In brief

• A nationwide ground stop on US flight departures was lifted after more than four and a half hours, following communications failures at air traffic control centers.
• Officials attributed the failure to an aging analog system overloaded during installation of new equipment, while no cyberattack has been found so far.
• Thousands of flights were delayed and cancelled, with further cancellations expected on Saturday.

Nationwide halt

Friday night's stop on departures at airports across the country came after communications breakdowns at air traffic control centers, which the Federal Aviation Administration said affected every regional facility (Tysiące lotów odwołano, chaos na lotniskach w USA. Jest nowy komunikat – RMF24) (Alert "ATC Zero" uziemił samoloty w USA. Tak przebiegał paraliż lotniczy – Onet). Departures were allowed again shortly after 8:16 p.m. Eastern time, following a pause of more than four and a half hours (Paraliż lotniczy w USA. Zniesiono ogólnokrajowy zakaz startów – TVN24). Airports had been shut for a period that stretched from before 10 p.m. Eastern to the early hours in Poland.

Cause under review

Transportation Secretary Sean Duffy said an aging analog communications system had failed, with devices, switches and routers overloaded by data. Homeland Security Secretary Markwayne Mullin said the fault seemed to have started while the FAA was installing new equipment to patch the system, and that the new hardware had overwhelmed the older network (Zawiódł stary system? Władze o przyczynach paraliżu lotów – Wirtualna Polska). Duffy rejected any link to the new AI-based air traffic tool. Mullin said there were no signs so far of a cyberattack or foreign involvement, but the investigation would continue until both possibilities were fully excluded (Co uziemiło samoloty w USA? Trump zabrał głos – Wirtualna Polska).

Effects on flights

Aircraft already in the air and those on the ground were both affected. At Fort Worth Meacham, controllers told a student pilot to land and asked where he wanted to go; he said he did not know what to do (Ruch lotniczy zamarł w USA. Młody pilot był zdezorientowany – Onet). Flight tracking services reported thousands of delays and cancellations on Friday, with more cancellations already scheduled for Saturday. Industry sources said airlines could need several days to restore normal schedules.

Rarity of the measure

The nationwide stop was only the third of its kind, after the halt following the September 11 attacks and a shorter stoppage in January 2023 caused by a failure of the pilot notice system (Paraliż ruchu lotniczego w USA. Podsumowanie nocy – Onet). President Donald Trump told Fox News that nothing pointed to an attack.

Read also

• FAA lifts nationwide ground stop after communication outage; nearly 7,000 flights disrupted
• US Grounds All Flights Nationwide, Then Lifts Ban After About Four Hours