Power Failure Paralyzes 3 N.Y. Airports : Transportation: A disruption in data used by traffic controllers forces planes to be held on the ground. Many flights to Northeast are canceled.

A communications power failure at an American Telephone & Telegraph Co. switching station in Lower Manhattan Tuesday disrupted traffic control at the three major airports in the New York area, grounding all departures and severely limiting arrivals for several hours.

All domestic flights to John F. Kennedy, La Guardia and Newark airports that were not already in the air at the time of the power failure were held on the ground throughout the United States.

The disruption, which began at about 4:50 p.m., caused problems at airports around the country, where many flights were delayed or canceled. Some planes, including a British Airways supersonic Concorde, were forced to land at other locations.

An AT&T; spokesman said a power supply problem affected the long distance switching office in New York’s Wall Street area, and communications lines carrying voice and data between air traffic controllers were knocked out.

The failure also affected long distance phone service to and from New York City, but Russell Thomas, the AT&T; spokesman, could not immediately estimate the extent of the problem. The precise cause of the disruption was still not clear Tuesday night and AT&T; was diverting calls and data through working switches.

A spokesman for the Federal Aviation Administration said initially that a fiber-optics cable in Lower Manhattan was accidentally severed but this report proved to be false. The power failure did disable the switch that sends data through the cable, which carries aircraft flight information to two key facilities, the New York Air Traffic Control Center at Ronkonkoma, N.Y., and to the final approach facility at Westbury, N.Y., both on Long Island near Kennedy Airport.

Flight controllers suddenly were denied vital data that identified aircraft but, since radars were still operating, could guide planes to safe landings, an FAA spokesman, Duncan Pardue, said.

AT&T; said communications were being restored at mid-evening. Flights resumed at all three airports by 9 p.m., said D. Joy Faber, a spokeswoman for the Port Authority of New York and New Jersey, which operates the three airports.

Stranded travelers battled frustration over delayed and canceled flights, with many complaining the lack of telephone service complicated their dilemmas because they could not notify family and friends at their destination points.

Fred O’Donnell, a spokesman for the FAA in Los Angeles, described Tuesday’s outage as a “major safety issue” for the nation’s airports.

“As far as we are concerned, when you lose communication it automatically becomes a safety issue,” he said.

The data interruption caused massive delays coast-to-coast, forcing thousands of passengers to wait in terminals at Kennedy and at other airports.

Some 35 planes loaded with passengers were stranded on the runways at Kennedy soon after the incident occurred. At La Guardia, police said 35 planes also were grounded, while 30 were backed up at Newark, a Port Authority spokesman said.

The outage blocked many long-distance calls into and out of the New York area, said McGann. The outage affected domestic as well as international calls.

The British Airways Concorde was forced to land at Bradley Airport outside Hartford, Conn.

In Washington, FAA officials said the flight data difficulties were confined to the New York area.