Mark, I sincerely wish that I could agree with you.

"Evildoers today can board an airliner secure in the knowledge that nobody else on board will be armed. If they would have even the slightest fear that anybody else, a sky marshall, crew member, etc, could possibly be armed, I rather think they might have second thoughts about attempting to do their deeds."

The nature of the fanatacism that causes these nutcases to do their deeds is not fear of retribution. They would do it anyway because
they get their rewards "in heaven". The problem is that those armed might intentionally do the wrong thing. A sky marshall might receive some training to deal with a terrorist but it can't be just
retributive. It would have to include the ability to assess behavioral patterns and predict when these actions might occur.

Pilots carrying weapons might be a prescription for disaster. A division of duty would make it hard to control an aircraft.

The only way to solve the big picture is to eliminate the effectiveness of this kind of terrorism by making it irrelevant.
Perhaps releasing chemical anesthetic gas into the area might be a deterrant. Locking bullet-proof cockpit doors is certainly important.

Preparing the passengers with the awareness of what to do in case
a terrorist strikes might be another possibility.

But the idea of terrorism as defined by 911 calls for not just a band-aid on cancer. We need to examine the root of the problem and counter-act the effects of the madrasas that are prevalent today in many Muslim countries that advocate ideological violence.

There's no quick fix to this horrendous problem. But working on the big picture rather than the small bits would help, ie: international cooperation and education.

Frank