Pilot Performance during Simulated Approaches and Landings made with Various Computer-Generated Visual Glidepath Indicators

Two simulator experiments were conducted to quantify the effectiveness, in terms of pilot performance, of four different visual glidepath indicator systems in the severely reduced nighttime visual environment often referred to as the black hole. A Convair 580 aircraft simulator was used with a computer-generated-image visual system attached for visual simulation of the airport scene. In Experiment I, four groups of six pilots flew simulated night approaches both with and without simulated glidepath indicators. Each group used a different type of indicator, either the standard RedWhite 2-bar or 3-bar VASI system, the Australian T-VASIS, or a British experimental system PAPI all were designed to define a 3 degrees glidepath. All indicators greatly reduced deviations from the 3 degrees glidepath reference. Performance was best with the T-VASIS and decreased with the 3-bar VASI, PAPI, and 2-bar VASI in that order, but differences between T-VASIS, 3-bar VASI, and PAPI were not statistically significant. Approaches flown without the ground-based glidepath indicators tended to be low and were extremely variable in this simulation where only runway lighting provided vertical guidance information. Experiment II compared the T-VASIS and 2-bar VASI regarding observing behavior in three pilots who made approaches with both systems. Differences in performance with different indicators were attributed to the rate of information change provided by a given system and to rate of observing the indicator during approaches.