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Midair CollisionMidair Collision


NTSB CHI97FA218A - This week's Air Safety Institute's "Accident of the Week" tells what the NTSB found in a midair collision about five years ago near Chicago, one with important similarities to last week's tragic Denver midair collision. The 1997 collision of a Cessna 172 and a Beech Bonanza three miles south of Meigs Field left all occupants of both airplanes dead.

The weather at the time of the accident was VFR, with scattered clouds at 15,000 feet and a visibility of 10 miles.

The 172 was southbound toward Meigs Field, sightseeing over Lake Michigan, while the Bonanza was approaching Meigs from the south for landing on runway 36. Meigs ATC asked the pilot of the 172 for an "abeam the airport" advisory, and advised of the Bonanza. (The Bonanza pilot was not advised of the 172.) Witnesses in the area said the airplanes collided at approximately 1000 feet over the lake.

The NTSB stated that the cause of the accident was the pilots' not maintaining visual separation. A factor was the failure of the 172 pilot to report abeam the airport.

An Air Safety Instituten study of midair collisions revealed that 49 percent occurred in the traffic pattern or on approach to or departure from an airport. Of the other 51 percent, about half occurred during en route climb, cruise, or descent, and the rest resulted from formation flights or other hazardous activities. Eighty percent of the midair collisions that occurred during "normal" flight activities happened within ten miles of an airport, and 78 percent of the midair collisions that occurred around the traffic pattern happened at nontowered airports. Important strategies for avoiding these mishaps can be found in two of the institutes's Safety Advisors, Operations at Nontowered Airports, and Collision Avoidance: Strategies and Tactics.

The recent collision over Denver is unique for many reasons. First, it occurred at night, with the possibility that ground lighting affected both pilots' ability to see and avoid the other. During 2000 and 2001, all midair collisions involving general aviation aircraft occurred during day VFR conditions. Second, both aircraft were utilizing VFR flight following. A preliminary search of the ASF database did not return any other midair collisions that occurred while flight following was being used by both aircraft. Third, the area where the airplanes were operating is congested. Mountains, class B airspace, and class D airspace surround the corridor in which the pilots were flying.

Although this midair collision was unique in some respects, it had elements often found in other midair collisions. Preliminary information on this accident from the FAA and NTSB indicates that the 172 (high wing) was climbing, and the Cheyenne (low wing) was descending. This results in a blind spot between the two aircraft.

Though ATC may provide traffic advisories while in radar contact, it is still the responsibility of the PIC to maintain separation. All pilots need to learn how and what to look for to avoid a mid air collision. Proper 'See and Avoid' techniques as well as proper scanning will help to reduce future midair collisions.

This accident report as well as others can be found in ASI's Online Database.