A communications failure at the Federal Aviation Administration (FAA) grounded flights across the United States for several hours and delayed or canceled thousands of flights. The disruption affected air traffic control radar data and prompted a response involving the White House Situation Room and national security agencies. Officials say they have found no evidence of a cyberattack; investigators are examining maintenance work on a contractor network and a possible router failure.
Officials say there is no evidence of a cyberattack
FAA Administrator Bryan Bedford said at a Saturday briefing that the White House Situation Room and national security agencies had activated a response, while the FBI sent personnel to assist with the investigation. Officials currently believe the incident was not caused by a cyberattack, he said.
Transportation Secretary Sean Duffy said FBI Director Kash Patel, the director of national intelligence and Defense Department officials took part in a conference call. Authorities initially considered whether the communications failure might be linked to a foreign cyberattack, but found no online activity indicating that hackers were involved.
The FAA identified and isolated the source of the communications problem, after which the system began returning to normal, Duffy said. The government believes it has found the root cause of the disruption and does not consider it the work of a foreign actor, he added. The precise technical cause and responsibility for the failure remain under investigation.
Router connection attempts surged during maintenance
Duffy said the disruption began when an L3Harris contractor was carrying out routine maintenance at a remote FAA facility, switching communications lines from older copper cables to fiber. During the changeover, routers in the air traffic control system received more than 1,000 connection attempts every four to five seconds. Some radar data was affected as a result.
The FAA ordered a nationwide ground stop as a safety precaution. It lasted several hours and led to thousands of delays and cancellations. The incident disrupted airline operations and travel, while underscoring how an anomaly in air traffic communications infrastructure can quickly affect the national flight network.
Investigators are still determining whether the problem stemmed from an operational error, the installation process or a defect in the router itself. Duffy said they need to establish whether L3Harris personnel made a mistake in handling or installing the equipment, or whether the hardware failed. No conclusion has been reached. L3Harris had not immediately responded to a request for comment.
L3Harris operates the legacy network as a new system is built
Duffy said L3Harris operates the existing legacy communications network and is the project’s lead contractor. The Department of Transportation is working with telecom companies including AT&T, Verizon and Lumen to build a new network architecture. The government will hold contractors accountable for service quality and expects its partners to improve their performance, he said.
The investigation is also expected to examine oversight of the contractor network, beyond the immediate equipment or maintenance issue. Public information has not established who was responsible. Duffy said L3Harris and the supplier of the routers both have a responsibility to do their work properly.
Broader cybersecurity concerns remain
The failure comes amid continued attention to cybersecurity risks. Hackers have previously manipulated refrigeration systems at European supermarkets and US military bases, raising the risk of food spoilage. A rise in cyberattacks last month was described as “Black October.” Researchers are also working to address a security vulnerability in PHP, a programming language used by about 70% of websites.
After the United States went to war with Iran, Iran warned of retaliation in cyberspace and threatened to cut undersea cables that carry internet traffic. A recent Microsoft service outage also disrupted email, collaboration and AI functions. Microsoft said Friday there was no indication that the global service disruption was connected to the FAA ground stop.
The FAA and other officials have confirmed that the communications failure affected some radar data and that operations recovered after the problem was isolated. Whether the cause was human error, an installation issue or a router defect remains unresolved. The investigation will focus on the safety rationale for the ground stop and the division of responsibility across the contractor network.