The controllers regularly talk with the pilots and the AWACS planes that are in the skies to help direct the fighters, keeping them away from other aircraft, FAA officials said Monday as they described new procedures that the Federal Aviation Administration and Defense Department are following in the wake of last month's terrorist attacks.

While controllers regularly track military airplanes, never before have they had to direct round-the-clock patrols designed to protect U.S. cities. Military planes have been patrolling the skies over New York and Washington 24 hours a day, and have conducted random patrols of other metropolitan areas.

Other changes include setting up new communication links between the controllers and the North American Aerospace Defense Command, responsible for protecting American air space.

While controllers previously would notify their supervisors if they saw the planes they were tracking behave unusually, they are now instructed to contact NORAD directly if they lose radio contact with a plane, if the plane's transponder stops transmitting or if the plane unexpectedly alters its route.

When hijackers commandeered four commercial airplanes on Sept. 11, they stopped responding to controllers trying to reach the cockpit radios, turned off transponders and diverted the planes.

After the attacks, the FAA and NORAD started keeping an open telephone link to quickly coordinate any military response. The military can scramble fighters "within a matter of minutes to anywhere in the United States," said Capt. Ed Thomas, a NORAD spokesman.

In addition, FAA and Pentagon employees are now working at each other's facilities. This allows Defense Department officials to talk to airplane cockpits, and would enable military officials to let hijackers know that an order has been given to shoot down the plane. Since Sept. 11, two NORAD generals have been given the power to order military jets to shoot down a commercial airliner.

Earlier this month, military jets have escorted at least two commercial planes to safe landings because of the behavior of passengers. In one case, a passenger gave a note to a flight attendant warning that the pilot should not change the route; in another, a passenger burst into the cockpit but was overpowered by others on the flight.

Michael A. Cirillo, the FAA's program director for air traffic planning and procedures, said it is up to the military to decide whether fighter escorts are needed if a problem on an airplane has been reported.

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