Wino, please don't start to insult people whose opinions differ from yours.
You have stated your opinion. Fair enough. The vast majority of the remainder here disagree with you. I am among that number.
I cannot envisage any situation in which firearms on board an aircraft will improve the situation. Further, knowing that firearms may be on board will simply persuade any potential terrorists to modify their method of attack.
The number of possible cases in which firearms will assist are so few and those in which they will not so large, plus those cases in which they will actively degrade the chances of a successful completion of the flight so large, that I cannot see any half-way decent case to be made for it.