I wouldnt go on a plane in the first place, its a flying metal death tube.
But its the air crews job to deal with secuirty issues and any attached police. And if landed the security/police at the field.
Only speaking for the U.S. here, but it's not the air crew's job at all. They have no training what-so-ever in that, nor will they ever. Strange, yes, but true.
An old friend of mine, may he Rest In Peace, was the nicest person anyone ever met. If he met you once, just for a few seconds and you were introduced - if he saw you again 25 years later, even if you had changed hair color and weight, he's speak to you by name, even the proper pronunciation. (yeah, he was one of those)
He was also one of the toughest people I've ever known. Deputy Superintendent, Boston P.D. Still ran the Gang Unit as a Deputy, boots on the ground every night.
Anyway, he and his wife were flying back to Boston from California. When he boarded he spoke to the flight attendant by the door, showed his badge, told her his seat number and said "If you need help with anything, just nod your head to me."
During the flight, two guys in their twenties jumped up, started screaming "We're all going to die!" and started ripping open the overhead compartments and throwing everything into the aisle.
People freaked, started screaming. The attendant nodded to Bobby Hayden, my dear departed friend, who got up, picked the first guy up, turned him over and smacked his head into the floor knocking him out, spun, hit the second guy with a right hand and left hook, knocking him out. Bobby and a retired Army Colonel then borrowed peoples belts, hog tied them, gagged them and dragged them to the back of the plane.
Time Magazine did a great story on it. And the last paragraph said (and I paraphrase here) Bob's wife Katy was reading a book. She never even looked up. Bobby had had the aisle seat, Katy the middle, but the guy in the window seat said "My God, you didn't even stop reading!
Katy looked at him and said, "He always does this. I've never read this book before."