Hi-jacking isn't new ground for us in aviation. It was much more common than I think we like to remember in the 60's-70's & even early 80's.
What's changed with them now is the hi-jacker isn't afraid to die along with the hostages & that makes the whole situation even more frightening. I don't think our manuals really reflected that changed in regards to what to expect. Yes we have added security but its still very much tow the line & comply when we know that might not work.
Previous decades hi-jackers would often get on, demanded xyz, get what they want & get off. We all know that's no longer the case since 9-11 and that is truly a situation that terrifies all of us.