Narrative:Curtiss C-46 N1693M was being ferried from Columbia, SC to Seattle for the purpose of later conducting a Civil Air Movement of military personnel. The flight arrived at Cheyenne at 18:35 for refueling. Departure from Cheyenne was delayed owing to repair of the left navigation light and the flight took off at 20:43. The flight proceeded uneventfully. Near Yakima the crew were cleared to descend from FL120 to FL100. Upon reporting over Yakima at 00:26, it was further cleared to descend to and maintain 8,000 feet. The pilot contacted Seattle Center at 00:47 and reported over Easton at 8,000 feet, inbound to Boeing Field. Seattle Center replied: "Nectar one six nine three metro you are cleared to cross Hobart at 8,000 Seattle at or above 4,000 maintain 4,000 no delay expected contact Seattle Approach Control over Hobart for further clearance over." The pilot read back: "Roger, cleared to ... cross there four thousand or above the range station, ah, four thousand, report Hobart to you." A correction, "negative report Hobart to Seattle Approach Control," was then immediately transmitted. The pilot replied, "Hobart to Seattle Approach Control Roger." These contacts were made at approximately 00:48. There was no record of further transmission from the aircraft.
The aircraft descended below the minimum altitude of 8,000 feet and crashed near the crest of a mountain at 4,000 feet MSL. The aircraft first struck a large tree located approximately 210 feet east of the crest of Cedar Mountain at about the 4,000-foot level. The plane crashed into trees and cut a 950-foot swath on both sides of the crest. On April 14 a DC-3 of Miami Airlines had also crashed on Cedar Mountain.
PROBABLE CAUSE: "The pilot's misunderstanding of the clearance, failure to check en route altitude against available charts, and descent below prescribed minimum en route altitude. The fact that the controller did not detect the first of two errors made by the pilot was a contributing factor."
» CAB File No. 1-0045
» ICAO Accident Digest Circular 39-AN/34 (72-74)
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 Cheyenne Airport, WY to Seattle-Boeing Field International Airport, WA as the crow flies is 1546 km (966 miles).