Originally Posted by k0nr4d

Not necessarily... depends what your goals are. Lets say you wanted to crash the plane into a crowded stadium during the world cup or some big building... you'd do your best to keep it quiet. The goal might not be to negotiate for the hostages but rather to do something with the actual plane, maybe even a year or two down the line - ergo you'd quietly execute all the passengers and keep the plane hidden until the heat dies down.