1937 – Feb 9, United Air Lines Flight 23 crash, San Francisco Bay, CA  — 11

Compiled by Wayne Blanchard; last edit 11-16-2024 for upload to: http://www.usdeadlyevents.com/

—  11  Bureau of Air Commerce, Accident Board. Report of the Accident Board.  April 12, 1937.

—  11  Notable California Aviation Disasters.  The 1930s.

Narrative Information

Bureau of Air Commerce: “On February 9, 1937, at approximately 8:50 p. m. at a point in the Bay about 2 miles off shore from the San Francisco Airport, an airplane of United States registry while being flown as a part of scheduled interstate operation, carrying mail, passengers and express, met with an accident which resulted in death to all on board, and the complete destruction of the aircraft….

“The aircraft, a Douglas, model DC-3A…was owned by the United Air Lines Transport Corporation and at the time of the accident as being operated on the Oakland Division of this Corporation as Trip No. 23, scheduled from Los Angeles to Oakland, California, with one stop, at San Francisco….

“The flight was cleared from the Union Air Terminal, near Los Angeles, on schedule at 7 00 p. m. and was due to arrive at the San Francisco Airport at 9.00 p. m. Good flying weather existed throughout the flight and nothing unusual was reported enroute.  At 8:44 p. m. when the flight had approached to within approximately 10 miles of San Francisco, the crew radioed to the control tower operator at the airport giving their position and requesting surface winds and directions for landing. The control tower replied that the wind was practically calm and requested the pilot to land south to north, which in effect meant to use the North-South runway. The crew acknowledged these directions.

“At 8:47 p.m. when approximately 3 miles from the airport, the crew again contacted the central tower stating that they would use the East-West runway. The control tower operator immediately acknowledged this message giving his approval. This was the last radio contact with the flight. However, the airplane was in sight of several witnesses on the airport from that time on.

“The airplane as observed to fly over the airport at an altitude estimate by several witnesses to be between 400 and 500 feet. Then just over the airport, the airplane started a wide turn to the right and out over the Bay, which, if completed, would have described a complete circle over the water and placed it in position for a direct approach to the East-West runway on the airport. The accident occurred before this turn was completed and witnesses vary in their impressions as to whether the turn to the point of accident was continuous or made up of two distinct turns.

“While in the turn and flying at an altitude of approximately 400 feet, the airplane was observed to assume a descending angle, estimated to be between 35 and 40 degrees, which continued up to the time of striking the water. The total time for this descent was estimated to be four seconds. One witness believed that the airplane was banked at quite an angle during this descent and the subsequent damage appears to bear this out.

“The evidence indicates that the right wing of the airplane contacted the water first and was torn off almost simultaneously with the right propeller, engine and a portion of the right nacelle structure. The propeller was found about 75 feet to the rear of the engine and the wing parts, which were scattered about the vicinity in a radius of approximately 800 feet.. The main body of the airplane was found approximately one mile away from this point in the direction of a four mile per hour tide which was running at the time. Most of the wreckage was recovered through dragging operations which lasted over a period of three weeks.

“A detailed investigation of this wreckage showed no evidence of failure the air of the airplane structure, engines or propellers. The separation of right propeller from the engine and the engine from the wing was proven beyond a reasonable doubt to be the result of the impact with the water….

“It is the opinion of the Accident Board that the probable cause of this accident was accidental jamming of the elevator controls as the result of a microphone being inadvertently dropped and lodging in such a position that the crew was unable to prevent rapid descent of the airplane.”  (Bureau of Air Commerce, Accident Board. Report of the Accident Board.  April 12, 1937.)

Notable California Aviation Disasters:

“Date / Time: Tuesday, February 9, 1937 / 9:02 p.m.

“Operator / Flight No.: United Air Lines / Flight 23

“Location: San Francisco Bay, Calif.

“Details and Probable Cause:  The United Air Lines aircraft, a twin-engine Douglas DC-3A-197 (NC16073), was nearing the end of its flight from Los Angeles to San Francisco and carrying eight passengers and a crew of three.  While flying in clear weather and descending on a routine nighttime approach to Mills Field (today’s San Francisco International Airport), the DC-3 inexplicably continued its 45-degree descent until it crashed into the waters of San Francisco Bay approximately 1-1/4 miles from the airfield.   All 11 persons on board were killed in the crash; some of the victims’ bodies were never recovered.

“Investigators were able to salvage and examine the wreckage, but the plane’s unexplained dive remained a mystery and the cause of the crash was thought to be pilot error.  However, five weeks after the accident, an American Airlines DC-3 was on its takeoff roll at Newark, New Jersey, when its pilot found that the aircraft’s controls had jammed.   He was able to safely abort the takeoff, and a closer examination of the jammed controls revealed that the co-pilot’s radio microphone had fallen off its hook and become wedged in a small, “V”-shaped recess at the base of the control yoke.   When the pilot pried the microphone loose, the aircraft’s controls once again operated normally.  Details of the Newark near-disaster were relayed to the investigators still probing the San Francisco accident, and the officials took another look at the wreckage.   There, amid the tangled debris of the cockpit, they discovered the United co-pilot’s microphone still wedged in the recess at the base of the yoke.   The Douglas Aircraft Company notified all DC-3 operators of the problem and a rubber boot was installed over the recess, a solution to prevent any similar accidents from occurring.

“The United Air Lines crash at San Francisco was the first fatal accident involving the legendary Douglas DC-3, which entered commercial airline service in 1936.”  (Notable California Aviation Disasters.  The 1930s.)

Sources

Bureau of Air Commerce, Accident Board. Report of the Accident Board…United Air Lines... San Francisco, California, February 9, 1937. Washington, U.S. Department of Commerce. April 12, 1937. Accessed 11-16-2024 at: file:///C:/Users/Wayne/Downloads/dot_32994_DS1.pdf

Notable California Aviation Disasters. “The 1930s.” Oct 23, 2008 update. Accessed 2-21-2009 at: http://www.jaydeebee1.com/crash30s.html