ASN Aircraft accident de Havilland Canada DHC-6 Twin Otter 300 C-GKBM John Day, OR
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Date:Thursday 14 July 1988
Type:Silhouette image of generic DHC6 model; specific model in this crash may look slightly different
de Havilland Canada DHC-6 Twin Otter 300
Operated by:Kenn Borek Air
On behalf of:United States Forest Service
Registration: C-GKBM
MSN: 417
First flight: 1974
Engines: 2 Pratt & Whitney Canada PT6A-27
Crew:Fatalities: 1 / Occupants: 1
Passengers:Fatalities: 0 / Occupants: 0
Total:Fatalities: 1 / Occupants: 1
Aircraft damage: Destroyed
Aircraft fate: Written off (damaged beyond repair)
Location:50 km (31.3 mls) W of John Day, OR (   United States of America)
Phase: En route (ENR)
Departure airport:Redmond-Roberts Field, OR (RDM/KRDM), United States of America
Destination airport:John Day Airport, OR (JDA/KGCD), United States of America
The DHC-6 Twin Otter, C-GKBM, was under contract to the U.S. Forest Service. It was to be repositioned to John Day, OR to pick up passengers.
At 11:35 PDT, the pilot checked in with John Day Dispatch and transmitted his expected time of arrival would be 12:15 PDT.
About 11:40 the aircraft contacted three trees with the right wing at the 5,000-foot level of Battle Creek Mountain. This impact separated the wing into three sections before the aircraft "exited" over the mountain edge. The final impact site was on this ridgeline with the aircraft coming to final rest in a steep canyon to the east. There was a high mountain further east on the flight path that also needed to be crossed before a descent to John Day, Oregon could be commenced.

The pilot's medical records indicated the he had been having medical problems, some of which he did not want brought to the attention of the Medical Doctor (MD) designated by the FAA to do flight physicals. In addition, he did not tell his supervisor that he was having medical problems. It was noted that he had complaints of chronic muscular neck pains, back problems, falling asleep, allergy problems, numbness in the top of his feet, feeling tired and run down, and pain in his legs.
The flight track showed a gradual descent of about 400 feet per minute. He was off course to the right for about five minutes before impacting with trees. This flight tract strongly supported a very high probability of sleep-induced unconsciousness.

Probable Cause:

The most probable cause of this mishap was determined to be the pilot’s acute in-flight incapacitation due to sleep.

Insufficient rest / fatigue
Controlled Flight Into Terrain (CFIT) - Mountain

» United States Department of Agriculture Forest Service Fatal Aviation Accident History / Compiled By: Candy S. Rock FitzPatrick


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This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Redmond-Roberts Field, OR to John Day Airport, OR as the crow flies is 174 km (108 miles).
Accident location: Global; accuracy within tens or hundreds of kilometers.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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