WASHINGTON (Reuters) -Major U.S. airlines have asked the Federal Aviation Administration to extend cuts to minimum flight requirements at congested New York City-area airports through October 2027, citing severe air traffic controller staffing shortages.

The FAA has previously issued a series of waivers to address the staffing issues at JFK, LaGuardia and Newark airports as well as Reagan Washington National airport. "We believe inadequate staffing will remain an immediate critical impediment to the efficient management of the NYC airspace," said Airlines for America, a trade group representing American Airlines ( AAL ), United Airlines, Delta Air Lines ( DAL ), Southwest Airlines ( LUV ) and others in asking for a two-year extension in a letter seen Wednesday by Reuters.

The FAA, which did not immediately comment Wednesday, last extended the waiver in 2024 through October.

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 FAA's waiver allows airlines to fly fewer flights and still retain slots.

The FAA last year relocated control of the Newark, New Jersey, airspace area to Philadelphia to address staffing and congested New York City area traffic. On Monday, Newark suffered dozens of flight disruptions due to equipment problems and staffing issues.

The airlines group notes FAA statistics say about 75% of all delays in the National Airspace System occur because of delays in the NYC Airspace. "Delays and cancellations in the NYC Airspace ripple across the entire NAS so it is critical to ensure this part of the system is healthy," the group said.

The FAA is about 3,500 air traffic controllers short of targeted staffing levels and a series of near-miss incidents has raised concerns in recent years. A persistent shortage of controllers has delayed flights and, at many facilities, controllers are working mandatory overtime and six-day weeks.

Congress is considering spending $12.5 billion to boost staffing and improve air traffic infrastructure. A January 29 fatal collision between an American Airlines ( AAL ) regional jet and Army helicopter that killed 67 people have raised new safety concerns.