A Human Subject Evaluation of Airport Surface Situational Awareness Using Prototypical Flight Deck Electronic Taxi Chart Displays

FA5E2/A5007
A study was conducted to test the effect on airport surface situational awareness of GPS derived position information
depicted on a prototypical electronic taxi chart display. The effect of position error and position uncertainty
symbology were also tested. Situational awareness was assessed by asking 12 airline pilots a series of probe questions
about their location on the airport surface. The pilots used static "snapshot" images of a north-up electronic taxi
chart as well as a supporting out-the-window view and an aircraft heading display to answer the situational awareness
probe questions.
Four levels of GPS position error were tested ranging from 4.5 to 90 meters. Two types of position uncertainty
symbology were also tested. The variable radius uncertainty circle displayed an estimate of the current GPS position
accuracy while the constant radius uncertainty circle displayed a worst-case system accuracy of 100 meters.
Situational awareness, as indicated by probe question response accuracy, increased when aircraft position information
was displayed on the electronic taxi chart. In addition, response time was also found to improve with the presence of
aircraft position information. Response accuracy improved as position error decreased from 90 to 22.5 meters and stayed
relatively constant from the 22.5 to 4.5 meter case. Pilots were faster at responding to the probe questions with the
variable radius uncertainty symbology. In addition, pilots subjectively preferred the variable radius uncertainty
circle.