FAA Ground Stop Explained: How a maybe Faulty Router Grounded Every Flight in America

Synopsis

On Friday, November 13, the FAA (Federal Aviation Administration) halted all US departures for over four hours, leaving thousands of flights cancelled and travellers sleeping on airport floors. Officials first blamed overloaded routers, then pointed to contractor L3Harris and a copper-to-fiber switch at a remote site. No cyberattack was found. Airlines expect normal schedules by Sunday night. Here’s what happened, who’s blamed, what you’re owed, and why the FAA says it could happen again.

FAA Nationwide Ground Stop: What Happened on Friday

Four hours, 3,500 planes in the air, and one very bad Friday afternoon. The FAA had earlier spotted instability in radar and communications systems at air traffic control centers. Because of this imbalance a nationwide ground stop followed: no plane could take off anywhere in the US. It lasted from Friday afternoon until 8:15 p.m. at night, more than four hours, and officials recorded it as the longest break since the September 11 attacks.

More than 3,500 aircraft were already airborne. Transportation Secretary Sean Duffy said controllers used standard procedures to land them, and fewer than 400 remained in the air until they came down safely too. No facilities “went dark,” FAA Administrator Bedford said that no facilities ‘went dark’ but the system couldn’t be trusted to keep running safely.

Why Were All US Flights Grounded? The Router Story

The explanation changed through the weekend, and here’s the current version. On Friday night, Duffy said routers “got overloaded with data” and started giving out inconsistent readings, because which the system was shut down. Homeland Security Secretary Markwayne Mullin pointed out that it was a new technology patched into an old system.

By Saturday the story became more specific. Duffy said the trouble began while contractor L3Harris Technologies was switching lines from copper wire to fiber at a remote FAA site. A router involved in that process flooded the network, with over 1,000 connection attempts every four to five seconds which in turn disrupted communications with planes and thus radar.

But an open question pops up : whether the router was faulty or had the contractor installed or configured it wrongly. Duffy said officials are checking “whether we had incompetence.” The FAA has since disabled the problem function on roughly 60 routers of the same type.

Was the FAA Outage a Cyberattack? What Officials Say

Short answer: no. The cause appears to be old gear and a bad Friday the 13th. Mullin said early on there was basically zero evidence of a cyberattack. Duffy repeated on Saturday that officials don’t believe that a foreign nation attacked the network. Bedford added there was “zero evidence of anything nefarious and zero evidence of anything AI related.”

The AI question came up because the FAA had just started rolling out a new AI traffic tool called SMART but its maker had assured that the ground stop was not caused by it. Microsoft also said it saw no link to its services, despite a big outage earlier in the week.

Flight Cancellations and Delays: How Long Will the Chaos Last?

You’d think Saturday was rough so definitely Sunday would be better but unfortunately your luggage may disagree.

The numbers are big though:

1. More than 9,100 flights into, out of, or within the US were cancelled Friday as per sources.

2. Bedford said about 12,000 flights couldn’t be completed that day.

3. Airlines were expected to cancel 4,000 to 5,000 of roughly 41,000 flights on Saturday.

4. Hubs like Atlanta, Chicago O’Hare, JFK and Dallas-Fort Worth were hit hard.

Planes and crews ended Friday night in the wrong places, so airlines are basically playing a giant game of musical chairs. Bedford said, “I do think the worst is behind us,” and expects schedules to be back to normal by the close of business Sunday. He also apologised to travellers.

Cancelled Flight, Refund Rights and What Happens Next for Air Traffic Control

You’re owed your money back, and the FAA says the system will keep breaking until it’s replaced.

1. Your rights: If the airline cancels your flight and you choose not to travel, you’re entitled to a refund. Taking a rebooking or credit means giving up the cash refund. And whereas most major airlines waive changing fees some airlines terms differ, so check your airline’s page. Hotel and meal vouchers are unlikely, since airlines generally don’t owe them for FAA ground stops. Check whether your travel credit card covers trip delays, and keep your receipts.

2. The bigger problem: The network that failed is the FAA Telecommunications Infrastructure (FTI), which carries controllers’ voice links with pilots and radar data. L3Harris has run it since 2002, and it still partly relies on decades-old copper. Bedford said it “will continue to break until we replace it,” and that there’s “no backup to the backup.” A 2023 safety review called it obsolete.

3. The money fight: Duffy wants $50 billion for a full overhaul. President Trump has asked for $30 billion, and Congress approved $12.5 billion last year. Bedford said finishing the current modernisation would take about $10.1 billion more. Lawmakers from both parties promised reviews, and New York Governor Kathy Hochul called for Duffy to resign.

And as for Thanksgiving? Duffy has said operations should be back up and running for the holiday rush.