NEW YORK (AP) – A week after authorities exposed what they said was a terrorist plot to bomb John F. Kennedy International Airport, flight delays of several hours on Friday left some passengers fearful.

“Everyone’s kind of edgy,” Pat Maio, 48, said from a JFK terminal where his departure for Atlanta had been delayed for more than four hours. “The explanations are real vague. Immediately you think the worst.”

Mr. Maio was among thousands of passengers coping with delays and cancellations after a cascading computer failure in the nation’s air-traffic control system caused severe flight delays along the East Coast on 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.

The scene at JFK was chaotic, Maio said Friday evening, with the line from the terminal’s bar stretching for about 50 feet as passengers dealt with delays that officials said were averaging more than 2 1/2 hours for arriving flights.

At LaGuardia Airport, the situation was even worse, with arriving flights running nearly four hours behind on average.

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.

One passenger, “Good Day New York” anchor Ron Corning, told Fox 5 News that he had sat on a LaGuardia 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,” Mr. 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.

Senator Schumer, Democrat of New York, urged the FAA to invest in improvements and called for an internal agency investigation of air-traffic control technology.

“When it comes to these computer systems, they’re way behind schedule,” he said. “The technology is there to make them much better.”

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

JetBlue Airways Corp., which has a hub at JFK, experienced delays on five out of its 16 daily flights at LaGuardia, said spokesman Bryan Baldwin.

“The New York metro area is the most congested air space in the country,” Mr. 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.”