EXPLAINED | The FAA Halted US Takeoffs. What About the 3,500 Planes Already in the Air?

The FAA ordered a nationwide ground stop on Friday after air traffic controllers began receiving inconsistent radar and communications data, affecting thousands of flights. About 3,500 aircraft were already airborne when the order was issued, according to US Transportation Secretary Sean Duffy. Departures were paused for several hours, with the restart occurring after about four hours.

During the disruption, flights already in the air were managed on a case-by-case basis while no new departures were added. Some aircraft landed as planned, others returned to their departure airports or landed at alternate airports. Cirium later counted hundreds of diversions, with most returning to origin airports and some landing elsewhere as the situation unfolded.

Officials indicated the problem began with instability in radar and communications data fed to regional centres and approach control facilities. While some radar and radio data remained available, newer internet-protocol-based switches continued to function, enabling limited ongoing operations. Investigations proceeded to determine the exact trigger and how the failure spread across centers.

The incident prompted questions about cyberattack links and external involvement. Officials said their initial checks found no evidence of a cyberattack, and Microsoft stated there was no connection. The FAA noted that older equipment became overloaded, leading to inconsistent data flows, while newer systems maintained some functionality.

As systems started to reopen, departures resumed gradually as capacity allowed, with some flights still delayed or re-routed. Restart was officially set for about 8:15 p.m. Eastern time, as the aviation network worked to recompose schedules and free up gates and crews. The broader disruption was expected to have ripple effects on schedules later in the day and into the weekend.