Visual display delay effects on pilot performance.

BACKGROUND

The Helmet Integrated Display Sight System (HIDSS), originally proposed for the RAH-66 Comanche, displays sensor data from FLIR and image intensifiers, as well as flight instrument and targeting data. All these data will be processed through onboard computers before being displayed on miniature CRT's. In addition to processing delays, delays also are arising from the helmet tracker and from sensor slewing that may increase the total visual display delay to as much as 250 ms.

METHODS

Because display lag is one of the most important limitations affecting the ability of an aviator to use a display, we investigated the effects of 0, 67, 133, 267, 400, and 533 ms visual display delays on the flight performance of 10 volunteer U.S. Army aviators in a full motion flight simulator.

RESULTS

There were few performance decrements at 67, 133, or 267 ms delays as compared with the 0 ms delay condition. Significant performance decrements consistently were observed at 400 and 533 ms delays.

CONCLUSIONS

Given the anticipated visual display delays for the proposed system, flight performance, as measured within the range of flight conditions and profiles examined, should not be affected significantly, although the aviators will experience an increase in workload to compensate for the delay effects. During low level flight, they will face additional risk due to their proximity to obstacles and a resulting decrease in their time to react and avoid collisions. Given the high accident rates, further research to investigate training strategies to offset delay effects clearly is necessary.