RAAF Institute of Aviation Medicine

Pilot selection anthropometry

Dr Adrian Smith16 AVN BDE / AVMED

MAJ (Dr) Sue SteeleArmy Aviation Training Centre

RAAF Institute of Aviation Medicine

Sitting height limit: Kiowa 92-95 cm

RAAF Institute of Aviation Medicine

Sources of differences

• Growth • Diurnal variation

• Repeatability– Inter-observer – Intra-observer

• Technique*– Measurement technique– Posture– Equipment– Training

Differences up to 2 cmnormal.

• Mistake/error– unintended, random

• Bias– systematic distortion

RAAF Institute of Aviation Medicine

RAAF Institute of Aviation Medicine

The present study

• Army Aviation Centre, Oakey• Single experienced AVMO• 56 student pilots

• Anthropometry measurement (“Measured”)– Stature, sitting height, BKL, BHL

• Recruit medical examination (“Recorded”)

• De-identified.• Analysed at AVMED

RAAF Institute of Aviation Medicine

Stature

165

170

175

180

185

190

195

165 170 175 180 185 190 195

Stature (cm), Measured

Stat

ure

(cm

), R

ecor

ded

Aircrew Data Linear (Perfect Match) Linear (+/-2 cm) Linear (+/-5 cm)

Correlation 0.881

RAAF Institute of Aviation Medicine

RAAF Institute of Aviation Medicine

Sitting Height

80

85

90

95

100

105

80 85 90 95 100 105

Sitting Height (cm), Measured

Sitt

ing

Hei

ght (

cm),

Rec

orde

d

Aircrew Data Linear (Perfect Match) Linear (+/-2 cm) Linear (+/-5 cm)

Correlation 0.705

RAAF Institute of Aviation Medicine

RAAF Institute of Aviation Medicine

Buttock-Knee Length

50

55

60

65

70

75

50 55 60 65 70 75

Buttock-Knee Length (cm), Measured

But

tock

-Kne

e Le

ngth

(cm

), R

ecor

ded

Aircrew Data Linear (Perfect Match) Linear (+/-2 cm) Linear (+/-5 cm)

Correlation 0.768

RAAF Institute of Aviation Medicine

Buttock-Heel Length

95

100

105

110

115

120

125

95 100 105 110 115 120 125

Buttock-Heel Length (cm), Measured

But

tock

-Hee

l Len

gth

(cm

), R

ecor

ded

Aircrew Data Linear (Perfect Match) Linear (+/-2 cm) Linear (+/-5 cm)

Correlation 0.588

RAAF Institute of Aviation Medicine

Difference Stature Sitting Height Buttock-Heel Buttock-Knee

<2 cm 91% 53% 53% 68%

2-5 cm 9% 27% 31% 25%

>5 cm 0 20% 16% 7%

RAAF Institute of Aviation Medicine

Measure Mean difference (cm)

Range (cm)

Over-recording(cm)

Under-recording(cm)

Stature 0.68±1.5 -2 to 5 1.75±0.83 -1.12±0.3

Sitting Height -2.50±3.0 -8 to 3 1.47±0.71 -3.90±2.5

Buttock-Heel Length

-1.50±3.5 -12 to 7 1.77±1.47 -4.07±2.4

Buttock-Knee Length

-0.29±2.8 -8 to 6 2.39±1.57 -2.87±1.9

RAAF Institute of Aviation Medicine

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6

Recruiting Location

Per

cent

of s

ittin

g he

ight

s m

easu

reds

Difference 2-5 cmDifference >5 cm

RAAF Institute of Aviation Medicine

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6

Recruiting Location

Per

cent

of s

ittin

g he

ight

s m

easu

reds

Difference 2-5 cmDifference >5 cm

Military Health Facilities DFRCs

RAAF Institute of Aviation Medicine

Correlation of measurements

Parameter Mil Centres DFRCs

Stature 0.926 0.943

Sitting Height 0.588 0.845

Buttock-heel length 0.730 0.812

Buttock-knee length 0.428 0.725

RAAF Institute of Aviation Medicine

Parameter Location Under-recorded(cm)

p

Stature DFR Centre -0.07±1.3 <0.05

Military Centre -1.33±1.5

Sitting Height DFR Centre -2.71±2.5 <0.05

Military Centre -4.63±2.3

Buttock-Heel Length DFR Centre -1.54±4.4 0.87

Military Centre -1.75±3.4

Buttock-Knee Length DFR Centre -0.04±3.3 0.15

Military Centre -1.36±1.7

Is the difference consistent?

What happens when you get close to an anthropometric limit?

RAAF Institute of Aviation Medicine

RAAF Institute of Aviation Medicine

RAAF Institute of Aviation Medicine

Under-recorded (cm)

Relative Difference (cm)

p

Sitting Height ≤98 cm

Military Centre -3.3±3.2 -2.0 0.03

DFRC -1.4±2.6

Sitting Height >98 cm

Military Centre -5.6±1.9 -4.9 0.01

DFRC -0.7±2.1

Under-recorded (cm)

Relative Difference (cm)

p

Military Centre

Sitting Height ≤98cm -3.3±3.2 -2.3 0.03

Sitting Height >98cm -5.6±1.9

DFR Centre

Sitting Height ≤98cm -1.4±2.6 -0.6 0.31

Sitting Height >98cm -0.7±2.1

• “But they may have grown.”

RAAF Institute of Aviation Medicine

RAAF Institute of Aviation Medicine

Sitting height, 12 months

2008-2009 n Under-recorded(cm)

p Range

Military Centre 20 -5.28±2.1 <0.001 -8 to 0

DFR Centre 14 -1.43±0.79 -3 to 0

“Growth”: it doesn’t add up

Stature ≈ sitting height + buttock-heel length1

Group-mean differences• Sitting Height 2.5 cm (grown)• Buttock-heel length 1.5 cm (grown)

but• Stature 0.7 cm (slightly smaller)

RAAF Institute of Aviation Medicine

1 Not quite, but close enough.

RAAF Institute of Aviation Medicine

Summary

• Differences in anthropometric measures– Frequent– Large (>5 cm)– Aeromedically significant

• Sitting height most affected– Critical dimension for current aircraft

Summary

• Current system of anthropometry– Not reliable– Inaccurate– May not inform the pilot-selection process.

• DFRCs more accurate than some ADF facilities.

• Some centres better than others.

RAAF Institute of Aviation Medicine

Summary• Pattern of differences

– SH, BHL >> ST – Under-recording error > over-recording– Magnitude greater close to anthro limit– Military > DFRC

• Unlikely due to:– Diurnal variation– Growth– Random Error

RAAF Institute of Aviation Medicine

RAAF Institute of Aviation Medicine

Possible explanations

• Staff– Untrained– Inexperienced– Competency, proficiency

• Primitive equipment• Non-standard facilities / room layout

• Candidate advocacy?

RAAF Institute of Aviation Medicine

What can be done?

• Formal training in anthropometry– For those engaged in measuring pilots

• QA, maintenance of competency, proficiency

• Standardised anthropometry– Equipment– Layout

• ? Centralised anthropometry

Centralisation

• Advantages– Equipment– Training– Experience

• ? Location– Demographics– Geographics– Logistics– Training

• ‘Hubbing’?

• DFRC-only anthro?

RAAF Institute of Aviation Medicine

RAAF Institute of Aviation Medicine

Which tool?

RAAF Institute of Aviation Medicine

Take-home message

• Anthropometry – Is important.– Can directly affect flight safety.– Needs to be done accurately.

• It is easy to measure pilots, • but hard to measure them well.

– Trained, experienced staff– Proper equipment

RAAF Institute of Aviation Medicine

Thank you.

Questions / Discussion

Dr Adrian Smithadrian.smith14@defence.gov.au

Ph: 08 7383 3169