"Under the old model of hijackings, the system worked well. That strategy was to accommodate, negotiate and do not escalate.
"But that was before. The cockpit has to be defended at all costs."
The union president, Captain Duane Woerth, questioned about fears that a bullet could penetrate the fuselage and depressurise the plane, said the bullets supplied to pilots would "basically come apart at first impact".
He added: "They're very destructive to human tissue but it's very unlikely that would do any serious damage to the fuselage and not such that would cause a depressurisation problem."
The union plans a voluntary programme that would require extensive background screening and psychological testing of pilots.
Pilots would also receive classroom and practical training in the use of firearms that would be equivalent to that given armed sky marshals.
Aviation consultant Michael Boyd said he believed arming pilots could work.
"These men and women operate $100 million pieces of equipment. They can sure learn to operate a .38 snub-nose if they want to.
"I'd rather have the gun in the hand of the pilot than the gun in the hand of some guy who wants to kill people."
Airline security has always tightened after attacks and hijacks.
In the early 1970s there was a spate of para-hijackings after Dan Cooper hijacked a plane, obtained a ransom and then parachuted from the aircraft's rear stairs.
In response, Boeing installed a special latch on its 727 model which stopped the tail stairs being lowered in flight.
Installing facial recognition systems at airports would represent a major leap in surveillance in the United States and is the sort of monitoring that until recently proved unpopular with many Americans.
But the Washington Post reported this week that a Government committee had recommended using the system, known as FaceIt, which has been tried at baseball games to identify people who might be a threat.
The system creates a digital map of a person's face, translating the contours into mathematical formulas that its designers claim are nearly as distinctive as a fingerprint.
The "faceprint" is compared with a database of images.
The system could be linked to cameras at security checkpoints and transmit information about suspected terrorists to Government officials via the internet.
Officials are considering Boston's Logan International Airport and another international airport for the initial installation.
Federal Aviation Administration chief Jane Garvey said a number of security measures were being discussed in advance of the final recommendations by two new taskforces.
Already, airports are being ordered to do criminal background checks on all employees with access to secure areas.
Officials are rechecking the backgrounds of all employees who have security badges permitting access to the aircraft at airports.
Some aviation officials think knives and box cutters used by the hijackers to commandeer the four airliners on September 11 were not smuggled in through the security checkpoints for passengers.
Instead, they believe they may have been planted on the planes while they were parked on the tarmac by someone with access to aircraft.
That is one of the reasons the taskforces are looking at eliminating assigned seats. Investigators found box cutters on at least two other airliners that were grounded after the hijackings.
The reason for banning carry-on baggage would be to give security screeners more time to check passengers who are boarding flights.
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