Update to the System Safety Study of TCAS (Traffic Alert and Collision Avoidance System) II.

摘要

This report is an update to the System Safety Study of the Traffic Alert and Collision Avoidance system TCAS II. Since the time of the original study, and its companion study for instrument weather conditions, new data and new concepts have become available. Recent measurements of the Mode C reported altitude in general aviation aircraft strongly indicate that the errors assumed in the previous studies were overly conservative. On the other hand, new data on the vertical separation of aircraft at their closest point of approach indicates that this factor may have been too optimistic. The Advisory Invalid feature of the collision avoidance logic, which would provide a warning against an intruder's sudden levelling-off maneuver, has been replaced with an explicit reversal or increase rate, as the case may require. These and other new concepts in the collision avoidance logic greatly reduce the computed susceptibility to a sudden intruder maneuver, given reasonable pilot reaction. Several features were also introduced into the modified logic to improve interaction with the ATC system. The effects of all of these changes are taken into account in this update. (kr)