Missed chance on 9/11

It was a moment that should have stopped the worst terrorist attack in American history.

One of five hijackers who was to fly American Airlines Flight 77 into the Pentagon is searched after triggering an alarm at Washington's Dulles Airport.

But after a perfunctory check he - along with three other terrorists who also triggered an alarm - was cleared to board the plane.

The picture from a security camera is part of a tape released last night that shows the mix of complacency and incompetence exploited by al Qaeda to attack America on September 11. Airport security staff missed hidden box-cutter blades used to hijack the aircraft.

The tape was made public by lawyers for families of those killed, who are suing the airlines and the security industry.

Its release is timed to coincide with the findings of the official government report into September 11 later today. It will identifying 10 occasions when the plot might have been foiled and call for a shake-up in US intelligence.