Here is what I think happened the 11.9.2001:
There were
five planes remote controlled by Israels secret service organisation
Mossad. NORAD (North American Aerospace Defense Command) managed to shoot down two of the five planes. Maybe there were arab terrorists in each plane, but they did never control any of the planes.
1. Flight 11 hit one of the Twin Towers
2. Flight 175 hit the other Twin Tower
3. Pentagon was hit not by a passenger plane, but by a smaller plane. See picture under.
4. Flight 77 was shot down over the Atlantic Ocean.
5. Flight 93 was shot down over Pennsylvania.
The goal for Flight 77 and Flight 93 might have been american navy ships in the Atlantic Ocean.
This to create a terror act which reminds of
Pearl Harbor. The suicide pilot attack against Pentagon would also have reminded about Pearl Harbor.

Pearl Harbor illustration
One film about Pearl Harbor was released in May 2001. It could be a coincident, but it could also have been timed on purpose close to 11.9.2001, to help to create Pearl Harbor emotions for the US-citizens.
http://www.cinemasavvy.com/p/pearlharbormovie.html
Quote:
Pearl Harbor Movie
Produced By: Jerry Bruckheimer Films & Touchstone Pictures
Release Date (US): May 21, 2001
President Bush sometimes, or often, compare 11.9.2001 with Pearl Harbor. Here is one example:
http://www.whitehouse.gov.edgesuite.net ... 207-1.htmlDecember 7, 2005
Quote:
President Discusses War on Terror and Rebuilding Iraq
Today we mark the anniversary of a fateful day in American history. On December the 7th, 1941, our peaceful nation awoke to an attack plotted in secret, and executed without mercy. The strike on Pearl Harbor was the start of a long war for America -- a massive struggle against those who attacked us, and those who shared their destructive ambitions.
....
On September the 11th, 2001, our nation awoke to another sudden attack. In the space of just 102 minutes, more Americans were killed than we lost at Pearl Harbor.
If Flight 77 and Flight 93 was shot down by NORAD, then it should be easier to understand why people in NORAD and Pentagon keep quiet. The motive for lying or keep quiet about the planes being shot down, could be to not hurt the feelings of the relatives of the passengers and plane crew who lost their lifes.
NORAD shot down both Flight 77 and Flight 93. Those two planes were the last planes to end their travels, while the planes which hit Twin Towers were the first two planes. NORAD was not able to react quickly enough to the first two passenger planes, but NORAD had time to react against the two last passenger planes.
The timelines of the planes are here:
http://killtown.911review.org/chart.html
http://thewebfairy.com/killtown/flight77/timeline.html
A very good article about Flight 77:
http://judicial-inc.biz/Dov_Zakheim_Fl_77.htm
A very good website about 11.9.2001:
http://thewebfairy.com/killtown/index.html