

Phoenix, AZ 85036-1111

602/869-1584

Mr. C. Bateman

Sundstrand Data Control

Overlake Industrial Park

P. O. Box 97001

Remond, WA 98073

Prof. Ernest Baxa

Clemson University

Electrical and Computer Eng'r

Clemson, SC 29634

803/656-5901

Mr. Rod Benoist

Litton Aero Products

6101 Condor Drive

Moorpark,, CA 93021

Ms. Gaudy Bezos

NASA Langley Research Center

MS 286

Hampton, VA 23665

Dr. David Bjorndahl

Litton Aero Products

6101 Condor Dr

Moo_park, CA 93021

805/378-2004

Mr. Jean-Louis Bonafe

Aerospatiale A/DET/SY

316, Route de Royonne 31

31060

Toulouse,

33 61 93.58.06

875

F,_i,SCZ_Z_ T,I_S LLA_,_ _OT FILMED
Dr. Roland Bowles

NASA Langley Research Center

Vehicle Operations Research Br.

Building 1168, MS 156A

Hampton, VA 23665

804/865-3621

Mr. Emedio Bracalente

NASA Langley Research Center

Building 1299, MS 490

Hampton, VA 23665

804/865-3631

Mr. Richard Bray

NASA Ames Research Center

MS 211-2

Moffett Field, CA 94035

415/694-6002

Dr. Charles Britt

Research Triangle Institute

NASA Langley Research Center

Hampton, VA 23665

804/865-3631

Prof. Gary Brown

VPI & SU

Dept. of Electrical Engineering

Blacksburg, VA 24061

703/961-4467

Mr. Gabe Bruno

Federal Aviation Administration

FAA/AFS-820

800 Independence Ave, SW

Washington, DC 20591

202/267-3830

Mr. James Bull

Boeing Electronics

MS 7J-65

P. O. Box 24969

Seattle, WA 98124

Dr. chris Busch

Spectron Development Laboratories

3535 Hyland Ave, Suite 102

Costa Mesa, CA 92626-1439

714/549-8477

Mr. Bryan Campbell

NASA Langley Research Center

MS 286

Hampton, VA 23665

Mr. Dave Carbaugh

Boeing Commercial Airplane Company

P.O. Box 3707

MS 66-25

Seattle, WA 98124

206/237-7286

Dr. Nee-Yin Chou

Science and Technology Corp

i01 Research Dr

Hampton, VA 23666

804/865-3761

Mr. Myron Clark

Federal Aviation Administration

FAA/AFS-210

800 Independence Ave, S.W.

Washington, DC 20591

202/267-3730

CPT Jay Clauzel

Douglas Aircraft Company

3855 Lakewood Boulevard

Long Beach, CA 90846

213/593-3886

Mr. Patrick Clyne

Airline Pilots Association

34 W. Minnehaha Parkway

Minneapolis, MN 55415

612/822-1009

876
Mr. Walter Coleman

Air Transport Association

1709 New York Ave., N-W

Washington,, DC 20006

Mr. J. Connelley

Raytheon

P.O. Box 5-1-631

528 Boston Post Road

Sudbury, MA 01776

617/440-4375

Mr. Stephane Corcos

SFACT/FF

246 rue Lecourbe

Cedex i

75732 Paris,

Mr. Ron Crabill

Federal Aviation Administration

FAA/ATO-324

800 Independence Ave, SW

Washington, DC 20591

202/267-9337

Mr. Norman Crabill

Aero Space Consultants

105 Inland View Dr

Newport News, VA 23603-1431

804/887-9339

Mrs. Lucille Crittenden

NASA/Langley Research Center

Hampton, VA 23665

804/865-3631

Mr. Willie Davis

Clemson University

Riggs Hall

Clemson, SC 29632

Mr. Vic Delnore

PRC Kentron, Inc.

NASA Langley Research Center

MS 490

Hampton, VA 23665

804/865-3631

Mr. John Diamond

NASA Langley Research Center

MS 471

Hampton, VA 23665

Mr. Don Dixon

Dixon Associates

1880 Dairy Ashford

Suite 107

Houston, TX 77077

713/558-1808

Mr. Earl Dunham

NASA Langley Research Center

Hampton, VA 23655

Mr. James Dzuik

Feder_l Aviation Administration

800 Independence Ave., SW

Washington, DC 20591

Mr. Carl Erickson

Boeing Commercial Airplane Company

P.O. Box 3707

MS 47-31

Seattle, WA 98124

206/655-8224

Mr. James Evans

MIT Lincoln Labs

Room HW-10

P. O. Box 73

Lexington, MA 02173

877
Mr. C. Gale

American Airlines, Inc.

M&E Center M_D #208

P.O. Box 582809

Tulsa, OK 74158

918/832-2188

Dr. Brian Gallagher

Delco Systems Operations

MS I421

P.O. Box 471

Milwaukee, WI 53201

414/768-2132

Ms. Catherine Gandolfi

STNA/3EC

246 rue Lecourbe

75045 Paris

France, 750ASParis

40-43-89-49

Mr. Hubert Gentou

Remtech

1044 Towne Circle

Congrant, CO 80501

Mr. Wally Gillman

American Airlines

P.O. Box 619617

DFW Airport

Dallas, TX 75261

817/355-5153

Mr. Craig Goff

Federal Aviation Administration

FAA/APS-550

800 Independence Ave, SWWashington, DC 20591

202/267-8547

Mr. David Gollings

FAA Atlanta

Aircraft Certification Program

1669 Phoenix Parkway

Atlanta, GA 30349

Mr. Donald Groot

Data Transformation Corp

FAATechnical Center

Atlantic City Int'l Airport, NJ 0840_

609/484-5366

Mr. Gregory Haeffele

Boeing Commercial Airplane Company

Windshear Studies;M/S 7K-02

P.O. Box 3707

Seattle, WA 98124-2207

206/865-6425

Mr. Robert Hall

Air Line Pilots Association

Engrg and Air Safety Department

P.O. Box 1169

Herdon, VA 22070

703/689-4205

Mr. Dick Hansen

Flight Dynamics

16600 Southwest 72nd Ave

Portland, OR 97223

503/684-5384

Mr. Arthur Hansen

Federal Aviation Administration

800 Independence Ave., SW

Washington,, DC 20002

Mr. Rolf Hansen

Boeing Commerical Airplanes

MS 6L-25

P. O. Box 3707

Seattle, WA 98124-2207

Dr. Robert Hess

NASA Langley Research Center

MS 468

Hampton, VA 23665

804/865-2818

878
Mr. David Hinton

NASA Langley Research Center

Vehicle Operations Research Br.

Building 1168, MS 156A

Hampton, VA 23665

804/865-3621

Mr. Robert Ireland

United Airlines Flight Center

Stapleton Int'l Airport

Denver, CO 80207

303/398-4553

Mr. David Johnson

Federal Aviation Administration

FAA/ADS-I

800 Independence Ave, SW

Washington, DC 20591

202/267-3557

Mr. William Jones

NASA Langley Research Center

AMRB

Hampton, VA 23665

804/865-3631

Dr. Wayne Keene

Raytheon

MS IK9

528 Boston Post Road

Sudbury, MA 01776

Mr. Bruce Kendall

NASA Langley Research Center

MS 490

Hampton, VA 23665

Ms. Diana Klinge-Wilson

Lincoln Laboratory

P.O. Box 73

244 Wood St.

Lexington, MA 02173

Mr. Michael Krause

Ratheon

528 Boston Post Road

Sudbury, MA 01776

Dr. Rhidian Lawrence

Spectra Technology, Inc

2755 Northup Way

Bellevue, WA 98004

206/827-0460

Mr. William Laynor

National Transportation Safety Board

800 Independence Ave, SW

Washington, DC 20594

202/382-6610

Dr. Alfred Lee

NASA Ames Research Center

Aero Human Factors Research Div

Moffett Field, CA 94560

415/694-6908

CPT Howard Long

Delta Airlines, Inc.

Operations Center

Hartsfield Atlanta Int'l Airport

Atlanta, GA 30320

404/765-4084

Ms. Carroll Lytle

NASA Langley Research Center

AMRB

Hampton, VA 23665

804/865-3631

Mr. Neil MacDonald

British Technology Group

Suite 1145

National Press Building

Washington, DC 20045

202/331-7858

879
Mr. W. Mace

PRC-Kentron

303 Butler Farm Road

Hampton, VA 23666

Ms. Anne Mackenzie

NASA Langley Research Center

AMRB

Mail Stop 490

Hampton, VA 23665

804/865-3631

Mr. James Magef

North West Airlines

Minneapolis St. Paul Airport

F7400

Minneapolis, MN 55111

612/726-8555

Dr. Burnell McKissick

NASA Langley Research Center

MS 156A

Hampton, VA 23665

804/865-3621

Mr. W. Melson

NASA Goddard Space Flight Center

Wallops Flight Facility

Wallops Island, VA 23337

804/824-1306

Mr. Mark Merritt

MIT Lincoln Laboratory

P.O. Box 73

244 Wood Street

Lexington, MA 02173

617/863-5500

Mr. Charles Miyake

Spectra Technology, Inc

2755 Northup Way

Bellevue, WA 98004

206/827-0460

Ms. Rosemary Macedo

SELF Corp

12944 Winthrop Ave.

Granada Hills, CA 91344

818/997-3636

Mr. Manjit Madar

Honeywell, Inc.

Manager, Products Planning

Box 21111

Phoenix, AZ 85036

602/869-6324

Dr. I. McClur

MS 7J04

P. O. Box 24969

Seattle, WA 98124-6269

Mr. Mark Mcglinchey

Honeywell

P.O. Box 21111

Phoenix, AZ 85036-1111

602/869-2664

Mr. William Melvin

Airline Pilots Association

ii01 W. Morton

Denison, TX 75020

703/689-4205

Mr. Ernest Millen

Chancelwyn Research

12909 Red Chestnut Dr

Midlothian, VA 23112

804/744-i174

Mr. Samuel Morello

NASA Langley Research Center

MS 153

Hampton, VA 23665

804/865-3953

880
Mr. Stephen Morrison

Federal Aviation Administration

800 Independence Ave, SW

Washington, DC 20591

202/267-3736

Mr. Tomas Murphy

RJO Enterprises, Inc.

4500 Forbes Boulevard

Lanham, MD 20706

301/731-9746

Mr. Kioumars Najmabadi

Boeing Commercial Airplane Company

P.O. Box 3707

MS 9W-38

Seattle, WA 98124

206/277-4280

Dr. Loren Nelson

OPHIR Corporation

7333 W. Jefferson

Suite 210

Lakewood, CO 80235

303/986-1512

Ms. Rosa Oseguera

NASA Langley Research Center

MS 156A

Hampton, VA 23665

804/865-3621

Mr. Robert Otto

Dept 97-01 Bldg 201

3251 Hanover Street

Palo Alto, CA 94304

Ms. Jen Pao

Vigyan Research Associates, Inc.

30 Research Drive

Hampton, VA 23669

Mr. Bill Pfeil

Kollsman

220 SW Highway

Merrimak, NH 03054

Mr. Greg Piesinger

Honeywell, Inc.

Sperry Comm Fit Sys Grp/MS 51EAV

5353 West Bell Road

Glendale, AZ 85308

602/863-4666

Mrs. Marie-Claude Pomery

Airbus Industrie

i Round Point M. Bellonte

31707 Blangnac,

Prof David Powell

Aero/Astro Department

Stanford University

Stanford, CT 94305

Dr. Fred Proctor

MESO, Inc.

28 Research Drive

Hampton, VA 23666

804/865-7800

Mr. William Rahr

Sundstrand Data Control

Overlake Industrial Park

P. O. Box 97001

Redmond, WA 98073

Mr. John Reed

FAATechnical Center

FAA/ACT-340

Atlantic City A/P, NJ 08405

609/484-4135

881
Ms. Anna Rivas

NASA Langley Research Center

MS 286

Hampton, VA 23665

Mr. Phillip Rogers

SELF Corporation

12944 Winthrop Ave.

Granada Hills, CA 91344

818/997-3636

Mr. L. Roberts

Douglas Aircraft Company

3855 Lakewood Boulevard

Building 202-29

Long Beach, CA 90846

213/593-3296

Mr. Robert Roll

Lockheed Missiles & Space Co.

3251 Hanover Street

Palo Alto, CA 94304

Mr. Lester Rose

NASA Langley Research Center

MS 139A

Hampton, VA 23665

Mr. Sam Saint

Safe Flight Instrument Corporation

Shelter Harbor

Westerly, RI 02891

401/322-7505

Mr. Greg Salottolo

National Transportation Safety Board

Washington, DC 20594

Mr. Herbert Schlickenmaier

Federal Aviation Administration

FAA/ADS-210, Room 727

800 Independence Ave, SW

Washington, DC 20591

202/267-8530

Dr. Wayne Sand

National Center for Atmospheric Res

P.O. Box 3000

Boulder, CO 80307

303/497-8654

Mr. Lyle Schroeder

NASA Langley Research Center

AMR

Hampton, VA 23665

804/865-3631

Mr. Nigel Slack

British Aerospace PLC

Hatfield

Hertfordshire, ALl0 9TL

62345 x.3643

Mr. Glenn Smythe

Data Transformation Corp

FAATechnical Center

Atlantic City Int'l Airport, NJ 08405

609/484-4032

Mr. Amos Spady

NASA Langley Research Center

Mail Stop 156A

Hampton, VA 23665

804/865-3917

Dr. Leo Staton

NASA Langley Research Center

MS 490

Hampton, VA 23665

804/865-3631

Mr. George Steinmetz

NASA Langley Research Center

MS 156A

Hampton, VA 23665

804/865-3621

Prof Robert Stengel

Princeton University

D-202 Engineering Quadrangle

Princeton, NJ 08544

609/452-5103

882
Mr. Benjamin Stevens, Jr.

M.I.T. Lincoln Lab

P.O. Box 73

Lexington, MA 02173

617/981-4566

Mr. Raymond Stoer

FAA Northwest Mountain Region

17900 Pacific Highway South

C-68966

Seattle, WA 98168

206/431-2117

Mr. Mark Storm

NASA Langley Research Center

MS 474

Hampton, VA 23665

Mr. D.A. Stratton

Princeton University

D-202 Engineering Quadrangle

Princeton, NJ 08544

609/452-5103

Mr. Russell Targ

Lockheed

Department 9701

3251 Hanover Street

Palo Alto, CA 94304

415/424-2436

Ms. Barbara Townsend

NASA Ames Research Center

MS257-I

Moffett Field, CA 94040

Mr. Jean-Claude Valentin

STNA/3EC

246 rue Lecourbe

750A5

Paris France, 750A5

Mr. Dan Vicroy

NASA Langley Research Center

Vehicle Operations Research Br.

Building 1168, MS 156A

Hampton, VA 23665

804/865-3621

Prof. David Watt

U. of New Hampshire

Dept of Mechanical Engineering

Kingsbury Hall

Durham, NH 03824

603/862-2555

Mr. James Wieler

Raytheon Company

MS 5-1-631

528 Boston Post Rd

Sudbury, MA 01776

508/440-4389

Dr. Leonard Winchester

Science and Technology Corp

I01 Research Drive

Hampton, VA 23666

804/865-0467

Mr. Joe Youssefi

Honeywell, Sperry

Box 21111

Phoenix, AZ 85027

602/869-1557

Mr. Allan Zuckerwar

NASA Langley Research Center

MS 238

Hampton,, VA 23665

Mr. Terry Zweifil

Honeywell, Sperry

Box 21111

Phoenix, AZ 85027

602/869-2979

883
Report Documentation Page

1. Rel>or_ No.

NASA CP-10050, Part 2

2. Government Acces_on No.

4. _fle and Sub_tte

Airborne Wind Shear Detection and Warning Systems -

Second Combined Manufacturers' and Technologists'

Conference

7. Aumo_s)

Amos A. Spady, Jr., Roland L. Bowles,

and Herbert Schlickenmaier, compilers

g. Pa_orming Organization Name and Address

NASA Langley Research Center

Hampton, VA 23665-5225

12. S_r_o_ingAgencyNamea_ Addr--,=.s

National Aeronautics and Space Administration

Washington, DC 20546

3. RtciDmnt'= Catalog No.

8. Pe#oem_ Otgan_mo. Code

8. Performing 0rgan,-,,t_on Report No.

10. Wod¢ Unit No.

505-67-41-54

11. Contract or Grant No.

13. TYPe of Report and Period Coveted

Conference Publication

14. Sl_onso"ng Agency Code

15. Supl:_ementaw Not_

Amos A. Spady, Jr. and Roland L. Bowles: Langley Research Center, Hampton, Virginia

Herbert Schlicker_maier: Federal Aviation Administration, Washington, D.C.

16. Absa-ac_

The Second Combined Manufacturers, _nd Technologists' Conference was

hosted jointly by NASA Langley (LaRC) and the Federal Aviation Administration (FAA)

in Williamsburg, Virginia, on October 18-20, 1988. The meeting was co-chaired by Dr

Roland Bowles of LaRC and Herbert Schlickenmaier of the FAA. The purpose of the

meeting was to transfer significant, ongoing results gained during the second year o

the joint NASA/FAA Airborne Wind Shear Program to the technical industry and to pose

problems of current concern to the combined group. It also provided a forum for

manufacturers to review forward-look technology concepts and for technologists =o

gain an understanding of the problems encountered by the manufacturers during the

development of airborne equipment and the FAA certification requirements. The

present document has been compiled co record the essence of the technology updates

and discussion which followed the session.

17. Key Words {Suggesled by Au{I_o,(sD

Microburs_s Doppler Radar

Wind Shear Infrared

Aircraft Hazards LIDAR

19. Secur=w Cla_=f (of th,s repot)

F

Unclassified

18. Oistr,bution Statement

Unclassified - Unlimited

Subject Category 03

_. Secur,W Cla_,f. (of this page)

Unclassifled 21 No.500of pages

22. Pr,ce

A21

NASA FORM 1626 OCT _ For sale by the National Technical Information Service, Springfield, Virginia 22161-2171