ASN Aircraft accident de Havilland Canada DHC-6 Twin Otter 300 N25RM Steamboat Springs, CO
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Status:Accident investigation report completed and information captured
Date:Monday 4 December 1978
Time:19:45 MST
Type:Silhouette image of generic DHC6 model; specific model in this crash may look slightly different
de Havilland Canada DHC-6 Twin Otter 300
Operator:Rocky Mountain Airways
Registration: N25RM
MSN: 387
First flight: 1973
Total airframe hrs:15145
Engines: 2 Pratt & Whitney Canada PT6A-27
Crew:Fatalities: 1 / Occupants: 2
Passengers:Fatalities: 1 / Occupants: 20
Total:Fatalities: 2 / Occupants: 22
Aircraft damage: Damaged beyond repair
Location:15 km (9.4 mls) ENE of Steamboat Springs, CO (   United States of America)
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Steamboat Springs Airport, CO (SBS/KSBS), United States of America
Destination airport:Denver-Stapleton International Airport, CO (DEN/KDEN), United States of America
Flightnumber: 217
The aircraft took off from Steamboat Springs at 18:55 but was forced to return after encountering severe icing conditions. The Twin Otter struck a mountain at 10530 feet.

Probable Cause:

PROBABLE CAUSE: "Severe icing and strong downdrafts associated with a mountain wave which combined to exceed the aircraft's capability to maintain flight. Contributing to the accident was the captain's decision to fly into probable icing conditions that exceeded the conditions authorised by company directive."

Accident investigation:

Investigating agency: NTSB
Status: Investigation completed
Duration: 150 days (5 months)
Accident number: NTSB/AAR-79-06
Download report: Final report

» NTSB Safety Recommendations A-79-70
» NTSB-AAR-79-6

Follow-up / safety actions

NTSB issued 4 Safety Recommendations

Show all...


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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 Steamboat Springs Airport, CO to Denver-Stapleton International Airport, CO as the crow flies is 186 km (116 miles).
Accident location: Approximate; accuracy within a few 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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