Already discussed several times, but will not change my opinion.
Bringing firearm on board is the worst you can do for safety.
Having policemen onboard is good. but there are alternatives to firearms.
Security mesures in the US (and not only in the US) are at least 95 % cinema, and inefficient.
Ecoute les orgues, Elles jouent pour toi...C'est le requiem pour un con