This document summarizes a study that found significant inaccuracies and inconsistencies in anthropometric measurements of student pilots taken at different military and recruiting centers. Measurements of sitting height, in particular, frequently differed by more than 5 centimeters between initial recordings and later measurements, with under-recording being more common. The inaccuracies appeared greater for measurements near anthropometric limits and at some military centers compared to recruiting centers. The document suggests improved training, standardized equipment and procedures, and potentially centralized anthropometry could help address the unreliable measurements that may not adequately inform pilot selection.

1. RAAF Institute of Aviation Medicine
Pilot selection
anthropometry
Dr Adrian Smith
16 AVN BDE / AVMED
MAJ (Dr) Sue Steele
Army Aviation Training Centre

2. RAAF Institute of Aviation Medicine
Sitting height limit: Kiowa
92-95 cm

3. RAAF Institute of Aviation Medicine

4. Sources of differences
• Growth
• Diurnal variation
• Repeatability
– Inter-observer
– Intra-observer
• Technique*
– Measurement technique
– Posture
– Equipment
– Training
Differences up to 2 cm
normal.
• Mistake/error
– unintended, random
• Bias
– systematic distortion
RAAF Institute of Aviation Medicine

5. 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

6. RAAF Institute of Aviation Medicine
Stature
165
170
175
180
185
190
195
165 170 175 180 185 190 195
Stature (cm), Measured
Stature(cm),Recorded
Aircrew Data Linear (Perfect Match) Linear (+/-2 cm) Linear (+/-5 cm)
Correlation 0.881

7. RAAF Institute of Aviation Medicine

8. RAAF Institute of Aviation Medicine
Sitting Height
80
85
90
95
100
105
80 85 90 95 100 105
Sitting Height (cm), Measured
SittingHeight(cm),Recorded
Aircrew Data Linear (Perfect Match) Linear (+/-2 cm) Linear (+/-5 cm)
Correlation 0.705

9. RAAF Institute of Aviation Medicine

10. 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
Buttock-KneeLength(cm),
Recorded
Aircrew Data Linear (Perfect Match) Linear (+/-2 cm) Linear (+/-5 cm)
Correlation 0.768

11. 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
Buttock-HeelLength(cm),
Recorded
Aircrew Data Linear (Perfect Match) Linear (+/-2 cm) Linear (+/-5 cm)
Correlation 0.588

12. 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%

13. 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

14. RAAF Institute of Aviation Medicine
0
5
10
15
20
25
30
35
40
45
50
1 2 3 4 5 6
Recruiting Location
Percentofsittingheightsmeasureds
Difference 2-5 cm
Difference >5 cm

15. RAAF Institute of Aviation Medicine
0
5
10
15
20
25
30
35
40
45
50
1 2 3 4 5 6
Recruiting Location
Percentofsittingheightsmeasureds
Difference 2-5 cm
Difference >5 cm
Military Health Facilities DFRCs

16. 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

17. 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

18. Is the difference consistent?
What happens when you get close to an
anthropometric limit?
RAAF Institute of Aviation Medicine

19. RAAF Institute of Aviation Medicine

20. 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

21. • “But they may have grown.”
RAAF Institute of Aviation Medicine

22. 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

23. “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.

24. 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

25. 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

26. 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

27. RAAF Institute of Aviation Medicine
Possible explanations
• Staff
– Untrained
– Inexperienced
– Competency, proficiency
• Primitive equipment
• Non-standard facilities / room layout
• Candidate advocacy?

28. 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

29. Centralisation
• Advantages
– Equipment
– Training
– Experience
• ? Location
– Demographics
– Geographics
– Logistics
– Training
• ‘Hubbing’?
• DFRC-only anthro?
RAAF Institute of Aviation Medicine

30. RAAF Institute of Aviation Medicine
Which tool?

31. 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

32. RAAF Institute of Aviation Medicine
Thank you.
Questions / Discussion
Dr Adrian Smith
adrian.smith14@defence.gov.au
Ph: 08 7383 3169