McGrath, AK, USA
N2413H
PIPER PA-18-150
The pilot and passenger were in the first in a flight of two airplanes operating as a personal cross-country flight. As the flight progressed, both airplanes descended due to deteriorating weather conditions as they passed over an area of steep mountainous terrain. The second pilot said that visibility deteriorated to a point that it was difficult to discern topographical features. He then lost sight of the first airplane, so he elected to turn around. No further radio communications were received from the accident airplane. The airplane’s wreckage was subsequently found in an area of mountainous terrain, along the anticipated flight path, at the end of a box canyon. During the on-scene examination of the wreckage, no preaccident mechanical anomalies were discovered. Given the lack of mechanical anomalies, the reported weather conditions, and the statement of the pilot of the second airplane, it is likely that the pilot of the accident airplane flew into instrument meteorological conditions while trying to maneuver the airplane through mountainous terrain. Additionally, given the impact signatures, it’s likely that the pilot was attempting to avoid rising terrain by climbing the airplane, which resulted in an aerodynamic stall.
HISTORY OF FLIGHT On August 12, 2010, about 1500 Alaska daylight time, a Piper PA-18-150 airplane, N2413H, sustained substantial damage during a loss of control and subsequent impact with terrain near McGrath, Alaska. The airplane was being operated as a visual flight rules (VFR) personal cross-country flight under 14 Code of Regulations Part 91, when the accident occurred. The pilot and passenger sustained fatal injuries. Instrument meteorological conditions were reported in the area at the time of the accident, and no flight plan was in effect. The cross-country flight originated from Tanana, Alaska, and was en route to McGrath, Alaska. The accident airplane was the first in a flight of two airplanes. The pilot of the second airplane reported that while following the lead airplane towards McGrath, he noticed that the weather was deteriorating in front of them. He stated that the weather to the west and east appeared better, but the lead airplane continued straight towards an area of mountainous terrain, and worsening weather. Thinking perhaps that the lead pilot was aware of a pass through the mountains, he continued to follow. He said that once they passed the first mountain ridge, the weather became turbulent, dark, and rainy, and that both airplanes had to descend to remain clear of clouds. Around this time, the pilot of the lead airplane radioed, “Buddy are you still with me?” The second pilot responded, “barely,” and then lost sight of the lead airplane. As soon as the second pilot lost sight of the lead airplane, he radioed that he was “out of here” and turned around. The lead pilot did not respond. Approximately 3 minutes after he turned around, the pilot heard a short burst of noise on the radio that sounded like an open microphone. He repeatedly attempted to contact the lead pilot to no avail, and eventually continued on to McGrath via a different route. The airplane wreckage was located by searchers the next day, in an area of rising terrain at the end of a box canyon. PERSONNEL INFORMATION The pilot, age 79, held a commercial pilot certificate with single engine land and sea airplane ratings. He held a third class Federal Aviation Administration (FAA) medical certificate, dated June 5, 2009, with a restriction that he must wear hearing amplification. No personal flight records were located for the pilot, and the aeronautical experience was obtained from insurance records updated in March 2010. The pilot indicated that he had accumulated 19,500 hours total flight time, with 7,000 hours in the PA-18, and 300 hours in the previous 12 months. AIRCRAFT INFORMATION The airplane was equipped with a Lycoming O-320 engine, rated at 150 horsepower. No aircraft or engine logs were located for review. METOROLOGICAL INFORMATION The closest official weather observation station to the accident site was the Nikolai Airport, Nikolai Alaska, which was located about 32 nautical miles southeast. On August 12, at 1456, an Aviation Routine Weather Report (METAR) reported in part: Wind, 210 degrees at 3 knots; visibility, 5 statute miles with light rain showers and mist; clouds, 500 feet scattered, 1,000 feet broken, 1,100 feet overcast; temperature, 52 degrees Fahrenheit; dew point, 48 degrees F; altimeter, 30.18 inHg. Remarks: One-hourly precipitation 0.19 inches. The area forecast for the lower Yukon Valley (which encompasses the accident area) called for scattered clouds at 1,500 mean sea level (msl), a broken ceiling at 3,500 feet msl, and broken skies at 9,000 feet msl with cloud tops to flight level 250. An occasional broken ceiling at 1,500 feet msl was forecast with 5 statute miles visibility and light rain. There was an Airmen's Meteorological Information advisory (AIRMET) issued for possible mountain obscuration in clouds and precipitation. The pilot of the second airplane reported that the weather in the area at the time of the accident was deteriorating, with rain, low cloud ceilings, and turbulence. WRECKAGE AND IMPACT INFORMATION On August 13, the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), and an inspector from the FAA’s Anchorage Flight Standards District Office examined the wreckage at the accident site. The airplane came to rest upright with its nose pointing downhill on an estimated heading of 130 degrees. Impact signatures were consistent with a left wing and nose low impact. All of the airplane's major components were accounted for, and control continuity was established to all flight controls. The left wing was displaced aft from its normal position, with extensive leading edge crushing, and upward bending from approximately the mid-span of the wing outboard. The right wing had leading edge damage and was displaced forward from its normal position. The fuselage showed extensive buckling of the frame structure. The empennage was canted approximately 10 degrees left of its normal position. The vertical and horizontal stabilizers were relatively free of impact damage. The engine propeller had separated from the engine crankshaft. Both propeller blades exhibited chord-wise scratches and gouges. The outer tips of both propeller blades were separated during impact with the rocky terrain. The engine remained attached to the airframe, but the top engine mounts were separated and displayed fractures consistent with an overload failure. The engine had impact damage to the front, underside, and the left forward side of the crankcase. The on-site inspection of the engine revealed no mechanical anomalies that would have prevented normal engine operation. The cockpit area was extensively damaged. The engine and firewall were displaced upward and aft, and the instrument panel was displaced upward. The airplane was not equipped with shoulder harnesses and neither occupant had been wearing a lap belt. The emergency locator transmitter was found in the “OFF” position. MEDICAL AND PATHOLOGICAL INFORMATION A postmortem examination of the pilot was done under the authority of the Alaska State Medical Examiner, Anchorage, Alaska, on August 16, 2010. The examination revealed the cause of death for the pilot was attributed to multiple blunt force trauma. The FAA's Civil Aerospace Medical Institute, Oklahoma City, Oklahoma, performed toxicological tests on specimens that were collected during the autopsy. Results were negative for carbon monoxide, cyanide, and ethanol. Diphenhydramine was detected in the urine, and 0.007 ug/ml Diphenhydramine was detected in the blood. Diphenhydramine is an over the counter sedating antihistamine used to treat allergies, hay fever, common cold symptoms, nausea, vomiting, and dizziness caused by motion sickness. Diphenhydramine may also be used as a sleep aid. Diphenhydramine is found in medications such as Benedryl, Unisom gelcaps, Nytol, and Sominex. TESTS AND RESEARCH At the time of the accident, the pilot was using a Garmin GPSMAP 396 portable global positioning system (GPS) receiver, capable of storing route-of-flight data for up to 50 flights. The unit was recovered from the accident site by the NTSB IIC, and was sent to the NTSB’s Vehicle Recorders Division for examination. A NTSB electrical engineer was able to extract the GPS data for the accident flight, which included, in part: time, latitude, longitude, and GPS altitude. Groundspeed and course information were derived from the extracted parameters. The GPS flight track data coincided with the description of the flight by the pilot of the second airplane. A flight track map overlay, and tabular data corresponding to the accident flight are available in the public docket for this accident.
The pilot’s continued visual flight into instrument meteorological conditions and the airplane’s subsequent aerodynamic stall, which resulted in an in-flight collision with mountainous terrain.
Source: NTSB Aviation Accident Database
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