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A inexperienced 747-400 pilot used ailerons for counteracting asymmetric thrust in 1998 aboard United Airlines Flight 863 (YouTube recreation).

Why would an airline pilot do such a mistake? Why would a pilot disregard the counter yaw training he got from the Baron 58 to the 737?

Is he the only pilot that did this or are there other pilots that do the same mistake too?

Perhaps he simply forgot rudder.

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This AOPA article "PROFICIENT PILOT LAZY-RUDDER SYNDROME" written about this incident, presents an interesting point of view on the matter, that basically good design and complacency leads to little regular rudder use so in emergencies its initially over looked.

This pilot might have been affected by "lazy-rudder syndrome," the reluctance to use a rudder to the extent dictated by given circumstances. Some believe that this reflects a general decline in basic stick-and-rudder skills. A commonly observed symptom of this is lowering the right wing during initial climb after takeoff to incorrectly compensate for a single-engine airplane's left-turning tendency.

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You do that stuff every year in the sim (your first V1 cut during your initial course in a jet is usually quite entertaining), but you never really know how anyone is going to perform until the real deal happens. 98% of the time the training and drill ensures that people can perform, but there are no guarantees, and sometimes people go straight to mental saturation or mental confusion mode even though they passed the simulated emergencies.

Another factor in this case:

In a twin, when an engine fails at takeoff thrust, they yaw pretty hard and start to roll hard immediately (because of the sweep of the wings), and both the yaw and the follow-on roll are really obvious. If you do nothing with your feet you will find yourself with full aileron and the thing is still rolling over into the dead engine.

With the #3 going south in a 4 engine airliner, the asymmetry is more subtle; the brick (skid indicator) doesn't slide all the way across, and you may not need anything close to full aileron. So not reacting the the engine failure with rudder doesn't have the same holy crap aspect to it and moderate aileron keeps the wings level, but you are still in a significant side slip in a giant flying barn and it kills the rate of climb.

So a pilot who gets that kind of surprise, new to the type, being mentally led astray by the noises that could be interpreted as tires blowing, it's not too hard to see that kind of reaction as a possibility.

What gets me is the Capt not really doing anything at the critical time. Very strange. I'll bet the Capt probably got in bigger trouble than the FO in the aftermath.

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    $\begingroup$ Not sure if everything that went on was in the video, or if video producer really understood what SHOULD have been done in that situation. Biggest surprise watching was they didn't immediately reduce pitch when engine went, and allowed airspeed to deteriorate. That may have been the better subject (along with almost flying into the mountain). $\endgroup$ – Robert DiGiovanni Jul 29 '19 at 2:53
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    $\begingroup$ Well if you're hand flying you just fly the flight director and it'll tell you what to do with pitch based on the speed selection (they should have been in speed mode by then). I think the FO was in brain freeze mode because he didn't comprehend what was happening and was probably fixated on just leveling the wings, ignoring the pitch command and the brick. The capt should have intervened a lot earlier tho. $\endgroup$ – John K Jul 29 '19 at 3:40
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Using ailerons to counter asymmetric thrust is a known technique and not necessarily a mistake, especially when flying a plane that is not designed for aggressive ruddering.

Asymmetric thrust creates yaw towards the side of the "dead" engine. Using a twin engine as a simple example, we want to create a yaw torque away from a left dead to counteract asymmetric thrust. Rudder away (to right) is one method.

Rolling away (to right) will indirectly create right yaw force as follows: dead left engine, roll right, slip right, plane moves laterally right, side force created on RIGHT side of tail, tail is pushed LEFT (nose is yawed right).

The procedure to counter an engine out certainly would be in the POH of the aircraft. Rather than say one is right or wrong, it may be best to get expert training for that particular type of aircraft.

Theoretically, both methods will work. Using opposite rudder creates drag too. The question is which method works better for the 747. As far as decrying "lack of stick and rudder skills" (from the peanut gallery), no, lack of engine out training, and, perhaps, too many cooks in the kitchen. Nice video. However, one of them knew to check the airspeed.

It may be possible to use both aileron (spoileron) and rudder together.

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  • $\begingroup$ Best to compensate asymmetric yaw with opposite yaw directly. Direct control of only the parameter in the 6-DoF matrix that requires correction. $\endgroup$ – Koyovis Jul 29 '19 at 1:46
  • $\begingroup$ Except if the rudder may tear off. The real mistakes were loss of airspeed and lack of awareness of the terrain. The 747 cleared the mountain on 3 engines!!! Amazing. $\endgroup$ – Robert DiGiovanni Jul 29 '19 at 1:51
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In the long run you want to do three things:

One: immediately arrest the initial yaw ( heading change) toward the bad engine. In the short run you can view the rudder as being the most important control for this purpose, but in the long run other things play important roles (see below).

Two: eliminate all sideslip so a yaw string (if it were present) would be centered. This is accomplished by putting the rudder in the position that almost centers the ball, but not quite. Typically it should be left about half a width toward the good engine. The reason for this is given in a related answer (link to be added.) This ball position should held while turning as well as while flying in a straight line.

Three: adjust the bank angle to eliminate any heading change that may have developed after accomplishing step 2 (unless you are trying to turn.) This may be accomplished with the ailerons. Given the condition established in (two), this will require a slight bank toward the good engine. After all, the slip-skid ball acts like a bubble level (in reverse- so a pendulum really) whenever heading is exactly constant, so it is clear from the ball position what bank angle must be required to hold the heading constant. The reason for this is given in the same related link noted above.

Functionally, the same result arises- at least when the goal is to simply fly in a straight line-- if the pilot uses rudder to hold heading and aileron to set the ball position, but this is really kind of a backwards way of doing things. Just as it is possible to fly blind using a turn rate indicator using the ailerons primarily to control the needle, and the rudder primarily to control the ball, or vice versa. Most would agree that the former is the better way, but both can accomplish the same result, due to feedback loops.

Anyway, anything that prevents the plane from rolling toward the dead engine is a good thing-- once a turn starts, it tends to continue- so adding an aileron input early in the game doesn't necessarily hurt anything and will probably help a least a little bit, even with no rudder input, as long as the aileron design is a style that doesn't create appreciable "adverse yaw".

I guess this answer doesn't really address why this particular pilot did what he did-- why he omitted any rudder input-- lack of recent training, poor training, poor understanding, too much time spent flying maneuvers that only require yoke inputs and not rudder inputs, or ???

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    $\begingroup$ disclaimer - I don't fly twin or multiengine planes $\endgroup$ – quiet flyer Jul 29 '19 at 2:42

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