Lockheed 14H accident at Billings, Montana, 8 Jul 1938

Accident narrative

On July 8, 1938, at approximately 2:56 A.M. Standard Time, a Northwest Airlines Lockheed 14H crashed shortly after takeoff from the Billings Municipal Airport in Montana. The aircraft, operating a scheduled interstate flight, struck the ground 1,100 feet beyond the end of the runway. Of the ten people aboard, one passenger was killed, two passengers were seriously injured, and five passengers and the two crew members sustained minor injuries. The aircraft was destroyed.

### The flight Northwest Airlines Trip 4 was scheduled from Seattle, Washington, to Chicago, Illinois, with intermediate stops. The flight departed Seattle the previous evening and arrived at Billings at 2:33 A.M., where the crew was relieved by Pilot Walter R. Bullock and Copilot Lester H. Doan. Pilot Bullock was an experienced pilot of this type of aircraft.

The aircraft carried eight passengers, mail, and express. Its gross weight at departure was 15,810 pounds, which was 590 pounds under the maximum authorized weight. Weather conditions at Billings were clear, with 50 miles of visibility and a light south-southeast wind. Because the wind sock was hanging limp and the runways sloped downward to the east, the crew elected to take off in an easterly direction, which was customary under those conditions.

### The accident sequence The takeoff run began from the southwest end of the SW-NE runway. The pilot testified that he opened the throttles to 35 inches of manifold pressure and set the propeller pitch control to approximately 2300 RPM. The airplane accelerated normally but left the ground in a stalled condition about 1,162 feet from the start of the run.

Witness testimony indicated the wheels may have touched the ground lightly further down the runway. The airplane passed over the boundary lights at a very low altitude. About two-thirds of the way down the 4,250-foot runway, the left wing dropped rapidly. The pilot applied full opposite aileron and advanced the throttles and propeller pitch controls to the emergency full power position. The wings responded very slowly, and the airplane was about level as it passed over the boundary lights.

The right wing then started to drop rapidly. Realizing a crash was imminent, the pilot cut the master switch. The right wing struck the ground almost immediately, dragging for 12 to 15 feet before the nose dug into the earth. The airplane skidded and rotated to the right, eventually moving tail-first until the tail struck a pine tree. The aircraft completed a revolution and came to rest against a group of small pines on the extreme edge of a canyon wall, 231 feet beyond the point of first impact.

Both motors and wheels tore loose and rolled to the bottom of the canyon. The baggage compartment and rear cabin floor were torn away by rocks on the hillside, and the fatally injured passenger was dragged out and thrown to a ledge below the wreckage.

### What the investigation found To determine the aircraft's performance, the investigating Board conducted flight tests at the Billings airport using another Northwest Airlines Lockheed 14H of the same model. The first test used the same power and pitch settings as the accident flight. This showed that the airplane left the ground before traveling the normal distance required for the altitude, temperature, and load conditions.

A second series of tests attempted to use emergency power after leaving the ground. Investigators discovered that the test airplane had a stop installed on the quadrant that restricted the forward movement of the propeller pitch control lever. Moving the levers to the full power and emergency low pitch settings produced no perceptible additional power, preventing the engines from reaching their full emergency rating of 850 horsepower. Once the stop was readjusted, full maximum rated horsepower was obtained.

The investigation disclosed that a similar control stop had been installed on the accident aircraft. Company records did not show that this stop had been installed, nor did they indicate that any flight test had been conducted to determine if full maximum rated horsepower could still be obtained. The Board noted that the similarity in performance between the test aircraft and the accident aircraft indicated the same limiting factor restricted the obtainable horsepower on the morning of the crash.

### Probable cause The Investigating Board concluded that the probable cause of this accident was "a stall at a low altitude, following which the pilot was unable to recover, due to lack of emergency power."