The Federal Aviation Administration ended a nationwide ground stop Friday night more than four hours after a communication issue affected the Air Route Traffic Control Centers, the high-altitude air traffic control facilities that manage flights between airports.
The ground stop was lifted at around 8:15 p.m. ET, but disruptions are expected to linger into the weekend.
As of Saturday morning, there were more than 4,000 flight cancellations, according to FlightAware. Airlines canceled over 9,000 flights on Friday.
During a televised briefing Friday night, Homeland Security Secretary Markwayne Mullin said there was no indication of a cyberattack.
Transportation Secretary Sean Duffy said at 3:36 p.m. ET the FAA started “experiencing instability” at radar and communication at air traffic control centers and TRACONs (Terminal Radar Approach Controls). He said 3,500 planes were in the air at the time.
“Our switchers and routers got ove