Isn't the existance of Air Marshalls providing a 'chilling effect' on potential troublemakers? How would we show the dimensions of that effect?
Until that's done, it's disingenuous to claim that Air Marshalls have prevented only thus-and-such incidents. That's not counting what didn't happen just because they are there (or might be there).
E.g. a reasonable argument is to diminish the Air Marshall service because they are individually problematic, while keeping the rumor that they may be on any flight. That doesn't fly in the face of statistics but uses it to reinforce an argument.
Is a single air Marshall more effective than an entire plane of passengers?
Post 9/11 a plane full of people is not going to let a guy with a knife take control of the plane. It is pretty unlikely that one Marshall is going to notice a suspicious person versus the 12 people sitting within 6 feet of them.
You can't just go around running expensive government programs on the basis of there being no proof that they don't help, that would lead to an infinite number of programs and a huge disincentive to run those studies.
It’s flying bus that a) can be rather easily converted to a missile, and b) is sealed until it touches down so any craziness is locked in for hours possibly.
I’m more comfortable as a flyer and as someone who’d like to do business in the US if I know that there are air marshals. Surely this pays for itself this way, especially given the ever increasing accessibility of air travel. I say this an American who knows how crazy our population can be.
The impression I get is that in-flight crimes (or general disturbances) have increased roughly proportionately (and sometimes beyond pace) with the flying population. If the object of the Air Marshals is to provide a "chilling effect," that effect has not been demonstrated.
Until that's done, it's disingenuous to claim that Air Marshalls have prevented only thus-and-such incidents. That's not counting what didn't happen just because they are there (or might be there).
E.g. a reasonable argument is to diminish the Air Marshall service because they are individually problematic, while keeping the rumor that they may be on any flight. That doesn't fly in the face of statistics but uses it to reinforce an argument.