This April 2009 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Piper Comanche. Injuries: 2 Fatal. Location: San Diego, Calif. Aircraft damage: Destroyed.
What reportedly happened: During the pilot’s preflight weather briefing for the cross-country flight, he was informed that while a portion of his anticipated hour-long flight could likely be flown under visual flight rules, instrument meteorological conditions, including multiple cloud layers, could be expected near the destination. En route, the pilot, who did have an instrument rating, cruised at 7,000 feet. Initially, all air traffic control communications with the pilot were routine. An airport located about six miles from the accident site reported a broken sky condition at 2,500 and 3,100 feet, and an overcast at 4,800 feet. As the pilot entered this area, which was about 29 miles north of his destination, he informed the approach controller that he was descending from 6,200 to 4,000 feet MSL. The controller acknowledged the statement. Two minutes later the controller instructed the pilot to descend to 2,600 feet, and “keep your speed up.” About five seconds later, the pilot responded “two thous.” The remainder of the pilot’s transmission was either interrupted or not recorded, and there were no further communications with the pilot. The destination airport was covered by a marine cloud layer, with cloud tops of 5,500 feet.
A witness, who was located about a half mile from the impact site, reported he heard a high-pitched sound, like that of an incoming missile. The sound was very loud. Its intensity increased until it terminated with a boom. Seconds later, the witness observed a fireball on a nearby hill. Pieces of irregular shaped wreckage were noted “floating” down near the site of the fireball. At the time the weather was overcast, and it had been misting.
A review of the recorded radar data and the wreckage distribution evidence indicated that the airplane broke apart after entering IMC. The structural failure occurred while the airplane was descending at 6,000 feet per minute and in a clockwise turn.
The subsequent examination of the airplane revealed that both wings failed in an upward direction, consistent with a pilot-induced structural overload. Then a portion of the right wing hit the stabilators right side, which caused it to separate from the airplane. No evidence of any preexisting structural weakness was found during the examination of the heavily fire-damaged main wreckage.
Probable cause: The pilot’s failure to maintain control during an en route cruise descent through multiple cloud layers, resulting in an in-flight breakup.
For more information: NTSB.gov