|
Up to now most Enhanced Vision Systems have been based on IR-sensors. Although the penetration of bad weather (dense fog and light rain) by MMW-radar is remarkably better than in the infrared spectrum MMW sensors still have the disadvantage that radar data are often difficult to interpret. Therefore, it's not always possible for the pilot to obtain a reliable detection of runway structures within the radar images. However, prior field tests have shown that the installation of two different types of radar retro-reflectors along the runway can ease the image analysis task significantly and can provide the visual cues necessary to perform precision straight-in landings. A set of corner reflectors has proven suitable to mark the runway edges needed to adjust for lateral deviations and a set of diplane reflectors provided cues to maintain a 3-degree glide path descend.
The present study obtains first objective human performance data to examine the question how efficient pilots are in utilizing these visual cues. The study tested seven VFR and seven IFR-rated pilots and used a low-fidelity human-in-the-loop visual tracking task to simulate a straight-in landing. Pilots were required to detect the lateral and vertical tracking error based on the intensity-coded visual cues provided by the simulated radar images. The study compares two display conditions derived from different spatial arrangements of the diplane reflectors that signal the glide path angles. The first, the so-called "Radar-PAPI", was a horizontal row arrangement of four diplanes, and the second, the "Radar VASI", was a two-over-two arrangement of four diplanes. A third condition simulated the existing visual color coded PAPI landing aid and served as a baseline reference. Performance evaluation was based on the calculation of the root-mean-square error for both axis and subjective preference statements of the pilots.
|
