On December 16, 1960, a United Airlines Douglas DC-8 bound for Idlewild Airport in New York City collided in midair with a TWA Lockheed L-1049 Super Constellation descending toward LaGuardia Airport. The Constellation crashed on Miller Field in Staten Island and the DC-8 in Park Slope, Brooklyn, killing all 128 aboard the two aircraft and six people on the ground. The accident was the world's deadliest aviation disaster at the time, and remains the deadliest accident in the history of United Airlines.

United Airlines, Inc. is a major American airline headquartered at the Willis Tower in Chicago, Illinois. United operates an extensive domestic and international route network across the United States and all six inhabited continents primarily out of its eight hubs, with Chicago–O'Hare having the largest number of daily flights and Denver carrying the most passengers in 2023. Regional service is operated by independent carriers under the brand name United Express.