BOSTON — The Federal Aviation Administration issued a rare nationwide ground stop Friday afternoon, halting departures to U.S. airports, including Boston Logan International Airport and airports across New England, Axios reported.

An advisory from the FAA's Air Traffic Control System Command Center cites "extraordinary circumstances" and "reasons of safety." "All departing traffic should remain ground stopped until further notice," the advisory says. It says inbound international flights "will be managed on a case by case basis."

The advisory took effect at about 3:54 p.m. Eastern time. It lists an event window running until 11 p.m., though the FAA has not said when flights will resume. Flights already in the air are being allowed to land, according to the flight-tracking service Flightradar24.

"The FAA issued a nationwide ground stop for all U.S. airports following communication issues impacting multiple Air Route Traffic Control Centers," the FAA said in a statement, according to CNBC. The agency said its technicians are investigating. U.S. Transportation Secretary Sean Duffy said on X that the communication issue was affecting all of the centers.

The FAA had not publicly detailed the underlying cause as of Friday afternoon. Flightradar24 said the stop is related to an FAA equipment outage. The flight-tracking app Flighty said it was due to an air traffic control frequency outage.

New England airports

The stop means no flights bound for U.S. airports may take off from Logan, Bradley International in Windsor Locks, Rhode Island T.F. Green International in Warwick, Manchester-Boston Regional, Portland International Jetport or Burlington International until it is lifted.

At Logan, several planes were lined up on taxiways and runways Friday afternoon, according to video from WBZ-TV's SkyEye. Logan had 315 total delays as of 4:30 p.m., according to flight-tracking data from FlightAware cited by WBZ.

"We are monitoring the situation and working with the FAA and our airline partners," Massport, which runs Logan, said in a statement.

Logan was already running behind before the national order. The FAA's airport status page showed a ground delay program at Boston for airport volume from 1 p.m. to 9:59 p.m. Friday, with average delays of about 26 minutes. Rain and low clouds were listed as constraints at Boston in the FAA's operations plan for the day.

At Bradley, a spokesperson said the stop was affecting departures there. "We are aware of a nationwide ground stop that's currently affecting departures – BDL included," the spokesperson told Patch, adding that it was unclear how quickly the matter would be resolved.

Travelers should check with their airline before heading to the airport.

Outage reports earlier in the day

Earlier Friday, the FAA issued ground stops at Chicago's O'Hare and Midway airports because of an "equipment outage," WGN-TV reported. The FAA said the problem was an unspecified outage involving communications systems used by air traffic controllers, according to WGN. The FAA's status page also listed departure delays tied to FAA equipment at airports including Newark, Teterboro and Las Vegas.

The last nationwide ground stop came on Jan. 11, 2023, when a failure of the FAA's system for alerting pilots to hazards halted departures across the country. It was the first nationwide ground stop since the Sept. 11, 2001, attacks.

This story will be updated.