Could UK flights be grounded like the US? What failed in 2023, 2025 and 2026, and what to carry

What the FAA said, and what it didn't

In a statement dated Friday 13 November, the US Federal Aviation Administration (FAA) said it had "issued a nationwide ground stop for all U.S. airports following communication issues impacting multiple Air Route Traffic Control Centers." It called the information "preliminary and subject to change". When we read its newsroom on 15 November, the FAA had published no start or end time, no length for the stop and no cause beyond those communication issues, so we don't give one.

On 14 November the CAA said: "While US flights have resumed, there may be some follow-on disruption as airlines work to re-book affected passengers". If your flight to or from America was hit, we've set out your rights if it was cancelled or delayed. Friday also brought a Microsoft outage, a separate problem we cover in what it meant at home.

28 August 2023: the flight-planning failure

On the August bank holiday Monday in 2023, the system NATS uses to process airlines' flight plans stopped working. NATS's preliminary report, dated 4 September 2023, traced the root cause to one flight plan that included two waypoints, outside the UK, with the same name. Both the main and backup systems failed safely, as designed, and NATS says the whole sequence "took less than 20 seconds". Automatic processing of flight plans stopped at 08:32.

Controllers then had to enter flight plans by hand, so NATS restricted traffic across the whole of the airspace run from its Swanwick and Prestwick centres. Automatic processing was back "to fully automated live operations at 14:27", NATS said. The Department for Transport said on 6 September 2023 that there were "over 1500 flights cancelled and hundreds more delayed".

The CAA published the Independent Review Panel's final report on 14 November 2024. The CAA estimated that "over 700,000 passengers were impacted, including 300,000 people by cancellations", 95,000 by delays of over three hours and 300,000 by shorter delays. The report made 34 recommendations for NATS, airlines and airports, the CAA and the government, including earlier warnings to airlines and airports and better support for passengers, especially vulnerable people and families with children.

30 July 2025: a radar fault over London

On Wednesday 30 July 2025, NATS had what it later called an "isolated radar-related technical issue" in London Area Control, which handles higher-level flights over England and Wales. NATS says it brought in temporary traffic restrictions to keep flights safe, causing delays and some cancellations.

In a bond prospectus of November 2025, NATS said it "promptly switched to a back-up system, resolving the immediate issue within 45 minutes", but that "residual impacts on air traffic operations continued for several hours thereafter." Its 2025 safety report puts the delay at about 21,000 minutes. We found no official count of flights cancelled that day, so we don't give one.

September 2026: two separate failures

On Tuesday 8 September 2026, controllers at London Area Control lost access to some live flight data because of a fault in the National Airspace System, the core flight data system behind NATS's domestic centres. NATS's preliminary report, dated 16 September, blames "a legacy and previously unknown software defect" and says there is no evidence at this stage of a cyber attack.

NATS's report says restrictions included "limiting or stopping departures from UK and overseas airports", and that the incident meant "more than 2,000 flights being delayed, cancelled or diverted". Its release of 18 September says the restrictions had to be placed across the UK so the system could be restarted, that "Restrictions were in place for some six hours", and that "it took more than two days for the backlog of passenger disruption to be cleared". NATS said this failure was not related to the 2023 or 2025 ones.

Early on Monday 21 September, a separate network fault at NATS's Prestwick centre in Scotland affected the automatic sharing of data between systems and controllers. NATS's report of 16 October says it cut Prestwick's capacity to 60% from 06:20 and 40% from 07:40, and all restrictions were removed by 14:00. It handled 7,933 of the 8,151 flights expected, with the largest impact on flights to and from Scotland and Northern Ireland; it cites Cirium data showing "airlines cancelled 117 departures, likely as a result of this incident." NATS found "no evidence of malicious cyber activity".

What has changed since

In a status report first published in December 2025, the CAA said "32 of the 34 recommendations have now been closed or integrated into operational practices and policies" from the 2023 review, with two still open. In the same report, CAA chief executive Rob Bishton wrote that NATS's response to the July 2025 incident "successfully mitigated the risk of a recurrence of the disruption experienced in 2023."

After the September 2026 failure, NATS said on 18 September that "mitigation is in place while a permanent fix is safety tested and deployed", and that it would soon submit plans to the CAA to invest a further billion pounds by the end of 2033.

Transport Secretary Heidi Alexander asked the CAA for an independent review. The CAA said on 25 September that it will look at NATS's plans to renew its critical systems and at "How well the recommendations from previous reviews have been implemented." Its initial report is due by the end of January 2027 and its final report by 8 March 2027.

Before you leave home, and your rights

The CAA's advice for this week's US disruption works for any big air traffic problem: "Anyone due to travel on flights between the UK and USA should check with their airline for the latest information before heading to the airport." Check the airline's app or website, and keep your phone charged and the booking reference to hand.

If your flight leaves a UK airport on any airline, lands in the UK on a UK or EU airline, or lands in the EU on a UK airline, the CAA says that when it is cancelled, "your airline must let you choose between two options": a refund or another flight. If you choose another flight, the airline must give you food, drink and, if needed, a hotel "until it is able to fly you to your destination, no matter how long the delay lasts or what has caused it." Fixed-sum compensation is less likely when air traffic control is the cause. Our rights story has the detail.

What to carry for a long wait

Your medicines, in your hand luggage, with a few days' spare. GOV.UK says you can carry "essential medicines of more than 100ml, including liquid dietary foodstuffs and inhalers"; you need proof they're prescribed to you, such as a doctor's letter or a copy of the prescription, only for liquid medicine in a container over 100ml (different rules apply to medicines containing a controlled drug). Cooling gel packs are allowed in hand luggage.

A charged power bank. The CAA says: "Always keep vapes and power banks with you in the cabin." It says "you can only take two power banks per person. These should never be re-charged onboard the aircraft", and that 100Wh to 160Wh power banks need airline approval. Check your airline's own limits too.

A refillable bottle, empty through security. GOV.UK says liquids include "all drinks, including water", and that at most airports "you cannot take liquids in containers larger than 100ml through security", though some allow up to 2 litres. Fill it once you're through.

Food, a warm layer and paper copies. A sandwich or snacks save queuing when every café is busy; GOV.UK notes that food in hand luggage can mean your bag is checked again by hand. Add a jumper for a cold terminal, and a printed note of your booking reference, the airline's phone number and your insurer's details in case your phone runs out.