Under minimum flight requirements, airlines can lose their takeoff and landing slots at congested airports if they do not use them at least 80% of the time. The waiver allows airlines to not fly some flights and still retain slots.

The FAA said the number of certified controllers at the New York Terminal Radar Approach Control (N90) "is still not sufficient to allow the FAA to handle normal traffic levels,"

The FAA said it continues working "on a long-term solution to solve the chronic low levels of fully certified air traffic controllers at N90."

Airlines for America, an industry group, said it appreciated "this latest waiver extension as the FAA navigates air traffic controller staffing shortages... U.S. airlines will continue to operate larger aircraft to help reduce pressure."

U.S. airlines Tuesday expressed growing frustration with ATC shortages, which have snarled flights.

Due to staffing shortages, the FAA previously in August extended temporary cuts to minimum flight requirements at congested New York City-area airports and Washington National Airport through Oct. 28 after first issuing the waivers in March after Delta Air Lines (DAL.N) and United Airlines sought permission not fly up to 10% of flights.

"The system can't cope with the number of flights today," JetBlue Airways (JBLU.O) CEO Robin Hayes told Reuters Tuesday. He said airlines received an initial waiver for flights in March "quite late... We have to get ahead of this."

Airlines have faced flight woes after a record-setting U.S. summer travel season and voluntary cut flights because of air traffic shortages. They want to add more flights to address demand.

The FAA in August said it met its yearly goal of hiring 1,500 controllers but is still about 3,000 controllers behind staffing targets.

A government watchdog said in June critical ATC facilities face significant staffing challenges, posing risks to air traffic operations.

In the summer of 2022, there were 41,498 flights from New York airports in which ATC staffing was a contributing factor in delays. N90 staffing was at just 54%, the report said.

The United States has experienced several near-miss aviation incidents this year, including some that could have been catastrophic involving apparent controller mistakes.

The FAA has 10,700 certified controllers, up slightly from 10,578 in 2022, virtually the same as 2021 and down 10% from 2012. At several facilities, controllers are working mandatory overtime and six-day work weeks to cover shortages.