Sadly, this suggests that it is only too possible.....
"Authorities have been working for months to build a paper trail of purchases made by the hijackers in the weeks before September 11.
"Sources have said that another of the 19 attackers, Ziad Samir Jarrah, purchased a GPS device at a store in Miami. Investigators say Jarrah was aboard United Airlines Flight 93, which crashed in Pennsylvania.
"Investigators believe at least three other GPS devices were purchased, one for each hijacked plane.
"In addition, the federal indictment of alleged would-be hijacker Zacarias Moussaoui -- now facing terrorism charges in a federal court in Virginia -- says he purchased flight deck simulator videos for two types of Boeing 747s on June 25, 2000, from Sporty's, an Ohio pilot's store.
"On November 5 and December 11, 2000, Atta also purchased flight deck simulator videos for Boeing 747, 757, 767 and Airbus A3-20 aircraft, authorities said. The videos, which show the cockpits of various airplanes, can be used by pilot students for flight training.
"Nawaf Alhazmi, a hijacker on American Airlines Flight 77, which slammed into the Pentagon, also bought flight deck videos from the Ohio store, including simulators for the 747 and 777, according to the indictment."
http://archives.cnn.com/2002/US/05/22/hijack.paper.trail/