‘Root cause’ of nationwide ground stop is unknown, FAA says

The root cause of the longest halt in flight departures to U.S. airports since 9/11 remains unclear after a Saturday press conference by U.S. transportation officials.

Routers and networking equipment appeared to be involved in the technological disruption that grounded flights across the country, but a definitive cause has not been established as of Saturday afternoon.

The inability to pinpoint the reason for the infrastructure malfunctions led the Federal Aviation Administration to take actions that resulted in the grounding order, Bryan Bedford, administrator of the Federal Aviation Administration, told reporters.

“Because of our lack of identifying the root cause, we were unwilling to take any risk that this propagation could actually result in a sensor losing connectivity with aircraft,” he said.

“What we saw was instability. We couldn’t explain the instability,” Bedford added.

Officials reported issues with routers and networking equipment on Saturday, citing products and services from Cisco and L3Harris Technologies.

“Until I can build [the new architecture], I’m stuck with L3Harris, who owns this network,” Transportation Secretary Sean Duffy said.

In a statement on X, L3Harris said that it, in partnership with other tech companies, has completed more than 70% of the planned airspace communications conversion from legacy copper wires to a fiber-optic system.

“We are supporting the FAA in its investigation to understand the conditions that led to the Nov. 13 ground stop of our nation’s air travel,” the statement said. “L3Harris takes the nationwide ground stop and its impact on travelers, airlines and air traffic operations seriously.”

On Friday, Duffy and Department of Homeland Security Secretary Markwayne Mullin called for an air travel overhaul, with Duffy requesting $50 billion from Congress.

FAA administrator Bedford said that router updates were a matter of regular business for his agency and distinct from modernization allocations.

“We are constantly replacing 2,000, you know, Cisco 600 routers with Juniper routers, right? So this is ordinary course of business stuff. This is not part of the … FAA $12.5 billion modernization efforts. So let’s not conflate those two things,” Bedford said.