Description

This article describes how transponder failure affects the different types of safety barriers and provides an overview of the measures that may mitigate the impact.

Airborne safety barriers (collision avoidance)

The most common airborne safety barriers are Airborne Collision Avoidance System (ACAS), also called TCAS, (equipment-based) and see-and-avoid practiced by the flight crew (human factor-based).

TCAS is one of the most robust barriers because it is installed on most aircraft and has proven to be highly reliable. Most transponder failures, however, can render the TCAS (almost) unusable: