9/11 kommissionens rapport går i detalj om kapers planering och förberedelse, inklusive ett (inte helt framgångsrikt) försök att få luftfartens GPS-enheter:
Moussaoui also purchased two knives and inquired of two manufacturers of GPS equipment whether their products could be
converted for aeronautical use
[...]
On August 22, moreover, Jarrah attempted to purchase four GPS units
from a pilot shop in Miami. He was able to buy only one unit, which he
picked up a few days later when he also purchased three aeronautical
charts (page 247-249)
Rapporten beskriver inte om det finns någon indikation på att enheten faktiskt användes. Men under sin flygträning tog två av kaparna också ett antal övningsflygningar som skulle ha bekantat sig med områdena kring New York och DC, vilket kunde ha hjälpt dem med visuella landmärken:
Jarrah and Hanjour also received additional training and practice
flights in the early summer.A few days before departing on his
cross-country test flight, Jarrah flew from Fort Lauderdale to
Philadelphia, where he trained at Hortman Aviation and asked to fly
the Hudson Corridor, a low-altitude “hallway” along the Hudson River
that passes New York landmarks like the World Trade Center. Heavy
traffic in the area can make the corridor a dangerous route for an
inexperienced pilot. Because Hortman deemed Jarrah unfit to fly solo,
he could fly this route only with an instructor.
Hanjour, too, requested to fly the Hudson Corridor about this same
time, at Air Fleet Training Systems in Teterboro, New Jersey, where he
started receiving ground instruction soon after settling in the area
with Hazmi. Hanjour flew the Hudson Corridor, but his instructor
declined a second request because of what he considered Hanjour’s poor
piloting skills. Shortly thereafter, Hanjour switched to Caldwell
Flight Academy in Fairfield, New Jersey, where he rented small
aircraft on several occasions during June and July. In one such
instance on July 20, Hanjour—likely accompanied by Hazmi—rented
a plane from Caldwell and took a practice flight from Fairfield to
Gaithersburg, Maryland, a route that would have allowed them to fly
near Washington, D.C. (page 242)
Rapporten säger också att flera av kaparna också hade tillgång till flygsimulatorsoftware och / eller simulatortid på flygskolor, vilket skulle ha gett dem ytterligare möjligheter att utöva navigering.
