Almost the truth

From Popular Mechanic's "Debunking the 9/11 Myths":

In the decade before 9/11, NORAD intercepted only one civilian plane over North America: golfer Payne Stewart's Learjet, in October 1999.

From Michael Meacher article "This war on terrorism is bogus":

Between September 2000 and June 2001 the US military launched fighter aircraft on 67 occasions to chase suspicious aircraft (AP, August 13 2002).

So, indeed, only one plane was intercepted because of the tragedy on board, but 67 times fighters were scrambled because of suspicious aircraft. 67 times in less than one year before 9/11 !