How long will the aviation industry take to recover from this crisis, after the crisis is over?

Unknown. Aviation in Alaska is rapidly collapsing. No tourists, no jobs. Many operators won't survive, even if things are back to normal next year. How it shakes out elsewhere is unknown, but a lot of heavily leveraged, low-margin companies are going to fail, particularly outside the USA unless governments bail them out. My prediction: look at the 2007 housing-market bubble that collapsed. It took the U.S. aviation industry a good 5-7 years to fully recover, and over the past 5 years it has over-expended, so I expect the worst with mass unemployment of flight and cabin crews. I was out of a flying job for half of that time from 2008-2012 . Couldn't even get an instructing gig with over 10,000 hours of flying experience. As of last week, I'm out of a job again and my 15,000 hours won't help because most flying jobs that were available 2 months ago have disappeared. Some of my major airline buddies are taking early retirement buyouts while they can. Hope for the best, expect the worst. 

Well it depends on how long people would feel comfortable about flying again. After the crisis is over, people won't feel overly happy about being crammed into a cabin with 100-600 other people depending on there flight (short to long haul) and how close they have to sit next to other passengers. Another crucial factor is the fact that airlines are putting flight prices up by 50% for the first couple of years but I don't see how people would want to fly at this rate. Airlines WILL go bust and so will aircraft producers who are not making enough sales. We will see a decline in aviation but it will rise up again once people are satisfied that they can travel, and if they want to go intercontinental, they will have to fly. So I say it would take a good couple of years before we see the mighty aviation industry back on its feet, but it won't be the same again. It will have changed.....

Boeing was already suffering big time due to its 737 MAX problems. Airbus was hurting over its A380 miscalculation. ORDERS for new planes have dropped to zero and some orders have been canceled so they are going to need quite a long time to recover. As far as the airlines, if they can not make it they will declare bankruptcy. Someone with money will buy them out cheap and start them up again. It is not like there will be no airlines around.

It may be relatively quick.People will want to put things behind them and forget about the mess. But then again, because of all the money that was lost from people not working... this means the government will have to step in and provide stimulus package.

Depends upon which part of the "aviation industry" you mean:

(Guesses)

aircraft makers--a couple years

airlines--a year

airport services--a few months

travel destinations--a few months

and of course, which countries. That is uncertain.

Which crisis would that be?