Description

A Airborne Collision Avoidance System (ACAS) Alert Prevention (TCAP) functionality has been introduced by Airbus to prevent the generation of Resolution Advisory (RA) in 1000-foot level-off geometries. The functionality which is currently available for the Airbus wide body aircraft (and expected to become available on the A320 family of aircraft) uses a new altitude capture law for flight guidance computers, which decreases aircraft’s vertical rate towards the selected altitude, once a Traffic Advisory (TA) has been generated and the autopilot and/or flight director are engaged.

The TCAP functionality is complementary to the flight guidance computer’s conventional altitude capture function.

The TCAP functionality has been specified in the Minimum Aviation System Performance Specification (MASPS) for Flight Guidance System (FGS) coupled to ACAS published by European Organisation for Civil Aviation Equipment (EUROCAE) (ED-224).

Illustration of an encounter without and with TCAP functionality

Related Articles

• Airborne Collision Avoidance System (ACAS)
• ACAS Resolution and Traffic Advisories
• Autopilot/Flight Director (AP/FD) TCAS capability

Further Reading

HindSight Articles:

• Hindsight 12 - TCAP: an altitude capture enhancement to prevent TCAS RAs

EUROCONTROL:

• ACAS Guide - Airborne Collision Avoidance Systems, December 2017