US halts all flight departures for more than four hours over telecommunications outage

The US Federal Aviation Administration (FAA), which regulates civil aviation, issued a nationwide ground stop on Friday, November 13, at 3:44PM Eastern Time (ET). Aircraft already in the air were allowed to land. The reason was a telecommunications outage affecting air traffic control, which the agency cited as a safety matter. The stop was lifted at 8:15PM ET and flights are resuming.

Shortly after 5PM, the FAA said a temporary telecommunications outage had occurred and that all flights were halted as a precaution. According to the agency, every aircraft was accounted for, and international flights would be handled case by case.

Impact on travelers

It is unclear how many flights will be able to depart and when. Airports are overloaded and some flight crews have run out of permitted duty time, so many passengers will remain stranded for now and more flights are likely to be delayed or canceled. The tracking site FlightAware listed 9,124 US flights as delayed and 5,901 as canceled at 8:39PM ET.

Possible causes

Transportation Secretary Ryan Duffy said at a press conference that an aging air traffic control system, which he is seeking funds to replace, was to blame. He said the Terminal Radar Approach Control facilities (TRACONs) in air traffic control centers began receiving inconsistent data from radars and from communications with aircraft. The problem was in analog telecom devices whose switches or routers became overloaded with data.

Earlier, CBS News, citing multiple sources, reported that an update to the system's private communications network, operated by L3Harris, caused a reboot and the resulting outage. L3Harris had not yet responded to a request for comment from The Verge.

Homeland Security Secretary Markwayne Mullin said there is currently no reason to suspect a cyberattack or other national security threat, or any link to the recent Microsoft Outlook outage, though no cause has been ruled out. Asked about the cloud-based AI Strategic Management of Airspace, Routes and Trajectories (SMART) system, activated nationwide on November 10, he said it was being examined. Air Space Intelligence, which built the system and won a 12-year, $875 million contract in June, denied any connection.

Jon Ostrower of The Air Current reported that the outage began at the Chicago air traffic control center, then spread to Boston, Washington, New York and Minneapolis, disrupting both radar and radio frequencies used by controllers and pilots. CNN noted that the previous nationwide ground stop, in 2023, lasted about 90 minutes, and the one before that followed the September 11, 2001 attacks.