This article has multiple issues. Please help improve it or discuss these issues on the talk page. (Learn how and when to remove these template messages) This article relies largely or entirely on a single source. Relevant discussion may be found on the talk page. Please help improve this article by introducing citations to additional sources.Find sources: "United Airlines Flight 521" – news · newspapers · books · scholar · JSTOR (September 2011) This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: "United Airlines Flight 521" – news · newspapers · books · scholar · JSTOR (September 2011) (Learn how and when to remove this template message) (Learn how and when to remove this template message)
United Airlines Flight 521
ILA 20000007.JPG
A Douglas DC-4 similar to the accident aircraft
DateMay 29, 1947
SummaryPilot error
SiteLaGuardia Airport,
New York City, United States
40°46′06″N 73°53′05″W / 40.7683°N 73.8847°W / 40.7683; -73.8847Coordinates: 40°46′06″N 73°53′05″W / 40.7683°N 73.8847°W / 40.7683; -73.8847
Aircraft typeDouglas DC-4
Aircraft nameMainliner Lake Tahoe
OperatorUnited Airlines
Flight originLaGuardia Airport,
New York
DestinationCleveland Municipal Airport, Cleveland, Ohio

United Airlines Flight 521 was a scheduled passenger flight operated by a Douglas DC-4 from LaGuardia Airport in New York City to Cleveland, Ohio. On May 29, 1947, while attempting to take off on runway 18, the aircraft failed to get airborne, overran the end of the runway, ripped through an airport fence onto traffic on the Grand Central Parkway, and slammed into an embankment, ultimately plunging into a pond and exploding. Ten people escaped the flaming wreckage; only five of them survived.[1]

It was the worst commercial aviation disaster in United States history at the time. Its record stood for less than 24 hours before an Eastern Airlines DC-4 crashed near Baltimore, Maryland, killing all 53 aboard.[1]


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).


  1. ^ a b "RUNWAY 18 Air Safety, May-June 1947 Chapter 197". Daily News. September 21, 2000. Retrieved May 16, 2009.[permanent dead link]