On all three of the 9/11 hijackings, passangers knew that the palne had been hijacked, and at least two of the fights, the passengers had made plans to thwart the attempts.
Ya think a gun might have come in handy?
Excuse me? Where are you getting your so-called 'facts'?
The passengers on the first two - of
four - planes had little to no idea the planes were being hijacked. Of course, we'll never know, since it all happened so suddenly nobody had the chance to contact anyone on the ground.
The third plane, it seems the
pilot - the passengers again having no idea of the hijacking or, if they did, then no idea that two planes had already crashed into buildings -may have foiled the hijackers' intended target by hitting part of the Pentagon instead.
Only on the fourth flight - the one that crashed in a Pennsylvania field - had the passengers been alerted (by family members on the ground) of the morning's events. Knowing that the hijackers' goal was to crash the plane anyway, they were at least able to overpower the hijackers and save whatever the target was - and the people in that target as well.
I admit, all the above is from memory - so some of my facts may not be completely accurate.
But, no - all hijackings were already in progress, i.e. the cockpit had already been breached, so, no, having guns would NOT have helped. To what end? The hijackers all knew they were going to die. Do you really think a gun would have changed their minds?