Accident Details
Probable Cause and Findings
THE PILOT'S IMPROPER USE OF CARBURETOR HEAT WHICH LED TO CARBURETOR ICING AND A PARTIAL LOSS OF ENGINE POWER. FACTORS CONTRIBUTING TO THE ACCIDENT ARE PREVAILING CARBURETOR ICING CONDITIONS, AND THE PILOT'S FAILURE TO PROPERLY JUDGE THE AIRPLANE'S DISTANCE AND SPEED DURING THE FORCED LANDING.
Aircraft Information
Registered Owner (Current)
Analysis
On July 21, 1995, about 1555 Alaska daylight time, N7755H, a Piper PA-12, collided with terrain during a forced landing in Anchorage and was substantially damaged. The forced landing was precipitated by a partial loss of engine power while the airplane was maneuvering. The private pilot received minor injuries and the sole passenger received serious injuries. Visual meteorological conditions prevailed and no flight plan had been filed. The personal flight was conducted under 14 CFR 91.
The pilot stated that the accident flight was the first flight since the engine was rebuilt. After a preflight inspection and successful engine run-up, the airplane departed from a private airstrip and maneuvered about 700 feet above the airstrip. The pilot reported that the "engine lost power," but did not stop. The pilot immediately descended and maneuvered to approach the airstrip and land to the north. He overshot the landing strip and purposely stalled the airplane in an effort to avoid colliding with obstructions. The airplane impacted terrain about 200 feet beyond the end of the runway and was substantially damaged.
An examination of the engine and fuel system did not reveal evidence of any mechanical deficiencies. The reported temperature and dew point near the time and place of the accident were 59 degrees F and 57 degrees F respectively. According to the Carburetor Icing Probability Chart published by the FAA (attached), the prevailing weather conditions could produce "serious icing at cruise power" in light aircraft piston engines.
The pilot stated that he had applied full carburetor heat immediately upon sensing the power loss, with no effect noted. He said the airplane could not maintain altitude, but the engine continued to run.
Data Source
Data provided by the National Transportation Safety Board (NTSB). For more information on this event, visit the NTSB Records Search website. NTSB# ANC95LA111