United Air Lines Flight 521

Investigation

The Civil Aeronautics Board concluded the report on the accident by citing pilot error. The report read: "The Board determines that the probable cause of this accident was either the failure of the pilot to release the gust lock before take-off, or his decision to discontinue the take-off because of apprehension resulting from rapid use of a short runway under a possible calm wind condition."

Although the board came to the conclusion that pilot error was likely the cause, the May 31, 1947, edition of The New York Times told a different (albeit preliminary) tale:

"The United Air Lines DC-4 that crashed and burned at La Guardia Field Thursday night never got into the air and the pilot, after using up about two-thirds of the 3,500-foot runway, was trying to halt his giant craft by braking and ground looping. All night, on-the-scene inquiries by both the company and officials of the Civil Aeronautics Board established these facts yesterday. They agreed also that the wind shift, described by a company official as 'of almost unbelievable suddenness', led Capt. Benton R. Baldwin, the pilot, to decide against proceeding with the take-off, but they differed on whether the pilot had been apprised of approaching wind shifts before the take-off."

It seemed, at least early on, the cause may have actually been wind shear (although it is referred to as "wind shift" in the article).