US airspace reopens after nationwide ground stop disrupts thousands of flights

MANILA, Philippines – Airspace across the United States has reopened following a rare, five-hour nationwide ground stop on all departing flights on Friday, which officials attributed to a telecommunication outage rather than a cyberattack.

Speaking during a news briefing on Friday night, Transportation Secretary Sean Duffy announced that the airspace was reopened at 8:15 p.m. Eastern time. However, he cautioned passengers that resuming normal operations would be a gradual process and advised travellers at airports to check directly with their airlines.

According to the flight-tracking website FlightAware, the disruption resulted in more than 10,000 delays and over 4,000 cancellations on Friday. Flightradar24 reported that approximately 3,100 airborne aircraft were bound for US airports when the stoppage began, with delays quickly mounting at major hubs in Boston, Atlanta, Miami, Pittsburgh, New York City, Los Angeles, and Baltimore.

In a social media statement following the briefing, the Federal Aviation Administration (FAA) confirmed that flight departures were resuming after officials thoroughly tested their systems to ensure stability and reliability. The agency had initially halted all departures due to "extraordinary circumstances and for reasons of safety."

Duffy attributed the failure to outdated air traffic control technology, explaining that the system's routers became overloaded with data and began producing inconsistencies, prompting officials to shut it down. Homeland Security Secretary Markwayne Mullin added during the briefing that new security patches introduced into the older infrastructure appeared to overwhelm the routers. Multiple sources also indicated that an update to the private communications network connecting the country's air traffic control system—operated by L3Harris—caused the system to reboot, leading to a crash and outage. L3Harris did not immediately respond to requests for comment.

Officials moved quickly to rule out foul play. Mullin stated that there was no indication of a "nefarious act" or cyberattack, and clarified that the incident had no connection to the massive global Microsoft outage. He assured the public that all airborne flights were accounted for and would land safely, though he acknowledged the gravity of having to implement a nationwide stoppage.

Looking ahead, Duffy noted that the FAA would attempt to move as many flights as possible on Friday night depending on crew capacity, with efforts continuing on Saturday morning alongside airline partners. He expressed confidence that operations would recover ahead of the busy Thanksgiving travel period later this month.

The incident has renewed calls from administration officials for major infrastructure upgrades. Duffy urged Congress to approve emergency funding to modernise the nation's air traffic control network, warning that similar disruptions would continue otherwise. Mullin argued that piecemeal updates were insufficient, stating that the Trump administration seeks a complete replacement of the system at an estimated cost of $50 billion.

The affected FAA Telecommunications Infrastructure (FTI), which transmits essential voice communications and operational data between air traffic control centres, has been managed by L3Harris and its predecessor, Harris Corp., since a contract was awarded in July 2002. A November 2023 FAA-commissioned safety review had previously described the network as obsolete, warning that its reliance on unsupported technology could leave individual facilities or regional centres disconnected during an unexpected failure.

Robert Sumwalt, a former chair of the National Transportation Safety Board, described the incident as unprecedented in the modern era, noting that the only other recent nationwide ground stop occurred in January 2023 due to an overnight failure in the FAA's flight personnel alert system.