Why Did Every US Flight Stop for More Than Four Hours? The FAA Ground Stop, Explained

If you are flying anywhere in the United States this weekend — or meeting someone who is — Friday afternoon's failure is still your problem on Saturday: planes and crews are not where they were supposed to be, and cancellations are still working through the system.

In short: on Friday, November 13, 2026, the Federal Aviation Administration (FAA) halted every departing flight in the United States for more than four hours after a telecommunications failure disrupted the control centres that guide planes between airports. Officials say overloaded, aging switches and routers began feeding controllers inconsistent data, and the agency stopped departures for safety. It was, according to the Associated Press, the longest nationwide ground stop in 25 years — and the first since January 2023.

Symbolic generated image: a quiet airport departure hall at dusk, grounded planes outside the windows and blank departure boards. It stands for a system paused nationwide — not a photograph of a real airport during the stop.

What happened on Friday, November 13?

The timeline officials gave at a White House briefing on Friday night is short and stark. Transportation Secretary Sean Duffy said the trouble began at about 3:36 p.m. Eastern Time, when radar and communications systems at the FAA's en route centres and terminal radar approach control facilities (TRACONs) became unstable. At 3:54 p.m. ET, the FAA's Air Traffic Control System Command Center issued a nationwide ground stop: all departing traffic was to remain on the ground until further notice, "due to extraordinary circumstances and for reasons of safety," in the wording reported from the advisory.

Flights already in the air were not ordered down. Homeland Security Secretary Markwayne Mullin told reporters that more than 3,000 flights in the air at the time landed safely, and officials said no one was in danger. Incoming international flights were handled case by case, and Europe's aviation authorities suspended U.S.-bound departures at the FAA's request for part of the evening, according to the Associated Press.

At 8:15 p.m. ET — four hours and twenty-one minutes after the stop was issued — Duffy announced that the airspace had reopened and departures could resume. A limited number of domestic flights departed on Friday night. But reopening the airspace did not reopen the schedule: aircraft and crews were stranded in the wrong cities, and the Associated Press reported on Saturday that airlines were still digging out, with officials expecting the effects to be felt for days — though they said the system should be back to normal in time for the Thanksgiving travel rush.

How many flights were affected? Why the numbers differ

Readers will see very different totals in different reports, and the gap is worth explaining rather than hiding. Flight counts in a disruption like this are snapshots, not final totals, and trackers count different things.

A FlightAware snapshot at 7:30 p.m. ET on Friday — while the stop was still in force — already showed 10,079 delays and 4,238 cancellations on flights within, into or out of the United States. By the end of Friday, one FlightAware-based tally put the day at 9,159 cancellations. The aviation analytics firm Cirium, using a different definition that combines cancelled flights with flights that had not departed within 180 minutes of schedule, counted 8,267 U.S. departures — 31.45% of Friday's 26,284 scheduled departures — in its "cancelled or no-fly" category as of 10:30 p.m. ET, along with 893 diverted flights. Cirium also estimated that about 1.5 million passengers were disrupted.

The figure to anchor on for Saturday is the Associated Press's: more than 2,500 flights cancelled in the United States on Saturday, with hundreds more delayed, according to FlightAware — and other trackers counting later in the morning put Saturday's cancellations higher still, above 3,500 by 8:17 a.m. ET in one tally. The honest summary is this: Friday's stop cancelled thousands of flights, Saturday added thousands more cancellations as airlines repositioned, and no final audited total exists yet.

What do officials say caused it — and what is not yet known?

This part of the story is preliminary, and it should be read that way. The FAA's own first description was narrow: "a temporary telecommunications outage," with flights halted out of an abundance of caution while technicians investigated.

At the Friday night briefing, Duffy gave a more specific account. The system's switches and routers, he said, "got overloaded with data" and began to give inconsistent data, and the system was shut down because of it. He blamed decades-old, analog equipment — the United States still uses legacy time-division multiplexing (TDM) telecommunications in parts of the network — and said equipment that had already been replaced was not affected. Mullin offered a related preliminary explanation: new technology being introduced into the old system had overwhelmed it, producing intermittent communications and radar gaps.

Three cautions belong with those accounts. First, they are initial explanations, not a completed investigation: the FAA has not named a specific failed component or published a technical root-cause report. Second, speculation spread quickly on Friday — including about a recently expanded artificial-intelligence traffic tool and about the separate Microsoft service outage this week. Officials addressed both: the Associated Press reported that Duffy said the failure was not caused by the FAA's newly deployed AI system, the company behind that tool denied it caused the stop, and Mullin said the FAA incident and the Microsoft outage were separate issues. Third, on a possible attack: Mullin said officials had found no indication of a cyberattack. That is an early assessment while an investigation continues, not a final finding.

The background: a control system watchdogs have warned about for years

Friday's failure landed on a system that official watchdogs had already described, in writing, as fragile. That background comes from a primary source readers can check directly: the U.S. Government Accountability Office (GAO).

In September 2024, the GAO reported that of the FAA's 138 air traffic control systems, 51 were rated unsustainable and 54 more potentially unsustainable — more than 75% combined — with problems including missing spare parts and upkeep funding that never arrived. The FAA's controllers rely on those systems to monitor weather, conduct surveillance and manage communications for up to 45,000 flights a day.

The current modernization programme, the Brand New Air Traffic Control System (BNATCS), was announced in May 2025. Congress appropriated an initial $12.5 billion in July 2025, and the first phase — covering communications, surveillance, weather and training systems — is to be fully completed by December 2028, according to the GAO's September 2026 report on the programme (GAO-26-107992). As of May 2026, the FAA reported it had replaced 2,560 of 5,170 old copper wires with high-speed fibre-optic cable — roughly half of that one workstream, two and a half years before the phase deadline.

The same GAO report is the source of the sharpest warning in this story. The FAA, it found, has not developed a comprehensive lifecycle cost estimate for the programme — officials gave high-level per-programme figures in June 2026 but could not provide the analysis behind them — and it has no integrated master schedule for phase 1, only 11,389 individual project schedules that are not integrated. The GAO's conclusion, in its own summary, is that these gaps raise the risk of repeating the FAA's history of cost overruns and delays, leaving the agency relying on "severely outdated systems that are prone to failure."

How much the full overhaul will cost is itself unsettled, and the figures in circulation differ by source and by date. The GAO records $12.5 billion appropriated for phase 1 and an FAA estimate of about $10.2 billion more for phase 2 automation, not including facilities. Administration officials have at different points put the additional need at $19–20 billion, and reporting on Friday night described calls for up to $30 billion more. Those numbers are not directly comparable — they cover different scopes — which is exactly the GAO's point about the missing lifecycle estimate.

Symbolic generated image: aging copper cables and an analog switchboard giving way to glowing fibre-optic lines. It stands for the modernization the FAA is partway through — not a photograph of real FAA equipment.

If your flight was cancelled: what you are actually owed

One part of this story is settled law rather than breaking news, and it is the part that can save readers money this weekend. Under the U.S. Department of Transportation's refund rule (14 CFR Part 260), if an airline cancels your flight — for any reason, including an FAA failure outside the airline's control — or significantly changes it, and you decline the rebooking, credit or other alternative offered, you are entitled to a refund to your original form of payment, even on a non-refundable ticket. A "significant" delay means arriving three or more hours late on a domestic trip, or six or more hours late on an international one. Refunds under the rule are automatic and prompt: within seven business days for credit-card payments and within 20 calendar days for other payment methods. A voucher you are offered instead must, if you accept it, remain valid for at least five years — but you do not have to accept it.

Hotels and meals are different. Because an FAA ground stop is an event outside the airlines' control, federal rules do not require carriers to pay for a hotel room or meals the way their customer-service commitments may require for disruptions they cause themselves. Airlines did issue travel waivers this weekend — United, for example, was reported to be waiving change fees and fare differences for affected travellers rebooking within its waiver window — but waiver terms differ by airline and change quickly, so check your own airline's advisory and your reservation before you travel to the airport. If you are still travelling, the practical advice from every source is the same: check your flight status in the airline's app before leaving home, and again before heading to the gate.

Key points

✔ The FAA issued a nationwide ground stop at 3:54 p.m. ET on Friday, November 13, 2026, and lifted it at 8:15 p.m. ET — a halt of more than four hours, the longest in 25 years and the first since January 2023, according to the Associated Press.
✔ Officials' preliminary explanation: aging switches and routers overloaded with data produced inconsistent radar and communications data; new technology added to the old system is also being examined. The FAA has not published a final root cause, and officials said there was no indication of a cyberattack.
✔ More than 3,000 flights in the air landed safely. Friday's tallies ran into the thousands of cancellations, and the Associated Press reported more than 2,500 further U.S. cancellations on Saturday as airlines repositioned planes and crews.
✔ The GAO reported in September 2024 that 51 of the FAA's 138 air traffic control systems were unsustainable and 54 more potentially unsustainable.
✔ Congress appropriated $12.5 billion in July 2025 for the Brand New Air Traffic Control System; phase 1 is due by December 2028, but the GAO's September 2026 report (GAO-26-107992) found no lifecycle cost estimate and no integrated master schedule for it.
✔ If your flight was cancelled or significantly delayed and you decline the alternative offered, DOT rules entitle you to a refund to your original payment method — seven business days for card payments — whatever the cause. Hotels and meals are not federally required for an FAA-caused disruption.

What to watch

☐ The FAA's technical explanation: whether it names a specific failed component, and whether its account matches the preliminary "overloaded routers" explanation given on Friday night.
☐ The recovery curve over the weekend — Saturday's cancellation count, and whether officials' expectation of normal operations in time for the Thanksgiving rush holds.
☐ Congress and the money: how the competing totals for completing the overhaul — $10.2 billion for phase 2 in the FAA's estimate recorded by the GAO, against larger figures officials have cited — are reconciled, and whether Friday's failure changes the funding debate.
☐ The GAO's two open warnings: whether the FAA produces a lifecycle cost estimate and an integrated master schedule for phase 1 before the December 2028 deadline pressure builds.
☐ The copper-to-fibre conversion pace: 2,560 of 5,170 lines replaced as of May 2026 is the clearest public progress marker to check at the next update.
☐ Any repeat instability during the modernization itself, since officials' own preliminary account involves new technology interacting with the old system it is replacing.

Sources

U.S. Government Accountability Office, "Air Traffic Control Systems: Ambitious New Modernization Effort Needs to Improve Cost and Schedule Planning," GAO-26-107992, September 14, 2026 — https://www.gao.gov/products/gao-26-107992 (primary source: BNATCS funding, schedule, copper-to-fibre progress, and the missing cost estimate)
U.S. Government Accountability Office, testimony GAO-25-108162, March 4, 2025, drawing on its September 2024 report — https://files.gao.gov/reports/GAO-25-108162/index.html (primary source: 51 of 138 systems unsustainable, 54 potentially unsustainable)
Associated Press, via PBS NewsHour, "FAA grounds all flights at U.S. airports due to air traffic control communications problems," November 13, 2026 — https://www.pbs.org/newshour/nation/faa-grounds-all-flights-at-u-s-airports-due-to-air-traffic-control-communications-problems
Associated Press, "Airlines work to recover after nationwide ground stop as more than 2,500 flights are canceled," November 14, 2026, via WVLT — https://www.wvlt.tv/2026/11/14/thousands-flights-canceled-airlines-work-dig-out-nationwide-ground-stop/
CNN, live coverage, "FAA issues nationwide ground stop for all flights," November 13, 2026 — https://edition.cnn.com/2026/11/13/us/live-news/flights-ground-stop-faa
FAA National Airspace System status page (checked November 14, 2026; no nationwide stop in effect Saturday morning) — https://nasstatus.faa.gov
U.S. Department of Transportation refund rule, 14 CFR Part 260, as summarised in "FAA nationwide ground stop: cancellations, cause and refunds," SourceFirst News, November 14, 2026 — https://sourcefirstnews.com/faa-nationwide-ground-stop-flights-canceled-refunds

Both images in this article are symbolic generated images. They do not show a real airport, real FAA equipment, or any person involved in this event.

This article is for general information only and is not legal or travel advice. It summarises official statements, a GAO report and news reporting as of the morning of November 14, 2026; flight counts are tracker snapshots that will change, and the FAA's investigation into the cause is continuing.

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