US pilots trained to shoot down hijacked planes

American air force pilots regularly practise "shooting down" hijacked airliners, the Pentagon has revealed. In some of the exercises - carried out three or four times a week - volunteers are packed into rented aircraft which are then "hijacked" and pursued by the fighter planes.

"We exercise this several times a week whether it's an airplane shooting down an airplane or air defences in the national capital area," said General Ralph Eberhart, head of the North American Aerospace Defence Command (Norad). "After September 11 it became obvious that this was a new world, even uglier than we had imagined."

Defence experts have paid great attention to preventing a repeat of the 11 September attacks on New York and Washington. In the hours after the attacks, President George Bush authorised the shooting down of any more airliners that appeared to have been hijacked and were threatening targets and refused commands to turn back.

Indeed, on 11 September fighters jets were scrambled over Washington and New York to pursue the fourth hijacked plane but it crashed in Pennsylvania - apparently after the hijackers were attacked by the passengers - before it could be intercepted.

The Vice President Dick Cheney said at the time: "It doesn't do any good to put [up] a combat air patrol if you don't give them instructions to act if in fact they feel it's appropriate.

"You have to ask yourself, if we had had combat air patrols up over New York and we'd had the opportunity to take out the two aircraft that hit the World Trade Centre, would we have been justified in doing it? And I think absolutely we would have."

Any pilots selected to fly missions that could involve shooting down civilian aircraft are specially trained and certified. They undergo psychological testing to ensure they are not "trigger hesitant" when confronted with the requirement to fire. They are assured that shooting down an airliner would only be ordered as a last resort and that "if we don't do this, innocent people on the ground are going to die too".

General Eberhart told the Defence Writers Group in Washington: "We have long discussions with people to see if they're mentally prepared to do this, pilots and operators on the ground for air defence systems. We certainly don't take this lightly."

The decision to shoot down a civilian aircraft lies ultimately with President Bush but he has authorised two mid-ranking air force generals to issue such an order in the event that he, the Defence Secretary Donald Rumsfeld or General Eberhart were out of contact and an attack was considered imminent.

In one exercise carried out in June last year, Norad - responsible for the air defences of the US mainland - hired a Delta 757 airliner and its crew, filled it with military volunteer passengers and staged a mock hijacking over the north-west of the US which then went into Canada and Alaska. Fighters followed the plane. The operation was monitored from Norad'sheadquarters in Colorado.

"I can guarantee that fighter pilots, they're thinking about it, and going through all the rules of engagement," General Eberhart said in comments published by The New York Times. "When you know that what you're about to shoot down has a lot of innocent people on board, and maybe one, two, three or a handful of terrorists, that's a much different thing."