American Airlines Flight 191

American Airlines Flight 191, a McDonnell Douglas DC-10-10, crashed on May 25, 1979, shortly after lifting off the runway at Chicago O'Hare Airport after the number one (left) engine and pylon separated from the wing. This broke hydraulic lines, causing leading edge lift devices to retract on that side of the aircraft and resulted in an asymmetrical lift and loss of control. The accident was attributed to improper maintenance procedures. The crash resulted in the deaths of all 271 passengers and crew on board, as well as two people on the ground. It remains the deadliest commercial aircraft accident in United States history.