American Airlines Flight 191

American Airlines Flight 191 was a regularly scheduled domestic passenger flight from O'Hare International Airport in Chicago to Los Angeles International Airport. On the afternoon of May 25, 1979, the McDonnell Douglas DC-10 operating this flight was taking off from then-existing runway 32R (the runway was subsequently demolished around 2015) at O'Hare International when its left engine detached from the wing, causing a loss of control. The aircraft crashed about 4,600 feet (1,400 m) from the end of runway 32R. All 271 occupants on board were killed on impact, along with two people on the ground. With a total of 273 fatalities, the disaster is the deadliest aviation accident to have occurred in the United States.

The National Transportation Safety Board (NTSB) found that as the aircraft was beginning its takeoff rotation, engine number one (the left engine) separated from the left wing, flipping over the top of the wing and landing on the runway. As the engine separated from the aircraft, it severed hydraulic lines that lock the wing's leading-edge slats in place and damaged a 3-foot (1 m) section of the left wing's leading edge. Aerodynamic forces acting on the wing resulted in an uncommanded retraction of the outboard slats. As the aircraft began to climb, the damaged left wing produced far less lift than the right wing, which had its slats still deployed and its engine providing full takeoff thrust. The disrupted and unbalanced aerodynamics of the aircraft caused it to roll abruptly to the left until it was partially inverted, reaching a bank angle of 112°, before crashing in an open field by a trailer park near the end of the runway. The engine separation was attributed to damage to the pylon structure holding the engine to the wing, caused by improper maintenance procedures at American Airlines.