​Mid-air Collision is an aviation accident category defined as a collision between aircraft in flight. This accident category is rare but when it occurs, it is catastrophic.

To resolve any risk of mid-air collision, immediate and correct flight crew response to Traffic Alert and Collision Avoidance System (TCAS) resolution advisories is crucial.

In 2017, the EUROCONTROL Safety Improvement Sub-Group (SISG) identified "Traffic Alert and Collision Avoidance System (TCAS) Resolution Advisory (RA) Not Followed" as one of the ‘Top 5’ Air Traffic Management (ATM) Operational Safety Priorities and launched a study, targeting pilots which were identified as the best source of information.

The online survey, supported by IATA and several European aircraft operators, prompted 3,800 responses from 90 countries. As a result, it has been decided that IATA, together with industry stakeholders, will be working on raising awareness of the importance of correct compliance with a TCAS RA and eliminating noncompliance.

IATA believes that operators should use their Flight Data Monitoring (FDM) programs to monitor pilot response to TCAS RA to ensure that they are carried out correctly and in a timely manner, addressing any identified shortcomings through training and awareness campaigns.

Assessing pilot compliance to Traffic Alert and Collision Avoidance System

IATA and EUROCONTROL jointly produced guidance on Performance assessment of pilot compliance to Traffic Alert and Collision Avoidance System (TCAS) using Flight Data Monitoring (FDM) (pdf). This document highlights that the most important single factor affecting the performance of TCAS is the response of pilots to RAs. It also states several recommendations to enable TCAS to deliver its safety objective of preventing mid-air collision (PDF).

This guide, which is based on the ICAO provisions and other applicable regulations, suggests that operators must establish procedures detailing how their flight crews should operate TCAS and respond to RAs. This includes but it is not limited to:

  • Pilot responses to RAs;
  • Pilot compliance with RAs;
  • Aircraft operations during an RA;
  • TCAS training;
  • RA reporting;
  • Use of Flight operations Quality Assurance (FOQA)/ and Flight Data Monitoring (FDM) for monitoring and follow up of TCAS RA events.

For further information, please contact safety@iata.org .