CNN.com - Chronology of terror - September 12, 2001
8:45 am (all times are EDT): A hijacked passenger jet, American Airlines Flight 11 out of Boston, Massachusetts, crashes into the north tower of the World ...
http://www.cnn.com/2001/US/09/11/chronology.attack/ - 36k - Jul 5, 2005 - Cached - Similar pages
I have been finding times in the 40's on the net, but not sure why the book would have it listed as :51. The author is very knowledgeable, I will have to dig out the 9/11 commission report.