A telecom frequency outage on Thursday forced the Federal Aviation Administration to impose a ground stop on arriving flights at Newark Liberty International Airport for about 75 minutes, from roughly 11:30 a.m. to 12:30 p.m. Eastern Time. The failure cut radio communications between air-traffic controllers and pilots, prompting controllers to hold inbound aircraft while departures continued. Once the restriction was lifted, the FAA said arrival delays averaged 158 minutes and were rising. Flight-tracking services showed more than 200 inbound flights delayed and some cancellations, as airlines struggled to re-sequence traffic ahead of the Labor Day holiday rush. To ease congestion, the agency reduced Newark’s arrival rate to 28 flights an hour—down from the 34 already in effect—until at least Friday, and instructed controllers to space aircraft about 20 miles apart on approach. The communications breakdown occurred at the Philadelphia Terminal Radar Approach Control facility, which manages Newark’s airspace, and was the second such incident within 24 hours. Similar equipment failures in April and May triggered ground stops and led the FAA earlier this year to order flight cuts at the United Airlines hub and relocate some control functions to Philadelphia while technology upgrades proceed. Jonathan Stewart, an air-traffic control supervisor at the Philadelphia center, called the agency’s handling of the aging system “akin to criminal negligence,” saying repeated outages underscore the need for faster modernization. Congress approved $12.5 billion in June toward the FAA’s multiyear plan to overhaul radar, radio and data systems, well short of the $22 billion the agency requested.