Investigation Summary
The flight was a multi-stop service that normally originated in Chicago, though on the day of the accident, the first leg was cancelled and the flight began in Minneapolis. It arrived at Miles City at 7:41 PM MST and had been delayed for over an hour due to weather conditions at its next planned stop, Billings. Shortly after departing at 9:14 PM, the aircraft reached 500 feet before entering a series of erratic maneuvers. It first turned left and lost altitude, nearly striking the ground, before pulling up into a steep climb back to 500 feet. A second left turn followed by a rapid descent ended in a fatal impact. Post-crash investigation by the Civil Aeronautics Authority (CAA) focused on the cockpit area, which showed signs of severe burning concentrated around the fuel cross-feed valve. This valve was part of a system that maintained a constant pressure of 4.5 psi. The investigation revealed that the valve was notoriously difficult to inspect or maintain due to its placement, and there had been prior reports of leakage. Because the aircraft lacked a dedicated drainage path for such leaks, the fuel could accumulate and ignite, creating a catastrophic fire in the immediate vicinity of the flight crew.
Final Conclusions
The Civil Aeronautics Authority concluded that the accident was caused by an intense in-flight fire in the cockpit. While the exact ignition source could not be definitively identified due to the extent of the wreckage, the fire was attributed to a leak in the cross-feed fuel system. The design was found deficient because it provided no way to safely drain leaked fuel away from the cockpit and made the valve assembly difficult to maintain.
Video Analysis
No video analysis linked for this case file yet.
Airframe & Maintenance
Crew Experience
Captain
Captain C. B. Chamberlain
First Officer
First Officer R. B. Norby
Systems & Failure Modes
Cross-feed Fuel Valve
A valve located in the cockpit between the pilots used to manage fuel flow between tanks; it was prone to leakage and lacked a drainage system.
Fuel Line Drainage
The design lacked a method to safely vent or drain leaked fuel, allowing it to pool or vaporize within the cockpit structure.
Interesting Facts
- 01The accident occurred exactly one year and three days after Northwest Flight 2 crashed in Montana.
- 02The cross-feed fuel system maintained a constant pressure of approximately 4.5 pounds per square inch.
- 03The aircraft was a Lockheed Model 14 Super Electra, a type that suffered four major accidents in 1938 and 1939.
- 04Northwest Airlines sold its remaining fleet of Super Electras shortly after this accident due to safety concerns.
- 05The crash site was located approximately 0.5 miles southwest of the Miles City Airport.
Safety Actions & Advisories
Fuel System Relocation
The CAA recommended relocating the cross-feed fuel system to allow for easier maintenance and inspection.
Drainage Modification
The CAA recommended modifying fuel line leakage areas to provide adequate drainage to prevent fuel accumulation.
Location
ACCIDENT SITE · Coordinates taken from the official investigation report.