United Airlines Flight 232
Photo of United Airlines Flight 232 from the NTSB report, with damage highlighted.
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| Accident summary | |
|---|---|
| Date | July 19, 1989 |
| Summary | Uncontained engine failure due to faulty metallurgic forging of fan disk leading to loss of flight controls due to ruptured hydraulic systems |
| Site |
Sioux Gateway Airport Sioux City, Iowa, United States |
| Passengers | 285 |
| Crew | 11 |
| Fatalities | 111 |
| Injuries (non-fatal) | 172 |
| Survivors | 185 |
| Aircraft type | McDonnell Douglas DC-10-10 |
| Operator | United Airlines |
| Registration | N1819U |
| Flight origin | Stapleton International Airport, Denver, Colorado |
| Stopover | O'Hare International Airport, Chicago, Illinois |
| Destination | Philadelphia International Airport, Philadelphia, Pennsylvania |
United Airlines Flight 232 was a DC-10 (registered N1819U) that on July 19, 1989 crash-landed in Sioux City, Iowa after suffering catastrophic failure of its tail-mounted engine, which led to the loss of all flight controls. The flight was en route from Stapleton International Airport in Denver, Colorado to O'Hare International Airport in Chicago. Of the 296 people on board, 111 died in the accident and 185 survived in total. Despite the deaths, the accident is considered a prime example of successful crew resource management due to the large number of survivors and the manner in which the flight crew handled the emergency and landed the airplane without conventional control. The flight crew became well known as a result of their actions, in particular the captain, Alfred C. Haynes, and a DC-10 instructor on board who offered his assistance, Dennis E. Fitch.
The National Transportation Safety Board determined that the probable cause of this accident was the inadequate consideration given to human factors limitations in the inspection and quality control procedures used by United Airlines' engine overhaul facility. These resulted in the failure to detect a fatigue crack originating from a previously undetected metallurgical defect located in a critical area of the stage 1 fan disk that was manufactured by General Electric Aircraft Engines. The uncontained manner in which the engine failed resulted in high-speed metal fragments being hurled from the engine; these fragments penetrated the hydraulic lines of all three independent hydraulic systems on board the aircraft, which rapidly lost their hydraulic fluid. The subsequent catastrophic disintegration of the disk resulted in the liberation of debris in a pattern of distribution and with energy levels that exceeded the level of protection provided by design features of the hydraulic systems that operate the DC-10's flight controls; the flight crew lost its ability to operate nearly all of them. Despite these losses, the crew was able to attain and then maintain limited control by using the throttles to adjust thrust to the remaining wing-mounted engines. By using each engine independently, the crew made rough steering adjustments, and by using the engines together they were able to roughly adjust altitude. The crew guided the crippled jet to Sioux Gateway Airport and lined it up for landing on one of the runways. Without the use of flaps and slats, they were unable to slow down for landing, and were forced to attempt landing at a very high ground speed. The aircraft also landed at an extremely high rate of descent due to the inability to flare (reduce the rate of descent before touchdown by increasing pitch). As a result, upon touchdown the aircraft broke apart, rolled over and caught fire. The largest section came to rest in a cornfield next to the runway. Despite the ferocity of the accident, 185 (62.5%) passengers and crew survived owing to a variety of factors including the relatively controlled manner of the crash and the early notification of emergency services.
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