If you wish to contribute or participate in the discussions about articles you are invited to join SKYbrary as a registered user



From SKYbrary Wiki

Article Information
Category: Loss of Separation Loss of Separation
Content source: SKYbrary About SKYbrary

Near Mid Air Collision

According to the TCAS MOPS[1], Near Mid Air Collision (NMAC) occurs when two aircraft come within 100 feet vertically and 500 feet horizontally.

An AIRPROX which, unlike NMAC, has a formal but non-empirical ICAO definition, is commonly described as a Near Midair Collision (NMAC) in the USA but without necessarily applying the defintion quoted above. So whereas an NMAC is usually likely to also be an AIRPROX, an AIRPROX is not necessarily an NMAC.

See the main article AIRPROX


  1. ^ Minimum Operational Performance Standards