I saw an interview of a commercial airlines pilot today that I imagine everyone else saw as well, and.......
The pilot said to always wear your seat belt when not up from your seat.
He and his co-pilot were in the air when the deed was done or being done and they discussed what their reaction would be under similar circumstances.
The co-pilot had a large flashlight that he would try to beat any would be hijacker off with and the pilot said he would concentrate on getting the airplane on the ground.
He also said there were several ways of combating any hijackers.
One was depressurizing the cabin and that the airplane could be jerked around the sky and that anyone not in their seatbelt wouldn't be able to get up.
I heard several years ago; when the 727 1st came out that one of the test pilots had done a full roll during one of the test flights.
I guess he was sorta reprimanded about it when he got it back on the ground, but that the aircraft flew so well it was almost like a small very acrobetic airplane.

And like everything else built today that has a top limit of service recommended for use, that in reality it will handle at least twice as much to prevent product liability.
There's no telling what a pilot would be able to do with an airplane going some 500-600 mph.
Perhaps they could even do as the Vomit Comet and have a couple of minutes of free fall.
I haven't always agreed with our president, but I do have to say he has the cojones to do what it takes; after hearing that he had issued the order to the pilots of the combat aircraft that was scrambled to intercept and deal with the airliners headed to Washinton DC with any means neccesary to stop them.
I can't say I'm surprised at that since sacrificing the few in order to save the lives of many is the right decision, but it still took a great deal guts in order to do that, all IMO of course.