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Often flying I have this fear, that something will snap, and the plane will start plunging to the ground in a spin.
My question is, once a passenger aircraft (e.g. an A320) goes into a spin, can the pilots recover it, stabilize it and make it glide, or is it too late?
A similar question was asked before, but I am looking specifically for answers regarding large passenger aircraft.
Stabilizing a spinning aircraft is fairly easy. If the center of gravity is not too far forward, the rudder is deflected in spin direction and the elevator fully up (adjusting the horizontal tail trim helps, too), the spin will continue until the aircraft hits the ground. In some cases, the spin might oscillate between two stable modes, and the aircraft will continuously pitch up and down between them. An airliner with its high wing loading will loose a couple of hundred meters per turn in a spin, but will not accelerate once the spin has fully developed. Increasing air density on the way down will actually decrease the rate of descent.
But I guess you wanted to ask something entirely different.
Ending the spin is equally easy and is performed by the opposite commands which stabilize the spin. Proving that the aircraft will easily come out of a spin is actually part of certification requirements. The stable rate of descent gives the pilots ample time to end the spin, and even if the engines have failed, emergency systems will ensure that the pilots can control the aircraft. The risk that an otherwise normal flight will end in an unrecoverable spin is practically zero.
I would actually prefer that the airplane enters a spin. If the center of gravity is in the forward part of the allowed range, it is more likely that it will enter a spiral dive after stalling. Now the pilots need to react quickly and with measure, because drag is much lower in a spiral dive than in a spin, and the resulting higher speed poses a real danger. For that reason the flight control system in the type of aircraft you mentioned, the A-320, will prevent the aircraft from entering a spiral dive in the first place.
So far, we have assumed that all systems work. What if something snaps? The surprising answer is: Mostly nothing. A fundamental design principle for aircraft demands that primary structural parts or equipment can snap without the aircraft breaking apart. This is called redundancy: Every primary structure and every flight-critical piece of equipment is duplicated, so if one part breaks, the other, redundant part will continue to carry the loads and the flight can be terminated as planned. Regular inspections make sure that such damage is caught quickly, and the manufacturers continue to improve the existing fleet once a weakness has been spotted.
Even if something snaps, it is extremely unlikely that the aircraft will enter a spin, and even if this happens, it is easy to end. Your fears are unfounded.
As DeltaLima said, it is kind of hard answering your question.
After looking at the question he linked you might have found the answer already.
Let me try to answer your specific question though:
Assuming an airliner, let's say the A320, for some reason got into a spin, can it be recovered? The general answer would be yes!
Here are some things to consider though:
The FAA requires all single-engine normal category aircraft to demonstrate spin recovery in FAR 23.221(2). It depends a lot on the center of gravity of the airplane whether it is recoverable from a spin or not. If the center of gravity is too far aft, it will not be recoverable from a spin. Gliders, being light, have an easy shiftable CG, and there is some that don't enter spins at all or need extra weights in the back in order to make them spinnable! Airliners are not required to do so as they are not as likely to get into a spin in the first place!
The structure of an airliner is designed for air flowing over it, not for being in a spin! Centrifugal forces will be applied to the structure due to angular acceleration. Also, spins by airliner would be a lot faster then by little aircraft and more forces would be applied to the frame. If the recovery from the spin is made too fast or abrupt, it can overstress the airplane as well!
All Airbus I know are fly-by-wire, and Airbus is well known for its computer based controls. Most airliners have a lot of systems, which prevent them from even getting into a stall. There a incidents where these systems failed and it went back to the pilot doing the right thing.
As a spin always always always requires a stall first, and pilots are trained to avoid stalls in the first place, it is very unlikely for an airliner to enter a spin, having the pilot and various systems working against entering a stall!
I wouldn't worry about something breaking in an airliner. The chance of that actually happening to you are orders of magnitude smaller than something breaking in your car on the way to the airport. Airline disasters make for much more sensational reading than car accidents do, so they tend to be hyped quite a bit more, but a major accident like that is really quite rare. Plus, there is so much that goes into inspecting those aircraft. Breaks do occur, but they are very rare. It's just not worth worrying about.
And I'll go back to my original answer. Pilots are taught the proper ways to deal with a spin, and a spin is a spin is a spin. The specific aircraft aerodynamics differ, but the general procedures are still the same. However, if you're in an airliner that gets to the point of spinning, then it's more about the pilot than it is the aircraft. And if the pilot let the aircraft even approach a spin, he's the wrong guy to be sitting in that seat to begin with.
