[generally]

It would be much easier to put a device on the plane that released gas that would affect the pilot/crew/passengers. It could kill, sedate, or probably some other things as well.

[defconw]

Sure, I was just looking for something that would be overlooked in the pre-flight check list or at least something that would not raise a red flag with an experienced flight crew.

I mean they have to check their craft before they take off, so the sabotage would have to be on a timer or something.