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Suppose I found myself in a rapid, steep descent, perhaps right after breaking a spin. E.g. a 60 degree nose down with 100kt and accelerating rapidly, on a Cessna 172.

What might be an ideal recovery strategy, other than trying to guess/feel the optimal back pressure on the yoke? Obviously, if I pull back too hard I risk overloading the wings (to the point of collapse?) whereas if I pull back too gently I risk gaining too much speed, losing too much altitude, etc. Among other considerations, would it be advisable to enter a slip to (greatly?) increase the drag?

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    $\begingroup$ In what conditions? A 172 is typically very easy to fly, and is self-righting so the conditions in order for the rate of climb/descent to extend past the typical envelope must be abnormal or intentional. What is the initial alt. of descent? In order for you to get a detailed answer you need a sufficiently detailed question. $\endgroup$ – Jihyun Sep 3 '18 at 2:29
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Sideslips at high G and/or high speed aren't a good idea structurally.

Absent a G meter, airspeed and judging G load is all you've got. If I found myself going straight down at 100 kt, I would try to keep the speed below maneuvering speed, 128 kt, but if I felt I was applying too much force and risked an accelerated stall, I would let it go faster and if the air was smooth I'd let it go up to Vne if necessary.

And in a really extreme case, if the choice was exceeding Vne or maybe pulling the wings off, I'd take my chances exceeding Vne. If you have to exceed a parameter, it's safer to go too fast than to pull too hard, because there is ample safety margin for flutter, and you know how much you are going over.

Of course, without a meter, with G load it's all judgement. The yield G limit for normal category is 3.8, so what can be really useful is go with your instructor and practice 60 degree banked level turns to become familiar with the sensation of 2Gs, which will at least give you a reference point. Even better if you can get a ride in an aerobatic airplane and learn what 4 Gs feels like and try to stay below that when the time comes.

The other big thing is knowing whether you are in a dive inverted or right side up. This is a problem for pilots who get flipped over by wake turbulence and end of upside down in a 45 degree dive, and instinctively pull right around in a split S through 90 degrees and rip the wings off. In an inverted dive most airplanes will accelerate past Vne in a heartbeat.

If you are in an inverted dive like that you have to roll the plane right side up before pulling out. Recognizing it takes training and professional pilots often get upset training in aerobatic aircraft to develop the correct reactions.

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First and foremost determine your attitude after you break the spin (or any other unusual attitude for that matter). You first stop with your eyes should be the airspeed indicator. If it’s rapidly increasing, you’re in a dive and your next step should be to get the throttle to idle - PRONTO. If your airspeed is rapidly decreasing, you’re in a climb and you need to increase the throttle to full power to delay the onset of a stall.

If you’re in a climb - relieve aft elevator pressure or push forward on the yoke until the nose of the aircraft returns to the horizon. Once you’re in a level pitch attitude, roll wings level with aileron input. Then set power and trim for straight and level flight.

If you’re in a dive - This one is far riskier as you’re both rapidly accelerating towards Vno and Vne, not to mention about to have an appointment with terra firma if you don’t do something quick about your situation. As such your corrections here need to be prompt but not excessive such that you induce a secondary stall or overloading the airframe, causing structural damage or failure. Your first step here will be to ROLL WINGS LEVEL. Attempting to recover here by first applying aft elevator pressure before rolling wings level may place the aircraft into an even tighter spiral with your inputs pushing the airfram to its structural load limits. Attempting to apply elevator pressure combined with aileron inputs at speeds at or beyond Va can potentially overload the airframe as well, resulting in structural damage, so your second step if you’re in a dive after reducing your throttle to idle MUST BE TO ROLL YOUR WINGS LEVEL. If you cannot ascertain your attitude by looking outside of the aircraft, look at your attitude and roll the airplane level accordingly. Once you have wings level, apply aft elevator pressure, being careful not to over stress the airfram nor so aggressive that you exceed the critical angle of attack induce a secondary stall. Once level, set power and trim for straight and level flight.

So to sum up:

In a climb - indicated by rapidly DECREASING AIRSPEED:

Throttle - Wide Open

Alleviate aft elevator pressure / push forward on the yoke until nose level with horizon.

Roll wings level

Set power and trim for straight and level flight.

In a dive - indicated by rapidly INCREASING AIRSPEED:

Throttle - Closed

ROLL WINGS LEVEL

Apply aft elevator pressure until nose level with horizon

Set power and trim for straight and level flight.

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PARE (power to idle, ailerons neutral, rudder to break spin, elevator to recover) works really well in the 172. Firstly, if you did your CG homework before you went flying and did some stalls with your instructor you would know the 172 has a very gentle, straight forward stall. No need to slam the yoke full forward to recover. If you do over do it, no time for sight seeing, immediately pull out of the dive. The key is not to wait even a second, as speed will quickly build.

The 172 is very stable, so once you break your spin (which you have to try very hard to get into), easy down el while checking your airspeed, and then fly out of it adding throttle as needed.

I would very much recommend going over this with a qualified instructor and make sure you have adequate altitude before even thinking about trying it.

Bob

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