near midair collision

near midair collision (NMAC)

An incident associated with the operation of an aircraft in which a possibility of a collision occurs as a result of a proximity of less than 500 ft (150 m) to another aircraft, or a report is received from a pilot or a flight crewmember stating that a collision hazard existed between two or more aircraft. It is the responsibility of the pilot and/or flight crew to determine whether a near midair collision did actually occur and, if so, to initiate an NMAC report. The report should include the time and the location of the incident and altitude; the identification and type of reporting as well as of other aircraft; the aircrew's destination; the name and home base of the pilot; the type of flight plans; the station altimeter setting used; the weather conditions at the altitude of the incident; the approximate course of both aircraft and if any of the aircraft was climbing or descending; the reported separation in distance at the first sighting; the proximity at the closest point horizontally and vertically and the length of time in sight prior to evasive action; and the details of evasive action and injuries to personnel, if any. There are various degrees of hazard (NMAC):
i. Critical. A situation in which collision avoidance was due to chance rather than an act on the part of the pilot. Less than 100 ft (30 m) of aircraft separation would be considered critical.
ii. Potential. An incident that would probably have resulted in a collision if either pilot had taken no action. A proximity of less than 500 ft (150 m) would usually be required in this case.
iii. No hazard. A situation in which direction and altitude would have made a midair collision improbable regardless of the evasive action taken.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved
References in periodicals archive ?
A search of the near midair collision (NM AC) database yields 819 events involving IFR aircraft since 1992 and 166 events in the last decade.
According to the official report, submitted by the four-man crew after the incident, they "encountered a near midair collision with an unidentified flying object" while flying over Mansfield, Ohio, around 11:00 p.m., and this incident still remains one of the most credible and terrifying in the history of the subject, the Huffington Post reported.
Staff of the US National Transportation Safety Board (NTSB) are investigating a near midair collision of a US Airways Airbus A319 and a Cargolux Boeing 747.
US National Transportation Safety Board said it is investigating a "near midair collision" between a Cayman Airways Boeing 737-300 and a LAN Airlines 767-300 over New York JFK on July 5.
One week after a frightening near miss between two Japan Airlines jetliners over Yaezu in Shizuoka Prefecture, it seems almost certain that the near midair collision was caused by a combination of human errors.
US National Transportation Safety Board said it is investigating a near midair collision Saturday involving a United Airlines 777-200 departing San Francisco and a private aircraft that came within 300 ft.
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