Frequency of Anti-Collision Observing Responses by Solo Pilots as a Function of Traffic Density, ATC Traffic, and Competing Behavior

Eighteen instrument-rated pilots were flown in two-hour simulated solo missions during which the frequency of traffic, ATC warnings, and ATC clearances were varied, while the visibility of the target was held constant at 100%. In order to observe the target, the pilot was required to make a simple, overt observing response; i.e., the pilot has to press a button on his control wheel. If traffic was present, a burst of flashes became visible through the windshield. Button presses in the absence of traffic produced no stimulus. Each pilot was his primary responsibility to maintain visula vigilance, although ATC would endeavor to warn him of possible conflicting traffic. Two values of traffic frequency were programmed independently of two values of ATC traffic warning frequency. The frequency of competing behavior was varied by independent scheduling of two values of ATC clearance frequency. (Modified author abstract)