General Findings

Responses were received from 13 ANSPs (including one military) and 1 CAA.

Incident seriousness

What are the criteria (if any), in terms of ‘seriousness’ of the incident, that might trigger withdrawal?

The matter of withdrawal is generally a subjective matter, however, ANSPs decide/consider using:

• Severity Cat A, B, C (as per RAT)
• Risk tolerability matrix
• ICAO Annex 13 definition
• Likelihood of national AAIB involvement
• Accident
• Effect of the incident on the controller (physical/mental condition)

There is also general recognition that many events are not of the controller’s making and they may have had no direct or indirect attribution. Nevertheless it is usually still considered prudent to relieve the controller(s) for their own benefit.

Initial Withdrawal

Is post-incident removal an automatic process or can some form of judgment be exercised?