Assume the pilot is flying too fast and high for an emergency landing. What movement of the control surfaces must they apply to land the aircraft safely on the runway? I heard this type of manuever is also used in gliders and light aircraft

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    $\begingroup$ You may want to read the story of "the Gimli glider", where this situation occurred. $\endgroup$
    – mins
    Jul 26, 2015 at 10:42
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    $\begingroup$ It's called a sideslip. Cross rudder and aileron controls and let the fuselage drag take care of the rest. $\endgroup$ Jul 26, 2015 at 16:56

2 Answers 2


Ah that's a good question indeed. You asked

How to reduce altitude in a passenger jet

Normally most of the passenger jets have spoilers They are effective and can be deployed at any speed.

Now what happens in case you don't have spoilers for any reason. I was discussing the subject with a pilot many years ago and he told me the trick you mentioned: you apply rudder to one direction (I assume opposite to the engine rotation to avoid unpleasant surprises). That increases dramatically the forward surface of the plane against the relative air flow. That results in increased drag and thus speed loss.

But yaw causes roll (and vice versa). Also the wing of the side you are yawing to, has less lift because it is shaded from the forebody of the plane. This is where the aileron is needed. You need aileron to maintain lateral stability and prevent the aircraft from rolling. See the image bellow. The orange lines denote the area of increased drag by the fuselage. The green area is the "shaded" area of decreased lift of the wing.

enter image description here

Top view from wikipedia. Derivative work by me.

According to that pilot, this is more effective than spoilers. But there is a trap: You need to be careful not to yaw the plane too much because the shaded wing will loose too much of its lift and will result in capsizing the plane.

EDIT: Finally, you mentioned emergency. There are different types of emergencies. Pressurization is an emergency situation but does not affect aircraft control (at least not directly). Hydraulics problems or engine loss is an emergency as well. But that will affect the way you will handle the aircraft. Here I cannot help you. A trained pilot perhaps can answer, though I believe that the answers will vary depending on each planes flight manual.


In addition to the standard aerodynamic controls - ailerons, rudder, elevator - many large aircraft also have a spoiler (also known as speed brake). This has the effect of adding drag without adding lift - in fact in some designs it will reduce lift. This allows a swift descent to be made without increasing airspeed. Gliders also have spoilers, as they only have one shot at a landing.

In the absence of a spoiler (or in addition to it) an aircraft can dump lift without increasing airspeed by carrying out a manouevre called a "forward slip". The ailerons are applied in one direction and the rudder in the opposite direction, meaning that the aircraft is actually moving at an angle to the direction the nose is pointing (see the answer by Stelios for a nice diagram). This adds drag and disrupts the aerodynamics of the wings. This was among the manouevres used in successfully landing the Gimli Glider.

In either case, just as in regular flight, forward speed and vertical speed can be manipulated together by using the elevator: lowering the nose increases both airspeed and descent rate.

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    $\begingroup$ Just wanted to point out that in a slip, speed and descent rate are manipulated by elevator. $\endgroup$
    – egid
    Jul 27, 2015 at 2:11
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    $\begingroup$ Two things, one, you may want to use "forward slip" to differentiate from a regular slip (part of an uncoordinated turn). And here's a genuine emergency that used that particular maneuver that you might consider including: en.wikipedia.org/wiki/Gimli_Glider $\endgroup$
    – Jay Carr
    Jul 27, 2015 at 2:15

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