WASHINGTON (AP) – A cascading computer failure in the nation’s air-traffic control system caused severe flight delays and some cancellations in New York City and along the East Coast Friday.

Although the computer problem was fixed shortly before 11 a.m., its impact lingered on into the late afternoon, especially in New York, where computer systems took two extra hours to get back online, Federal Aviation Administration spokeswoman Diane Spitaliere said, adding that flight delays in the rest of the country were not as severe.

Among the hardest hit hubs was New York City’s LaGuardia Airport. Delays for arriving flights averaged three hours early Friday evening, according to the FAA.

Backups were so bad, air-traffic controllers temporarily stopped LaGuardia-bound flights from taking off in other parts of the country to keep the skies over Queens from filling with too many planes, said Jim Peters, an FAA spokesman in New York.

Things were only slightly better at John F. Kennedy International and Newark Liberty International airports, where delays were averaging more than 2½hours.

One passenger, “Good Day New York” anchor Ron Corning, told Fox 5 News that he had sat on a metro area tarmac for four hours before his shuttle flight to Bangor, Maine, departed.

The pilot “apologized for what he described as a major air-traffic control meltdown,” Corning said, describing how temperatures had risen on the plane as the single flight attendant had run out of ice and drinks for passengers.

When the US Airways plane finally took off at around 4:30 p.m., passengers burst into applause, he said.

A computer system in Atlanta that processes pilots’ flights plans and sends them to air-traffic controllers failed early Friday, Spitaliere said. In response, the agency rerouted the system’s functions to another computer in Salt Lake City, which overloaded due to the increased volume of data, magnifying the problem.

The FAA could not immediately calculate the number of flight delays caused by the problem, which was made worse by bad weather, Spitaliere said.

Doug Church, a spokesman for the National Air Traffic Controllers Association, said the problem forced controllers to enter flight information manually, which he described as a time-consuming practice. “With some of these East Coast airports, nothing is getting in right now,” Church said Friday afternoon.

AMR Corp.’s American Airlines spokesman Tim Wagner acknowledged the computer troubles and said the nation’s largest carrier experienced about 50 cancellations on the East Coast, with LaGuardia departures being hit the hardest.

Hundreds of flights in both directions were delayed for two to three hours at LaGuardia, JFK and Newark, said Steve Coleman, spokesman for the Port Authority of New York and New Jersey.

Friday evenings are among the busiest, most congested, and most delay-plagued times of the week at the region’s airports. Peters said the problems were expected to continue late into the evening.

Bryan Baldwin, a spokesman for JetBlue Airways Corp., said some flights experienced delays as long as four hours, and said the problem was likely to continue into the evening.

The company, which has a hub at JFK, experienced delays at five out of its 16 daily flights at LaGuardia, he said.

“The New York metro area is the most congested air space in the country,” Baldwin said. “When there’s any type of interruption to the air traffic system, it’s going to affect the most congested areas the most.”

Betsy Talton, a spokeswoman for Delta Air Lines Inc., said the Atlanta-based airline was experiencing delays of roughly two hours Friday in the Northeast, but she attributed the backlog to thunderstorms.

Linda Rutherford, a spokeswoman for Southwest Airlines Co. said the airline experienced delays on about 40 percent of its 3,300 daily flights – the majority due to the air-traffic control problems.

Earlier this year, the FAA highlighted an expanded air-traffic control strategy intended to minimize weather-related delays this summer. The agency’s “airspace flow program” is designed to allows airlines to choose between flying longer routes to avoid stormy weather or accepting delays that are aggravating for fliers and costly for the industry.

FAA officials said the program would allow airlines to choose between taking a delay or flying around the storm.