even more ominous thought. What if the hijackers need an airplane for some terrorist mission. Possibly something as horrible as loading a nuke on the plane and flying it into some city. That would also explain why no one has claimed the hijacking, they would want to keep this quite until their plan is carried out.
I just can't see that as a possibility. Just grabbed a trade a plane and looked. B747-200 combi $2 million US. Last time I looked 727's were going for under $250K. I would think that anyone that could come up with a nuke would have the scratch to just go buy a plane, and not draw the attention a hijacking would bring.