If spoilers are released in flight without descending, what could happen?

  • 3
    $\begingroup$ Welcome to Aviation.SE! Can you add some more details about the situation you are asking about? "what could happen?" is very broad... $\endgroup$
    – Bianfable
    Commented Apr 22, 2022 at 7:14

3 Answers 3


Spoilers are also called speedbrakes. If used in level flight, the aircraft will slow down. They are usually used to slow down and descend, but they can also be used to slow down in level flight to meet a speed restriction.

On large jetliners, spoilers can also used for roll control, so it is quite common to see them deployed in all phases of flight.


Well that depends on what else you do. Spoilers will increase drag and destroy lift.

So if you are on autopilot and do not increase power(thrust), the A/P would increase AOA to increase lift sufficiently to maintain level flight, (further increasing drag), and the aircraft would start slowing down.

If you were flying manually, you would probably manually increase back pressure to increase AOA and lift to maintain level flight and increase power to maintain airspeed. This would be necessary to prevent a descent.

If you didn't take those actions the nose would drop and the aircraft would descend at an increasing speed and descent rate until your speed increased sufficiently to generate enough lift to maintain a stable descent.

  • $\begingroup$ In some sailplanes at least, spoilers do not cause the nose to drop and airspeed to increase. In fact on those sailplanes they can be used in an emergency to descend through clouds with no horizon reference because the craft will enter stable ( in both roll and pitch) descending flight. $\endgroup$
    – Jim
    Commented Apr 22, 2022 at 13:11
  • $\begingroup$ I'm not a sailplane person, but I'm curious. How does it descend without the nose dropping? And also since lift is at least initially,, decreased, won't the airspeed increase due to altitude loss to stop the glide angle from just continuously dropping? $\endgroup$ Commented Apr 22, 2022 at 13:17
  • $\begingroup$ @CharlesBretana -- well, if spoilers cause the glider to trim to a higher angle-of-attack, but also a higher sink rate-- there you go. However if there is a substantial increase in sink rate I have a hard time believing that the nose is not going to end up at a somewhat lower pitch attitude, due to the changed direction of the flight path. I'd want to see video evidence (or see it first-hand) before accepting idea that spoilers might not cause nose to drop at all. $\endgroup$ Commented Apr 22, 2022 at 13:36
  • $\begingroup$ Of course the whole question of how the airspeed responds depends on starting conditions. If in an extremely steep dive (very low a-o-a), drag from spoilers may be more important than loss of lift, causing airspeed to decrease. That's the whole point of "terminal velocity" dive brakes, which some sailplanes do have-- you can point the nose straight down (e.g. accidentally, in cloud) and not blow through redline. $\endgroup$ Commented Apr 22, 2022 at 13:42
  • $\begingroup$ @quietFlyer, yes, I guess every scenario has a spectrum of actually possible conditions under which it can occur. I'm (again), not a sailplane pilot, so I don't have any expertise on their behavior... But I agree with your skepticism. On your point about airspeed, yes, remember the Stukas in WW2! As dive angle increases, it takes less and less increased lift to maintain (or stabilize) that increased dive angle without increasing it further. $\endgroup$ Commented Apr 22, 2022 at 16:30

"Without descending" means that the aircraft cannot land. Therefore it will run out of fuel. In an attempt to avoid descending, it will slow and eventually stall. At this point, the conditions of the question, no descent, are violated.

As asked, the question is unanswerable.

  • $\begingroup$ Hah! What if there's higher terrain ahead? (Grin) $\endgroup$ Commented Apr 22, 2022 at 12:51
  • $\begingroup$ @CharlesBretana Ohhh... interesting consideration! The homework problem didn't specify not climbing, so maybe that could be allowed. $\endgroup$
    – Ralph J
    Commented Apr 22, 2022 at 12:53
  • $\begingroup$ Sorry, just injecting a bit of humor there! $\endgroup$ Commented Apr 22, 2022 at 13:02

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