How does this make sense? Shoe bombs to storm the cockpit? How does that work? If they detonate, no one gets to hit the Library Tower. If they use them as a ruse to GET into the cockpit, it would NEVER have worked in Oct '01. The Flight 93 heroes were BIG in everyone's mind, and no passengers would let that happen.
Or did they have some kind of controlled bomb that they knew would ruin the cockpit door but not touch the fuselage?