FAA Ground Stop Watch

The FAA halted departures nationwide for about four hours and 22 minutes after communications problems affected multiple air traffic control centers. Inbound international flights were handled case by case. Departures were cleared to resume at 8:15 p.m. Eastern, with delays and cancellations continuing as airlines recovered. FAA ground-stop order · The Air Current’s independent reporting

Timeline (Eastern time)

• 8:15 p.m. — The nationwide stop lifted. The FAA cancellation advisory was posted at 8:19 p.m. FAA cancellation advisory · Duffy’s reopening announcement
• 3:53 p.m. — The national stop took effect. The command center signed the order at 3:54 p.m. FAA advisory 111
• 3:10 p.m. — The O’Hare stop began, according to an advisory signed at 3:28 p.m. that cited equipment and communications problems. A controller later reported losing radio frequencies and automation used to hand off flights. FAA advisory 107 · CNN reporting on controller audio

What may have caused it

Transportation Secretary Sean Duffy said older routers became overloaded and produced inconsistent data. CBS News separately reported, citing multiple unnamed sources, that an update to the private air traffic communications network triggered a reboot and crash. L3Harris confirms it operates and modernizes the network. The update time, who deployed it, and what restored service were still unverified when these notes were published. CBS News on the update and briefing · L3Harris on its role

Bloomberg reported that the FBI was examining whether a software update caused the outage. Homeland Security Secretary Markwayne Mullin said officials had seen no evidence of a cyberattack at the time of the briefing. Air Space Intelligence denied that its SMART system contributed. Microsoft said it saw no connection to its separate outage, which began the previous day. Bloomberg’s FBI report · Briefing coverage · SMART developer’s statement · Microsoft’s statement · Microsoft service record

Records that could resolve the cause include the deployment ticket, the first router and backup system logs, and the record of what restored service.

The FAA paused U.S. departures after its Notice to Air Missions (NOTAM) system, which provides safety information to flight crews, went down. Departures resumed gradually after the stop lifted. In its preliminary review, the FAA found that contract personnel accidentally deleted files while working on synchronization between a primary database and its backup. FAA incident statements and preliminary findings