On March 3, 1974, in an accident circumstantially similar to American Airlines Flight 96, a cargo-door blowout caused Turkish Airlines Flight 981 to crash near Ermenonville, France, in the deadliest air crash in history at the time. The cargo door of Flight 981 had not been fully locked, though it appeared so to both cockpit crew and ground personnel. The Turkish aircraft had a seating configuration that exacerbated the effects of decompression, and as the cabin floor collapsed into the cargo bay, control cables were severed and the aircraft became uncontrollable. Investigators found that the DC-10's relief vents were not large enough to equalize the pressure between the passenger and cargo compartments during explosive decompression. Following this crash, a special subcommittee of the United States House of Representatives investigated the cargo-door issue and the certification by the Federal Aviation Administration (FAA) of the original design. An airworthiness directive was issued, and all DC-10s underwent mandatory door modifications. The DC-10 experienced no more major incidents related to its cargo door after FAA-approved changes were made.