Part-Task Simulation Study of Candidate Terrain Alerting Displays (1993)
Evaluate three advanced electronic terrain alerting displays: (1) plan
view depiction based on EHSI, (2) profile view showing vertical path of
aircraft relative to terrain, (3) three-dimensional perspective view of
terrain on the EADI. Determine which displays are best suited to
different hazard situations, as well as the displays' abilities to
convey the true level of hazard posed to the aircraft.
Plan View Terrain Display (click on picture for full size)
Profile View Terrain Display (click on picture for full size)
Perspective View Terrain Display (click on picture for full size)
Three display formats (plan, profile, and perspective) were evaluated in
a part-task simulation study using active line pilots on the MIT
Advanced Cockpit Simulator. Subjects flew 12 terrain alert scenarios
with each display format: 4 involved straight & level flight, 4 were
situations where the aircraft was turning, and 4 were descents. The 4
scenarios for each type of flight condition were further broken down
into 4 levels of terrain hazard ranging from non- hazardous to extremely
hazardous. These hazard levels were quantified according to the minimum
pull-up maneuver required to avoid terrain. Terrain hazards popped up
on the display, after which the pilot made a subjective assessment of
the hazard level by pressing one of 4 buttons on the sidestick
controller, each corresponding to a different hazard level. The pilot
then flew an avoidance maneuver as appropriate to the situation.
No display format was entirely effective in conveying
the true level of hazard when descending into flat terrain. In 50% of
the cases where pilots used the plan or perspective views, the
aircraft impacted the terrain before pulling out. The profile and
perspective displays overemphasized the level of hazard when the
aircraft was turning safely in front of a ridge line. Lateral
maneuvers were initiated 80% of the time when using the plan view
display, 30% of the time when using the perspective display, and in 5%
of the cases with the profile display. Subjects performed
significantly fewer wings-level pull-up maneuvers when using the plan
view display as opposed to the perspective or profile displays.
Subjects preferred the plan or perspective displays, stating that the
increased lateral information available on these displays was
Lateral Maneuver Initiation
Maneuvers While Turning
Subjective/True Hazard Level Results
Each display format had drawbacks, though the data suggest that a
combined plan-profile system may provide the lateral information needed
during turning maneuvers and the vertical profile information needed
when monitoring pull-up maneuvers. The high rate of lateral maneuver
initiation shows a tendency to turn rather than perform wing-level
pull-up maneuvers as are presently prescribed, especially when given
lateral terrain information on the display.
"Part-Task Simulator Evaluations of Advanced Terrain Displays", SAE
Aerotech '93 paper 932570, Costa Mesa, CA, September, 1993.
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