Safety Publications/Articles

Air Safety Institute Safety Spotlight

Hypoxia impairment dooms flight

Hypoxia--an oxygen deficiency that impairs the brain and other organs--can affect pilots flying above 12,000 feet msl. Hypoxia creates a euphoric sense of well being that masks the associated lapses in judgment, memory, and coordination. A pilot robbed of these critical skills (and blissfully unaware of it) is headed for trouble.

On January 23, 2003, a Piper PA-28R was destroyed when it struck terrain and burned during a forced landing attempt near La Sal, Utah. The 140-hour, noninstrument-rated private pilot and her three passengers were killed.

The VFR flight departed Longmont, Colorado, for Las Vegas at 4:57 p.m., about 10 minutes before sunset. During the flight, the pilot flew above 12,500 feet msl for two hours, 17 minutes; above 14,000 feet msl for one hour, 49 minutes; and at approximately 16,000 feet msl for about 45 minutes. The unpressurized aircraft was not equipped with supplemental oxygen, and the pilot did not bring a portable oxygen unit.

While flying above 14,000 feet msl, the pilot received numerous heading corrections from ATC--some of them as large as 70 degrees. At one point, the pilot reported that she was over Montrose, Colorado. The controller informed her that she was actually over Telluride, about 35 nautical miles south of Montrose. The pilot responded, "Roger that, I appreciate it. Can't see a darn thing out here." (Hypoxia can cause rapid deterioration of night vision, even at altitudes as low as 5,000 feet msl.)

Radio communication between the pilot and ATC became increasingly erratic. At 8:30 p.m., the airplane began to descend from 14,800 feet msl. The rate of descent increased to more than 1,000 feet per minute. At 8:35 p.m., the pilot transmitted the following: "Denver radio, Mayday, Mayday. I've got myself in (unintelligible)." Two minutes later, another aircraft in the area reported picking up a strong but brief ELT signal.

The wreckage was found upright on sloping, tree-covered terrain at an elevation of approximately 7,100 feet msl. The aircraft's landing gear was in the down position. The NTSB determined that the pilot likely was attempting an emergency landing after losing power because of fuel starvation. An estimated 10 to 15 gallons of fuel remained in the unselected tank of the low-wing aircraft--and it fed the post-impact fire that consumed the cabin and fuselage. The pilot's hypoxic impairment was cited as a contributing factor in her failure to follow proper fuel-management procedures.

According to FAR Part 91.211, pilots must use supplemental oxygen when the cabin pressure altitude is above 12,500 feet msl for longer than 30 minutes. It must be used continuously when flying above 14,000 feet msl. At cabin pressure altitudes above 15,000 feet msl, each occupant must be provided with supplemental oxygen.

Unfortunately, none of this occurred during the accident flight. When the brain-dulling effects of hypoxia set in, the fate of this pilot--and that of her three passengers--was tragically sealed. For more information, take the AOPA Air Safety Foundation's Mountain Flying online course or visit the Fuel Management Safety Hot Spot.

An aviation technical writer with the AOPA Air Safety Foundation, Carl Peterson creates interactive courses and other safety education materials for the aviation community. He has been flying since 1989.

By Carl Peterson

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