What is the definition of...

[megreene]

...a near mid air collision?

 

[avbug]

The AIM (7-6-3) defines a near mid air collision (NMAC) as "“an incident associated with the operation of an aircraft in which a possibility of collision occurs as a result of proximity of less than 500 feet to another aircraft, or a report is received from a pilot or a flight crew member stating that a collision hazard existed between two or more aircraft.”

A good paper about the subject:

http://www.fs.fed.us/r6/fire/aviation/airspace/web/links/dover.pdf

 

[erj-145mech]

Wouldn't that be a "near hit"?

A near miss would be more appropriate, dontcha think?

 

[avbug]

Semantics, I suppose. When I was just out of high school and started spraying, we used each other for markers to save on flags. Normally, we'd fire a flag off the wing as we exited the field, and entered the field, and at one or two points in the field, sometimes, to mark our run (all done with GPS, today). The flags cost about a quarter, and running big fields and lots of acres, it could add up. What we did was space ourselves so that the airplane inbound on a swath run used the airplane pulling off the field as a marker. Passing within a few feet of one another wasn't at all uncommon. Some might call that a near hit, others a near miss.

Technically a near miss would be a hit...because the two aircraft nearly missed. Two aircraft that come close but don't hit would be a near hit. The media loves the term near miss, and it's obtained industry acceptance as a NMAC, or near mid-air collision. In this case, near miss is short for the hyphenated near mid-air collision, or in short, near collision. In theory, one could say there are near or nearly collisions, and far misses too...which hardly make great headlines.

I've flown with a lot of pilots who think their throad is cut if they pass within a mile of another airplane laterally. I guess for them a NMAC is being able to see the other airplane. Others, of course, live in the TCAS window, and never seem to look outside...

 

[igneousy2]

It depends on the situation - if both pilots see each other - know what they are doing then there is no "collission hazard". Sometimes that means 50 feet is okay if you are in a C152 and that guy is going to stay on the other side of that road. When you are in RVSM airspace at FL390, 700' could be a near miss with 900 knots closure.

I've also considered my actions when declaring a "near miss". If I respond to an RA or because I saw the airplane at the last minute, and I feel I would have hit the other aircraft - but for the RA or my drastic actions - I usually report it as a near miss even if the closure may not have been less than 500'.

later