Hypoxic pilot crashes

Aircraft: Cessna T182. Injuries: 1 Fatal. Location: Ludlow, Calif. Aircraft damage: Destroyed.

What reportedly happened: The pilot was on a cross-country flight in night visual meteorological conditions and requested flight following from air traffic control. According to radar data, about 11 minutes after takeoff, the airplane leveled off at 14,800 feet MSL. About 30 minutes later, when the plane was still about 150 miles from its destination, controllers noticed the plane beginning to descend.

When controllers questioned the pilot as to his intensions, his responses were garbled and unintelligible. The airplane continued a meandering descent, passing through 11,000 feet MSL, then radar contact was lost. The airplane crashed in a right-wing-low attitude, and the debris field extended about 830 feet.

The post-accident investigation revealed that the pilot had flown for about 40 minutes at altitudes exceeding 12,500 feet MSL, with much of that time spent at 14,600 feet MSL without using supplemental oxygen.

At these altitudes, without the use of supplemental oxygen, the pilot would have become hypoxic. The pilot’s wife indicated that he typically used supplemental oxygen when operating above 11,000 feet MSL. While supplemental oxygen was available to the pilot during the flight, the post-accident investigation indicated that no cockpit oxygen ports were in use when the accident occurred.

Both the garbled transmissions to air traffic controllers and the airplane’s meandering flight path are consistent with the pilot experiencing hypoxia. The degree of hypoxia experienced by the pilot would have severely degraded his performance. As the airplane descended during the last few minutes of the flight, the pilot’s oxygen saturation would have slowly improved, however, the rate of descent was likely too rapid to allow the pilot to recover in time to prevent the accident.

Probable cause: The in-flight loss of control due to the pilot’s impairment as a result of hypoxia. Contributing to the accident was the pilot’s operation of the airplane above 12,500 feet without the use of supplemental oxygen.

NTSB Identification: WPR12FA154

 This April 2012 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.

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