Officials blame aging FAA telecom gear as U.S. airspace reopens, see no link to Microsoft or AI

Updated with officials’ explanation of the cause and the reopening of U.S. airspace.

The nationwide ground stop that halted U.S. commercial air travel Friday was not caused by the Microsoft 365 outage that began a day earlier, federal officials said at an evening news conference, blaming aging FAA telecom equipment that was overloaded with data.

Homeland Security Secretary Markwayne Mullin opened the news conference by raising the Microsoft outage himself. “I want to make sure everybody understands that there is no connection between this and Microsoft,” he said. “I know a lot of people are making that jump.”

Transportation Secretary Sean Duffy likewise ruled out a role for SMART, the FAA’s new AI traffic-planning tool, saying it isn’t connected to the core systems controllers use to track flights.

“There was no possible way SMART would have impacted what happened today,” he said.

The FAA reopened U.S. airspace at 5:15 p.m. Pacific, more than four hours after the problems began, Duffy said. He said flights would resume slowly, depending on whether airlines had crews available, and some may not depart until Saturday morning.

Microsoft confirmed in a statement that it had no indication the FAA ground stop was related to its service disruption.

Asked whether a cyberattack or “rogue AI” could be ruled out, Mullin said there was “nothing completely certain right now,” but “it appears that this was mechanically driven.” He said he could not rule out the possibility of a cyberattack but said there was “zero evidence” of one so far.

What happened: Duffy said the FAA began seeing unstable radar and communications data at air traffic control facilities across the country at 12:36 p.m. Pacific. Aging switches and routers in the agency’s telecom network “got overloaded with data” and began producing inconsistent information, he said, adding that the FAA still relies on “1980s little copper lines.”

Duffy said newer equipment held up.

“Our new IP switches did not go down. It’s the old hardware that went down,” he said. The FAA restored service after deploying fixes to reduce the overloading on its switches, he said.

Mullin said the overload appeared to have been triggered by new equipment the FAA was installing. As the agency put “patches into the system” and added “new equipment and new technology,” he said, it “was overwhelming the older system.” Neither official said exactly what that equipment was.

The FAA is in the middle of replacing its legacy telecom network with a modern internet-protocol network. AT&T took over the lead role on that project in August with an initial $74.3 million award, as the FAA works toward a goal of finishing by the end of 2028.

Duffy and Mullin used the briefing to press Congress for money to finish rebuilding the air traffic control system. Mullin said President Trump has declared the situation a national emergency.

The administration has asked Congress for an additional $30.1 billion for aviation infrastructure, AeroTime reported. Duffy said at the evening news conference that he wants $50 billion.

Earlier in the day, Mullin had said officials were looking into a possible link to SMART, including through DHS’s Cybersecurity and Infrastructure Security Agency (CISA). The FAA said Tuesday it was expanding the system to the airspace managed by all 22 of its en route air traffic control centers.

The agency describes SMART as a cloud-based system that pulls in about 200 data streams, including weather, flight paths and controller staffing, to recommend flight schedules and routes. FAA specialists review its recommendations, and local facilities decide whether to act on them.

SMART is part of a 12-year, $875 million FAA contract with Boston-based Air Space Intelligence, which denied any connection to the issue. “The current ground stop is not based on or a result of the SMART system, any product of ASI or our integration with FAA and ATC,” the company said.

The FAA halted departures nationwide shortly before 1 p.m. Pacific. More than 3,500 planes were in the air at the time, Duffy said. It’s the second nationwide ground stop since the Sept. 11 attacks, after a January 2023 failure of the FAA’s Notice to Air Missions system.

FlightAware counted nearly 7,000 flights delayed or canceled as of Friday afternoon.