The Smart Marty Sky Dispatch
EXPLAINED | Why the FAA Ordered the Biggest US Ground Stop Since 9/11
A telecom outage on 13 November made radar and communications unreliable at US air traffic control centres. Takeoffs resumed that evening, but hundreds of flights had already turned back or landed somewhere else
An nationwide FAA ground stop was ordered on Friday after air traffic controllers began experiencing inconsistent radar and communications data, affecting the ability to manage departures and arrivals.
About 3,500 aircraft were already airborne when the ground stop began, according to US Transportation Secretary Sean Duffy. Departures could resume shortly after 8 p.m. Eastern time, more than four hours after the order.
Controllers continued to handle flights already aloft while the FAA halted most new departures. Some aircraft landed as planned, others returned to their departure airports, and some landed at alternative airports. By 7:05 p.m. Eastern, aviation data firm Cirium counted 827 diversions, with 670 returning to the departure airport and 157 landing elsewhere.
FAA officials stated that critical flights, including medical evacuations and flights carrying life-saving medicines, were allowed to continue. The restart was later set for 8:15 p.m. Eastern, with departures resuming as capacity allowed and affected flights gradually returning to service.
Officials said initial checks found no evidence of a cyberattack, and Microsoft reported no connection to its outage. The disruption was attributed to older networking equipment becoming overloaded, while newer switches using internet protocol-based data transfer remained operational.
The incident prompted comparisons to past outages, including a January 2023 pause of domestic departures and a 2025 Newark telecommunications breakdown. Investigations focused on identifying which equipment overloaded first and how the impact spread, guiding ongoing and future replacement and redundancy plans.
The broader context includes ongoing FAA modernization funding and plans to replace aging links with fibre, with phased implementation targeted for December 2028. The aim is to improve resilience across radar and communications networks while maintaining flight operations during upgrades.