United Airlines Flight 232
Encyclopedia
United Airlines Flight 232 was a scheduled flight from Stapleton International Airport
in Denver, Colorado, to O'Hare International Airport
in Chicago
, with continuing service to Philadelphia International Airport
. On July 19, 1989, the DC-10
(Registration ) operating the route crash-landed in Sioux City, Iowa
, after suffering catastrophic failure of its tail-mounted engine
, which led to the loss of all flight controls. 111 people died in the accident while 185 survived. Despite the deaths, the accident is considered a prime example of successful crew resource management
due to the manner in which the flight crew handled the emergency, and the high number of survivors considering that the airplane was landed without conventional control. The flight crew became well known as a result of their actions that day, in particular the captain, Alfred C. Haynes
, and a DC-10 instructor on board who offered his assistance, Dennis E. Fitch
.
The manner in which the engine failed resulted in high-speed shrapnel being hurled from the engine; this shrapnel penetrated the hydraulic lines of all three independent
hydraulic systems on board the aircraft, which rapidly lost their hydraulic fluid. As the flight controls on the DC-10 are hydraulically powered, the flight crew lost their ability to operate nearly all of them. Despite these losses, the crew were able to attain and then maintain limited control by using the only systems still workable: the two remaining engines. By utilizing 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 flight controls, they were unable to slow down for landing, and were forced to attempt landing at much too high a speed and rate of descent. On touchdown, the aircraft broke apart, caught fire, and rolled over. The largest section came to rest in a cornfield next to the runway. Despite the ferocity of the accident, approximately two-thirds of those on board survived due to multiple factors. The cause of the engine failure was traced back to a manufacturing defect in the fan disk, which had microscopic cracks due to impurities. The cracking was present during maintenance inspections and should have been detected by maintenance personnel, revealing shortcomings in the maintenance processes.
The accident had a strong impact on the industry. DC-10s were modified to prevent catastrophic loss of hydraulic fluid should a similar failure occur again. These modifications were also included in the DC-10's direct successor, the MD-11. Research has been conducted to see if computers might be able to control aircraft using the engines alone, improving on what humans can do unaided. The accident is cited as an example of why "lap infants"—children without a seat of their own—should have their own seat and be properly restrained on all flights. This campaign has been led by United 232's chief flight attendant, one of the notable survivors of the accident. Several other notable people survived, and the news photography in the direct aftermath led to an iconic image being produced; that image was transformed into sculpture and now serves as flight 232's memorial.
, Denver, Colorado
, bound for O'Hare International Airport
in Chicago
, with ongoing service to Philadelphia International Airport
. At 15:16, while the plane was in a shallow right turn at 37,000 feet, the fan disk
of its tail-mounted General Electric
CF6-6
engine failed and disintegrated. The debris from the failed disk was not contained by the engine's nacelle
, a housing that protects the engine. Pieces of the structure penetrated the aircraft tail section in numerous places, including the horizontal stabilizer
. This shrapnel punctured the lines of all three hydraulic systems, allowing the fluid to rapidly drain away.
Captain Alfred C. Haynes
and his flight crew, First Officer William Records, copilot, and Second Officer Dudley Dvorak, flight engineer
, felt a jolt go through the aircraft. Warning lights illuminated which indicated that the autopilot
had disengaged and the tail-mounted number two engine was malfunctioning. Captain Haynes watched First Officer Records place his hands on the flight controls in response to the autopilot disconnecting and therefore focused his attention on the malfunctioning engine. Second Officer Dvorak obtained the engine failure checklist and read the first item: throttle power must be reduced to idle. Haynes was unable to move the throttle; the linkage had been jammed as a result of the engine failure. The second item called for the fuel supply lever to be pulled to shutoff, but it would not move either. At this point, at Dvorak's suggestion, the firewall shutoff valve was actuated, and the fuel flow to the engine was shut off. This part of the emergency took 14 seconds.
Meanwhile, Records noticed that the airliner was off course, and moved his control column
to correct this, but the plane did not respond. Records reported to Captain Haynes that he could not control the airplane. Haynes, having just shut off the fuel supply to the malfunctioning engine, looked at Records and was surprised by what he saw: Records had the control column turned all the way to the left, commanding maximum left aileron
, and pulled all the way back, commanding maximum up elevator
. These inputs would never be utilized simultaneously in normal flight. What was more, despite these inputs, which command a roll to the left and the aircraft's nose to rise, the aircraft was instead banking to the right with the nose dropping. Haynes took the flight controls and attempted to level the aircraft with his own control column. When this was ineffective, both Haynes and Records utilized their control columns at the same time in an attempt to recover from the steepening bank. The aircraft still did not respond. Out of options, and in danger of the aircraft rolling into a completely inverted position (an unrecoverable situation which would result in a crash), the crew took the throttle for the left wing mounted number 1 engine and reduced the power to idle, while also taking the throttle for the right wing mounted number 3 engine and commanding maximum power. The resulting differential thrust (no power on the left side and maximum power on the right side) caused the airplane to slowly level out.
With the imminent danger over for the time being, the crew began to diagnose the situation on the flight deck. Dvorak discovered that the pressure gauges and quantity gauges on his instrument panel for the three hydraulic systems were registering zero, and reported this to Haynes. The three hydraulic systems were separate; a single event in one system would not disable the other systems, but lines for all three systems shared the same 10 inches (254 mm) route through the tail where the engine debris had penetrated. There was no additional backup system. The flight crew quickly realized that the initial failure had left all hydraulic systems, and therefore all control surfaces, inoperative. The crew called United Airlines maintenance base using one of their radios, but as a total loss of hydraulics on the DC-10 was considered "virtually impossible", there were no procedures or guidelines for dealing with such an event.
Due to the damage in the tail, the plane had a continual tendency to turn right, and without flight controls it was difficult to maintain a stable course. The plane began to slowly oscillate vertically in a phugoid
cycle, which is characteristic of planes in which control surface command is lost. With each iteration of the cycle the aircraft lost approximately 1500 feet (457.2 m) of altitude. Dennis E. Fitch
, an off-duty United Airlines DC-10 flight instructor
, was seated in the first class section and, noticing the crew were having trouble controlling the airplane, offered his assistance to the flight attendants. Upon being informed that there was a DC-10 instructor on board, Haynes immediately invited him to the cockpit, hoping his instructional knowledge of the aircraft would help them regain control. Upon entering the cockpit and looking at the hydraulic gauges, Fitch determined that the situation was beyond anything he had ever faced. The flight crew, while using the engines to control the airplane, were also still trying to fly the airplane using their control columns. Haynes asked Fitch to go into the passenger cabin and see if their control inputs were having any effect on the ailerons. Fitch reported back that the ailerons were not moving at all. Despite this news, the crew would continue trying to fly the airplane with their control columns for the remainder of the flight, hopeful that it was at least having some effect. Fitch, his first task concluded, asked how he might be of further assistance. Haynes, still trying to fly the airplane with his control column while simultaneously working the throttles, asked Fitch to work the throttles instead. With one throttle in each hand, Fitch was able to mitigate the phugoid
cycle and make rough steering adjustments.
Air traffic control
(ATC) was contacted and an emergency landing at nearby Sioux Gateway Airport
was organized.
Haynes kept his sense of humor during the emergency, as recorded on the plane's cockpit voice recorder
(CVR):
and later:
A more serious remark often quoted from Haynes was made when ATC asked the crew to make a left turn to keep them clear of the city:
Haynes later noted that "We were too busy [to be scared]. You must maintain your composure in the airplane or you will die. You learn that from your first day flying."
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. However, the complete hydraulic failure left the landing gear lowering mechanism inoperative. Two options were available to the flight crew. The DC-10 is designed such that if hydraulic pressure to the landing gear is lost, it will fall down slightly and rest on the landing gear doors. Placing the regular landing gear handle into 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 alternate system is also available where the gear will fall into position by pulling a lever in the cockpit floor. 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 alternate system. Although the gear deployed successfully, there was no change in the controllability of the aircraft.
Landing was originally planned on the 9000 feet (2,743.2 m) Runway 31. Difficulties in controlling the aircraft made lining up almost impossible. While dumping excess fuel, the plane executed a series of mostly right-hand turns (it was easier to turn the plane in this direction) with the intention of lining up with Runway 31. When they came out they were instead lined up with the shorter (6,600 ft) Runway 22, and had little capacity to maneuver. Fire trucks had been placed on Runway 22, anticipating a landing on Runway 31, so all the vehicles were quickly moved out of the way before the plane touched down.
Fitch continued to control the aircraft's descent by adjusting engine thrust. With the loss of all hydraulics, the crew were unable to control airspeed
independent from sink rate
. On final descent, the aircraft was going 240 knots and sinking at 1,850 feet per minute, while a safe landing would require 140 knots and 300 feet per minute. Fitch needed a seat for landing; 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. Unfortunately, right before touchdown, the aircraft began a downward phugoid
and veered right. The flight crew had no time 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 sheared off and the main part of the aircraft skidded sideways, rolled over on to its back, and slid to a stop upside-down in a corn field to the right of Runway 22. Witnesses reported that the aircraft cartwheeled, but the investigation did not confirm this. News reports that the aircraft cartwheeled were due to misinterpretation of the video of the crash that showed the flaming right wing tumbling end-over-end and the intact left wing, still attached to the fuselage, rolling up and over as the fuselage flipped over.
Of the 296 people on board, 111 died in the crash. 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 185 survivors were seated behind first class and ahead of the wings. Many passengers were able to walk out through the ruptures to the structure, and in many cases got lost in the high field of corn adjacent to the runway until rescue workers arrived on the scene and escorted them to safety.
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 due to smoke inhalation were seated in rows 14, 16, and 22–30. A person assigned to 20H moved to an unknown seat and died due to smoke inhalation.
One crash survivor died 31 days after the accident; in accordance with official rules, the NTSB classified his injuries as "serious."
Fifty-two children, including four "lap children" without their own seats, were on board the flight due to the United Airlines "Children's Day" promotion. Eleven children, including one lap child, died. Many of the children had traveled alone.
Rescuers initially ignored the cockpit, as it had been compressed in the crash to approximately waist high and was completely unrecognizable. It was not until 35 minutes after the crash that rescuers discovered that the debris was the cockpit and that the four pilots were still alive inside. All four would recover from their injuries and return to work: Haynes, Records, and Dvorak would return in three months, while Fitch, more seriously injured than the others, would return in 11 months.
officials were on scene within hours of the accident. As the investigation unfolded, it became apparent that the entire fan disk and blade assembly from engine number 2, a component approximately 8 feet (2.4 m) in diameter and made of titanium
alloy, was missing from the accident scene. Despite an extensive search in the weeks following the crash, the fan disk could not be located. Realizing that finding the fan disk was potentially the key to understanding the reasons for the engine failure, the engine's manufacturer, GE, offered a $50,000 reward to whoever could locate the disk, and $1,000 for each fan blade. On October 10, 1989, three months after the crash, a farmer harvesting corn near Alta, Iowa
felt resistance on her combine
, and after getting out to see what was causing it, discovered most of the fan disk with a number of blades still attached partially buried in her cornfield. The rest of the fan disk would also be located later in the harvest.
Examination of the fan disk would indeed solve the mystery. Investigators discovered an impurity and fatigue
crack in the disk, and traced this back to the Alcoa
foundry from which the engine part originated. The investigation showed there was a defect in the elimination of gaseous anomalies during the purifying of the titanium disk ingot. An excess amount of nitrogen
was in the material, causing a 'hard alpha inclusion
', which cracked during forging and then fell out during final machining. This formed a cavity with microscopic cracks at the edges. During the engine's normal running cycle, one of these cracks grew slowly each time the engine was powered up and brought to operating temperature
, until it grew large enough for the disk to fail structurally. Newer batches used much higher melting temperatures and a "triple vacuum" process to eliminate these impurities.
The subsequent investigation and Airworthiness Directive
revealed several other fan disks already in service from the same batch of ingots which had started to exhibit the initial cracking symptoms of part failure.
maintenance processes and personnel to detect an existing fatigue crack. Post-crash analysis of the crack surfaces showed the presence of a penetrating fluorescent dye used to detect cracks during maintenance. The presence of the dye indicated that the crack was present and should have been detected at a prior inspection. The detection failure arose from poor attention to human factors
in United Airlines' specification of maintenance processes.
(NTSB) investigation, after subsequent reconstructions of the accident in flight simulator
s, deemed that training for such an event involved too many factors to be practical. While some level of control was possible, no precision could be achieved, and a landing under these conditions was stated to be "a highly random event". The NTSB further noted that "under the circumstances the UAL flight crew performance was highly commendable and greatly exceeded reasonable expectations."
Because this type of aircraft control is difficult for humans to achieve, some researchers have attempted to integrate this control ability into the computers of fly-by-wire
aircraft. Early attempts to add the ability to real airplanes were not very successful; the software was based on experiments conducted in flight simulators where jet engines are usually modeled as "perfect" devices with exactly the same thrust on each engine, a linear relationship between throttle setting and thrust, and instantaneous response to input. Later, computer models were updated to account for these factors, and planes have been successfully flown
with this software installed.
Newer aircraft designs such as the MD-11 have incorporated hydraulic fuses to isolate a punctured section and prevent a total loss of hydraulic fluid. Following the UAL 232 accident, such fuses were installed in the number 3 hydraulic system in the area below the number 2 engine on all DC-10 aircraft to ensure sufficient control capability remained if all three hydraulic system lines should be damaged in the tail area in the future. Although elevator and rudder control would be lost, the aircrew would still be able to control the aircraft's pitch (up and down) with stabilizer trim
, and would be able to control roll (left and right) with some of the aircraft's aileron
s and spoilers
. Although not an ideal situation, the system provides a greater measure of control than was available to the crew of United 232.
It is still possible to lose all three hydraulic systems if serious damage occurs elsewhere, as nearly happened to a cargo airliner in 2002 during takeoff when a main gear tire exploded in the wheel well area. The damage in the left wing area caused total fluid loss from the number 1 and the number 2 hydraulic systems. The number 3 system was dented but not penetrated. DC-10s still have no fuse protection for any of the three hydraulic systems in the event of an exploding main gear tire.
Of the four children deemed too young to have seats of their own ("lap children"), one died from smoke inhalation. The NTSB added a safety recommendation to the FAA on its "List of Most Wanted Safety Improvements" in May 1999 suggesting a requirement for children under 2 to be safely restrained, which was removed in November 2006. The accident sparked a campaign led by United Flight 232's senior flight attendant, Jan Brown Lohr, for all children to have seats on aircraft.
The accident has since become a prime example of successful Crew Resource Management
. For much of aviation's history, the Captain was considered the final authority, and crews were to respect the Captain's expertise and not question him. This began to change in the 1970s especially after the Tenerife Disaster
. Crew Resource Management, while still considering the Captain the final authority, instructs crewmembers to speak up when they detect a problem, and instructs Captains to listen to crewmember concerns. United Airlines instituted a Crew Resource Management class in the early 1980s. The NTSB would later credit this training as valuable toward the success of United 232's crew in handling their emergency. The FAA made Crew Resource Training mandatory in the aftermath of the accident.
"Had any of those things not been there," Haynes said, "I'm sure the fatality rate would have been a lot higher."
As with the Eastern Air Lines Flight 401
crash of a similarly-sized Lockheed L-1011
in 1972, the relatively shallow angle of descent likely played a large part in the relatively high survival rate. The National Transportation Safety Board concluded that under the circumstances, "a safe landing was virtually impossible."
The disintegration of a turbine disc, leading to loss of control, was a direct cause of two major aircraft disasters in Poland:
Stapleton International Airport
Stapleton International Airport was Denver, Colorado's primary airport from 1929 to 1995. At different times it served as a hub for TWA, People Express, Frontier Airlines and Western Airlines as well as a hub for Continental Airlines and United Airlines at the time of its closure.In 1995 Stapleton...
in Denver, Colorado, to O'Hare International Airport
O'Hare International Airport
Chicago O'Hare International Airport , also known as O'Hare Airport, O'Hare Field, Chicago Airport, Chicago International Airport, or simply O'Hare, is a major airport located in the northwestern-most corner of Chicago, Illinois, United States, northwest of the Chicago Loop...
in Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
, with continuing service to Philadelphia International Airport
Philadelphia International Airport
Philadelphia International Airport is a major airport in Philadelphia, Pennsylvania, United States, and is the largest airport in the Delaware Valley region and in Pennsylvania...
. On July 19, 1989, the DC-10
McDonnell Douglas DC-10
The McDonnell Douglas DC-10 is a three-engine widebody jet airliner manufactured by McDonnell Douglas. The DC-10 has range for medium- to long-haul flights, capable of carrying a maximum 380 passengers. Its most distinguishing feature is the two turbofan engines mounted on underwing pylons and a...
(Registration ) operating the route crash-landed in Sioux City, Iowa
Sioux City, Iowa
Sioux City is a city in Plymouth and Woodbury counties in the western part of the U.S. state of Iowa. The population was 82,684 in the 2010 census, a decline from 85,013 in the 2000 census, which makes it currently the fourth largest city in the state....
, after suffering catastrophic failure of its tail-mounted engine
Jet engine
A jet engine is a reaction engine that discharges a fast moving jet to generate thrust by jet propulsion and in accordance with Newton's laws of motion. This broad definition of jet engines includes turbojets, turbofans, rockets, ramjets, pulse jets...
, which led to the loss of all flight controls. 111 people died in the accident while 185 survived. Despite the deaths, the accident is considered a prime example of successful crew resource management
Crew Resource Management
Crew resource management or Cockpit resource management is a procedure and training system in systems where human error can have devastating effects. Used primarily for improving air safety, CRM focuses on interpersonal communication, leadership, and decision making in the cockpit...
due to the manner in which the flight crew handled the emergency, and the high number of survivors considering that the airplane was landed without conventional control. The flight crew became well known as a result of their actions that day, in particular the captain, Alfred C. Haynes
Alfred C. Haynes
Alfred C. "Al" Haynes is a former airline pilot and a regular guest speaker at social events. Haynes gained international fame in 1989, when he, together with the rest of his crew and Dennis E...
, and a DC-10 instructor on board who offered his assistance, Dennis E. Fitch
Dennis E. Fitch
Dennis E. "Denny" Fitch is a retired commercial airline pilot. He is best known for his critical actions as an off-duty DC-10 training captain who helped captain Al Haynes minimize loss of life on United Airlines Flight 232 when all flight controls were lost, on July 19, 1989...
.
The manner in which the engine failed resulted in high-speed shrapnel being hurled from the engine; this shrapnel penetrated the hydraulic lines of all three independent
Redundancy (engineering)
In engineering, redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe....
hydraulic systems on board the aircraft, which rapidly lost their hydraulic fluid. As the flight controls on the DC-10 are hydraulically powered, the flight crew lost their ability to operate nearly all of them. Despite these losses, the crew were able to attain and then maintain limited control by using the only systems still workable: the two remaining engines. By utilizing 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
Sioux Gateway Airport
-History:The construction of Sioux City Army Air Base began in March 1942, about three months after the Japanese attack on Pearl Harbor. Opened on 5 July 1942, it became a major training center during World War II for crew members of B-24 Liberators and B-17 Flying Fortresses...
and lined it up for landing on one of the runways. Without flight controls, they were unable to slow down for landing, and were forced to attempt landing at much too high a speed and rate of descent. On touchdown, the aircraft broke apart, caught fire, and rolled over. The largest section came to rest in a cornfield next to the runway. Despite the ferocity of the accident, approximately two-thirds of those on board survived due to multiple factors. The cause of the engine failure was traced back to a manufacturing defect in the fan disk, which had microscopic cracks due to impurities. The cracking was present during maintenance inspections and should have been detected by maintenance personnel, revealing shortcomings in the maintenance processes.
The accident had a strong impact on the industry. DC-10s were modified to prevent catastrophic loss of hydraulic fluid should a similar failure occur again. These modifications were also included in the DC-10's direct successor, the MD-11. Research has been conducted to see if computers might be able to control aircraft using the engines alone, improving on what humans can do unaided. The accident is cited as an example of why "lap infants"—children without a seat of their own—should have their own seat and be properly restrained on all flights. This campaign has been led by United 232's chief flight attendant, one of the notable survivors of the accident. Several other notable people survived, and the news photography in the direct aftermath led to an iconic image being produced; that image was transformed into sculpture and now serves as flight 232's memorial.
Chronology of the flight
The flight took off at 14:09 (CDT) from Stapleton International AirportStapleton International Airport
Stapleton International Airport was Denver, Colorado's primary airport from 1929 to 1995. At different times it served as a hub for TWA, People Express, Frontier Airlines and Western Airlines as well as a hub for Continental Airlines and United Airlines at the time of its closure.In 1995 Stapleton...
, Denver, Colorado
Denver, Colorado
The City and County of Denver is the capital and the most populous city of the U.S. state of Colorado. Denver is a consolidated city-county, located in the South Platte River Valley on the western edge of the High Plains just east of the Front Range of the Rocky Mountains...
, bound for O'Hare International Airport
O'Hare International Airport
Chicago O'Hare International Airport , also known as O'Hare Airport, O'Hare Field, Chicago Airport, Chicago International Airport, or simply O'Hare, is a major airport located in the northwestern-most corner of Chicago, Illinois, United States, northwest of the Chicago Loop...
in Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
, with ongoing service to Philadelphia International Airport
Philadelphia International Airport
Philadelphia International Airport is a major airport in Philadelphia, Pennsylvania, United States, and is the largest airport in the Delaware Valley region and in Pennsylvania...
. At 15:16, while the plane was in a shallow right turn at 37,000 feet, the fan disk
Fan disk
A fan disk is the part of a turbofan jet engine that contains the fan blades. It is considered one of the most critical components of the engine and has four main functions:...
of its tail-mounted General Electric
GE-Aviation
GE Aviation, a subsidiary of General Electric, is headquartered in Evendale, Ohio . GE Aviation is the top supplier of aircraft engines in the world, and offers engines for the majority of commercial aircraft. GE Aviation is part of the General Electric conglomerate, which is one of the world's...
CF6-6
General Electric CF6
The General Electric CF6 is a family of high-bypass turbofan engines produced by GE Aviation. A development of the first high-power high-bypass jet engine available, the TF39, the CF6 powers a wide variety of civilian airliners. The basic engine core formed the basis for the LM2500, LM5000, and...
engine failed and disintegrated. The debris from the failed disk was not contained by the engine's nacelle
Nacelle
The nacelle is a cover housing that holds engines, fuel, or equipment on an aircraft. In some cases—for instance in the typical "Farman" type "pusher" aircraft, or the World War II-era P-38 Lightning—an aircraft's cockpit may also be housed in a nacelle, which essentially fills the...
, a housing that protects the engine. Pieces of the structure penetrated the aircraft tail section in numerous places, including the horizontal stabilizer
Tailplane
A tailplane, also known as horizontal stabilizer , is a small lifting surface located on the tail behind the main lifting surfaces of a fixed-wing aircraft as well as other non-fixed wing aircraft such as helicopters and gyroplanes...
. This shrapnel punctured the lines of all three hydraulic systems, allowing the fluid to rapidly drain away.
Captain Alfred C. Haynes
Alfred C. Haynes
Alfred C. "Al" Haynes is a former airline pilot and a regular guest speaker at social events. Haynes gained international fame in 1989, when he, together with the rest of his crew and Dennis E...
and his flight crew, First Officer William Records, copilot, and Second Officer Dudley Dvorak, flight engineer
Flight engineer
Flight engineers work in three types of aircraft: fixed-wing , rotary wing , and space flight .As airplanes became even larger requiring more engines and complex systems to operate, the workload on the two pilots became excessive during certain critical parts of the flight regime, notably takeoffs...
, felt a jolt go through the aircraft. Warning lights illuminated which indicated that the autopilot
Autopilot
An autopilot is a mechanical, electrical, or hydraulic system used to guide a vehicle without assistance from a human being. An autopilot can refer specifically to aircraft, self-steering gear for boats, or auto guidance of space craft and missiles...
had disengaged and the tail-mounted number two engine was malfunctioning. Captain Haynes watched First Officer Records place his hands on the flight controls in response to the autopilot disconnecting and therefore focused his attention on the malfunctioning engine. Second Officer Dvorak obtained the engine failure checklist and read the first item: throttle power must be reduced to idle. Haynes was unable to move the throttle; the linkage had been jammed as a result of the engine failure. The second item called for the fuel supply lever to be pulled to shutoff, but it would not move either. At this point, at Dvorak's suggestion, the firewall shutoff valve was actuated, and the fuel flow to the engine was shut off. This part of the emergency took 14 seconds.
Meanwhile, Records noticed that the airliner was off course, and moved his control column
Yoke (aircraft)
A yoke, alternatively known as control column, is a device used for piloting in most fixed-wing aircraft.- Principle :The aviator uses the yoke to control the attitude of the plane, usually in both pitch and roll. Rotating the control wheel controls the ailerons and the roll axis...
to correct this, but the plane did not respond. Records reported to Captain Haynes that he could not control the airplane. Haynes, having just shut off the fuel supply to the malfunctioning engine, looked at Records and was surprised by what he saw: Records had the control column turned all the way to the left, commanding maximum left aileron
Aileron
Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...
, and pulled all the way back, commanding maximum up elevator
Elevator (aircraft)
Elevators are flight control surfaces, usually at the rear of an aircraft, which control the aircraft's orientation by changing the pitch of the aircraft, and so also the angle of attack of the wing. In simplified terms, they make the aircraft nose-up or nose-down...
. These inputs would never be utilized simultaneously in normal flight. What was more, despite these inputs, which command a roll to the left and the aircraft's nose to rise, the aircraft was instead banking to the right with the nose dropping. Haynes took the flight controls and attempted to level the aircraft with his own control column. When this was ineffective, both Haynes and Records utilized their control columns at the same time in an attempt to recover from the steepening bank. The aircraft still did not respond. Out of options, and in danger of the aircraft rolling into a completely inverted position (an unrecoverable situation which would result in a crash), the crew took the throttle for the left wing mounted number 1 engine and reduced the power to idle, while also taking the throttle for the right wing mounted number 3 engine and commanding maximum power. The resulting differential thrust (no power on the left side and maximum power on the right side) caused the airplane to slowly level out.
With the imminent danger over for the time being, the crew began to diagnose the situation on the flight deck. Dvorak discovered that the pressure gauges and quantity gauges on his instrument panel for the three hydraulic systems were registering zero, and reported this to Haynes. The three hydraulic systems were separate; a single event in one system would not disable the other systems, but lines for all three systems shared the same 10 inches (254 mm) route through the tail where the engine debris had penetrated. There was no additional backup system. The flight crew quickly realized that the initial failure had left all hydraulic systems, and therefore all control surfaces, inoperative. The crew called United Airlines maintenance base using one of their radios, but as a total loss of hydraulics on the DC-10 was considered "virtually impossible", there were no procedures or guidelines for dealing with such an event.
Due to the damage in the tail, the plane had a continual tendency to turn right, and without flight controls it was difficult to maintain a stable course. The plane began to slowly oscillate vertically in a phugoid
Phugoid
A phugoid or fugoid is an aircraft motion where the vehicle pitches up and climbs, and then pitches down and descends, accompanied by speeding up and slowing down as it goes "uphill" and "downhill." This is one of the basic flight dynamics modes of an aircraft , and a classic example of a positive...
cycle, which is characteristic of planes in which control surface command is lost. With each iteration of the cycle the aircraft lost approximately 1500 feet (457.2 m) of altitude. Dennis E. Fitch
Dennis E. Fitch
Dennis E. "Denny" Fitch is a retired commercial airline pilot. He is best known for his critical actions as an off-duty DC-10 training captain who helped captain Al Haynes minimize loss of life on United Airlines Flight 232 when all flight controls were lost, on July 19, 1989...
, an off-duty United Airlines DC-10 flight instructor
Flight instructor
A flight instructor is a person who teaches others to fly aircraft. Specific privileges granted to holders of a flight instructor qualification vary from country to country, but very generally, a flight instructor serves to enhance or evaluate the knowledge and skill level of an aviator in pursuit...
, was seated in the first class section and, noticing the crew were having trouble controlling the airplane, offered his assistance to the flight attendants. Upon being informed that there was a DC-10 instructor on board, Haynes immediately invited him to the cockpit, hoping his instructional knowledge of the aircraft would help them regain control. Upon entering the cockpit and looking at the hydraulic gauges, Fitch determined that the situation was beyond anything he had ever faced. The flight crew, while using the engines to control the airplane, were also still trying to fly the airplane using their control columns. Haynes asked Fitch to go into the passenger cabin and see if their control inputs were having any effect on the ailerons. Fitch reported back that the ailerons were not moving at all. Despite this news, the crew would continue trying to fly the airplane with their control columns for the remainder of the flight, hopeful that it was at least having some effect. Fitch, his first task concluded, asked how he might be of further assistance. Haynes, still trying to fly the airplane with his control column while simultaneously working the throttles, asked Fitch to work the throttles instead. With one throttle in each hand, Fitch was able to mitigate the phugoid
Phugoid
A phugoid or fugoid is an aircraft motion where the vehicle pitches up and climbs, and then pitches down and descends, accompanied by speeding up and slowing down as it goes "uphill" and "downhill." This is one of the basic flight dynamics modes of an aircraft , and a classic example of a positive...
cycle and make rough steering adjustments.
Air traffic control
Air traffic control
Air traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
(ATC) was contacted and an emergency landing at nearby Sioux Gateway Airport
Sioux Gateway Airport
-History:The construction of Sioux City Army Air Base began in March 1942, about three months after the Japanese attack on Pearl Harbor. Opened on 5 July 1942, it became a major training center during World War II for crew members of B-24 Liberators and B-17 Flying Fortresses...
was organized.
Haynes kept his sense of humor during the emergency, as recorded on the plane's cockpit voice recorder
Cockpit voice recorder
A cockpit voice recorder , often referred to as a "black box", is a flight recorder used to record the audio environment in the flight deck of an aircraft for the purpose of investigation of accidents and incidents...
(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? (Haynes was alluding to the extreme difficulty in controlling the aircraft and their extremely low chances of making it to the airport at all.)
A more serious remark often quoted from Haynes was made when ATC asked the crew to make a left turn to keep them clear of the city:
- Haynes: Whatever you do, keep us away from the city.
Haynes later noted that "We were too busy [to be scared]. You must maintain your composure in the airplane or you will die. You learn that from your first day flying."
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. However, the complete hydraulic failure left the landing gear lowering mechanism inoperative. Two options were available to the flight crew. The DC-10 is designed such that if hydraulic pressure to the landing gear is lost, it will fall down slightly and rest on the landing gear doors. Placing the regular landing gear handle into 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 alternate system is also available where the gear will fall into position by pulling a lever in the cockpit floor. 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 alternate system. Although the gear deployed successfully, there was no change in the controllability of the aircraft.
Landing was originally planned on the 9000 feet (2,743.2 m) Runway 31. Difficulties in controlling the aircraft made lining up almost impossible. While dumping excess fuel, the plane executed a series of mostly right-hand turns (it was easier to turn the plane in this direction) with the intention of lining up with Runway 31. When they came out they were instead lined up with the shorter (6,600 ft) Runway 22, and had little capacity to maneuver. Fire trucks had been placed on Runway 22, anticipating a landing on Runway 31, so all the vehicles were quickly moved out of the way before the plane touched down.
Fitch continued to control the aircraft's descent by adjusting engine thrust. With the loss of all hydraulics, the crew were unable to control airspeed
Airspeed
Airspeed is the speed of an aircraft relative to the air. Among the common conventions for qualifying airspeed are: indicated airspeed , calibrated airspeed , true airspeed , equivalent airspeed and density airspeed....
independent from sink rate
Variometer
The term variometer also refers to a type of variable transformer or an instrument for measuring the magnitude and direction of a Magnetic field....
. On final descent, the aircraft was going 240 knots and sinking at 1,850 feet per minute, while a safe landing would require 140 knots and 300 feet per minute. Fitch needed a seat for landing; 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. Unfortunately, right before touchdown, the aircraft began a downward phugoid
Phugoid
A phugoid or fugoid is an aircraft motion where the vehicle pitches up and climbs, and then pitches down and descends, accompanied by speeding up and slowing down as it goes "uphill" and "downhill." This is one of the basic flight dynamics modes of an aircraft , and a classic example of a positive...
and veered right. The flight crew had no time 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 sheared off and the main part of the aircraft skidded sideways, rolled over on to its back, and slid to a stop upside-down in a corn field to the right of Runway 22. Witnesses reported that the aircraft cartwheeled, but the investigation did not confirm this. News reports that the aircraft cartwheeled were due to misinterpretation of the video of the crash that showed the flaming right wing tumbling end-over-end and the intact left wing, still attached to the fuselage, rolling up and over as the fuselage flipped over.
Of the 296 people on board, 111 died in the crash. 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 185 survivors were seated behind first class and ahead of the wings. Many passengers were able to walk out through the ruptures to the structure, and in many cases got lost in the high field of corn adjacent to the runway until rescue workers arrived on the scene and escorted them to safety.
Of all of the passengers:
- 35 died due to smoke inhalation (none were in first class)
- 76 died for reasons other than smoke inhalation (17 were in first class)
- 47 were seriously injured (8 were in first class)
- 125 had minor injuries (1 was in first class)
- 13 had no injuries (None were in first class)
The passengers who died for reasons other than smoke inhalation were seated in rows 1–4, 24–25, and 28–38. Passengers who died due to smoke inhalation were seated in rows 14, 16, and 22–30. A person assigned to 20H moved to an unknown seat and died due to smoke inhalation.
One crash survivor died 31 days after the accident; in accordance with official rules, the NTSB classified his injuries as "serious."
Fifty-two children, including four "lap children" without their own seats, were on board the flight due to the United Airlines "Children's Day" promotion. Eleven children, including one lap child, died. Many of the children had traveled alone.
Rescuers initially ignored the cockpit, as it had been compressed in the crash to approximately waist high and was completely unrecognizable. It was not until 35 minutes after the crash that rescuers discovered that the debris was the cockpit and that the four pilots were still alive inside. All four would recover from their injuries and return to work: Haynes, Records, and Dvorak would return in three months, while Fitch, more seriously injured than the others, would return in 11 months.
Investigation
National Transportation Safety BoardNational Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
officials were on scene within hours of the accident. As the investigation unfolded, it became apparent that the entire fan disk and blade assembly from engine number 2, a component approximately 8 feet (2.4 m) in diameter and made of titanium
Titanium
Titanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
alloy, was missing from the accident scene. Despite an extensive search in the weeks following the crash, the fan disk could not be located. Realizing that finding the fan disk was potentially the key to understanding the reasons for the engine failure, the engine's manufacturer, GE, offered a $50,000 reward to whoever could locate the disk, and $1,000 for each fan blade. On October 10, 1989, three months after the crash, a farmer harvesting corn near Alta, Iowa
Alta, Iowa
Alta is a city in Buena Vista County, Iowa, United States. The population was 1,865 at the 2000 census.-Geography:Alta is located at . It is located 6 miles from the city of Storm Lake...
felt resistance on her combine
Combine harvester
The combine harvester, or simply combine, is a machine that harvests grain crops. The name derives from the fact that it combines three separate operations, reaping, threshing, and winnowing, into a single process. Among the crops harvested with a combine are wheat, oats, rye, barley, corn ,...
, and after getting out to see what was causing it, discovered most of the fan disk with a number of blades still attached partially buried in her cornfield. The rest of the fan disk would also be located later in the harvest.
Examination of the fan disk would indeed solve the mystery. Investigators discovered an impurity and fatigue
Fatigue (material)
'In materials science, fatigue is the progressive and localized structural damage that occurs when a material is subjected to cyclic loading. The nominal maximum stress values are less than the ultimate tensile stress limit, and may be below the yield stress limit of the material.Fatigue occurs...
crack in the disk, and traced this back to the Alcoa
Alcoa
Alcoa Inc. is the world's third largest producer of aluminum, behind Rio Tinto Alcan and Rusal. From its operational headquarters in Pittsburgh, Pennsylvania, Alcoa conducts operations in 31 countries...
foundry from which the engine part originated. The investigation showed there was a defect in the elimination of gaseous anomalies during the purifying of the titanium disk ingot. An excess amount of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
was in the material, causing a 'hard alpha inclusion
Inclusion (mineral)
In mineralogy, an inclusion is any material that is trapped inside a mineral during its formation.In gemology, an inclusion is a characteristic enclosed within a gemstone, or reaching its surface from the interior....
', which cracked during forging and then fell out during final machining. This formed a cavity with microscopic cracks at the edges. During the engine's normal running cycle, one of these cracks grew slowly each time the engine was powered up and brought to operating temperature
Operating temperature
An operating temperature is the temperature at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the...
, until it grew large enough for the disk to fail structurally. Newer batches used much higher melting temperatures and a "triple vacuum" process to eliminate these impurities.
The subsequent investigation and Airworthiness Directive
Airworthiness Directive
An Airworthiness Directive is a notification to owners and operators of certified aircraft that a known safety deficiency with a particular model of aircraft, engine, avionics or other system exists and must be corrected....
revealed several other fan disks already in service from the same batch of ingots which had started to exhibit the initial cracking symptoms of part failure.
Cause
The investigation, while praising the actions of the flight crew for saving lives, would later attribute the cause of the accident to a failure of United AirlinesUnited Airlines
United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees United Air Lines, Inc., is the world's largest airline with 86,852 employees (which includes the entire holding company United Continental...
maintenance processes and personnel to detect an existing fatigue crack. Post-crash analysis of the crack surfaces showed the presence of a penetrating fluorescent dye used to detect cracks during maintenance. The presence of the dye indicated that the crack was present and should have been detected at a prior inspection. The detection failure arose from poor attention to human factors
Human factors
Human factors science or human factors technologies is a multidisciplinary field incorporating contributions from psychology, engineering, industrial design, statistics, operations research and anthropometry...
in United Airlines' specification of maintenance processes.
Influence on the industry
The National Transportation Safety BoardNational Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
(NTSB) investigation, after subsequent reconstructions of the accident in flight simulator
Flight simulator
A flight simulator is a device that artificially re-creates aircraft flight and various aspects of the flight environment. This includes the equations that govern how aircraft fly, how they react to applications of their controls and other aircraft systems, and how they react to the external...
s, deemed that training for such an event involved too many factors to be practical. While some level of control was possible, no precision could be achieved, and a landing under these conditions was stated to be "a highly random event". The NTSB further noted that "under the circumstances the UAL flight crew performance was highly commendable and greatly exceeded reasonable expectations."
Because this type of aircraft control is difficult for humans to achieve, some researchers have attempted to integrate this control ability into the computers of fly-by-wire
Fly-by-wire
Fly-by-wire is a system that replaces the conventional manual flight controls of an aircraft with an electronic interface. The movements of flight controls are converted to electronic signals transmitted by wires , and flight control computers determine how to move the actuators at each control...
aircraft. Early attempts to add the ability to real airplanes were not very successful; the software was based on experiments conducted in flight simulators where jet engines are usually modeled as "perfect" devices with exactly the same thrust on each engine, a linear relationship between throttle setting and thrust, and instantaneous response to input. Later, computer models were updated to account for these factors, and planes have been successfully flown
F-15S/MTD
|-F-15 ACTIVE:-See also:- External links :* * *...
with this software installed.
Newer aircraft designs such as the MD-11 have incorporated hydraulic fuses to isolate a punctured section and prevent a total loss of hydraulic fluid. Following the UAL 232 accident, such fuses were installed in the number 3 hydraulic system in the area below the number 2 engine on all DC-10 aircraft to ensure sufficient control capability remained if all three hydraulic system lines should be damaged in the tail area in the future. Although elevator and rudder control would be lost, the aircrew would still be able to control the aircraft's pitch (up and down) with stabilizer trim
Stabilizer (aircraft)
In aviation, a stabilizer provides stability when the aircraft is flying straight, and the airfoil of the horizontal stabilizer balances the forces acting on the aircraft....
, and would be able to control roll (left and right) with some of the aircraft's aileron
Aileron
Ailerons are hinged flight control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. The ailerons are used to control the aircraft in roll, which results in a change in heading due to the tilting of the lift vector...
s and spoilers
Spoiler (aeronautics)
In aeronautics, a spoiler is a device intended to reduce lift in an aircraft. Spoilers are plates on the top surface of a wing which can be extended upward into the airflow and spoil it. By doing so, the spoiler creates a carefully controlled stall over the portion of the wing behind it, greatly...
. Although not an ideal situation, the system provides a greater measure of control than was available to the crew of United 232.
It is still possible to lose all three hydraulic systems if serious damage occurs elsewhere, as nearly happened to a cargo airliner in 2002 during takeoff when a main gear tire exploded in the wheel well area. The damage in the left wing area caused total fluid loss from the number 1 and the number 2 hydraulic systems. The number 3 system was dented but not penetrated. DC-10s still have no fuse protection for any of the three hydraulic systems in the event of an exploding main gear tire.
Of the four children deemed too young to have seats of their own ("lap children"), one died from smoke inhalation. The NTSB added a safety recommendation to the FAA on its "List of Most Wanted Safety Improvements" in May 1999 suggesting a requirement for children under 2 to be safely restrained, which was removed in November 2006. The accident sparked a campaign led by United Flight 232's senior flight attendant, Jan Brown Lohr, for all children to have seats on aircraft.
The accident has since become a prime example of successful Crew Resource Management
Crew Resource Management
Crew resource management or Cockpit resource management is a procedure and training system in systems where human error can have devastating effects. Used primarily for improving air safety, CRM focuses on interpersonal communication, leadership, and decision making in the cockpit...
. For much of aviation's history, the Captain was considered the final authority, and crews were to respect the Captain's expertise and not question him. This began to change in the 1970s especially after the Tenerife Disaster
Tenerife disaster
The Tenerife airport disaster occurred on March 27, 1977, when two Boeing 747 passenger aircraft collided on the runway of Los Rodeos Airport on the Spanish island of Tenerife, one of the Canary Islands...
. Crew Resource Management, while still considering the Captain the final authority, instructs crewmembers to speak up when they detect a problem, and instructs Captains to listen to crewmember concerns. United Airlines instituted a Crew Resource Management class in the early 1980s. The NTSB would later credit this training as valuable toward the success of United 232's crew in handling their emergency. The FAA made Crew Resource Training mandatory in the aftermath of the accident.
Factors contributing to survival
Of the 296 people aboard, 111 were killed in the crash, while 185 survived. Captain Haynes later told of three contributing factors regarding the time of day that allowed for a better chance of survival:- The accident occurred during daylight hours;
- The accident occurred as a shift change was occurring at both a regional trauma center and a regional burn center in Sioux City, allowing for more medical personnel to treat the injured; and
- The accident occurred when the Iowa Air National GuardIowa Air National GuardThe Iowa Air National Guard is the air force militia of the U.S. state of Iowa. It is, along with the Iowa Army National Guard, an element of the Iowa National Guard.-Units:The Iowa Air National Guard consists of the following units:...
was on duty at Sioux Gateway Airport, allowing for 285 trained personnel to assist with triageTriageTriage or ) is the process of determining the priority of patients' treatments based on the severity of their condition. This rations patient treatment efficiently when resources are insufficient for all to be treated immediately. The term comes from the French verb trier, meaning to separate,...
and evacuation of the injured.
"Had any of those things not been there," Haynes said, "I'm sure the fatality rate would have been a lot higher."
As with the Eastern Air Lines Flight 401
Eastern Air Lines Flight 401
Eastern Air Lines Flight 401 was a Lockheed L-1011 Tristar 1 jet that crashed into the Florida Everglades on the night of December 29, 1972, causing 101 fatalities...
crash of a similarly-sized Lockheed L-1011
Lockheed L-1011
The Lockheed L-1011 TriStar, commonly referred to as the L-1011 or TriStar, is a medium-to-long range, widebody passenger trijet airliner. It was the third widebody airliner to enter commercial operations, following the Boeing 747 and the McDonnell Douglas DC-10. Between 1968 and 1984, Lockheed...
in 1972, the relatively shallow angle of descent likely played a large part in the relatively high survival rate. The National Transportation Safety Board concluded that under the circumstances, "a safe landing was virtually impossible."
Notable survivors
- Spencer Bailey – Subject of a famous photograph showing Lt. Colonel Dennis NielsenDennis NielsenDennis Nielsen is a retired United States Air Force Colonel and was a Democratic candidate for Governor of North Carolina in 2008. Nielsen was part of the rescue effort of the United Airlines Flight 232 crash in Sioux City, Iowa in 1989....
carrying the three-year-old survivor to safety. His brother Brandon also survived the crash, but their mother, Francie, did not. A statue in part of Sioux City's riverfront development is based on the picture. The 1994 memorial commemorates the rescue efforts by the Sioux City community following the crash, and features contemplative areas and a tree-lined approach with plaques describing the accident. Bailey works as an editor and journalist in New York City. - Jerry SchemmelJerry SchemmelJerry Schemmel is the radio announcer for the MLB's Colorado Rockies and the Colorado State Rams football and men's basketball teams. He was formerly the play-by-play announcer for the NBA's Denver Nuggets, calling their full regular season from 1992 to 2009, when he assumed home-only duties until...
– Radio announcer for the Colorado RockiesColorado RockiesThe Colorado Rockies are a Major League Baseball team based in Denver, Colorado. Established in 1991, they started play in 1993 and are in the West Division of the National League. The team is named after the Rocky Mountains...
, Denver's Major League BaseballMajor League BaseballMajor League Baseball is the highest level of professional baseball in the United States and Canada, consisting of teams that play in the National League and the American League...
team, and a former radio announcer for the Denver NuggetsDenver NuggetsThe Denver Nuggets are a professional basketball team based in Denver, Colorado. They play in the National Basketball Association . They were founded as the Denver Rockets in 1967 as a charter franchise of the American Basketball Association, and became one of that league's more successful teams...
, Denver's National Basketball AssociationNational Basketball AssociationThe National Basketball Association is the pre-eminent men's professional basketball league in North America. It consists of thirty franchised member clubs, of which twenty-nine are located in the United States and one in Canada...
basketball team. He wrote a book about United Airlines Flight 232 titled Chosen to Live, and was credited with saving the life of a child in the crash. - Michael R. Matz – Trainer of the 2006 Kentucky DerbyKentucky DerbyThe Kentucky Derby is a Grade I stakes race for three-year-old Thoroughbred horses, held annually in Louisville, Kentucky, United States on the first Saturday in May, capping the two-week-long Kentucky Derby Festival. The race is one and a quarter mile at Churchill Downs. Colts and geldings carry...
favorite and winner BarbaroBarbaroBarbaro was an American thoroughbred who decisively won the 2006 Kentucky Derby, but shattered his leg two weeks later in the 2006 Preakness Stakes, ending his racing career and eventually leading to his death....
. He was credited with saving the lives of four children in the crash, three of whom were in the same family. Matz competed for the US in equestrian show jumping in several Summer OlympicsEquestrian at the Summer OlympicsEquestrianism made its Summer Olympics debut at the 1900 Summer Olympics in Paris, France. It disappeared until 1912, but has appeared at every Summer Olympic Games since. The current Olympic equestrian disciplines are Dressage, Eventing, and Jumping...
, including 19761976 Summer OlympicsThe 1976 Summer Olympics, officially known as the Games of the XXI Olympiad, was an international multi-sport event celebrated in Montreal, Quebec, Canada, in 1976. Montreal was awarded the rights to the 1976 Games on May 12, 1970, at the 69th IOC Session in Amsterdam, over the bids of Moscow and...
, 19921992 Summer OlympicsThe 1992 Summer Olympic Games, officially known as the Games of the XXV Olympiad, were an international multi-sport event celebrated in Barcelona, Catalonia, Spain, in 1992. The International Olympic Committee voted in 1986 to separate the Summer and Winter Games, which had been held in the same...
, and 19961996 Summer OlympicsThe 1996 Summer Olympics of Atlanta, officially known as the Games of the XXVI Olympiad and unofficially known as the Centennial Olympics, was an international multi-sport event which was celebrated in 1996 in Atlanta, Georgia, United States....
. He won silver in the team show jumping event at the 1996 games. - Alfred C. HaynesAlfred C. HaynesAlfred C. "Al" Haynes is a former airline pilot and a regular guest speaker at social events. Haynes gained international fame in 1989, when he, together with the rest of his crew and Dennis E...
– The Captain of United Airlines flight 232. His actions, along with the actions of the entire flight crew, are partially credited for saving the lives of the survivors. He returned to flying after recovering from his injuries and would continue to fly DC-10s as captain until reaching mandatory retirement age in 1991. Several rescuers, crew members, and passengers from flight 232 flew with Haynes on his final flight. Haynes became a public speaker soon after the accident, giving speeches about what happened aboard flight 232. He continues these to the present day, and credits this work with helping his own healing process. - Dennis E. FitchDennis E. FitchDennis E. "Denny" Fitch is a retired commercial airline pilot. He is best known for his critical actions as an off-duty DC-10 training captain who helped captain Al Haynes minimize loss of life on United Airlines Flight 232 when all flight controls were lost, on July 19, 1989...
– A DC-10 pilot and instructor, he helped Captain Al Haynes fly United Airlines Flight 232. "For the 30 minutes I was up there," Fitch said, "I was the most alive I've ever been. That is the only way I can describe it to you." - Pete WernickPete WernickPete Wernick, also known by many as "Dr. Banjo", is an American musician.He is a five-string banjo player who has been involved in the bluegrass music scene since the 1970s, writing several instruction books and videos on how to play the banjo. He's also known for his own musical style called...
– Prominent banjo player with the Hot RizeHot RizeHot Rize is a bluegrass band that rose to prominence in the early 1980s. Established in 1978, the founding members were Mike Scap , Tim O'Brien on mandolin and fiddle, Pete Wernick on banjo and Charles Sawtelle on bass....
bluegrass bandBluegrass musicBluegrass music is a form of American roots music, and a sub-genre of country music. It has mixed roots in Scottish, English, Welsh and Irish traditional music...
and instructor, he was on his way to a festival in the Albany, New YorkAlbany, New YorkAlbany is the capital city of the U.S. state of New York, the seat of Albany County, and the central city of New York's Capital District. Roughly north of New York City, Albany sits on the west bank of the Hudson River, about south of its confluence with the Mohawk River...
area. Wernick walked away from the crash with his young son, and along with his wife, they took a later flight to go to the festival. He gave his personal account of the day's events in the song "A Day in '89 (You Never Know)". Wernick has yet to release a recording of the song, but has published the lyrics on his website. - Jan Brown Lohr – United 232's Senior Flight Attendant. She was forced by regulation to ask parents with "lap children" aboard flight 232 to place their children on the cabin floor during the flight's final moments before impact. One of four children died from smoke inhalation. The deceased child's grief-stricken mother confronted Lohr at the crash scene. Since then, Lohr has tirelessly lobbied in Washington D.C. to promote the safety of children on all civilian aircraft and airlines, asking that federal regulations require all children to have a seat belt on every flight.
In popular culture
- The accident was the subject of the 1992 television movieTelevision movieA television film is a feature film that is a television program produced for and originally distributed by a television network, in contrast to...
, Crash Landing: The Rescue of Flight 232, (also known as A Thousand Heroes). - It was featured in an episode of Seconds From DisasterSeconds From Disaster-By original broadcast date:National Geographic Channel has broadcast many episodes under multiple titles. The title currently or most recently listed on the NGC Calendar is shown first...
on the National Geographic ChannelNational Geographic ChannelNational Geographic Channel, also commercially abbreviated and trademarked as Nat Geo, is a subscription television channel that airs non-fiction television programs produced by the National Geographic Society. Like History and the Discovery Channel, the channel features documentaries with factual...
and MSNBC Investigates on the MSNBCMSNBCMSNBC is a cable news channel based in the United States available in the US, Germany , South Africa, the Middle East and Canada...
news channel. - It was one of the inspirations for the crash in Peter WeirPeter WeirPeter Lindsay Weir, AM is an Australian film director. After playing a leading role in the Australian New Wave cinema with his films such as Picnic at Hanging Rock, The Last Wave and Gallipoli, Weir directed a diverse group of American and international films—many of them major box office...
's 1993 film version of FearlessFearless (1993 film)Fearless is a 1993 film directed by Peter Weir and written by Rafael Yglesias from his novel of the same name. It was shot entirely in California....
, adapted from a novel by Rafael YglesiasRafael YglesiasRafael Yglesias is an American novelist and screenwriter. His parents were the novelists Jose Yglesias and Helen Yglesias. The blogger and journalist Matthew Yglesias is his older son; his younger son, Nicholas, is also a novelist and has applied to become a police cadet.Yglesias was born and...
. - The DC-10 crash in the 1991 Dean KoontzDean KoontzDean Ray Koontz is a prolific American author best known for his novels which could be described broadly as suspense thrillers. He also frequently incorporates elements of horror, science fiction, mystery, and satire. A number of his books have appeared on the New York Times Bestseller List, with...
novel Cold FireCold Fire (Koontz novel)-Plot:Recently retired teacher Jim Ironheart risks his life to save lives. In Portland, he saves a young boy from an oblivious drunk driver in a van. In Boston, he rescues a child from an underground explosion. In Houston, he disarms a man who was trying to shoot his own wife – and he is not just...
is based on this accident. - The cockpit voice recording of the accident became part of the script of a play called Charlie Victor RomeoCharlie Victor RomeoCharlie Victor Romeo is a 1999 play whose script consists of almost-verbatim transcripts from six real-life aviation accidents and incidents. "Charlie Victor Romeo," or CVR, derived from the NATO phonetic alphabet, is aviation lingo for cockpit voice recorder...
. - Dennis Fitch described his experiences in Errol MorrisErrol MorrisErrol Mark Morris is an American director. In 2003, The Guardian put him seventh in its list of the world's 40 best directors. Also in 2003, his film The Fog of War: Eleven Lessons from the Life of Robert S. McNamara won the Academy Award for Best Documentary Feature.-Early life and...
' television show First Person. - Martha Conant told her story of survival to her daughter-in-law, Brittany Conant, on "StorycorpsStoryCorpsStoryCorps is an American non-profit organization whose mission is to record, preserve, and share the stories of Americans from all backgrounds and beliefs. StoryCorps grew out of Sound Portraits Productions as a project founded in 2003 by radio producer David Isay...
" during NPRNPRNPR, formerly National Public Radio, is a privately and publicly funded non-profit membership media organization that serves as a national syndicator to a network of 900 public radio stations in the United States. NPR was created in 1970, following congressional passage of the Public Broadcasting...
's Morning EditionMorning EditionMorning Edition is an American radio news program produced and distributed by National Public Radio . It airs weekday mornings and runs for two hours, and many stations repeat one or both hours. The show feeds live from 05:00 to 09:00 ET, with feeds and updates as required until noon...
of January 11, 2008. - The History ChannelThe History ChannelHistory, formerly known as The History Channel, is an American-based international satellite and cable TV channel that broadcasts a variety of reality shows and documentary programs including those of fictional and non-fictional historical content, together with speculation about the future.-...
distributed a documentary named ShockwaveShockwave (TV series)Shockwave is an American documentary television series that premiered on November 30, 2007, on History. The program compiles video footage and eyewitness accounts to the headline making events and attempts to educate the viewer as to what really happened in a particular event.The series is a...
; a portion of Episode 7 (originally aired January 25, 2008) detailed the events of the crash. - The episode "A Wing and a Prayer" of The Black Box featured the accident.
- The Biography Channel series I Survived...I Survived...I Survived... is a documentary television series produced by NHNZ that airs on The Biography Channel. The series premiered on March 24, 2008 and airs new episodes Sunday nights. The show allows survivors to explain, in their own words, how they overcame life-threatening circumstances without...
explained in detail the events of the crash through passenger Jerry, flight attendant Jan Brown Lohr, and pilot Alfred Haynes. - The band Leæther StripLeæther StripLeæther Strip is a Danish musical project founded on January 13, 1988 by Claus Larsen. Its influence has been most felt in the electronic body music and electro-industrial genres. Perhaps to a certain extent, it may have influenced various film score productions. Leæther Strip was one of the...
released a song called Crash Flight 232, which mentions the crash throughout the entire song.
Similar accidents
The odds against all three hydraulic systems failing simultaneously had previously been calculated as high as a billion to one. Yet, similar flight control failures have occurred:- In 1971 a Pan American 747Pan Am Flight 845Pan Am Flight 845 was a Boeing 747-121, registration N747PA, operating as a scheduled international passenger flight between Los Angeles, CA and Tokyo, with an intermediate stop at San Francisco International Airport...
struck approach light structures for the reciprocal runway as it lifted off the runway at San Francisco Airport. Major damage to the belly and landing gear resulted, which caused the loss of hydraulic fluid from three of its four flight control systems. The fluid which remained in the fourth system gave the captain very limited control of some of the spoilers, ailerons, and one inboard elevator. That was sufficient to circle the plane while fuel was dumped and then to make a hard landing. There were no fatalities, but there were some injuries. - In 1981, Eastern Airlines Flight 935, operated by a Lockheed L-1011Lockheed L-1011The Lockheed L-1011 TriStar, commonly referred to as the L-1011 or TriStar, is a medium-to-long range, widebody passenger trijet airliner. It was the third widebody airliner to enter commercial operations, following the Boeing 747 and the McDonnell Douglas DC-10. Between 1968 and 1984, Lockheed...
suffered a similar kind of massive failure of its tail mounted number two engine. The shrapnel from that engine inflicted damage on all four of its hydraulic systems, which were also close together in the tail structure. Fluid was lost in three of the four systems. While the fourth hydraulic system was impacted with shrapnel too, it was not punctured. The hydraulic pressure remaining in that fourth system enabled the captain to land the plane safely with some limited use of the outboard spoilers, the inboard ailerons, and the horizontal stabilizer, plus differential engine power of the remaining two engines. There were no injuries. - In 1985 Japan Airlines flight 123Japan Airlines Flight 123Japan Airlines Flight 123 was a Japan Airlines domestic flight from Tokyo International Airport to Osaka International Airport on August 12, 1985. The Boeing 747-146SR that made this route, registered , suffered mechanical failures 12 minutes into the flight and 32 minutes later crashed into two...
, a Boeing 747, suffered a rupture of the pressure bulkhead in its tail section. The damage was extensive and caused the loss of fluid in all four of its hydraulic control systems. The pilots were able to keep the plane airborne for almost 30 minutes using differential engine power, but eventually control was lost, and the plane crashed in mountainous terrain. There were only 4 survivors among the 524 on board. This accident is the deadliest single-aircraft accident in history. - In 1994, RA85656, a Tupolev Tu-154Tupolev Tu-154The Tupolev Tu-154 is a three-engine medium-range narrow-body airliner designed in the mid 1960s and manufactured by Tupolev. As the mainstay 'workhorse' of Soviet and Russian airlines for several decades, it serviced over a sixth of the world's landmass and carried half of all passengers flown...
operating as Baikal Airlines Flight 130, crashed near IrkutskIrkutskIrkutsk is a city and the administrative center of Irkutsk Oblast, Russia, one of the largest cities in Siberia. Population: .-History:In 1652, Ivan Pokhabov built a zimovye near the site of Irkutsk for gold trading and for the collection of fur taxes from the Buryats. In 1661, Yakov Pokhabov...
shortly after departing from Irkutsk Airport, Russia. Damage to the starter caused a fire in engine number two (located in the rear of fuselage). High temperatures during the fire destroyed the tanks and pipes of all three hydraulic systems. The crew lost control of the aircraft. The unmanageable plane, at a speed of 275 knots, hit the ground at a dairy farm and burned. All passengers and crew, as well as a dairyman on the ground, died. - In 2003, OO-DLL, a DHL Airbus A300 was struck by a surface-to-air missile shortly after departing from Baghdad International AirportBaghdad International AirportBaghdad International Airport, originally Saddam International Airport, , BIAP is Iraq's largest airport, located in a suburb about west of downtown Baghdad in the Baghdad Governorate...
, Iraq. The missile struck the port side wing, rupturing a fuel tank and causing the loss of all three hydraulic systems. With the flight controls disabled, the crew was able to use differential thrust to execute a safe landing at Baghdad. This is the first and only documented time anyone has managed to land a transport aircraft safely without working flight controls.
The disintegration of a turbine disc, leading to loss of control, was a direct cause of two major aircraft disasters in Poland:
- On March 14, 1980, LOT Polish Airlines Flight 007LOT Polish Airlines Flight 007LOT Polish Airlines Flight 007 crashed near Okęcie Airport in Warsaw, Poland, on 14 March 1980, due to mechanical failure as the crew aborted a landing and attempted to go-around. All 87 crew and passengers died.- The aircraft :...
, an Ilyushin Il-62Ilyushin Il-62The Ilyushin Il-62 is a Soviet long-range jet airliner conceived in 1960 by Ilyushin. As successor to the popular turbo-prop Il-18 and with capacity for almost 200 passengers, the Il-62 was the largest jet airliner when it first flew in 1963. It entered Aeroflot service on 15 September 1967 with...
, attempted a go-aroundGo-aroundA go-around is an aborted landing of an aircraft that is on final approach.- Origin of the term :The term arises from the traditional use of traffic patterns at airfields. A landing aircraft will first join the circuit pattern and prepare for landing in an orderly fashion...
when the crew experienced troubles with a gear indicator. When thrust was applied, low pressure turbine disc in engine number 2 disintegrated because of material fatigue; parts of the disc damaged engines number 1 and 3 and severed control pushers for both horizontal and vertical stabilizers. After 26 seconds of uncontrolled descent, the aircraft crashed, killing all 87 people on board. - On May 9, 1987, improperly assembled bearings in engine number 2 on LOT Polish Airlines Flight 5055LOT Polish Airlines Flight 5055LOT Polish Airlines Flight 5055 crashed in the Kabaty Woods nature reserve on the outskirts of Warsaw on May 9, 1987. The aircraft was an Ilyushin Il-62M bearing the name Tadeusz Kościuszko...
overheated and exploded during cruise over Lipniki village, causing the shaft to break in two; this caused the low pressure turbine disc to spin to enormous speeds and disintegrate, damaging engine number 1 and cutting the control pushers. The crew managed to return to Warsaw, using nothing but trim tabsTrim tabsTrim tabs are small surfaces connected to the trailing edge of a larger control surface on a boat or aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aero-dynamic forces and stabilise the boat or aircraft in a particular desired attitude without the need for the...
to control the Il-62M, but on the final approach, the trim controlling links burned and the crew completely lost control over the aircraft. Soon after, it crashed on the outskirts of Warsaw; all 183 on board perished. Had the plane stayed airborne for 40 seconds more, it would have been able to reach the runway.
See also
- American Airlines Flight 96American Airlines Flight 96American Airlines Flight 96 was a regular McDonnell Douglas DC-10-10 flight operated by American Airlines. The flight suffered a cargo door failure on 12 June 1972 while flying over Windsor, Ontario; it is thus sometimes referred to as the Windsor incident.The rapid decompression in the cargo hold...
– the Windsor accident - Flight with disabled controlsFlight with disabled controlsSeveral aviation incidents and accidents have occurred in which the control surfaces of the aircraft became disabled, often due to failure of hydraulic systems or the flight control system. Other incidents have occurred where controls were not functioning correctly prior to take-off, either due to...
- Turkish Airlines Flight 981Turkish Airlines Flight 981Turkish Airlines Flight 981 was a McDonnell Douglas DC-10, registered TC-JAV and named the Ankara, that crashed in Fontaine-Chaalis, Oise, France, outside Senlis, on 3 March 1974...
- Japan Airlines Flight 123Japan Airlines Flight 123Japan Airlines Flight 123 was a Japan Airlines domestic flight from Tokyo International Airport to Osaka International Airport on August 12, 1985. The Boeing 747-146SR that made this route, registered , suffered mechanical failures 12 minutes into the flight and 32 minutes later crashed into two...
- Tan Son Nhut C-5 accidentTan Son Nhut C-5 accidentThe Tan Son Nhut C-5 accident refers to the 4 April 1975 crash of 68-0218, a Lockheed C-5A Galaxy participating in Operation Babylift, which crashed on approach to an emergency landing at Tan Son Nhut Air Base, Vietnam. The cause was ascribed to loss of flight control due to explosive...
External links
- NTSB Accident report of United Airlines Flight 232
- Cockpit voice-recorder transcript (pdf) (NB contains error)
- A talk given by the pilot describing the crash at NASA Dryden in 1991
- Flight 232 Memorial depicting Lt. Colonel Dennis Nielsen carrying Spencer Bailey
- "17th Anniversary Tribute of Flight 232"
- Google Video Film of the crash landing
- Pre-crash landing photos from Airliners.netAirliners.netAirliners.net is an aviation website founded by Johan Lundgren, Sweden, in 1997, evolving from his previous Pictures of Modern Airliners site started in 1994...
- Martha Conant tells her story of surviving the crash. – 1992 TV movie
- Cockpit voice-recorder recording at time of impact
- Accident photos
- A detailed description of the accident
- Errol Morris’ First Person (Interview with Denny Fitch)