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Bird strikes in military aviationAn introductionArie Dekker

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•Loss of mission time •Aborted take-off 10 •Precautionary landing 27•Returned to base 50

•Damage to aircraft •15 % of BS results in damage

•Aircraft grounded• from 1 hour to 91 days

•Loss of aircraft• 1 F-16

Bird strikes and their consequencesRNLAF, 2004 / 2006, N=164

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The nature of bird strikes (1)

0%

5%

10%

15%

20%

25%

30%

35%

0 50 100 150 200 250 300 350 400 450 500 >550

Speed (kts)

Frac

tion

(%)

Bird strikes with jet fighter aircraft over speed

EURBASE N-17,732

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2009

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The nature of bird strikes (2)

0%

5%

10%

15%

20%

25%

30%

35%

0 50 100 150 200 250 300 350 400 450 500 >550

Speed (kts)

Frac

tion

(%)

En-route (71.9%)Local (28.1%)

Bird strikes with jet fighter aircraft over speed

EURBASE N-17,732

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2009

5

The nature of bird strikes

0%

5%

10%

15%

20%

25%

30%

35%

0 50 100 150 200 250 300 350 400 450 500 >550

Speed (kts)

Frac

tion

(%)

En-route (71.9%)Local (28.1%)

Bird strikes with jet fighter aircraft over speed

EURBASE N-17,732

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RNLAF birdstrikes, jet-fighters, 1976-2008

Local En-route

Bird strikes 1,116 2,236

Aborted take-off 58 NA

Returned to base 280 370

Precautionarylanding other base

NA 474

AC grounded ? ?

Damage 139 (12,5%) 487 (21,8%)

Loss of aircraft 3 (2 F-16 + 1 NF-5) 2 (2 F-104)

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Bird Strike Density (BS per 10,000 flying hours)Based on 29,292 locations in EURBASEen-route, JETS, 1991-2000

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How to prevent en-route bird strikes?

Birds try to avoid aircraft

But are too lateHUD films

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How to prevent en-route bird strikes?

Birds try to avoid aircraft

But are too lateHUD films

T (detection + recognising + processing + action) bird

> T (distance / speed) aircraft

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2009

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How to prevent en-route bird strikes?

Birds try to avoid aircraft

But are too lateHUD films

Ultimate prevention

Timely warning of birds for approaching aircraft by ???

T (detection + recognising + processing + action) bird

> T (distance / speed) aircraft

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2009

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How to prevent en-route bird strikes?

Birds try to avoid aircraft

But are too lateHUD films

Ultimate prevention

Timely warning of birds for approaching aircraft by ???

In the mean time: aircraft have to avoid birds

T (detection + recognising + processing + action) bird

> T (distance / speed) aircraft

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Avoiding birdsIn flight detection by pilot => seldom in time

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Avoiding birdsIn flight detection by pilot => seldom in time

Adapting operations to bird density

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Avoiding birdsIn flight detection by pilot => seldom in time

Adapting operations to bird density

• Only sensible if bird densities vary in time and space

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Avoiding birdsIn flight detection by pilot => seldom in time

Adapting operations to bird density

• Only sensible if bird densities vary in time and space

• Bird strikes are clustered in time and space => supporting variation in bird densities

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Avoiding birdsIn flight detection by pilot => seldom in time

Adapting operations to bird density

• Only sensible if bird densities vary in time and space

• Bird strikes are clustered in time and space => supporting variation in bird densities

• Birds can be detected by radar => densities vary

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Average bird density (radar)

0

0,5

1

1,5

2

2,5

3

3,5

1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 1-10 1-11 1-12

Bird

ech

o de

nsity

(ech

o / k

m²)

Restriction level

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Daily variation in bird density (radar) 2001

0

2

4

6

8

10

12

1-1

1-2

1-3

1-4

1-5

1-6

1-7

1-8

1-9

1-10

1-11

1-12

Mea

n ec

ho d

ensi

ty (e

cho

/ km

²)

eveningmorning

Restriction level

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Bird detection by radar (1)

Taken from: L.S. Buurma & B. Bruderer. 1990. The application of radar for bird strike prevention.

Time exposure picture of the screen

Bird detection by radar (2)

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Nowadays electronic filtering of bird echoes is possible

Bird detection by radar (2)

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Nowadays electronic filtering of bird echoes is possible

Bird detection by radar (2)

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Nowadays electronic filtering of bird echoes is possible

Bird detection by radar (2)

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Nowadays electronic filtering of bird echoes is possible

Bird detection by radar (2)

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Nowadays electronic filtering of bird echoes is possible

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Bird intensity scale defined in STANAG 3879“The bird intensity levels for international BIRDTAMs willbe expressed on an exponential scale with indices as follows”:

Intensity Bird strike risk0 Nil1 Extremely small2 Very small3 Small4 Fairly small5 Fairly great6 Great7 Very great8 Extremely great

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The making of a BIRDTAM• Sampling airspace using radar• Interpretation of images• Spatial extrapolation• Estimating altitude

• Assign bird densities per Georef• Add info for georefs from neighbouring countries• Publish in National Operational Information System• Contribute to international network

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Pilots are informed by BIRDTAM´s

www.notams.faa.gov/common/birdtam.html

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Pilots are informed by BIRDTAM´s

www.notams.faa.gov/common/birdtam.html

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RNLAF en-route bird strike ratio

0

10

20

30

40

50

60

1980 1985 1990 1995 2000 2005

ratio

(BS

/ 100

00 h

rs)

intro

duct

ion

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En-route bird strike prevention

Great progress has been made,

BUTThe system is still very vulnerable, needs improvements and lacks forecasts