FAA ground stop lifted: Why were US flights grounded, and what’s next?

The US Federal Aviation Administration (FAA) lifted a nationwide ground stop on Friday evening, ending a four-hour disruption that grounded thousands of flights and stranded millions of passengers.

The order, which halted all departing aircraft, was initially issued at 3:54pm Eastern Time (20:54 GMT) due to a telecommunications outage affecting air route traffic control centres.

US Transportation Secretary Sean Duffy announced that airspace reopened at 8:15pm ET (01:15 GMT on Saturday), though he warned that flights would not resume immediately.

Technical failure and response

The FAA cited “extraordinary circumstances and reasons for safety” for the order, which was the third nationwide ground stop of all departures since the September 11, 2001, attacks.

Duffy explained that the outage was caused by switches and routers becoming overloaded with data, adding that the incident did not involve a total loss of communications or radar capabilities.

Homeland Security Secretary Markwayne Mullin assured the public that there was no cyberattack linked to the nationwide ground stop and that everyone was safe.

Impact on passengers and airlines

Aviation analytics firm Cirium reported that after 4pm ET on Friday, about 11,000 flights carrying more than 1.5 million passengers were still scheduled to depart from US airports.

By 7:05pm ET, at least 827 flights had been diverted, with 670 returning to their departure airports and 157 diverted elsewhere.

More than 4,700 flights were cancelled and 10,000 delayed on Friday, with another 700 already cancelled for Saturday, according to FlightRadar24.

Aviation analysts said it could take days for airlines to restore their schedules.

Questions over system redundancy

The failure appeared to be concentrated in the country’s 21 air route traffic control centres, which handle aircraft transiting between regions and rely on multiple handoffs between controllers.

Ron Bartsch, a professor of international aviation law, questioned why backup systems did not kick in immediately, noting that the aviation community is based on redundancy.

Resuming operations and future outlook

Duffy said it would take time to get back to capacity but expected operations to be “back up and operational as we come into the heat of travel during Thanksgiving”.

The Thanksgiving travel period, which begins in less than two weeks, is usually one of the busiest times of the year for air travel in the US.

Duffy acknowledged the tens of thousands of stranded travellers and called for $50bn in upgrades to the nation’s air traffic control system.

Aviation safety expert Todd Curtis warned that the disruption could continue affecting passengers even after the technical problems were resolved.