I know two people who have been on hijacked flights. They both sat tight and were fine. The world's changed though so I'm not sure that's the right approach.

I believe I sat next to one a few years ago - he didn't drink anything, he kept his jacket on all flight, despite it being warm, he was already in his seat when everyone else got on to board (I was at the front of the pre-boarding line, he was not in front of me), and he looked at everyone walking past as they boarded. His bag was stashed in the FA's locker (not the overhead). During the flight he didn't nap, didn't watch IFE, had a book but didn't seem to ever read it. I also wondered if he was put in the seat next to me to make it seem like we were a couple - there were a lot of men on this particular flight, so perhaps seating them next to a woman makes it seem more inconspicuous?

I can spot some FAMs and their foreign equivalents. In some cases I even can figure out precisely where all the guns are on my flights.

On the US, European and Asian carriers where I have been aware of the presence of FAMs/FAM-equivalent, they aren't allowed to be under the influence of alcohol in the course of their flight duties.

The chance of being involved in a hijacking is so incredibly remote I don't give it a second though. Much more chance of being run over on the way to the airport or killing myself putting some trousers on.

Can't go through life preparing for things like this that are almost certainly never going to happen.

I don't think you're going to find many US air marshalls on non-US carriers.

This thought has crossed my mind. As a young man, I feel that it's up to me/my demographic to step up first.

1) I hope I never have to find out if I have the steel to be (potentially) useful.

And no one but you seems to have suggested the above.

I find plenty of FAM equivalents on non-US carriers. ;)

The US isn't the only country with airlines that have air marshals (by whatever name they go) on them.

There are some US dual citizens who are air marshals on some non-US carriers.

Yeah it would be impossible to test this out even in a experimental way. There are too much ethical issues involve so I guess making an article or research would be impossible.

I wonder how you go about identifying them. My guess (and it is only that) is that air marshals are on board a statistically insignificant number of flights worldwide. I'm not sure if you are privileged with insider information (i.e. you or someone close to you is in the business) but, given that most countries don't use them or acknowledge their - or their program's - existence in any way, using the word 'plenty' seems, prima facie, a bit casual.

Sounds like you sat next to one.

I fly on certain routes that have a higher -- much higher -- proportion of armed personnel on board than most other flights. My flight patterns are not a mirror image of all "flights worldwide", but it's been "plenty" on some non-US carriers routes of which I have made good use.

You can keep wondering about how I know which of my flights have plain clothes armed personnel on board, but it's not all that difficult to figure out how I have known.

Of the countries where there is a FAM style program, public acknowledgement of the use of such personnel as a security measure has taken place in a variety of them.

Remember David Blunkett? ;)

Beer - check.
Popcorn - check.

Unless it's non-alcoholic beer, a consumption of beer and popcorn in-flight would be a give away that either you're not legally authorized to carry a gun in the passenger cabin of common carrier flights or that you're not abiding by the rules set by the employer. ;)

Or a FAM who thinks outside the box--put non-alcoholic beer in an ordinary beer bottle. Any bad guy will note the beer bottle and conclude the guy isn't a FAM.

Not necessarily, for the ways for a person to know if a man or woman on a flight is a FAM/FAM-equivalent doesn't depend upon that person not being a bad guy. Not that it matters that much when it comes to terrorists on flights with the interest and means and opportunity to attack their own flight as they are few and far between. I'd worry more about carjackings than hijackings if I were a proverbial worry wart.