HEAD ALIGNMENT OF = THE

LIST OF FIGURES

Figure = 1.-Computer=20 graphics attitude display. =20 4

Figure = 2.-Variation in=20 Attitude Indicator design. = 4

Figure = 3.-View of AI=20 and the horizon. =20 5

Figure = 4.-Head roll of=20 F-16 pilot in 9 G turn. =20 9

Figure = 5.-Research=20 airplane. Cessna C172L = Skyhawk,=20 fixed-gear, 4-place. =20 12

Figure = 6.-Instrument=20 layout of the research airplane. &nbs= p; =20 12

Figure = 7.-Visual=20 Flight Rule 1:500,000 sectional chart for the flight test air = space. = 13

Figure = 8.-Videocamera=20 mounted on a headset. =20 16

Figure = 9.-Data=20 acquisition system diagram. = &nbs= p;=20 16

Figure = 10.-Dimension=20 of videocamera setting in the research airplane. &nbs= p; =20 17

Figure = 11.-Calibration=20 of videocamera angle. =20 18

Figure = 12.-Cockpit=20 picture in analysis. = 18

Figure = 13.-Head=20 alignment of a pilot in 45=81=8B bank turn to the left. =20 19

Figure = 14.-Head roll=20 angle around head x-axis, in Attitude Indicator mode of flight. = 30

Figure = 15.-Head roll=20 angle around head x-axis, in vidual flight mode. 30

Figure = 16.-Head roll=20 angle around head x-axis, in non flying flight mode. =20 30

Figure = 17.-Pilot head=20 roll around head x-axis during aircraft turn, in Attitude Indicator mode = of=20 flight. &nbs= p; =20 32

Figure = 18.-Pilot head=20 roll around head x-axis during aircraft turn, in visual mode of = flight. = 33

Figure = 19.-Pilot head=20 roll around head x-axis during aircraft turn, in non-flying mode of = flight. &nbs= p; =20 34

Figure = 20.-Regression=20 coefficient (ordinate) for aircraft bank angle vs. head roll angle. &nbs= p;=20 36

Figure = 21.-Regression=20 analysis for head roll angle vs. aircraft roll angle. &nbs= p;=20 = 37

Figure = 22.-Field of=20 view for Cessna 172L. 43

Figure = 23.-Scattergram=20 of subject age vs. head roll angle, left aircraft roll. =20 = 47

Figure = 24.-Scattergram=20 of subject age vs. head roll angle, right aircraft roll. = 48

Figure = 25.-Scattergram=20 of subject flight time vs. head roll angle, left aircraft roll. =20 49

Figure = 26.-Scattergram=20 of subject flight time vs. head roll angle, right aircraft roll. = 50

Figure = 27.-Head roll=20 angle around head x-axis of each subjects. = 51

Figure = 28.-Time course=20 of aircraft and head roll around their x-axis, Attitude Indicator flight = mode.=20 &nbs= p; =20 53

Figure = 29.-Time course=20 of aircraft and head roll around their x-axis, visual flight mode 54

Figure = 30.-Time course=20 of aircraft and head roll around their x-axis, non-flying mode. 55

Figure = 31.-Head roll=20 in ground turn. =20 57

Figure = 32.-Head roll=20 during a 180=81=8B course reversal on the ground, time series. 58

Figure = 33.-Head roll=20 during a 180=81=8B course reversal on the ground. = 59

Figure = 34.-The=20 relation between elapsed time and aircraft heading for Figure 32 and = Figure 33.=20 60

Figure = 35.-Head=20 position of a passenger in 90=81=8B bank flight. 63

Figure = 36.-Automobile=20 driver=81fs head alignment during roll of vehicle around its x-axis = (longitudinal=20 axis). 66

Figure = 37.-Head=20 alignment of an automobile driver. 67

Figure = 38.-Motorcycle=20 rider and passenger=81fs head alignment in turn. 68

Figure = 39.-Latest Head=20 Up Display symbols. &nbs= p;=20 79

Figure = 40.-Cervical=20 spine alignment on head roll. 81

Figure=20 41.-Nomenclature for axes. &nbs= p; =20 92

&nbs= p; = ; = =20 LIST OF=20 TABLES

Table 1.-Terms equivalent = to =81emoving=20 horizon=81f and =81emoving aircraft=81f. = 7

Table 2.-Profile of pilot=20 subjects. 11

Table 3.-Ground simulator = study=20 result. 24

Table 4.-Head roll with = body lean,=20 subject #9. =20 28

Table 5.-Result of pilot = head roll=20 angle around head x-axis during aircraft turn. 31

Table 6.-ANOVA table for = subject and=20 flight mode. 39

Table 7.-Post-hoc test for = head roll=20 angle difference among flight modes. 39

Table 8.-A matrix of t-test = for=20 difference in head roll among flight modes at each aircraft roll (bank) = angle.=20 = 41

Table 9.-Comparison of head = roll angle=20 between left and right aircraft roll, all flight modes. =20 44

Table 10.-Comparison of = head roll angle=20 between left and right aircraft roll, Attitude Indicator flight mode. = =20 44

Table 11.-Comparison of = head roll angle=20 between left and right aircraft roll, visual flight mode. 45

Table 12.-Comparison of = head roll angle=20 between left and right aircraft roll, non-flying flight mode. 45

Table 13.-Regression = coefficients from=20 simulator and flight study. = 76

Table 14. +Gz values for = aircraft roll=20 angles. =20 85

Table 15. - Flight maneuver = sequence=20 for subject #8. =20 93

Table 16.-In-flight raw = data. 94

&nbs= p; = ; = =20 ACKNOWLEDGEMENTS

=20 I would like to extend my sincerest thanks to the following = people for=20 their assistance in the undertaking of this study:

Stanley R. Mohler, M.D., Anthony J. = Cacioppo,=20 Ph.D., Satya P. Sangal, Ph.D., Robin E. Dodge, M.D., and Frederick R. = Patterson,=20 Ph.D.

=20 I am grateful to = Terry=20 Taddeo, M.D. and Fumi Shimada for their help in manuscript=20 preparation.

&nbs= p; = ; =20 1. =20 INTRODUCTION

=20 Spatial disorientation is still a pilot killer. Spatial disorientation is = associated=20 with the experiencing of an orientational illusion for pilots = [Gillingham=20 1985]. Loss of = situational=20 awareness has been a major concern in military aviation, where one = encounters a=20 wide aircraft aerodynamic envelope (acceleration and velocity) [Barnum = 1968,=20 Cheung 1995]. = Requirements for=20 close formation flying under poor weather conditions is another factor = related=20 to this phenomenon. = Civilian=20 aviation has not placed much emphasis on this pilot-system limitation = [Kirkham=20 1978, Johnson 1989, AOPA 1993]. = Is=20 it a problem only for high-performance fighter = pilots?

=20 Recently spatial disorientation was identified as a link in the = causal=20 chain of factors related to a major US air carrier crash. A DC-9 jetliner had a = collision with the=20 ground because of an encounter with a microburst and the pilots=81f = subsequent loss of situational awareness = due to=20 somatogravic illusion [NTSB =20 1994]. The flight = crew=20 became disoriented during the transition from Visual Meteorological = Conditions=20 to Instrumental Meteorological Conditions.

=20 What type of computer graphic display, head-up display, or = head-mounted=20 display might facilitate spatial orientation? What should be the contents of = a=20 training syllabus against disorientation? =20 Is our understanding of its pathophysiology sufficient to permit = the=20 design of truly better instruments and training?

=20 In aerospace medicine textbooks, there has been no quantitative=20 description about natural body and head alignment of pilots other than = in a=20 straight and level flight. = Only=20 recently this was challenged by two ground simulator studies [Patterson = 1995A,=20 Smith 1995]. Some flight=20 instructors teach students that keeping their head and body straight = along the=20 body z-axis (longitudinal axis, Figure=20 41) is the proper body alignment. =20 But the simulator study found that pilots laterally deflect their = heads=20 during turning maneuvers.

=20 Positional alignment of head and body during flight maneuvers is = a=20 significant limiting factor for the design of instruments and cockpit=20 layout. The latest = designs of=20 Head-Up Displays or Head-Mounted Displays are more sensitive to this = geometry=20 because of their limited angle of view. =20 In order to view some military head-up displays, the eyes must be = kept=20 within an 8 x 13 cm (3 x 5 inch) field. =20 These limits are easily exceeded if pilots roll their head around = their=20 head x-axis (deflect the head laterally).

=20 The physiological dynamics of pilot head motion during flight has = yet to=20 be investigated.

&nbs= p; = ; =20 2. =20 BACKGROUND

=20 Actively controlled human flight began with hang gliders, under = visual=20 flight condition. The = Wright=20 Brothers from Dayton, Ohio began controlled, powered flight after their=20 extensive experiments with gliders. =20 The next breakthrough, was the invention of the aircraft=81fs = attitude=20 display.

=20 Prior to the emergence of the apparatus, there was an interesting = instrument arrangement used by Charles A. Lindbergh for his solo = transatlantic=20 flight in 1927. Since his = forward=20 view was blocked by a fuel tank, he used a periscope to provide a visual = reference [Roscoe 1966]. = Although=20 he is said to have used forward slipping during approach to gain a = better view=20 of the runway, the periscope deprived him of peripheral vision, which is = important for pilots [Kochhar 1978].

=20 Based upon his design of a gyroscopic stabilizer for ships, Elmer = Sperry,=20 Jr. [Laboda 1995], in 1910, extended the technology by developing a = gyroscope=20 for use by pilots for determining aircraft attitude. The Sperry Artificial Horizon = allowed=20 Lt. James H. Doolittle to fly his NY-2 Navy trainer airplane = =81eblind=81f on 24=20 September 1929. This = historic=20 apparatus is on display at the US Air Force Museum, Dayton, Ohio.

Figure 1.-Computer graphics attitude=20 display.

A display of a Fokker F-100 = jetliner. It is the latest design in = use, but=20 stays with the concept of a stationary aircraft symbol with a moving=20 horizon.

Figure 2.-Variation in Attitude Indicator=20 design.

This AI in a 1966 Piper = PA30B twin=20 piston-engine airplane has a bank pointer that moves with the horizon = bar,=20 instead of with the miniature airplane. Many AI=81fs of this design are = still in=20 use today. This kind of = design=20 variation is also seen in VOR (Very High Frequency Omni Range) = indicators.Figure 3.-View of AI and the = earth=20 horizon.

The Attitude Indicator = (arrow) and the=20 earth horizon seen from cockpit of a CH2000 single engine airplane. The roll angle of the aircraft = is 64=81=8B to=20 the left. This picture is = aligned=20 to the page so that it looks natural to the reader, while actually it = differs=20 from the retinal image of the pilots in the cockpit because of the = limited=20 motion of the head in flight.

[ AOPA Pilot, 36(12),1993: = 47=20 ]

=20 There is a speculation that Lindbergh=81fs success with the = periscope may=20 have affected the design of the artificial horizon (now called the = Attitude=20 Indicator, Figure 1, Figure = 2). All operational attitude = indicators,=20 except for those of Russian design, use =81emoving horizon=81f symbolic = design. The horizon bar (Figure 1) resembles that of a = short=20 portion of the earth horizon as if seen through a periscope (Figure = 3).

=20 Peripheral displays, such as the para-visual director, peripheral = command=20 indicator, HOVERING display, and the Malcolm horizon stimulate = peripheral vision=20 to provide aircraft attitude information [Stokes 1988]. They have proven to be = relatively=20 effective despite degraded visual acuity associated with peripheral = vision. Visual acuity in Snellen=81fs = fraction=20 decreases from 1.0 in the visual center to 0.2 at 10=81=8B off center, = 0.1 at 20=81=8B,=20 and 0.07 at 30=81=8B [Westheimer 1992].

=20 How can we present attitude information to maximize foveal = vision? Although the options are many, = modern=20 Russian fighters use an attitude display whose miniature airplane, = instead of a=20 horizon bar, rolls.

=20 In the past, no commercial competition was seen between the = =81emoving=20 horizon=81f and =81emoving airplane=81f display. =20 This is probably due to the initial success of the Sperry = artificial=20 horizon and the comprehensive analogy of periscopic view (=81ecut = out=81f earth=20 horizon appears in an Attitude Indicator) [Poppen 1936, Roscoe = 1966]. Other equivalent terms, which = are often=20 confusing, are summarized in Table=20 1. It is worth noting = that an=20 integrated display which changes from =81emoving aircraft=81f to = =81emoving horizon=81f for=20 roll-in has been devised [Fogel 1959, Roscoe = 1975].

Table 1.-Terms equivalent to =81emoving = horizon=81f and =81emoving=20 aircraft=81f.

=20 moving horizon &nbs= p; = ; = =20 moving airplane

=20 inside-out &nbs= p; = ; = &= nbsp; =20 outside-in =20

=20 fly-to &nbs= p; = ; = &= nbsp; &n= bsp; =20 fly-from

=20 moving card or tape &nbs= p; = ; =20 moving pointer

=20 earth referenced &nbs= p; = ; = =20 aircraft referenced

=20 aircraft stabilized &nbs= p; = ; = =20 space stabilized

=20 in aircraft coordinates &nbs= p; = ;=20 in earth coordinates

=20 mo