On the morning of September 11, 2001, as hijackers Khalid al- “Mihdhar and [Majed] Moqed entered Dulles Airport’s [Washington, D.C.] west security screening checkpoint, where they placed their carry-on bags on the belt of the x-ray machine and proceeded through the arched magnetometer. Both set off the alarm, and they were directed to a second metal detector. Mihdhar did not trigger the alarm and was permitted through the checkpoint. After Moqed set it off, a screener quickly passed a wand around him and he was allowed to pass.”
– James Bamford, The Shadow Factory, Pages 84-85