The UK Civil Aviation Authority confirmed on Friday 25 September that it has launched a formal independent review into the air traffic control failure that disrupted flights nationwide, including at Heathrow, on 8 September. The review was requested by Transport Secretary Heidi Alexander after the incident caused more than 2,000 flights to be delayed, cancelled or diverted across the UK.
The CAA published the terms of reference for the review on its website on Friday. It said the review will examine the causes of the disruption, assess the impact on passengers, and identify what further steps are needed to strengthen confidence in the resilience of the UK's air traffic system. A preliminary report from NATS, published on 18 September, attributed the outage to a software defect in its flight planning systems.
As part of the review, the CAA will look at NATS' plans to renew and modernise its critical operational systems, including its business continuity arrangements, how well recommendations from previous reviews have been carried out, and the effectiveness of the CAA's own regulatory oversight. The review will also take into account a second, separate NATS technical issue on 21 September, which caused further delays and cancellations at airports including Heathrow.
An independent challenge panel will support the review, with members proposed by the CAA and approved by the Transport Secretary. An initial report is due to the Transport Secretary by the end of January 2027, with a final report due by 8 March 2027.
Reuters reported that NATS said it welcomed the publication of the review's scope and would cooperate fully with the regulator. Some airlines, including Ryanair, have called for NATS chief executive Martin Rolfe to resign over the repeated failures, while easyJet said the incidents "once again call into question the resilience of Nats' systems".
Heathrow passengers experienced some of the heaviest knock-on effects from the 8 September outage, with high calculated take-off times pushing delays into the afternoon and evening. The airport has also seen intermittent delays in the weeks since, including further disruption on 21 September linked to a separate NATS technical fault at its Prestwick centre in Scotland.
The review's outcome will not change how passengers are compensated for the September disruption in the short term. The CAA has previously said the 8 September outage is likely to be treated as "extraordinary circumstances" under passenger rights rules, meaning airlines are not automatically liable for cash compensation, though they must still offer care, rebooking or refunds.
What this means for your journey: if you are travelling through Heathrow in the coming months, build in extra time and check your flight status directly with your airline before setting off, particularly during periods of high traffic. For getting to and from the airport smoothly regardless of any air traffic disruption, see our guide to Heathrow public transport options.