FAA ground stop: Overloaded routers halted US flights for hours

The Federal Aviation Administration halted all departures from US airports on Friday evening. According to the FAA statement, the ground stop followed communication issues at several Air Route Traffic Control Centers, the facilities that manage high-altitude traffic. It began at 3:54 p.m. ET and was lifted at 8:15 p.m. ET. Aircraft already in the air were allowed to land. Flightradar24 counted just 336 flights bound for US airports at the low point, compared with more than 3,600 at that time of day.

Routers sent inconsistent data

At a White House news conference, Transportation Secretary Sean Duffy blamed aging equipment. He said the routers "got overloaded with data" and "started to give us inconsistency in the data," so the FAA shut the system down. Duffy pointed to "1980s little copper lines" and said none of the newly installed equipment failed. Multiple sources told CBS News that an update to the private communications network behind US air traffic control caused the system to reboot and then crash. That network, the FAA Telecommunications Infrastructure (FTI), is operated by L3Harris. Homeland Security Secretary Markwayne Mullin said new security patches on the older system appeared to overwhelm its routers.

The weakness was documented years ago. A safety review commissioned by the FAA in November 2023 called the FTI network obsolete, CBS reported. It relies on an older technology known as TDM, which the underlying telecom infrastructure no longer supports. The review warned that an unexpected failure could cut off individual facilities or an entire regional control center from the network.

No link to the Microsoft outage

Earlier the same day, a global Microsoft outage hit Xbox sign-ins, saves and Cloud Gaming, and it also disrupted rail operations in Germany. Mullin rejected any connection between the two. "I want to make sure everybody understands that there is no connection between this and Microsoft," he said. He added that there was no sign of a cyberattack so far but that the investigation was ongoing. The FAA said it tested its systems before clearing flights to resume.

Cancellations will continue through the weekend. As of 11:30 p.m. ET on Friday, Flightradar24 counted nearly 10,000 canceled flights to and from US airports through Saturday, including more than 2,200 each at Delta and American Airlines. Travelers flying to or within the US in the coming days should check their flight status with the airline. Duffy is asking Congress for $50 billion to fully overhaul air traffic control technology. "You will have more of these," he warned, according to ABC News, unless the system is rebuilt.