Head Position and Frame of Reference in Flight:
The Opto-kinetic Cervical Reflex
Jennie J. Gallimore, Ph.D.
June 24, 2009
NASA Langley
Department of Biomedical, Human Factors, & Industrial Engineering
Topics
•
•
•
•
•
Spatial Disorientation
Attitude Indicator
OKCR Research
Considerations for Cockpit Displays
Other On Going Research at WSU
Department of Biomedical, Human Factors, & Industrial Engineering
Spatial Disorientation
• The inability of the flight crew to correctly perceive
attitude, altitude, or airspeed of the aircraft in
relationship to the earth and other points of reference.
• SD has been categorized into three types.
• Type I unrecognized (where most mishaps are
classified)
• Type II recognized
• Type III incapacitating
Department of Biomedical, Human Factors, & Industrial Engineering
Spatial Disorientation
Accidents
• US Air Force 1991-2000, 20.2% of accidents, 60 lives,
1.4 billion dollars [Davenport00].
• US Army reported 27% [Kuipers90].
• US Navy and Marine Corp, 26%, 101 accidents
[Johnson00]
– Three times as many lives were lost for SD related mishaps
compared to non-SD related mishaps.
– Mishap data also indicate that pilots who experience SD are
very experienced, and the mishap rate has not decreased in the
last 20 years.
Department of Biomedical, Human Factors, & Industrial Engineering
First Flight Instrument?
Wright 1909 Military Flyer
Slip Ribbon (first flight instrument)
Department of Biomedical, Human Factors, & Industrial Engineering
First Mechanical Flight
Instrument
• Sperry’s bank and
turn indicator, 1918
• Worked best in
clear weather
Department of Biomedical, Human Factors, & Industrial Engineering
First “Blind” Sortie
• Sep 24th 1929 under
direction of Guggenheim
in NY (Mitchel Field)
•First ‘Blind’ sortie,
takeoff to landing
•First use of artificial
horizon, Kollsman
altimeter, and directional
gyro
Department of Biomedical, Human Factors, & Industrial Engineering
Attitude Indicator
Level flight
20-degree turn
Department of Biomedical, Human Factors, & Industrial Engineering
Attitude Indicator Example
• Real World
– Plane moves
– Horizon remains static
• Indicated World
– Plane remains static
– Horizon moves
– Indicator reverses reality
• Dangerous if visual reference
• is lost
– Pilot disorientation
– Control reversal errors
Department of Biomedical, Human Factors, & Industrial Engineering
Pilot Spatial Awareness Models
Conventional Paradigm
Revised Paradigm
PrimaryVisual
Visual
Primary
SpatialCue
Cue
Spatial
(stablehorizon)
horizon)
(stable
SecondaryVisual
Visual
Secondary
SpatialCue
Cue
Spatial
(movingcockpit)
cockpit)
(moving
Department of Biomedical, Human Factors, & Industrial Engineering
Pilot Spatial Awareness Models
Conventional Paradigm
Revised Paradigm
PrimaryVisual
Visual
Primary
SpatialCue
Cue
Spatial
(stablehorizon)
horizon)
(stable
SecondaryVisual
Visual
Secondary
SpatialCue
Cue
Spatial
(movingcockpit)
cockpit)
(moving
Department of Biomedical, Human Factors, & Industrial Engineering
Pilot Spatial Awareness Models
Conventional Paradigm
Revised Paradigm
PrimaryVisual
Visual
Primary
SpatialCue
Cue
Spatial
(stablehorizon)
horizon)
(stable
SecondaryVisual
Visual
Secondary
SpatialCue
Cue
Spatial
(movingcockpit)
cockpit)
(moving
Department of Biomedical, Human Factors, & Industrial Engineering
Opto-Kinetic Cervical Reflex
(OKCR)
• Pilots align their heads toward the horizon during
Visual Meteorological Conditions (VMC) flight.
• Pilots do not tilt their heads during Instrument
Meteorological Conditions (IMC) flight.
• Visual to Instrument transition can cause
reversal errors.
Department of Biomedical, Human Factors, & Industrial Engineering
Head Tilt
• Patterson (1989) noticed that pilots align their
heads with the horizon.
• If they are aligning their heads with the
aircraft then the view from the windscreen is a
fixed horizon (not moving).
Department of Biomedical, Human Factors, & Industrial Engineering
Opto-Kinetic Cervical Reflex (In-flight)
Horizon Line
with 73 degrees
of bank angle
F/A-18 aircraft (Blue Angel)
73 degrees of bank (VMC, +Gz Turn).
OKCR Head tilt = 31degrees away from the Gz axis.
Department of Biomedical, Human Factors, & Industrial Engineering
WSU Research
Investigating Head Tilt
–
–
–
–
–
–
–
Patterson (1995, 1997)
Smith et al (1997)
Merryman et al (1997)
Gallimore et al (1999, 2000)
Liggett & Gallimore (2001)
Gallimore, Liggett & Patterson (2001)
Others since
Department of Biomedical, Human Factors, & Industrial Engineering
OKCR Studies
Author
Platform
Visual
Field
Size
Instruments
Patterson
(1995)
Fixed
aircraft
sim
Full
dome
180o
HDD
AI
Smith et al.
(1997)
Fixed
aircraft
sim
Full
dome
180o
HDD
AI
Merryman
et al. (1997)
F-15
aircraft
Real
world
HDD
AI
HUD
Braithwaite
et al (1998)
Moving
Helicopter
Sim
Half
dome
160o H
FOV
HDD
AI
NVG
Gallimore
et al. (1999)
Fixed
aircraft
sim
Full
dome
180o
HDD
AI
Gallimore
et al. (2000)
Fixed
aircraft
sim
Full
dome
180o
HDD
AII
VMC
Task
OCKR
Found?
Yes
IMC
Task
X
OKCR
Found?
No
UA
Task
CRE
%
Subs
X
65%
16
X
Yes
16
Yes
9
X
X
Yes
X
No
X
25%
20
Yes
X
No
X
31%
12
Yes
X
No
X
X
X
Department of Biomedical, Human Factors, & Industrial Engineering
26
Horizon Roll Vs. Head Roll for
Low-Level Route
Patterson etDepartment
al. of Biomedical, Human Factors, & Industrial Engineering
Three graduate studies: Patterson,
Merryman, Smith
Department of Biomedical, Human Factors, & Industrial Engineering
Merryman & Smith
Department of Biomedical, Human Factors, & Industrial Engineering
Results: Head tilt with respect to
aircraft bank during low-level route
Gallimore, et al (1999)
12
10
8
6
2
-4
-6
-8
-10
-12
Aircraft Bank
Department of Biomedical, Human Factors, & Industrial Engineering
90
80
70
60
50
40
30
20
10
0
-10
-20
-30
-40
-50
-60
-70
-2
-80
0
-90
Head Tilt
4
OKCR Results
30
Patterson: Dome
Smith Active: Dome
Smith Passive: Dome
Merryman: F-15
25
20
Head Tilt (Degrees)
15
Braithwaite: Helicopter
Gallimore 1999:Dome
10
5
0
-80
-5
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
-10
-15
-20
-25
-30
Aircraft Bank (Degrees)
Department of Biomedical, Human Factors, & Industrial Engineering
60
70
80
OKCR as a function of task
and field of view
30
Solo Figure 8, 180 FOV
25
Formation Flight, 180 FOV
20
Solo Figure 8, 40-100 FOV
Formation Flight, 40-100 FOV
Head Tilt (Degrees)
15
10
5
0
-80
-5
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
-10
-15
-20
-25
-30
Aircraft Bank (Degrees)
Department of Biomedical, Human Factors, & Industrial Engineering
50
60
70
80
Reversal Error
• Tendency for pilots to mistake motion of the
artificial horizon as a relative motion of the
wings.
• Pilots roll or pitch the aircraft in opposite
direction.
• Researchers who have documented this error
– Fitts and Jones (1947)
– Johnson and Roscoe (1972)
– Roscoe and Williges (1975)
– Roscoe (1986) - Boeing 747 accident
Department of Biomedical, Human Factors, & Industrial Engineering
Sensory-Spatial Conflict and Control Reversal Error
(Patterson et al findings)
• Experienced U.S. military rated
pilots commit 25-65% reversal
errors.
• Likelihood of reversal errors by
general aviation pilots is
probably even greater.
• A reversal error can lead to
flight into terrain or a graveyard
spiral.
• This is likely what happened to
the pilot of Air India and to
John F. Kennedy, Jr.
Control reversal error
during IMC “out” to
“in” visual transition.
References on reversal errors:
Patterson, et al, 1997
Braithwaite,et al, 1998
Gallimore, et al., (1999)
Liggett & Gallimore (in press)
Department of Biomedical, Human Factors, & Industrial Engineering
Number and Magnitude of
Reversal Errors
Gallimore, et al findings
40 Degrees
8 errors out of 24
60 Degrees
100 Degrees
6 errors out of 24
9 errors out of 24
VMC
4(17.39%)
1(.04%)
5(20.83%)
IMC
4(17.39%)
5(20.83%)
4(17.39%)
Combined
Average reversal Average reversal
error magnitude error magnitude
28.96 o
9.30 o
Average reversal
error magnitude
9.34 o
Department of Biomedical, Human Factors, & Industrial Engineering
Transitions
What happens during the transition from visual to
instruments?
 The pilot’s view of the cockpit suddenly becomes
stationary as his view of the display’s artificial
horizon begins moving.
 Pilots must instantly reverse their orientation
strategy.
 Pilots sensory-spatial compatibility between the
control stick motion and visual feed back.
Department of Biomedical, Human Factors, & Industrial Engineering
Summary
• Pilots reflexively tilt heads toward horizon during
VMC roll maneuvers.
• Head movement acts to stabilize retinal image.
• Generated by motion on retina, not vestibular.
• Stabilized horizon is the primary visual cue.
• Peripherally viewed cockpit structures secondary
cues.
• Secondary cues move with airframe.
• Control movement compatible with secondary
cues.
Department of Biomedical, Human Factors, & Industrial Engineering
Summary (Cont.)
• Beyond 40 degrees of aircraft roll there is a
decrease in head displacement, so pilots can not
stabilize the horizon.
• Horizon acceleration, stabilization of secondary
cues.
• Sudden switch may lead to false perceptions.
• When transitioning from visual to instruments
– motion reversal b/w outside and inside visual cues
– control display incompatibility
– need to switch cognitive model
Department of Biomedical, Human Factors, & Industrial Engineering
How does OKCR affect current
display technologies?
• Head down Attitude Indicator
– Reversal errors
• HUD
– Head may tilt out of the HUD eye box and pilot may
not see a pull up X.
Department of Biomedical, Human Factors, & Industrial Engineering
HUD
• The Head Up Display
(HUD) presents
symbols to the pilot,
displaying them over
the real world.
Department of Biomedical, Human Factors, & Industrial Engineering
HUD Symbology is Conformal
Department of Biomedical, Human Factors, & Industrial Engineering
HUD Symbology
Department of Biomedical, Human Factors, & Industrial Engineering
How does OKCR affect current
display technologies? (cont)
• NVG
– HUD symbology on the NVG. Head movements are
not tracked. As pilot changes head position, display
horizon line is no longer conformal to the real
horizon.
– Pilots see HUD information designed for fixed onaxis aircraft viewing regardless of head position.
Pilots may not realize they are not flying in the
direction they are looking.
Department of Biomedical, Human Factors, & Industrial Engineering
Research Issues
• What frames of reference are important for a
pilot to maintain orientation?
– World - world is fixed and everything moves
within it.
– Aircraft - aircraft is fixed and everything
moves around it.
– Pilot - pilot is fixed and everything moves in
relation to him.
Department of Biomedical, Human Factors, & Industrial Engineering
Research Issues
• What symbology is appropriate for HMDs?
– HUD symbology is being considered for use
on HMDs.
– HUD symbology is being used on NVGs.
• How do sensory reflexes affect perceived frame
of reference?
– OKCR, under VMC pilots align their head
with the horizon.
Department of Biomedical, Human Factors, & Industrial Engineering
Research Issues
• How do visual frames of reference interact with
vestibular and proprioceptive inputs to provide
the pilot with an "awareness" of their
orientation?
• What contributing cognitive factors affect
spatial orientation?
• How will HMD attitude symbology affect
frames of reference in VMC and IMC?
• How will transitions be impacted?
• How can we detect when a pilot is spatially
disoriented?
Department of Biomedical, Human Factors, & Industrial Engineering
Research Issues for HMD
Symbology Design
• What spatial sensory reflexes and visual illusions
influence pilot’s perception of frame of reference?
• Will cognitive capture affect pilots perceptions of
frame of reference? Will cognitive capture result in
more transitions between symbology and the real
world?
• When pilots transition between a perceived stationary
horizon (real world cues) to a moving symbol horizon
on the HMD, do they perceive the horizon symbol as
stationary?
• What type of symbology will help provide the
perception of a stationary horizon?
Department of Biomedical, Human Factors, & Industrial Engineering
Research Issues for HMD
Symbology Design
• If HMD symbology is used for attitude information as
well as targeting, how will switching between these
tasks affect frame of reference?
• Will pilots have a greater risk of spatial disorientation
if they look off-axis more often?
• How will secondary flight cues be affected by use of
HMDs?
• What current or new measures should be employed to
determine if a pilot is spatially disoriented?
Department of Biomedical, Human Factors, & Industrial Engineering
HMD Research and the OKCR
Experiment I
• Test adequacy of Mil-Std HUD symbology
presented on a see-through HMD during various
tasks.
– VMC flight task
• Pilots were instructed to bank at specific angles, rather
than to bank around a waypoint.
– 12 Subjects
– HMD Kaiser Pro – Binocular HMD, 40o circular
FOV, 100% overlap, 1280 x 1024 resolution.
Department of Biomedical, Human Factors, & Industrial Engineering
HMD Research and the OKCR
Experiment II
• Investigate visual cues in an immersed HMD
simulation system using HUD symbology.
– VMC Flight task
– Varied resolution (640 x 480 & 800 x 600), HUD
symbol size (small and large)
– Pilots instructed to follow a yellow track line over
Pensacola, FL
– 6 subjects
– Virtual Research V8 HMD system, 48o H x 32o V,
100% overlap
Department of Biomedical, Human Factors, & Industrial Engineering
HMD Research and the OKCR
Experiment III
• Investigate the effects of non-congruent motion
on performance in an immersive HMD system.
– VMC flight task flown on land and on Navy mind
sweeper in Pensacola Bay.
– Pilots instructed to follow a yellow track line over
Pensacola, FL
– 9 subjects
– Sony i-glasses , 24o H x 18o V, 100% overlap, 789 x
230 Resolution
Department of Biomedical, Human Factors, & Industrial Engineering
HMD Results
30
25
HMD Experiment I
20
HMD Experiment II
HMD Experiment III (Land)
15
Head Tilt (Degrees)
HMD Experiment III (Ship)
10
5
0
-80
-5
-70 -60
-50
-40 -30
-20 -10
0
10
20
30
40
50
-10
-15
-20
-25
-30
Aircraft Roll (Degrees)
Department of Biomedical, Human Factors, & Industrial Engineering
60
70
80
OKCR Differences
• Different visual scenes/cues cause difference in
pilot OKCR response
– Reducing FOV
– Manipulating altitude
• Amount of head tilt depends on amount of
retinal movement.
• Reduction in peripheral vision may play a role
• Reducing FOV may reduce how compelling the
visual horizon appears
Department of Biomedical, Human Factors, & Industrial Engineering
OKCR Differences
• Immersive HMD simulation studies did not
provide any secondary visual cues (cockpit
structures).
– Do pilots reduce head movements when they lack a
stabilizing cue?
• If experiencing simulator sickness may reduce
head movements.
Department of Biomedical, Human Factors, & Industrial Engineering
Control Reversal Errors HMD
Liggett and Gallimore findings
• Overall CRE rate 28%, similar to previous studies.
• Magnitude range: 6 degrees to
201 degrees
• A conformal horizon symbol did not reduce CREs.
• Because we know they were not tilting in IMC, they
still had to change frames of reference from world to
aircraft.
Department of Biomedical, Human Factors, & Industrial Engineering
Control Reversal Errors HMD
Liggett and Gallimore findings
• Dependent measure: Altitude Change
– Significant difference
• CRE group average: 3382 ft MSL
• No CRE group average: 1810 ft MSL
• Pilots with CREs obviously confused.
• Focusing on pitch and bank information in central part
of symbology.
• Fail to scan airspeed and altitude information.
Department of Biomedical, Human Factors, & Industrial Engineering
1. Recognition of pilot spatial
awareness strategies
3. Avoidance and recognition
of Visual Illusions (perspective illusion)
Pilot Spatial Awareness Models
Conventional Paradigm
Revised Paradigm
PrimaryVisual
Visual
Primary
SpatialCue
Cue
Spatial
(stablehorizon)
horizon)
(stable
SecondaryVisual
Visual
Secondary
SpatialCue
Cue
Spatial
(moving
cockpit)
(moving cockpit)
2. Avoidance and recognition
of spatial disorientation
(VMC-IMC form/ reversal error)
4. Design of flightdeck displays
Department of Biomedical, Human Factors, & Industrial Engineering
Spatial disorientation
factor
Perspective (moon)
illusion
Department of Biomedical, Human Factors, & Industrial Engineering
Example: Perspective Illusion
Department of Biomedical, Human Factors, & Industrial Engineering
Department of Biomedical, Human Factors, & Industrial Engineering
References Aviation Research
• Jenkins, J. C., and Gallimore, J.J. (2008). Configural display design features to
promote pilot situation awareness in helmet-mounted displays. Aviation,
Space and Environmental Medicine, 79, 397-407
• Stephens, M., Gallimore, J., and Albery, W. (2002) Spectral Analysis of
Electroencephalographic Response to Spatial Disorientation. Proceedings of
the 12th International Symposium on Aviation Psychology: Dayton OH. (pp.
1131-1136).
• Liggett, K.K. and Gallimore, J.J. (2002). The effects of frame of reference and
HMD symbology on control reversal errors. Aviation, Space, and
Environmental Medicine;73:102-111.
• Gallimore, J.J., Liggett, K.K. and Patterson, F.R. (2001). The Opto-Kinetic
Cervical Reflex in Flight Simulation. Proceedings of the American Institute of
Aeronautics and Astronautics Modeling and Simulation Conference and
Exhibit, Aug 6-9, 2001, Montreal, Canada, Paper No: 2001-4191: pp 1-7. *
Best Paper.
Department of Biomedical, Human Factors, & Industrial Engineering
References Aviation Research
•
•
•
•
•
Liggett, K. and Gallimore, J.J. (2001) The OKCR and Pilot Performance During
Transitions Between Meteorological Conditions Using HMD Attitude Symbology.
In Proceedings of the Human Factors and Ergonomics Society 45th Annual
Meeting, (pp. 115-119) Santa Monica. CA HFES.
Gallimore, J.J., Patterson, F.R., Brannon, N.G., and Nalepka, J.P. (2000). The
opto-kinetic cervical reflex during formation flight. Aviation, Space and
Environmental Medicine 2000;71:812-821
Gallimore J. J., Brannon, N. G., Patterson, F.R., and Nalepka, J.P. (1999). Effects
of FOV and aircraft bank on pilot head movement and reversal errors during
simulated flight. Aviation, Space and Environmental Medicine, 70(12):1152-60.
Gallimore, J.J., Brannon, N.G., and Patterson F.R. (1998). The Effects of Field-ofView on Pilot Head Movement During Low Level Flight. In Proceedings of the
Human Factors and Ergonomics Society 42nd Annual Meeting, Chicago, IL (pp.
6-10). Patterson F. R., Cacioppo, A.
J., Gallimore, J.J., Hinman, G.E., and Nalepka, J.P. (1997). Aviation spatial
orientation in relationship to head position and attitude interpretation. Aviation,
Space and Environmental
Medicine, 68(6), 463-471.
Department of Biomedical, Human Factors, & Industrial Engineering
Other Research
• A Predictive Model Of Cognitive Performance Under
Acceleration Stress
– Submitted to Aviation, Space, Environmental Medicine, June 09
• Three-Dimensional Technology for Space Operation
Applications
• Multi-modal Displays for Portraying Meta-Info to
Support Net-Centric C2
• Process Control Displays
• Virtual Patients
• Collaborative Computer Agents with Personality
Department of Biomedical, Human Factors, & Industrial Engineering
Acknowledgements
CDR Frederick Patterson, Ph.D.,
Retired
Naval Aerospace Medical Research Laboratory
United States Navy
Department of Biomedical, Human Factors, & Industrial Engineering
Thank You
Department of Biomedical, Human Factors, & Industrial Engineering