Aviation Accident Summaries

Aviation Accident Summary ANC86FA167

PORT ALSWORTH, AK, USA

Aircraft #1

N9109D

Piper PA-18

Analysis

On September 13, 1986, a Piper PA-18 departed Merrill Field Airport, Anchorage, Alaska, about 1145, and was en route to a remote, undisclosed hunting camp. When the pilot failed to return for a second trip, an aerial search was initiated on September 20, 1986, one day after the pilot's wife reported the flight overdue. An extensive search was conducted in the area believed to be the accident pilot's intended destination. The airplane was not found until October 6, 1999, thirteen years later, by a pilot scouting for game. The accident airplane was located in an area of steep mountainous terrain, about 3,000 feet msl. The airplane was destroyed by impact and postimpact fire.

Factual Information

On September 13, 1986, at an estimated time of 1350 Alaska daylight time, a tundra tire equipped Piper PA-18 airplane, N9109D, collided with steep terrain about 50 miles northeast of Port Alsworth, Alaska, at 60.55 north latitude, 153.29 west longitude. The airplane was being operated as a visual flight rules (VFR) cross-country personal flight when the accident occurred. The airplane, operated by the pilot, was destroyed by impact and postimpact fire. The certificated private pilot, and the one passenger aboard, received fatal injuries. Visual meteorological conditions prevailed at the time of departure, and no flight plan was filed. The flight originated at the Merrill Field Airport, Anchorage, Alaska, about 1145, and was en route to a remote hunting camp. According to a family friend, the accident pilot was to drop off the passenger at an undisclosed hunting site, and return to Anchorage to pick up a second passenger. The pilot failed to return for the second trip, and an aerial search was initiated on September 20. Low ceilings along the pilot's intended route of flight limited airborne search efforts. No emergency locator transmitter (ELT) signal was received from the airplane. On October 6, 1999, the pilot of an airplane scouting game, located the airplane wreckage about 3,000 feet msl, in an area of mountainous terrain. INJURIES TO PERSONS Both occupants received fatal injuries. DAMAGE TO AIRCRAFT The airplane was destroyed by a combination of impact forces, and a postcrash fire. PERSONNEL INFORMATION The pilot held a private pilot certificate with airplane single-engine land privileges. His original private pilot certificate was issued on July 25, 1981. According to Federal Aviation Administration (FAA) Aeromedical Certification Branch, the pilot held a third class medical certificate, issued on July 18, 1986, and contained the limitation that the pilot must wear corrective lens. On the application the pilot indicated that he was being treated for high blood pressure. On September 16, 1986, three days before the accident pilot was reported missing, the FAA's Aeromedical Certification Branch, sent a letter to the accident pilot requesting that a "cardiovascular evaluation" be completed within thirty days. On January 13, 1987, after no response from the pilot's family, the accident pilot's third class medical certificate was revoked. No personal flight records were located for the pilot. The aeronautical experience listed on page three was obtained from the pilot's last medical application of July 18, 1986. On the application, the pilot indicated that his total aeronautical experience consisted of 1,200+ hours. AIRCRAFT INFORMATION The airplane was a 1958 Piper PA-18, equipped with a belly mounted 65 gallon auxiliary fuel tank. FAA records revealed that the pilot first purchased the airplane on May 21, 1980. The airplane's maintenance records were not located. METEOROLOGICAL INFORMATION No historical meteorological information was available for weather conditions near the accident site. WRECKAGE AND IMPACT INFORMATION The National Transportation Safety Board investigator-in-charge examined the airplane wreckage at the accident site on October 11, 1999. The airplane impacted in a near vertical attitude, on a rock-covered mountain slope. The main fuselage had been consumed by fire. The engine sustained extensive fire and impact damage. The engine oil sump was crushed upwards against the engine case. The exhaust tubes were crushed, and folded producing sharp creases that were not cracked or broken. The propeller spinner was crushed aft, around the propeller hub assembly, and displayed rotational scouring signatures. The propeller blades had leading and trailing edge gouging, and chordwise scratching. The wings remained attached to the fuselage, but were extensively crushed and distorted. Due to impact, and postaccident damage from falling rocks, flight control continuity could not be established. The inboard 2/3 portion of both wings had been consumed by fire. The unburned portions of both wing tips measured about 48 inches inboard. Both wing leading edges were crushed aft about eight inches. The empennage was located about 300 feet downhill from the main fuselage wreckage. Small amounts of green fabric, and the airframe tubular structure, showed signs of heat damage. MEDICAL AND PATHOLOGICAL INFORMATION The only human remains that were found at the accident site were two small bone fragments. The recovered bone fragments were released to the Alaska State Troopers. FIRE ASPECTS The entire airplane, except for the outer four feet of both wings, was consumed in the postcrash fire. SEARCH AND RESCUE The accident airplane was not reported overdue until September 19, 1986, by the pilot's wife. On September 20, search personnel from the Civil Air Patrol, U.S. Air Force, U.S. Coast Guard, National Park Service, U.S. Fish and Wildlife Service, and various civilian aircraft, searched along the pilot's anticipated route of flight. Records from the 1986 search indicated that the accident pilot was "very secretive" concerning the location of his remote hunting camps, which complicated the search efforts. The search was suspended on October 10, 1986. During the aerial search, about 444.0 hours were flown. ADDITIONAL INFORMATION During the on-scene investigation the National Transportation Safety Board investigator-in-charge discovered an aircraft data plate in the airplane wreckage. The data plate had extensive fire and corrosion damage, and was unreadable. The data plate was sent to the National Transportation Safety Board Materials Laboratory for examination. A Safety Board metallurgist examined the fire and corrosion damaged data plate using a bench binocular microscope, revealing the model number as PA-18-150, and aircraft serial number 18-6488. A copy of the metallurgist's factual report is included in this report. Supplements A and B were not completed for this report. WRECKAGE RELEASE On April 18, 2000, the National Transportation Safety Board investigator-in-charge released the airplane's data plate to a Federal Aviation Administration (FAA) airworthiness inspector, Anchorage Flight Standards District Office. No other parts or components were retained by the Safety Board.

Probable Cause and Findings

Undetermined.

 

Source: NTSB Aviation Accident Database

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