United Airlines Flight 232

United Airlines Flight 232 is a scheduled United Airlines Flight from Denver to Philadelphia, stopping in Chicago. On July 19, 1989 the DC-10 operating the flight crash-landed in Sioux City, Iowa after an uncontrolled engine failure which lead to a complete loss of all hydraulic systems. Of the 296 people on board 112 died. The accident is considered an example of successful crew resource management bacause of the manner in which the flight crew handled the emergency.

Aircraft
The aircraft, a McDonnell Douglas DC-10-10, registration N1819U was delivered to United Airlines in 1971. The plane had been operated for a total of 43,401 hours and 16,997 flights. The aircraft was powered by General Electric CF6-6D engines.

Crew
Flight 232's captain was Alfred Clair (Al) Haynes. Haynes, 57, was hired by United Airlines in 1956. He had 29,967 hours of total flight time with United Airlines and 7,190 hours in the DC-10.

Haynes' co-pilot was first officer William R. (Bill) Records, 48, first hired by National Airlines in 1969. He then worked for Pan American World Airways. He had approximately 20,000 hours of total flight time. He was hired by United Airlines in 1985, and had accrued 665 hours as a DC-10 first officer while working for United.

Flight Engineer Dudley J. Dvorak, 51, was hired by United Airlines in 1986. He had aproximately 15,000 hours of total flying time. While working for United, he had accumulated 1,903 hours as a flight engineer in the Boeing 727 and 33 hours as a flight engineer in the DC-10.

Dennis Edward Fitch, 46, a training-check airman aboard Flight 232 as a passenger, was hired by United Airlines in 1968. His total DC-10 time with United was 2,987 hours, including 1,943 hours accrued as a flight engineer, 965 hours as a first officer, and 79 hours as a captain. He had practiced under conditions of hydraulic failure on a flight simulator.

Eight flight attendants were also aboard the flight.

Takeoff and engine failure
Flight 232 took off at 14:09 Central Daylight Time from Stapleton International Airport, Denver, Colorado, and headed for O'Hare International Airport.

At 15:16, 67 minutes after Flight 232 took off, the fan disk of its tail-mounted Engine No. 2 exploded while the plane was at its cruising altitude of 37,000 feet (11,000 m). The engine's fan disk detached from the aircraft as a result of the uncontained engine failure, damaging the tail as well as parts of the No. 2 hydraulic system and supply hoses. Engine debris caused damage to the the horizontal stabilizer, severing the No. 1 and No. 3 hydraulic system supply hoses.

The pilots felt a jolt, and the autopilot disengaged. As Records took hold of his control column, Haynes focused on the tail engine, whose instruments indicated it was malfunctioning; he found its throttle and fuel supply controls jammed. At Dvorak's suggestion, a valve cutting fuel to the tail engine was shut off. This part of the emergency took 14 seconds.

Attempts to control the plane
Meanwhile, Records found that the plane did not respond to his control column inputs. Even with the control column turned all the way to the left and pulled all the way back, the aircraft was banking to the right with the nose dropping. Haynes attempted to level the aircraft with his own control column, then both Haynes and Records tried using their control columns together, but the aircraft still did not respond. Afraid the aircraft would roll into a completely inverted position, the crew reduced the left wing-mounted engine to idle and applied maximum power to the right engine. This caused the airplane to level out. While Haynes and Records performed the engine shutdown checklist for the failed engine, Dvorak observed that the gauges for fluid pressure and quantity in all three hydraulic systems were indicating zero. The loss of all hydraulic fluid meant that control surfaces were inoperative. The flight crew deployed the DC-10's air-driven generator in an attempt to restore hydraulic power by powering the auxiliary hydraulic pumps, but this was unsuccessful. The crew contacted United Airlines maintenance personnel via radio, but were told that as a total loss of all three hydraulic systems on the DC-10 was considered "virtually impossible", no procedures were established for such an event. At this point the plane was tending to bank right and was oscillating in a phugoid cycle. It would descend until it gains speed and thrust, then it would climb until it loses enough speed and thrust to start descending again. This cycle continued on and on, and the plane lost an altitude of about 1,500 feet at each cycle. Fitch, a United Airlines DC-10 flight instructor, was travelling as passenger and volunteered to help. The message was relayed by a flight attendant to the flight crew, who invited Fitch up to the cockpit. he arrived and began assisting at about 15:29. Haynes asked Fitch to observe the ailerons through the passenger cabin windows to see if control inputs were having any effect. Fitch reported back that the ailerons were not moving at all. Nonetheless, the crew continued to manipulate their control columns for the remainder of the flight, hoping for at least some effect. Haynes then asked Fitch to take over control of the throttles so that Haynes could concentrate on his control column. Fitch was able to mitigate the phugoid cycle and partially control the plane.

Crash landing
The flight crew contacted air trafic control and decided to land at Sioux Gateway Airport. Haynes kept his sense of humor during the emergency, as recorded on the plane's CVR:
 * Fitch: "I'll tell you what, we'll have a beer when this is all done."
 * Haynes: "Well I don't drink, but I'll sure as hell have one."

and later:
 * Sioux City Approach: "United Two Thirty-Two Heavy, the wind's currently three six zero at one one; three sixty at eleven. You're cleared to land on any runway."
 * Haynes: "[laughter] Roger. [laughter] You want to be particular and make it a runway, huh?"As the crew began to prepare for arrival at Sioux City, they questioned whether they should deploy the landing gear or belly-land the aircraft with the gear retracted. They decided that having the landing gear down would provide some shock absorption on impact. The complete hydraulic failure left the landing gear lowering mechanism inoperable. Two options were available to the flight crew. The DC-10 is designed so that if hydraulic pressure to the landing gear is lost, the gear will fall down slightly and rest on the landing gear doors. Placing the regular landing gear handle in the down position will unlock the doors mechanically, and the doors and landing gear will then fall down into place and lock due to gravity. An alternative system is also available using a lever in the cockpit floor to cause the landing gear to fall into position. This lever has the added benefit of unlocking the outboard ailerons, which are not used in high-speed flight and are locked in a neutral position. The crew hoped that there might be some trapped hydraulic fluid in the outboard ailerons and that they might regain some use of flight controls by unlocking them. They elected to extend the gear with the alternative system. Although the gear deployed successfully no hydraulic fluid was recovered.

Landing was originally planned on the 9,000-foot (2,700 m) Runway 31. Difficulties in controlling the aircraft made lining up almost impossible. While dumping some of the excess fuel, the plane executed a series of mostly right-hand turns (turning the plane in this direction was easier) with the intention of lining up with Runway 31. Such attempts were unsuccessful and the plane instead lined up with the closed 6,888-foot (2,099 m) Runway 22. Fire trucks had been placed on Runway 22, anticipating a landing on nearby Runway 31, so all the vehicles were quickly moved out of the way before the plane touched down. Runway 22 had been permanently closed a year earlier. ATC also advised that a four-lane Interstate ran north and south just east of the airport, which they could land on if they did not think they could make the runway. Captain Haynes replied that they were passing over the interstate at that time and they would try for the runway instead. Fitch continued to control the aircraft's descent by adjusting engine thrust. With the loss of all hydraulics, the flaps could not be extended, and since flaps control both the minimum required forward speed and sink rate, the crew was unable to control both airspeed and sink rate. On final approach, the aircraft's forward speed was 220 knots (410 km/h) and it had a sink rate of 1,850 feet per minute (9.4 m/s), while a safe landing would require 140 knots (260 km/h) and 300 feet per minute (1.5 m/s). Fitch needed a seat for landing and Dvorak offered up his own, as it could be moved to a position behind the throttles. Dvorak sat in the cockpit's jump seat for landing. Moments before landing, Fitch noticed the high sink rate and that the plane started to yaw and roll right again and pushed the throttles to full power in an attempt to correct the high sink rate and level the plane. It was now 16:00. The CVR recorded these final moments:
 * Records: "Close 'em off."
 * Haynes: "Left turn, close 'em off."
 * Records: "Pull 'em all off."
 * Fitch: "Nah, I can't pull 'em off or we'll lose it, that's what's turning ya."
 * Records: "Okay."
 * Fitch: "Back, Al!"
 * Haynes: "Left, Left throttle, left, left, left, left, left, left, left, left, left, left, left!"
 * GPWS: "Whoop whoop pull up. Whoop whoop pull up. Whoop whoop pull up."
 * Haynes: "Everybody stay in brace!"
 * GPWS: "Whoop whoop pull up."
 * Haynes: "God!"
 * [Sound of impact, end of recording]

Not enough time remained for the engines to respond to Fitch's inputs, nor was there time for the flight crew to react. The tip of the right wing hit the runway first, spilling fuel, which ignited immediately. The tail section broke off from the force of the impact, and the rest of the aircraft bounced several times, shedding the landing gear and engine nacelles and breaking the fuselage into several main pieces. On the final impact, the right wing was shorn off and the main part of the aircraft skidded sideways, rolled over onto its back, and slid to a stop upside-down in a corn field to the right of Runway 22.

Aftermath
Of the 296 people on board, 112 died. Most were killed by injuries sustained in the multiple impacts, but 35 people in the middle fuselage section directly above the fuel tanks died from smoke inhalation in the post-crash fire. Of those, 24 had no traumatic blunt-force injuries. The majority of the 184 survivors were seated behind first class and ahead of the wings. Many passengers were able to walk out through the ruptures to the structure.

Of all of the passengers: The passengers who died for reasons other than smoke inhalation were seated in rows 1–4, 24–25, and 28–38. Passengers who died because of smoke inhalation were seated in rows 14, 16, and 22–30. The person assigned to 20H moved to an unknown seat and died of smoke inhalation.
 * 35 died because of smoke inhalation (none were in first class).
 * 76 died for reasons other than smoke inhalation (17 in first class).
 * One died 31 days after the crash.
 * 47 were seriously injured (eight in first class).
 * 125 had minor injuries (one in first class).
 * 13 had no injuries (none in first class).

One crash survivor died one month after the accident; he was classified according to NTSB regulations as a survivor with serious injuries.

Fifty-two children, including four "lap children" without their own seats, were on board the flight because of the United Airlines "Children's Day" promotion. Eleven children, including one lap child, died. Many of the children were traveling alone.

Rescuers did not identify the debris that was the remains of the cockpit, with the four pilots alive inside, until 35 minutes after the crash. All four recovered from their injuries and eventually returned to flight duty.