are really air marshals on airlines

yes only on international flights.

l hope so. However l do not think they are on all international flights across the world. On US flights, but doubt if they are in Europe.

Yep, personally know one.(well Australian Federal Police anyhow).you would not be able to tell him apart from any of the other passengers! (Since that is his role on the plane, then l guess that is a good thing!)

Yes , they act as regular passengers , dressed in civilian clothing. He walks on the plane just like anybody else , and could stuff his bags in the overhead bin , he could be the guy next to you.

yup. on every flight? maybe. on every flight into & out of Reagan & Dulles? you betcha.

In the coach cabin? l doubt it.

To what Cessna 172 Man says, l would add ''he or SHE could be the guy or GAL next to you . . .''

Yep, and they're not just on international flights.

My wife is a CSA, and has check through AM is often on long domestic flight's.

Yes. There are Air Marshals flying international and domestic flights all the time.