The NATS air traffic failure of 8 September 2026 cancelled around 2,000 UK flights and left the country’s busiest airports clearing backlogs into a second day. NATS, the UK’s air navigation service provider, says the fault was in its flight data processing system — the software that handles flight plans and departure data — and has ruled out a cyber attack. The company’s chief executive agreed to give the government a report on the cause by 16 September, and the transport secretary has ordered a separate six-month independent review by the Civil Aviation Authority.
What’s below
What broke, and for how long
The failure hit the system that processes flight plans and departure data, not radar or air-to-ground communications. That distinction matters: controllers could still see and talk to aircraft, which is why this was a capacity crisis rather than a safety one. With automated flight-plan processing degraded, traffic has to be handled with manual procedures, and manual handling means far fewer movements per hour. Restrictions follow, and airlines cancel.
The outage itself has been reported at around four hours. The disruption lasted much longer, because a four-hour restriction in European airspace displaces aircraft and crews for the rest of the day and often the next. NATS has said it has ruled out a cyber attack.
Where the cancellations landed
Aviation analytics firm Cirium’s count of roughly 2,000 cancelled flights, cited across UK reporting, covers services to, from and within the United Kingdom across 8 and 9 September. Heathrow, Gatwick, Manchester and Birmingham were worst affected. Ryanair cancelled around 260 flights, which it said affected about 48,000 passengers; British Airways cancelled close to 200.
The pattern is familiar from previous large ATC events: the first-day cancellation count understates the disruption, because the recovery consumes the following day’s slack. Aircraft finish the evening in the wrong airports, crews run out of legal duty hours, and the timetable has no spare capacity in September to absorb either.
Airways Magazine reported the regulator’s move to review the outage alongside ministerial comments that resilience fell short.
Two deadlines that matter
16 September — the cause report. NATS chief executive Martin Rolfe agreed to provide the government with a report on the cause within a week of the failure. A one-week report is a preliminary technical account, not a root-cause analysis; the useful content is whether it identifies a specific defect and whether that defect had been flagged before.
March 2027 — the CAA review. The independent six-month review commissioned from the Civil Aviation Authority is the substantive piece. Its remit covers the root cause of the September failure and the broader resilience of UK air navigation infrastructure.
There is a precedent sitting directly underneath both. In August 2023, a NATS flight planning system failure caused comparable disruption. The CAA commissioned an independent review; the interim report was published as CAP2981, and the final report made 34 recommendations directed at NATS, airlines, airports, the regulator and government.
The obvious question for the 2027 review is therefore not what went wrong in September 2026, but which of those 34 recommendations were implemented, by whom, and whether any of them would have prevented this. A second failure in the same broad system three years after a review that produced 34 recommendations is a governance question as much as an engineering one.
What passengers are actually owed
Under the UK’s retained air passenger rights rules, an airline that cancels must offer a choice between a refund and rerouting, and must provide care — meals, communication and, where an overnight stay is required, accommodation — while you wait. Those duties apply regardless of the cause.
Fixed cash compensation is different. Air traffic control failures are generally treated as extraordinary circumstances outside the airline’s control, which removes the compensation entitlement while leaving the refund, rerouting and care duties intact. In practice that means: do not expect a compensation payment for this event, do expect the airline to rebook you or refund you and to cover reasonable costs in the meantime, and keep receipts.
If an airline refuses a refund or leaves you to fund your own accommodation, the escalation route is the airline’s alternative dispute resolution scheme, and then the CAA’s passenger advice service.
Passenger questions
What caused the NATS air traffic failure?
NATS says a technical fault affected its flight data processing system, which handles flight plans and departure data. It has ruled out a cyber attack. A fuller account was due to government on 16 September.
How many flights were cancelled?
Around 2,000 across 8 and 9 September, per figures from aviation analytics firm Cirium cited in UK reporting.
Which airports were worst hit?
Heathrow, Gatwick, Manchester and Birmingham.
Am I entitled to compensation?
Generally not for an ATC failure, which is usually treated as an extraordinary circumstance. You remain entitled to a refund or rerouting, and to meals and accommodation where applicable.
Has this happened before?
Yes. A NATS flight planning system failure in August 2023 caused similar disruption and led to an independent CAA review whose final report made 34 recommendations.
When will the independent review report?
The CAA’s six-month review is expected to conclude in March 2027.