1938 – Jan 10, Northwest Airlines structural failure crash/storm, Bridger Canyon, MT– 10

Compiled by Wayne Blanchard; last edit 11-10-2024 for upload to: http://www.usdeadlyevents.com/

–10  Investigating Board, DOC. Report of the Investigating Board.  January 29, 1938.

–10  U.P. “Remove Bodies in Plane Wreck.” The Oxnard Daily Courier, CA. 1-11-1938, p. 1.

Narrative Information

Department of Commerce Investigating Board: “On January 10, 1938, at 3:07 P.M., Mountain Standard Time, at a point in Bridger Canyon approximately 12 miles northeast of Bozeman, Montana, an airplane of United States registry, while being flown in scheduled interstate operation, carrying mail, passengers and express, met with an accident resulting in death to all on board and the destruction of the aircraft….

“The aircraft, a Lockheed, model 14-H, was owned and operated by Northwest Airlines, Incorporated, of St. Paul, Minnesota….The Lockheed model 14-H is a new high speed type of aircraft and was placed in scheduled airline operation about November 1, 1937….At the time of the accident, this aircraft was being operated between Seattle, Washington, and Billings, Montana, as a part of Trip 2 of January 10, 1938, which was scheduled to terminate in Chicago, Illinois. Scheduled intermediate stops between Seattle and Billings were Spokane and Butte.

“Trip 2, scheduled to arrive at Butte at 2:30 P.M., MST., arrived at 2:31 P.M. Departure from Butte was made at 2:41 P.M…. After departing Butte, Trip 2 was contacted by the company radio operator at Billings at 3:05 P.M., MST., for the purpose of giving the pilot the 2:51 weather. In response, the pilot replied at 3:05, “Cruising 2:53. 9000 feet”, which meant that after taking off from Butte at 2:41, the airplane reached an indicated pressure altitude of 9000 feet at 2:53 P.M.   As nearly as can be determined, the airplane struck the ground approximately two minutes after the 3:05 contact….

“In tracing the course followed by Trip 2, several witnesses were located who saw the airplane pass on course over Belgrade, Montana, which is to the west of Bridger Mountain Range and approximately 12 miles west of the scene of the accident. From this point on, a sufficient number of witnesses were found to definitely trace the flight of the airplane eastward.  Bozeman Pass is immediately south of the Bridger Mountain Range, on course for visual contact flying, and at the time of this flight was obscured by a dust storm.  As the airplane proceeded toward Bozeman Pass, it was seen to turn toward the northeast to avoid the dust storm and to cross the Bridger Range at a point slightly north of Bridge Mountain Peak.  The range is approximately 8,500 feet above sea-level at the point of crossing. From the testimony of witnesses, it is apparent that the airplane went out of control in turbulent air conditions almost immediately after it cleared the Bridger Mountain.  It was observed to assume a stall attitude, then a glide, and what was variously described as a spin, a tight spiral or dive to the ground.  Fire followed immediately.  No witnesses, however, saw the airplane during the last 200 to 400 feet of descent due to uneven wooded terrain. The ground elevation at the scene of the accident is approximately 6,000 feet.

“Witnesses who immediately rushed to the scene of the accident were prevented from rendering any possible assistance by the intensity of the fire. Local authorities were notified at once and investigating officials reached the scene that night and the following morning.

“The weight of the evidence leads the Investigating Board to the conclusion that the loss of the upper vertical fins with the upper rudders in flight was the result of flutter. The loss of these surfaces deprived the pilot of sufficient control of the airplane to avoid the resulting crash.

“`Flutter’ as an aeronautical term refers to a vibration of increasing severity which sometimes occurs in the wings and control surfaces of an aircraft while in flight. A certain amount of vibration, due to airflow and engine vibration, is present in these and other parts of any aircraft while in flight. Ordinary vibration is normally of small amplitude and intensity and has no immediate damaging effect on the aircraft structure. In order that flutter may occur, the vibrations of one part of the aircraft must be at or close to the natural frequency (rate of vibration) of same related movable control surface. When influenced in this manner, the vibration of one part may continuously increase in amplitude (distance through which the vibration occurs) to a point beyond the capacity of any normal structure of withstand it and a structural failure will result….

“As soon as flutter became suspected as a factor in this accident, the Department of Commerce at mid-afternoon of January 11, 1938, grounded all airplanes of this model. Shortly thereafter, tests were started on another airplane of the model 14-H type as a check against the figures obtained in the original vibration tests. This check test, made with a more highly developed machine, definitely indicated the possibility of flutter and demonstrated that the vibration machine used by the factory and recognized by the Department of Commerce for measuring the natural vibration periods of the component parts of the airplane apparently gave misleading results….

“In summation, the evidence indicates that this flight was dispatched out of Butte in accordance with normal company procedure, was progressing normally, flying by visual contact method, cleared the mountain range with a fair margin of safety and that the loss of control of the aircraft as in no way the fault of the pilot….

“As has been indicated, it is the opinion of the Investigating Board that the probable cause of this accident was structural failure of the upper vertical fins and rudders due to flutter which resulted in a loss of control of the aircraft.”  (Investigating Board, DOC. Report of the Investigating Board.  January 29, 1938.)

Newspaper

Jan 11, UP: “Bozeman, Mont., Jan. 11. (U.P.) – Forest rangers and ranchers today began removing the bodies of ten men who died when a Northwest Airlines luxury liner crashed and burst into flames during a blizzard in rugged Bridger canyon. The bodies of the two pilots and eight passengers aboard the plane were to be hauled by sleds three and a half miles to the Alfred Nickols ranch. From there they will be driven to a Bozeman mortuary….all but one of the bodies was burned beyond recognition….

“There was only a light snow and a steady breeze today in contrast to the swirling blizzard which enveloped the canyon last night.” (U.P. “Remove Bodies in Plane Wreck.” The Oxnard Daily Courier, CA. 1-11-1938, p. 1.)

Sources

Investigating Board, DOC. Report of the Investigating Board.  Washington, DC:  Department of Commerce, 1-29-1938, 10 pages. Accessed at:  http://dotlibrary1.specialcollection.net/scripts/ws.dll?file&fn=8&name=*P%3A%5CDOT%5Cairplane%20accidents%5Cwebsearch%5C011038.pdf

United Press. “Remove Bodies in Plane Wreck.” The Oxnard Daily Courier, CA. 1-11-1938, p. 1. Accessed 11-10-2024 at: https://newspaperarchive.com/oxnard-daily-courier-jan-10-1938-p-1/