You may remember this for the famous photo showing the DC 10 from the terminal at O’Hare banked on it’s side just before crashing after takeoff in 1979.
What happened was the left engine completely separated from the wing and fell off during takeoff. The pilot thought he had only lost power in the left engine. He didn’t know it was completely gone. When it came off, he was past the point of aborting takeoff.
If he had known the engine was completely ripped off the wing, could he have compensated differently than he did for just a loss of power and made an emergency landing or was it doomed as soon as the engine fell off.?
I am a perpetual flight student and lifelong aviation buff. The main sentence that stands out to me in the linked article is “it severed hydraulic lines and damaged the left wing resulting in a retraction of the slats”.
That indicates that there was nothing else that could be done. The aircraft lost part of the wing, its weight and balance, as well as pilot control authority. It becomes an unguided missile at that point and it will crash. The laws of physics don’t care what it was designed for or how many people are onboard at that point.
That accident happened in 1979 when airliners had the same basic body shape and design they do today but they were more sensitive to mechanical failures because fly-by-wire systems weren’t as widespread. Airliners are safer today than ever before and unbelievable safe as a whole but catastrophic, unrecoverable failures can still occur.
I am not a pilot, but my understanding of it is that the engine coming off wasn’t the problem. The problem was that it took out the hydraulic lines when it went, and this caused all of the flaps on that side to retract. The DC-10 was designed to survive the loss of one engine during takeoff, but the combination of the flaps retracting and the loss of speed from the loss of the engine meant that the left wing stalled.
I don’t know if pilots know some fancy trick to get out of this, but if the left wing is no longer providing lift I can’t picture much of anything happening except the plane rolling over and crashing.
That flight was doomed the moment they lost hydraulic pressure. There has been one recorded safe landing of a plane without control surfaces. The rest were either totally destroyed or had high casualty counts with a few survivors.
Flight 191 in particular had no chance whatsoever because they couldn’t effectively use differential thrust even if they had somehow recovered from the extreme bank.
If I haven’t got my accidents mixed up, this case was also exacerbated by the engine-out procedure. Following the procedure, the pilot actually intentionally reduced his airspeed to the takeoff safety speed, which was intended to improve single-engine climb performance. The stall warning system was also damaged during the event, and the pilots had no idea that they were about to stall.
The reason the left wing stalled and the plane rolled was the pilots intentionally reduced speed by gaining altitude after they lost the engine. Does a DC-10 become unflyable with the loss left wing hydraulics? The article implies this is not the case.
The flight crew was following the appropriate procedures given the information available to them at that moment. The engine separation had disabled both hydrauulic and electrical systems, which meant that, among other things, they hadn’t received a stall warning. Pilots who recreated the conditions in a simulator were able to escape, but only because they knew that what the flight crew thought at the time was simply a roll, was, in fact, the beginning of a stall.
The damage to the plane’s electrical system was such that the flight crew would have had to manually activate the electrical backups that would have powered the stall warning system. If they had been able to do so immediately, they might have had time to accellerate out of the stall. However, they were focused on leveling the plane and likely weren’t even aware of the warning system failure.
the loss of hydraulics caused the flaps to retract on one side. They would have had to complete the roll out to gain time while they retracted the remaining flaps while using the rudder to compensate for the loss of engine. I’d say no way in hell. Even if it were technically possible they would have to know exactly what was going on. If the plane isn’t responding to control inputs AND it’s on it’s way down it’s a lost cause.
Long time lurker, but actually got to discuss this with an American Airlines DC-10 captain who’d flown this scenario in the sim.
His response was essentially what kunilou quoted. You could fly the airplane out of the situation but only because of the lessons learned from this accident.
After the accident, the DC-10 manual was rewritten so that when losing an engine on take-off, the recommended airspeeds would be based on the flaps being retracted rather than on a flaps extended airspeed.
IIRC the sequence correctly:
Aircraft launches, loses engine, takes-off
Left wing dips slightly on uncommanded slat retraction but aircraft accelerates through the stall to about 160kts so wing picks up and the airplane is flying.
Pilots reduce speed to 154 (I think, just remember it was 5kts too slow) as recommended for 2-engine climb.
With slats retracted on the left wing, that wing stalls, aircraft enters uncontrolled roll at low altitude, crashes.
I bet it took me longer to type that than for the crash to occur.
What else other than a stall of the left wing could have caused it to begin rolling like that? What would the pilot have thought was causing the beginning of a roll he couldn’t get out of?
It is typical for an aircraft to roll and yaw toward the failed engine so what they experienced was consistent with the problem they had but grossly exaggerated. What the pilot thought would depend on his experience in training scenarios and how well he thinks on his feet. If it was me my first thought would probably be that the simulator hadn’t prepared me very well, then I might consider control problems and I might consider increasing speed to improve control, but that is with the benefit of knowing about this accident and sitting comfortably in my chair at home. No one really knows how they will react in a stressful situation until they face it for themselves.
Something to keep in mind is that pilots normally only train for single failures. You train for an engine failure at take-off, and you train for roll malfunctions but there’s no requirement to train for both at the same time and because simulator time is expensive you wouldn’t normally have a look at odd combinations of failures unless you had a bit of time left at the end of your training session.
Some pilots will think through weird failure scenarios. I’ve found myself thinking about what I would do if we lost an entire wing. Obviously we lose control and crash but then I’d think about how much wing we could lose and still maintain control and what is available to me to keep control (asymmetric power for example.) I amuse myself with this kind of stuff when I’m out running.
I don’t know. What do people speculate happened when the front wheel of someone’s car comes off just as they are entering the interstate highway severing brake lines and damaging the steering just before they slam into the side of that passing 18 wheeler? Probably just another bad driver. Pity.
It only took a few seconds for it to go out of control. A sudden aileron deflection on a wing could cause that as well as loss or deflection of tail control surfaces. All of those things have caused other crashes before and it is so rare that there isn’t any time to run through checklists of every one in a million scenario even if they existed in the first place. Hindsight is 20/20.
Let’s not forget that, according to the crash report, the time between the engine falling off and the plane’s crashing was 31 seconds, and the plane never got higher than 325 feet off the ground. The crew didn’t have a lot of time to work their way through multiple scenarios.
Does this imply that the tower controllers, who witnessed the engine separation but never communicated it to the aircraft, bear some part of the responsibility?
I am in no way implying that, nor does the crash report. As txtumbleweed pointed out, when the engine fell off, the wing slats retracted.
Now take a good look at this photo of the plane about to crash. Keep in mind that tower personnel do not have to be certified pilots. Could a controller, with attention divided among all the other traffic at O’Hare on a Friday afternoon, and having never flown a DC-10, which was probably a mile away from the tower, positively identify that the wing slats weren’t in the correct position, and convey that information to the flight crew?
I can bearly tell that from that picture, but I have the advantage of being able to look at a static frame for over a minute. No way the tower could have told them anything more then “Hey, you dropped your engine on the runway!”
Sorry to bring up an old thread, but i’ve read a bit more about this.
Why was the procedure in an engine failure to decrease engine power in the still working engine to just barely above stall speed? Why not throttle up and get all the power you can?
