What happened
A non-instrument rated pilot was operating a Piper PA-28RT aircraft registered as N29665. The flight involved a climb to flight level 200. During the ascent, the pilot's speech became slurred, indicating physiological distress. Air traffic control instructed the pilot to check his oxygen equipment and instruments and to descend to 15,000 feet. The pilot acknowledged the instruction but did not comply with the descent or verify his oxygen supply.
Radio contact was lost shortly after this exchange. A C-130 crew conducted a rendezvous at night but detected no occupants or signs of aircraft control. Approximately three hours after takeoff, the aircraft began to descend and was observed entering a fog bank near the crash site. The aircraft impacted terrain with the landing gear extended and the fuel selector positioned on the empty left tank, while the right tank remained full.
The investigation
The wreckage was located at an elevation of 6,250 feet MSL. Examination of the aircraft revealed that the fuel selector was set to the left tank, which contained no fuel, despite the right tank being full. The aircraft was equipped with an autopilot featuring altitude hold, an oxygen system, and an auto-gear lowering mechanism.
The oxygen tank was found empty with the valve in the off position. Although oxygen was available for pilot use, the oxygen masks were still in their original packaging and had not been removed or donned by the occupant.
Findings
The pilot was discovered alive 6.5 hours after the accident. The primary factors contributing to the event included the pilot's failure to maintain adequate oxygen supply during high-altitude flight, resulting in incapacitation due to hypoxia. Additionally, the fuel exhaustion occurred because the pilot failed to switch fuel tanks before the left tank was depleted.
Safety message
Pilots operating at high altitudes must ensure that supplemental oxygen is available and properly fitted before ascent. Regular monitoring of fuel quantities and timely switching of fuel selectors are critical to preventing fuel exhaustion.