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If a wing is severed due to structural damage or from a mid-air collision, what is the best control input to make?

I would think opposite aileron and rudder, i.e. if right wing falls off, input full left aileron and left rudder.

We know from previous events that it is possible to come out of such an event safely.

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    $\begingroup$ Here's the way to do it: youtube.com/watch?v=lObfaKxqUwA And, an analysis of that video: youtube.com/watch?v=I89EMDZ0dsc $\endgroup$
    – Adam
    Commented May 30, 2023 at 22:50
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    $\begingroup$ @Criggie: With Aviate and Navigate no longer possible, Communicate where to look for your crash site? $\endgroup$ Commented May 30, 2023 at 23:26
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    $\begingroup$ @Adam The video discussion has a link to the actual film making youtube.com/watch?v=naSZBdJoEbM $\endgroup$ Commented May 31, 2023 at 8:25
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    $\begingroup$ Being pedantic (and a little facetious...), a wing won't fall off a plane in flight. The wing is generating lift, therefore when first severed the wing will rise with the weight of the body no longer holding it down... so (initially at least) the plane falls off the wing! ;-) $\endgroup$
    – John
    Commented May 31, 2023 at 9:46
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    $\begingroup$ Does kissing your arse goodbye count as a control adjustment? $\endgroup$
    – Richard
    Commented May 31, 2023 at 18:07

5 Answers 5

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This one:

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Yes, an F-15 has once landed with a lost wing. However, the landing was a close call - 20 more feet and the plane would've overrun the runway. That landing took both skill and luck, as well as a very capable aircraft.

In this case, the pilot applied afterburners to stabilize the aircraft, then performed a carrier-style landing - which isn't a normal flared landing, more like a CFIT (controlled flight into terrain) with a hook and cables arresting you while you're crashing.

What made that landing possible is:

  • The plane in that configuration had a TWR of at least 1.3, possibly more with one wing.
  • Modern jet fighters use all-moving tailplanes aka tailerons, which can move differentially, providing a powerful secondary roll input.
  • The F-15's lifting body works even when its wings lose it at zero AoA, reducing lift asymmetry.
  • There was a runway close enough to reach it on afterburners, and long enough to stop after landing at unusually high speed.

The engines and large all-moving tailplanes were able to overpower the asymmetric lift. It might not have worked, were the damage slightly different. The other necessary control input is using roll to compensate for asymmetric lift - on a fighter, it moves both the ailerons and the tailplanes, and the latter were working.

What makes such a feat impossible in most aircraft is:

  • Most subsonic, non-aerobatic, non-combat aircraft use fixed tails with elevators, which only move together - they can't affect roll.
  • Aileron forces on one wing are smaller than its lift, so the wing will still produce positive lift, rolling the plane towards the lost wing.
  • Cambered airfoils need negative AoA for zero lift, so the plane can't be flown in a straight line.

Jet fighters are uniquely equipped to handle this kind of emergency. Their thin supersonic airfoils work almost linearly across a wide range of AoA, and they have especially large control surfaces. Basically, their controls are more powerful than their wings.

The only planes without ejection seats or ballistic parachutes which have any chance to survive this might be high-end aerobatic or racing aircraft, some of which have stabilators (and some also have ejection seats). The input is essentially the same: go full throttle, counteract roll and spin, counteract whatever else is going on.

In any other aircraft, a crash is inevitable. It's impossible to make a versatile recommendation, but if you can't bail out, and still have any control, bleed energy while you can, and brace for impact.

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    $\begingroup$ Best advice to not die. $\endgroup$
    – Questor
    Commented May 31, 2023 at 15:06
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    $\begingroup$ If the wing hasn't quite fallen off, you could try the Neil Williams inverted Zlin approach: aopa.org/news-and-media/all-news/2020/october/pilot/… $\endgroup$ Commented May 31, 2023 at 19:00
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    $\begingroup$ Why is overrunning the end of the runway considered so terrible? Do they make you pay to reset the EMAS or something? :) So you plow into landing lights at 30 knots and fire trucks arrive in 2 minutes, beats hard crashing off field with rescue 15 minutes away. $\endgroup$ Commented Jun 1, 2023 at 21:21
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    $\begingroup$ @Harper-ReinstateMonica depends on what you're going to hit after overruning that runway. If it just extends into reasonably hard and flat terrain you may well be fine, but more often than not you're going to go into soft sand or dirt, or worse go off a cliff or hit a building, which is definitely detrimental to your health. $\endgroup$
    – jwenting
    Commented Jun 2, 2023 at 6:56
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Yes, it is indeed possible to come out of such an event safely..... if you happen to be in an aircraft where some of the lift is generated by the body, have an excess amount of thrust available by way of afterburners, and unknown (but probably decades) of flight experience under your belt.

Any other situation... not so much.

If you lose an entire wing, or the majority thereof I would hazard a guess that there is absolutely no control inputs that you can make that will cause you to regain any form of control. A violent crash is inevitable.

There is one class of light aircraft where you have a very high chance of walking away from a catastrophic structural loss, that is one fitted with a Ballistic parachute. The control input in this case is pull the chute!

That said, not all mid-air collisions cause unrecoverable loss of control. Even what looks like major damage might allow you to remain in control. The first rule of aviation still applies - fly the plane. For example, If you notice a roll to one side, adjust with opposing aileron. The same with the use of elevator and rudder. Most importantly, keep the speed up, there's no point having marginal control if you stall it into the ground.

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  • $\begingroup$ I like wikipedia's characterization of "overabundant engine thrust" to describe what that F-15 had going for it! $\endgroup$
    – Ralph J
    Commented May 30, 2023 at 15:10
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    $\begingroup$ My understanding of the Wikipedia article is that the instructor ordered to eject, but he didn't eject himself. In fact, it's not clear whether the instructor was in the plane, because the other crew member is called "navigator" in the sources. $\endgroup$
    – Pere
    Commented May 30, 2023 at 20:24
  • $\begingroup$ @Pere: From the pilot's own telling of the story, quoted on the skeptics.SE Q&A linked from this answer: "I turned back to shake the hand of my instructor, who had urged me to eject, and then I saw it for the first time - no wing !!!" - So both of them were still in the plane on touchdown. So I guess the instructor's first reaction was to recommend ejection, but after realizing the plane was controllable enough, he didn't force it. $\endgroup$ Commented May 30, 2023 at 23:20
  • $\begingroup$ I think normally fighters are configured so either handle being pulled ejects both seats, although they can be set not to do that (the story of the passenger who got "rewarded" with a back seat ride, and was holding on for dear life... to the ejection seat handles. Pilot's seat didn't fire, but they no canopy. I remember reading that they reviewed their procedures afterward since SOP was for the ejection seat selector to be set to "both"; it was only good luck in that case that this failure to follow that happened with someone in the back seat accidentally ejecting.) $\endgroup$ Commented May 30, 2023 at 23:24
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    $\begingroup$ They do say the most important thing about a share isn't the aircraft but the other shareholders. If their values do not align with yours it might be worth exploring options for a different group. $\endgroup$
    – Jamiec
    Commented May 31, 2023 at 10:46
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If a wing is severed or suffers severe damage, and the airplane isn't an F-15 with a lifting body for a fuselage, all-flying tail surfaces can can compensate for much of the lost wing area, and a thrust-to-weight of better than one, there is no control input that will save you.

Maybe, some minor damage out at the wing tip that doesn't compromise the wing spar's bending strength or make it collapse backwards, say from the tip getting struck by a propeller that mangles a couple of feet of tip, you can save it by aileron and rudder inputs to stop the resulting roll, but if that doesn't work, you are done.

Worrying about structural failure is like worrying about a ball joint letting go in your car and sending you careening into oncoming traffic. It can happen at any time, but you put it out of your mind, because the world's full of dangers and you have to live.

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  • $\begingroup$ Thanks for the thoughtful answer as always John.... have you seen what holds a C42 wing together though? It's just a pin. Although a wing has never fallen off of one yet, I do quadruple check that pin before going anywhere and it makes me nervous $\endgroup$
    – Cloud
    Commented May 31, 2023 at 8:58
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    $\begingroup$ @Cloud I marvel at that too. But if you do the calcs, you discover the pin, being 8mm steel having a shear strength 95000 psi, it takes over 7000 lbs to shear it off. Over three metric tons. The entire airplane is less than half a metric ton. Each wing is holding up about 500 lbs. It takes over 10 times that force to break the thing. The pin holding the wing root to the fuselage is under very little load at all, almost all the forces being borne by the struts due to the geometry. You could stick a wooden dowel in there and it would work. Not to say you don't check it carefully... $\endgroup$
    – John K
    Commented May 31, 2023 at 12:15
  • $\begingroup$ Thanks for the info.... well that's re-assuring. Could heavy turbulence 'shimmy' it out? $\endgroup$
    – Cloud
    Commented May 31, 2023 at 13:26
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    $\begingroup$ Not if the retention is installed, which is what you are checking mainly. Other thing to look for is elongation of the holes in the structural fitting the pin goes through, which can happen over many hours of wear & tear. On a preflight of a strutted airplane I always take the wing tip and shake it up and down a little, listening/feeling for obvious slop or free play going clunk clunk in the strut connections. You want it to be tight, or just barely discernable (there's always some tolerance in the holes). A preflight should include GENTLE tugging and pulling at things, looking for looseness. $\endgroup$
    – John K
    Commented May 31, 2023 at 13:38
  • $\begingroup$ Thanks John, much appreciated, I'll add that to my DI routine :) $\endgroup$
    – Cloud
    Commented Jun 1, 2023 at 9:14
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If the airplane is aerobatic enough to sustain knife-edge flight without descending rapidly, roll 90 degrees, fly down to a landing, and roll level just before touchdown. Large radio-control models have demonstrated this often, although I don't know of a full-scale occurrence.

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If a wing becomes detached you must make sufficient control inputs to counteract the roll moment generated by the still-attached wing. This means that you must:

  1. Negate some or all of the lift generated by the remaining wing.
  2. Produce lift on the side of the missing wing equal to the lift generated by the remaining wing, minus the lift removed by the control inputs.

So you would want to roll hard into the remaining wing by turning the control wheel or pushing the stick hard to the side of the remaining wing. This will not, however, be sufficient, as the ailerons on an aircraft can reduce but cannot eliminate all of the lift generated by that wing.

The downside to the above is that you're essentially trying to remove all lift generated by the wings from the aircraft. In a fighter such as the F-15 where the body produces significant lift there may be enough lift to allow the aircraft to fly if you fly fast enough, but in almost any other type of aircraft the lift removed by the control inputs (if sufficient control inputs were possible) would turn the airplane into a brick, which has well-established glide characteristics.

In general, if a wing detaches the aircraft is not going to land safely, and no control inputs you might apply will be sufficient to make it land safely. This leaves you with three options:

  1. Get out of the aircraft before impact and descend via parachute or some other independent system
  2. Use a parachute or some other system attached to the aircraft to enable the aircraft to make a reduce-speed crash into terrain, or
  3. Die.

Those are your options. Plan accordingly.

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    $\begingroup$ I like something like "3. Crash. Keep flying the airplane through the crash, to try to reduce impact force as much as possible. Even with a crippled airplane, maybe you can make it crash into treetops or something and at least land upright, and infinitesimally increase your chances of survival," more than "Die." Never give up while you have even one flight control under your control. $\endgroup$
    – Chris
    Commented Jun 2, 2023 at 17:33
  • $\begingroup$ @Chris-RegenerateResponse Alaskan airlines 261 embodied that $\endgroup$
    – Cloud
    Commented Jun 5, 2023 at 13:45

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