How do you 'start' a big commercial jet like a 757 or A330? Do they have ignition keys? Is there a master on / off switch? Do the doors have keys? Or if someone were to scale a fence, pop the door, get in the cockpit, and just turn it on could they grab one?
I don't have anything approaching the means or knowledge to do this, but I've often wondered if they are "locked" when they're sitting in the airport at 3 AM... Or whether they ever "lose the key" (wouldn't that be embarrassing - "ladies and gentlemen, on behalf of Delta I'd like to apologize for the delay in our departure from Atlanta. Our pilot today thought the first officer had the ignition key, and the first officer could have sworn he put it on his key chain when he left the hotel, but no one seems to be able to find it..")