Date:	Wednesday 7 January 1953
Time:	04:12
Type:	Curtiss C-46F-1-CU Commando
Owner/operator:	Associated Air Transport
Registration:	N1648M
MSN:	22395
Year of manufacture:	1945
Total airframe hrs:	1941 hours
Engine model:	Pratt & Whitney R-2800
Fatalities:	Fatalities: 40 / Occupants: 40
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	13 km W of Fish Haven, ID -   United States of America
Phase:	En route
Nature:	Passenger - Non-Scheduled/charter/Air Taxi
Departure airport:	Seattle-Boeing Field International Airport, WA (BFI/KBFI)
Destination airport:	Cheyenne Airport, WY (CYS/KCYS)
Investigating agency:	CAB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The Curtiss was chartered to fly military personnel from Seattle to Fort Jackson, SC. A scheduled stop was planned in Cheyenne. The flight departed Boeing Field at 00:50 and made the required position reports along the route, with no mention of any irregularities, reporting over Malad City at 13,000 feet, time 03:58, and estimating Rock Springs at 04:45. There were no further radio contacts with the aircraft. The C-46 started picking up some ice. It is likely that an involuntary descent was made into an area of increasing ice and turbulence which extended two or three thousand feet above the mountains. The mountains between Malad City and Bear Lake range from 8.000 feet to in excess of 9,000 feet. The westerly winds were lifting the moist unstable air over those mountains, producing zero ceilings, moderate to seven turbulence, moderate to heavy icing and snow, with updrafts on the windward side of the slopes and downdrafts on the leeward sides. The aircraft was unable to regain altitude until it struck a small pine tree at an altitude of approximately 8,545 feet. It struck several other pine trees and began to disintegrate as it continued down the slope at an approximate 50-degree angle shearing numerous trees. Contact with the ground was made at the base of the hill at the north end of a 93-foot ravine where the aircraft gouged three large holes in the ground. The aircraft then continued up a 32-degree rise approximately 200 feet where the tail section came to rest. Five days later, on January 12, 1953, at 1320 hours, the wreckage was sighted from the air by a Civil Air Patrol pilot.

PROBABLE CAUSE: "The inadvertent descent into an area of turbulence and icing which resulted in the flight's inability to regain a safe altitude."

CAB File No. 1-0006
ICAO Accident Digest Circular 39-AN/34 (21-24)

photo (c) Tropenmuseum, part of the National Museum of World Cultures; Makassar Airport (UPG/WAAA); 30 December 1948; (CC:by-sa)

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