Just look at some other hijacking throughout history:
19 September, 1995: A lone unarmed man hijacked a Boeing airliner with over 174 people on board. The passengers and crew never overwhelm him.
23 November, 1996: Three men, initially unarmed, took over a Boeing 767 with 172 people on board. They grabbed a fire ax and a fire extinguisher, and with these were able to keep the passengers and crew under control even though it is obvious to the crew that the airplane is in danger of running out of fuel and crashing into the ocean. . .which it does.
9 June, 1997: Two unarmed men hijacked a Boeing 737 with about 80 people on board. They were able to keep all of the passengers and crew under control for over three hours, despite being unarmed and far more outnumbered than were the 9/11 hijackers.
23 July, 1999: A lone man armed only with a knife takes control of a Boeing 747 with over 500 people on board. He killed the pilot and chased everybody else out of the cockpit; it took 20 minutes for the people on board the airplane to rally and overwhelm this one man, even though he was outnumbered 500 to 1 (as compared to 87 to 5, 60 to 5, 59 to 5, or 40 to 4 as on the 9/11 hijackings).
3 October, 2006: A single unarmed man hijacked a Boeing 737 with 106 other passengers on board. In spite of being totally alone and unarmed, the passengers and crew did not overwhelm him.