Many flights in history have been labelled as miracles and amazing, such as the Hudson River landing. Yet one certain aviation incident is a head and shoulders above all else; United flight 232. On July 19th, 1989, Denny Fitch was walking through the terminal building in Denver airport, looking for a flight to Chicago. Denny always dreamt of flying, and was a highly successful Douglas DC-10 check training captain. There was a flight to Chicago leaving from the gate he was standing at, a Boeing 727, or he could walk for an extra gate and take a United DC-10. He chose the DC-10, and to this day does not know why he did. He boarded United flight 232 and settled into his first class seat. The aircraft took off and climbed out uneventfully.
He recalls that the flight was routine until they were established in the cruise. The cabin crew were serving lunch, when a very loud and muffled explosion was heard from the rear of the cabin. The airplane yawed violently to the right for about 10 seconds, and he found himself sitting on his left armrest. After that however, the airplane began flying smoothly again, although he noticed that it began to bank to the right; steeper, and steeper, and steeper. It got to 40 degrees of bank until it finally raised up again, and the captain came onto the intercom to the passengers. “Ladies and Gentlemen, we have shut down the number 2 engine, and we will be a few minutes late arriving in Chicago’. Then he hung up.
Denny Fitch was confused at this. The DC-10 has three engines, two under the wing and one in the tail. From the violent yawing and bank, he thought there must have been a problem in the right engine as the tail engine does nothing aerodynamically to the aircraft. The captain had said though, that he had shut down the number two engine. He looked out his window, and noticed that the airplane was climbing, which gave him more concerns. At this altitude, the aircraft cannot fly with only two engine, to do so you must descend to thicker air. However, they were doing the opposite an climbing. In other words, they were going the wrong way. A flight attendant walked past him, and he tapped her arm for her attention. She looked worried, so he said to her “Don’t worry, we can fly on two engines, we just need to descend and we’ll be ok”. She just gave him a focused look and said “Oh no Danny. Both the pilots are trying to fly the plane, and the captain has just told us that we’ve lost all hydraulics”.
A DC-10 will not fly without hydraulics. Period. Control surfaces on airplanes such as ailerons, rudders and elevators, can be the size of barn doors and cannot be moved physically with control cables; they are just too heavy. Instead, they are moved with pressurised hydraulic fluid. Naturally, when you remove a system like control cables, you must ensure that the new system (hydraulic fluid) is extremely reliable. The system on the DC-10 did in fact have triple redundancy, in other words it was a one in a billion chance that all three independent hydraulic systems would fail. Yet, on that day in 1989, the number two engine had fractured and punctured all of the hydraulic lines. There had never in history been a situation where all hydraulics were lost and people survived the flight. Not one person ever got off a plane in that situation alive.
Denny said back to the flight attendant to tell the captain that he was on board and if they needed any assistance. She went to the cockpit, and came running out gesturing furiously that they wanted him on the flight-deck. He walked into an amazing sight; both pilots had the yokes pushed over fully to the left. They were wearing short sleeve shirts, and he could see the tendons in their arms straining from the force they had to put on the yokes. They were also trying to get the plane to descend by pushing downwards on the yokes, and the first officer was slouched and had his knee pressed against it to put as much force on it as possible. Despite this, the right wing kept dropping downwards and the plane continued to climb. He glanced over at the flight-engineers panel and saw that they did indeed have no hydraulic pressure left in any of the systems.
The captain asked Denny to go back to the cabin and look at the control surfaces on the wing. By design, if one set of ailerons raise up, the ailerons on the other side fall down. That is how an aircraft banks. It is impossible by design for both ailerons to either fall or raise; the don’t work like that. When he looked out the window he saw that both ailerons on either side of the plane were upright. He then knew that they had really lost all the hydraulic fluid, and that they were in very serious trouble.
The plane began climbing and descending uncontrollably, and the flight crew quickly realised the only real way of controlling it was with the engines. Denny said to the captain “would you like me to work the throttles for you?” and he replied yes. Denny had to try and keep the plane flying by simply varying engine power on either side of the plane, an extremely difficult thing to do. Amidst all that was happening, the captain took one hand of the yoke and reached outwards over his shoulder to Denny and said “I’m captain Al Haynes. Nice to meet you”.
They decided to call the United Airlines Maintenance line, who knew the DC-10 inside and out and would know any trick check-lists or back-doors to try to get control back to the aircraft. They called them on the radio, and told them they had no hydraulic fluid at all. The maintenance team however thought they had a communication problem. They thought they mustn’t have fluid in system 1, or maybe system 2. They simply couldn’t believe they had none at all. Captain Haynes said to them “Listen, number 1 hydraulic quantity. Zero. Got it? Number 2 quantity. Zero. Number 3 quantity. Zero”. Later on in post accident investigation, they said “We didn’t know what to say to you. We were talking to four dead men”.
They began talking about the prospect of lowering the landing gear. They new that there would be some extra hydraulic fluid that would be trapped in the raised landing gear that would be released into the system if they lowered it. However, there is a golden rule in aviation. If you ever find yourself upstairs with minimum control of your airplane, don’t change it’s configuration. In other words, don’t put flaps down or lower landing gear, because you could lose complete control of it. You know the devil you have now, if you change something, you might not like the devil you get.
They decided to try it though. Partly because they couldn’t really see how they could have any less control than they already did, and even if it did go wrong the gear would be extra cushioning when they hit the ground. The extra fluid sadly went straight overboard, but the airplane did seem a little more stable with it down. The airplane was losing height fast, but they decided to try to make it to Sioux city airport, as that was close by and that’s the direction that the plane was heading towards. The found themselves lined up with runway 22, and the controller told them they were cleared to land on any runway. Captain Haynes just laughed, and said back “You want to make it a runway huh?”
They approached runway 22 at about 100mph faster than usual, and had no brakes to stop with. They hit the runway hard, and the landing gear was torn off. The airplane broke into pieces and rolled over multiple times. The cockpit separated from the rest of the plane and became a rolling ball at 200mph. When everything finally came to a stop, rescue teams arrived and amazingly 184 people survived the crash, while 111 died.
The flight crew also survived the crash. After the accident, the data from the black boxes was placed into a simulator. The chief DC-10 test pilot and head DC-10 training captain was called in to fly the exact same scenario as the crew of 232 did. They crashed short of the runway 28 times. On the 29th attempt, they called in Denny to help, and with his advice they finally got it to a runway. It really is amazing how well Denny flew the airplane with nothing but engine power, and how the crew as a whole worked together to get a survivable outcome out of a situation in which really, 296 people should not be alive.
United flight 232 on final descent. Damage to the tail cone and horizontal stabilizer can be seen.
