When the immediate scenario is being played out, having armed Sky Marshals on board is a bit like a car alarm - useful in some situations, not in others. You'll never really know until it starts to unfold. To experienced offenders such things are often just a nuisance.
My real concern would be the possible situations where it drags out into a standoff. What if the unlikely circumstances coincide where there is some form of contact between the Marshall and the aircraft Captain, but a disagreement, probably under time and emotional pressure, about the course of action? Will said Sky Marshall be correctly trained, AND not ignore such training, about the very real, very legal and very absolute authority the Captain has for the safety of the aircraft? Or will he decide he is the man, and calls all the shots? (Sorry) Overlapping terms of reference, backed by real authority (legal/tradition vs Glock), are a recipe for disaster in any complex situation.
Maybe now the Captain will have to deal with
two threats to the safety of his/her aircraft.....
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