Definition
An incident in flight in which the possibility of a collision occurs as a result of two or more aircraft coming within 500 feet of each other. The pilot or flight crew of either aircraft may file a Near Midair Collision (NMAC) report with the FAA.
Plain English
A close call in the air. Two aircraft pass within 500 feet of each other, close enough that a crash was a real possibility. It didn't happen, but it almost did.
Context Anchor
Seen in collision avoidance discussions, pilot reports, and safety material about scanning for traffic and avoiding other aircraft.
Derivation
Near means close to something. Midair means while in the air. Collision means a crash or impact. Together, the phrase points to a situation where aircraft nearly hit each other while flying.
Why Pilots Care
Near midair collisions are reported so that safety data can reveal patterns and reduce the chance of an actual collision.
Intuition Check
Do not read near midair collision as just any uncomfortable sighting of another airplane. In this aviation use, it means the aircraft were close enough to create a real collision hazard, often within 500 feet.
Example Sentence 1
After landing, the pilot filed a near midair collision report describing the traffic that had passed less than 300 feet below the airplane.
Example Sentence 2
Good lookout and radio calls help prevent a near midair collision when several aircraft are operating at the same nontowered airport.