Accident Summary
On August 22, 2010, about 0833 Pacific daylight time, a Cessna 172E airplane, N7807U, sustained substantial damage following an in-flight collision with terrain at the Mammoth Yosemite Airport, Mammoth Lakes, California. The private pilot and three adult passengers received serious injuries. The airplane, which was being operated by the pilot as a personal cross-country flight under 14 Code of Federal Regulations Part 91, originated from Mammoth Lakes.
Pilot and Witness Accounts
The pilot reported in a written statement to the National Transportation Safety Board that shortly after takeoff the airplane encountered turbulence and a downdraft, resulting in a rapid loss of altitude. The pilot attempted to control the airplane, but it impacted terrain in a nose-low attitude.
The front seat passenger, in a telephone conversation with an NTSB investigator, stated that the takeoff roll was long and they "had a little time taking off, gradually going up with the buzzer going off." Shortly after liftoff, the airplane encountered an updraft followed by a downdraft. The pilot initiated a left turn, which the passenger described as a "stall."
Aircraft and Weather Information
The four-seat, high-wing, fixed-gear airplane was manufactured in 1964 and powered by a Continental O-300, 145-hp engine with a fixed-pitch propeller. Its published maximum gross takeoff weight was 2,300 pounds; the pilot did not report the actual takeoff weight.
Recorded weather data from the airport's automated station at 0829 showed wind from 220 degrees at 5 knots, visibility 10 statute miles, temperature 18 degrees Celsius, and altimeter setting 30.18 inches of mercury. The airport elevation is 7,135 feet, resulting in a calculated density altitude of approximately 8,900 feet at the time of the accident.
A post-impact examination of the airframe and engine found no anomalies that would have precluded normal operation.