WPR10LA417

Factual narrative

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 sustained serious injuries. The airplane sustained structural damage to the forward fuselage and wings. The airplane was being operated by the pilot as a personal cross-country flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91, when the accident occurred. Visual meteorological conditions prevailed, and no flight plan was filed. The flight originated from Mammoth Lakes. In a written statement to the National Transportation Safety Board (NTSB), the pilot reported that shortly after takeoff the airplane encountered turbulence and a downdraft, and began to lose altitude rapidly. The pilot stated he tried to control the airplane; however, it impacted terrain in a nose-low attitude. During a telephone conversation with the NTSB investigator-in-charge, the front seat passenger stated that the takeoff roll was long and they "had a little time taking off, gradually going up with the buzzer going off." He reported that shortly after liftoff, the airplane encountered an updraft followed by a downdraft. He stated the pilot initiated a turn to the left which was followed by a "stall." The four-seat, high-wing, fixed-gear airplane was manufactured in 1964, and powered by a Continental O-300, 145-hp engine. The airplane was equipped with a fixed-pitch propeller. The published maximum gross takeoff weight for the airplane was 2,300 pounds. The pilot did not report the actual takeoff weight of the airplane. A review of recorded weather data from the automated weather observation station at the airport revealed at 0829 conditions in part were: wind from 220 degrees at 5 knots, visibility of 10 statute miles, temperature 18 degrees Celsius, and altimeter 30.18 inches of mercury. The airport elevation was 7,135 feet. Using the reported temperature and altimeter setting, the calculated density altitude during the time of the accident was approximately 8,900 feet. A post impact examination of the airframe and engine did not reveal any anomalies with the airframe or engine that would have precluded normal operation. The pilot reported that, shortly after takeoff, the airplane encountered turbulence and a downdraft and began to rapidly lose altitude. The pilot was unable to maintain control, and the airplane subsequently collided with the terrain in a nose-low attitude. According to the front-seat passenger, the takeoff roll was long, and the airplane gradually climbed with the stall warning indicator buzzing. He stated that the airplane encountered an updraft followed by a downdraft, the pilot initiated a turn to the left, and the airplane subsequently stalled. The calculated density altitude at the airport at the time of the accident was about 8,900 feet. A postaccident examination of the airframe and engine did not reveal any anomalies that would have precluded normal operation. Source: NTSB Aviation Accident Database Retrieved: 2026-02-12

NTSB Findings

FAA avdata. C = Cause, F = Factor.

• C Aircraft-Aircraft oper/perf/capability-Performance/control parameters-Airspeed-Not attained/maintained - C
• C Personnel issues-Task performance-Use of equip/info-Aircraft control-Pilot - C
• — Environmental issues-Conditions/weather/phenomena-Temp/humidity/pressure-High density altitude-Effect on equipment
• — Environmental issues-Physical environment-Terrain-High elevation-Effect on operation