SOCATA TBM700 — Corfu, NY

What happened

The airplane was in cruise flight at FL280 when the instrument-rated pilot failed to contact air traffic control (ATC) following a frequency change assignment. After about 25 minutes, and when 30 miles east of the destination airport, the pilot contacted ATC on a frequency other than the one that was assigned. He requested the instrument landing system (ILS) approach at his intended destination, and the controller instructed the pilot to descend to 8,000 ft and to expect vectors for the ILS approach at the destination airport. The controller asked the pilot if everything was “okay,” to which the pilot replied, “yes sir, everything is fine.” The controller then observed the airplane initiate a descent. About 2 minutes later, the controller asked the pilot where he was headed, and the pilot provided a garbled response. The controller instructed the pilot to stop his descent at 10,000 ft, followed by an instruction to stop the descent at any altitude. The pilot did not respond, and additional attempts to contact the pilot were unsuccessful. The airplane impacted terrain in a heavily wooded area 17 miles from the destination airport.

All major components of the airplane were located in the vicinity of the main wreckage. Examination of the airframe and engine revealed no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.

The investigation was unable to determine why the pilot was not in contact with ATC for 25 minutes. The pilot’s eventual contact with ATC about 30 miles from his intended destination, while still operating at his cruise altitude, suggests a clear breakdown in awareness of his position through distraction or impairment. However, upon re-establishing contact with ATC, the pilot’s communications were clear, nominal, and timely, which did not suggest impairment or use of an oxygen mask. Additionally, in response to a direct query from ATC the pilot did not indicate any difficulty. Further, there was no sign of airframe depressurization and examination of the wreckage did not reveal deployment of the passenger oxygen masks. Toxicology results were positive for ethanol at a low level, which was likely due to post-mortem production.

Meteorological data and a performance study indicated that the pilot initiated a descent through multiple cloud layers about 15 seconds after acknowledging the descent clearance. During the initial portion of the airplane’s descent, its airspeed and rate of descent appeared to be nominal. About 2 minutes later, excessive airspeeds, descent rates, bank angles, and pitch attitudes were achieved. The performance study depicted the airplane entering a spiral dive during which the airplane exceeded airspeed, maneuvering, structural, and autopilot limitations. At 6,000 ft above ground level, and about 10 seconds before ground contact, the airplane descended through a final cloud layer, the descent profile shallowed, and the rate of descent decreased to 6,800 ft/min before radar data ended.

In addition, there were no clearances issued by ATC that would have required the pilot to change either the airplane’s rate of descent or track about this time; however, the airplane’s proximity to the destination airport may have created a heightened sense of urgency for the pilot to descend and or configure his avionics for the approach, which may have served as an operational distraction. Although it was possible that restrictions to visibility during the descent may have affected the pilot’s ability to maintain positive airplane control, there is insufficient information to determine how or why the pilot lost control.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.