NTSB Identification: WPR12FA154
14 CFR Part 91: General Aviation
Accident occurred Thursday, April 05, 2012 in Ludlow, CA
Probable Cause Approval Date: 08/13/2013
Aircraft: CESSNA T182, registration: N5201F
Injuries: 1 Fatal.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

After departing on a cross-country flight in night visual meteorological conditions, the pilot requested flight following from air traffic control. According to radar data, about 11 minutes after takeoff, the airplane leveled off at 14,800 feet mean sea level (msl). About 30 minutes later, when the airplane was still about 150 miles from its destination, air traffic controllers observed the airplane beginning to descend. When air traffic controllers subsequently questioned the pilot as to his intensions, the pilot’s responses were garbled and unintelligible. Radar data indicated that the airplane continued a meandering descent until it descended through about 11,000 feet msl and radar contact was lost. The airplane impacted terrain in a right-wing-low attitude, and the debris field extended about 830 feet.

Postaccident examination revealed no preimpact mechanical malfunctions or failures that would have precluded normal operation. The 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. At these altitudes, without the use of supplemental oxygen, the pilot would have become hypoxic (insufficient brain oxygen). Although the pilot’s wife indicated that he typically used supplemental oxygen when operating above 11,000 feet msl and supplemental oxygen was available to the pilot during the flight, postaccident investigation indicated that no cockpit oxygen ports were in use when the accident occurred.

The degree of hypoxia experienced by the pilot would have severely degraded his performance. Both the garbled transmissions to air traffic controllers and the airplane’s meandering flight path are consistent with the pilot experiencing symptomatic hypoxia. 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 his vision and judgment in time to prevent the accident.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

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 aid of supplemental oxygen.

Full narrative available

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