NTSB Identification: FTW98FA378.
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Accident occurred Saturday, August 29, 1998 in FORT COLLINS, CO
Probable Cause Approval Date: 03/30/2000
Aircraft: Mooney M20F, registration: N377X
Injuries: 2 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

The pilot was returning from a cross-country flight and was observed by witnesses to enter the traffic pattern downwind at an estimated 450 feet agl and very close to the runway. One witness reported that when the aircraft turned base it 'appeared to be a kind of wing-over maneuver.' Another witness said that he 'turned left to the base leg of an approach to runway 11, and [he] quickly increased the bank so that in less than five seconds I could see a full plan view of the airplane at an altitude of approximately 200 feet.' Post-accident investigation indicated that the airplane's bank angle was approximately 30 degrees to the left and 30 degrees nose down upon ground impact. The airport (elevation 4,935 feet, density altitude 7,844 feet) had a local published traffic pattern altitude of 800 feet agl. Post-accident examination of the airplane's altimeter revealed a Kollsman Window setting of 29.96 inches. The closest recorded weather station (7 nautical miles distant and 81 feet above the destination airport elevation) was reporting a barometric pressure of 30.21 inches of mercury. The pilot's altimeter read approximately 250 feet higher than the airplane's actual altitude.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

The pilot's inadvertent stall/mush due to his excessive angle of bank during his traffic pattern turn to base. Factors were the pilot's improper downwind altitude, the pilot not properly setting his Kollsman Window in his altimeter, and the high density altitude.

Full narrative available

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