WPR11LA025

The pilot reported that, while the airplane was level at 15,000 feet in instrument meteorological conditions, he failed to apply carburetor heat to the engine. After several minutes, the engine began losing power, and the airplane was not able to sustain flight. During the descent for a forced landing in mountainous terrain, the airplane descended below the cloud base about 2,000 feet above the ground, and the pilot observed a road and a clearing. During the landing rollout, the airplane impacted trees, which severed its wings. Icing probability charts indicated that carburetor ice was probable under the atmospheric conditions in which the airplane had been flying. The pilot reported that if he had applied the carburetor heat during flight, the accident likely would not have occurred.

On October 23, 2010, about 1427 Pacific daylight time, a Piper PA-28-236, N228KK, experienced a partial loss of engine power during cruise flight. Unable to sustain flight, the pilot made a forced landing in mountainous terrain, about 4 miles east of Dorrington, California. The airplane was owned and operated by the pilot, and it was substantially damaged. The instrument rated private pilot received minor injuries. Instrument meteorological conditions prevailed at the time of the personal flight that was performed under the provisions of 14 Code of Federal Regulations Part 91. An instrument flight rules (IFR) flight plan was filed. The flight originated from Truckee, California, about 1330. The pilot reported to the National Transportation Safety Board investigator that he was cruising at 15,000 feet and was en route to Borrego Valley Airport, Borrego Springs, California. The engine became rough, and then most of the power was lost. The pilot notified the Oakland Air Route Traffic Control Center of his emergency, and they tracked the airplane's descending flight path until it disappeared from radar about 1418. The pilot stated that he broke out of the clouds about 2,000 feet above the ground and observed a road and a clearing. During landing rollout, the airplane collided with trees, which severed the airplane's wings and bent the stabilator. From the crash site, the pilot used his cell phone to telephone the Federal Aviation Administration (FAA). He provided the FAA and local rescue authorities with his precise global positioning system's coordinates in the Stanislaus National Forest. The pilot was rescued from his 5,400-foot mean sea level (msl) crash site location before sunset. The closest airport to the accident site was located about 44 miles from the crash site at South Lake Tahoe, California (TVL). This airport’s elevation is 6,264 feet msl. At 1353, TVL reported an overcast sky condition at 2,900 feet above ground level and light rain. Its temperature and dewpoint were 8 and 5 degrees, respectively. The pilot reported to the Safety Board investigator that the airplane climbed to about 15,000 feet msl approximately 10 minutes before the accident. He was cruising in actual instrument meteorological conditions. The outside air temperature was about -10 degrees Celsius. No ice was observed on the windshield or wings. The carburetor heat was off. Although the engine slowly lost manifold pressure, it never quit running. The pilot additionally stated that he did not initially think of turning on the carburetor heat. Eventually, the engine lost so much power that he could not sustain flight. Published icing probability charts indicate that at -10 degrees Celsius (14 degrees Fahrenheit) with 100 percent humidity, icing is likely when operating at cruise engine power. In the pilot’s completed aircraft accident report, he opined that the cause of the loss of engine power was due to carburetor ice. He stated that had he used the carburetor heat,the accident likely would have been avoided.