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I know this is not practical (considering there is normally not much use to use up to 30 degrees of elevator trim), but if you were on a Boeing 777 or 737, or similar, and the elevator trim was set into said position, and stuck there, would it be possible to safely land said aircraft in that condition?

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From the Boeing 737 emergency procedures:

After all attempts fail to free the stabilizer...

  • Anticipate higher than normal elevator forces during approach and landing.
  • The thrust reduction at flare will cause a nose down pitch.
  • Note: Elevator control is sufficient to safely land the airplane regardless of stabilizer position.

Note on terminology: Most jet-liners (including the 777 and 737 as the question requests) use a trimmable horizontal stabilizer (THS), in which the pitch trim is achieved by positioning the whole rear wing up/down -- as opposed to using trim tabs.

enter image description here
(airteamimages.com) THS of an Embraer ERJ-190.

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  • $\begingroup$ Wow! Short answer, and you still hit the nail right on the head! $\endgroup$ – mins Sep 11 '16 at 10:02
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The answer is a resounding Yes! You can safely land an aircraft with Elevator Trim jammed either up or down. Maintaining straight and level flight with Elevators alone can be difficult because the aircraft is sensitive to other conditions, airspeed, wind, etc These can be compensated for through the use of Trim. Trim is a much smaller version of an Elevator, often adjusted up or down by a small wheel between the front seats.

Use of trim can give you much more stability by making smaller adjustments so the Pilot doesn't need to fight the Elevators to maintain height.

During takeoff or landing the affects of a jammed trim can be compensated for by applying small amounts of opposite Elevator.

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  • $\begingroup$ @ymb1, most jets, B737 included, don't have trim tabs on elevator. The trim control in cockpit controls the stabilizer pitch. So elevator trim is the same as the stabilizer in the question. $\endgroup$ – Jan Hudec Jun 13 '16 at 19:34
  • $\begingroup$ @ymb1, right; I read your comment and didn't read the answer well. Yes, the answer is totally wrong. I don't agree a stuck trim tab would not be as big issue though; basically whatever the trim mechanism, it needs to produce similar forces for the pilot to overcome. $\endgroup$ – Jan Hudec Jun 13 '16 at 20:06
  • $\begingroup$ @ymb1 The question didn't mention Stabilizer at all. My answer may not have be complete but it is still correct, you can easily overcome a stuck trim tab. It will affect control, but you can land safely - that was the question. $\endgroup$ – Admiral Noisey Bottom Jun 13 '16 at 21:22
  • $\begingroup$ @ymb1 See the Aircraft section here en.wikipedia.org/wiki/Trim_tab for some more information. $\endgroup$ – Admiral Noisey Bottom Jun 13 '16 at 21:30
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    $\begingroup$ @AdmiralNoiseBottom, the problem is that trim tabs don't affect the authority of the elevator, only the control forces, the movable stabilizer does affect authority. So the general statement you make for trim tabs does not apply and can only be made with specific reference to the design in question. $\endgroup$ – Jan Hudec Jun 13 '16 at 22:02

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