United Air Lines Flight 521 was a scheduled passenger flight operated by a Douglas DC-4 from LaGuardia Airport, New York City, United States, to Cleveland, Ohio, United States. 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.
LaGuardia Airport, colloquially known as LaGuardia or simply LGA, is a civil airport in East Elmhurst, Queens, New York City, situated on the northwestern shore of Long Island, bordering Flushing Bay. Covering 680 acres as of July 1, 2025, the facility was established in 1929, and began operating as a public airport in 1939. It is named after Fiorello H. La Guardia, a former mayor of New York City.
May 29 is the 149th day of the year in the Gregorian calendar; 216 days remain until the end of the year.