The 9/11 Commission Report: Assembling The Teams

During the summer and early autumn of 2000, Bin Laden and senior Al Qaeda leaders in Afghanistan started electing the muscle hijackers-the operatives who would soon storm the cockpit and control the passengers. Despite the phrase widely used to describe them, the so-called muscle hijackers were not at all physically imposing as most were no taller than 5'7".

Chapter 7:: Part 7.3 "Assembling the Teams"