Amid another day of travel chaos at Newark Liberty International airport, the chief executive of United Airlines is urging the Federal Aviation Administration to cap the number of flights at the delay-afflicted airport.

In a 7 May letter to employees, United CEO Scott Kirby said the FAA should “return [Newark] to a Level 3 slot-controlled airport” and prohibit airlines from scheduling more than 77 flights there hourly – the maximum the FAA says the airport can accommodate.

The letter marks the CEO’s latest response to widespread, ongoing flight disruptions at Newark that are due in part to air traffic control (ATC) system outages and shortages of controllers. United operates a massive hub at Newark.

“Every other large capacity constrained airport in the world uses slots to make sure that the number of scheduled flights in any given hour does not exceed the airport’s maximum capacity,” Kirby says. Newark “is the only large airport in the world that no longer has this basic common-sense rule”.

The FAA did not immediately respond to a request for comment, nor did several US airlines that operate at Newark.

The FAA can set slot restrictions at airports it deems as having insufficient infrastructure to meet demand. It classifies those as “Level 3” airports, and only three are now in that category: John F Kennedy International, New York LaGuardia and Ronald Reagan Washington National.

At those airports, the FAA awards “slots” that permit take-offs and landings.

Newark is one of four US airports classified by the FAA as “Level 2”. At those, the agency does not limit flights. But it does coordinate flight schedules with those airports to minimise congestion.

The FAA reclassified Newark from a Level 3 to a Level 2 airport in 2016.

In his letter, Kirby urges the FAA to shift Newark back to Level 3 and to cap operations there to 44 flights hourly amid current ongoing runway construction, and to 77 flights hourly after construction is complete.

Flight disruptions began piling up at Newark last week after ATC systems failed and controllers took leaves of absence due to factors including “trauma”, according to the National Air Traffic Controllers Association.

In response, Kirby last week said United was cutting 70 flights at Newark

Kirby’s 7 May letter, however, argues that other airlines will simply backfill those cuts with new flights of their own unless the FAA limits operations via slots.