Performance evaluation of evasion maneuvers for parallel approach collision avoidance

Abstract

Current plans for independent instrument approaches to closely spaced parallel runways call for an automated pilot alerting system to ensure separation of aircraft in the case of a "blunder," or unexpected deviation from the normal approach path. Resolution advisories by this system would require the pilot of an endangered aircraft to perform a trained evasion maneuver. The potential performance of two evasion maneuvers, referred to as the "tum-climb" and "climb-only," was estimated using an experimental NASA alerting logic (AILS) and a computer simulation of relative trajectory scenarios between two aircraft. One aircraft was equipped with the NASA alerting system, and maneuvered accordingly. Observation of the rates of different types of alerting failure allowed judgement of evasion maneuver performance. System Operating Characteristic (SOC) curves were used to assess the benefit of alerting with each maneuver. This analysis shows the climb-only maneuver to be a poor substitute for the turn­climb. For a 2500 ft runway spacing and an expected 2 sec pilot reaction time, and with the nominal alerting threshold settings chosen by NASA for the tum-climb, false alarms during blunders are approximately 40 times as likely to induce collisions when using the climb­only as when using the tum-climb, and 40 times as many collisions occur during blunders with the climb-only overall. SOC analysis shows that the safety possible with the climb­only is difficult to distinguish from having no alerting system at all. With the tum-climb there is a clear safety benefit. Alerting performance with the tum-climb is also more resistant to errors in trajectory prediction and evasion maneuver execution.