Primary finding
Probable cause
The pilot's delay in aborting the takeoff. The pilot's premature rotation and his failure to follow the procedures in the airplane flight manual regarding use of the mixture control, the high density altitude condition and the pilot's lack of total flight expereince were factors in the accident.
Investigator assessment
Analysis narrative
The pilot said he was departing the Alturus municipal airport, which has an elevation of 4,375 feet MSL. The official weather observation for the airport reported a temperature of 83 degrees 20 minutes after the accident, for a computed density altitude of 7,100 feet. The pilot noted that the engine ran smoothly during the takeoff ground roll, but did not seem to reach full RPM. He said that at about 50 knots he rotated the nose of the aircraft and it climbed about 10 feet, then settled back onto the pavement. The pilot noted that he attempted several times to lift off the runway, but the aircraft would not climb off of the pavement. The pilot stated that he then aborted the takeoff, over ran the departure end of the runway and collided with a ditch and a fence. The flight manual for the aircraft states that the mixture should be leaned for takeoff at fields with elevations above 3,000 feet. The rotation speed specified in the flight manual for a normal takeoff is 55 knots.
Source record
Factual narrative
On July 9, 1993, at 1325 Pacific daylight time, a Cessna 172N, N75901, collided with a ditch during an on ground takeoff runway over run at the Alturus municipal airport, Alturus, California. The aircraft was operated by Executive Flyers, Inc., of Sacramento, California, and was rented by the pilot for a cross country flight. Visual meteorological conditions prevailed at the time and included calm winds. The aircraft incurred substantial damage. Neither the certificated private pilot nor his one passenger were injured. The flight was originating at the time of the accident as a cross country personal flight to Sacramento, California. According to oral and written statements by the pilot, he said he was departing on the 3,600 foot long runway 21 at the Alturus municipal airport, which has an elevation of 4,375 feet MSL. The pilot noted that the engine ran smoothly during the takeoff ground roll, but did not seem to reach full RPM. He said that at about 50 knots he rotated the nose of the aircraft and it climbed about 10 feet, then settled back onto the pavement. The pilot noted that he attempted several times to lift off the runway, but the aircraft would not climb off of the pavement. The pilot stated that he then aborted the takeoff, over ran the departure end of the runway and collided with a ditch and a fence. Based on an official weather observation taken for the National Weather Service at Alturus, the temperature was recorded as 83 degrees about 20 minutes after the accident. The density altitude was computed at about 7,100 feet. The Airplane Flight Manual for the aircraft states that the mixture should be leaned prior to takeoff at fields with elevations above 3,000 feet. The rotation speed listed in the flight manual for normal takeoff's is 55 knots. -