When will the flight chaos end? For the second time this month, UK airports are grappling with technical issues and flight cancellations.Thousands of passengers were left stranded after hundreds of flights were grounded early this week due to a ‘connectivity issue’ at the National Air Traffic Services (NATS) offices in Prestwick, Scotland. Some 35 flights leaving the UK were cancelled or did not fly – while 37 scheduled to arrive in Britain were axed, according to the aviation analytics firm Cirium. It comes just two weeks after an air traffic control issue on September 8 led to more than 2,000 flights being cancelled at airports including London Heathrow and Gatwick. If you’ve been affected, you will undoubtedly have questions, and will be eager to know what your rights are when it comes to rerouting and compensation. Here, we reveal everything you need to know about the crisis… What caused the flight chaos?Flights across Scotland, Northern Ireland and the north of England were disrupted on September 21 following a further technical issue at NATS Prestwick control centre. Passengers at UK airports have been affected by disruption after a system issue struck NATS, which provides air traffic control services to 15 UK hubsWhile NATS has since confirmed the issue has been resolved, the disruption caused delays and cancellations across several major airports including Glasgow, Prestwick and Edinburgh airports, with passengers experiencing significant travel uncertainty. Tomasz Pawliszyn, CEO of AirHelp, said: ‘Despite NATS confirming that the technical issue affecting air traffic control operations has now been resolved, many passengers may continue to experience delays and cancellations as airlines work through the operational consequences of the disruption.’He added that the ‘disruption is another reminder of how quickly technical issues within aviation infrastructure can affect thousands of passengers. ‘Clear communication from airlines and airports, paired with greater awareness of passenger rights, remains essential whenever widespread disruption occurs.’Hasn’t this also happened recently?It comes after a technical issue hit NATS, which provides air traffic control services to 15 airports across the country, earlier this month too. It follows another issue earlier this month, which saw thousands of flights affectedNATS suffered an issue with its ‘flight processing system’, which has since been resolved.NATS said the issue on September 21 was not related to the software defect causing cancellations earlier this month. What does this mean for NATS? The latest issues have piled further pressure on under-fire NATS chief executive Martin Rolfe, who had faced mounting calls to quit after the previous outage.There have been four meltdowns during Mr Rolfe’s time in the £1.4million-a-year post since becoming CEO in 2015 – including in 2023, last year and earlier this month.EasyJet said the new issue ‘calls into question the resilience of NATS’s systems’; British Airways called the failure ‘disappointing’ and warned of disruption; Jet2 said customers and airlines need ‘action, accountability and proper resilience’.How do you know if your flight has been affected?Most of the disruption has now been resolved. You will need to check with your individual airline to see if there are any issues. Delays and cancellations affected travellers, with some being forced to sleep at airports last time aroundAviation analytics firm Cirium said EasyJet was the worst-affected airline followed by British Airways, Loganair, Ryanair, Aer Lingus and KLM. Flights were cancelled and delayed at London City, Heathrow, Luton, Manchester, Liverpool, Bristol, Glasgow, Edinburgh and Belfast airports.Should you still go to the airport?Airports across the UK are still open.You should check with your individual airline and airport before heading to the airport – some will have updates online, and many will have contacted you directly.Passengers should check directly with their airline before travelling to the airport.What are your rights if your flight is delayed? In the event that your flight has been delayed by at least three hours, your airline must provide you with food and drink. The flights have largely returned to normal now, so journeys should be unaffectedThey may provide you with a voucher for this.If not, make sure to keep hold of your receipts as you may be able to reclaim some of the costs later on.If your delay is overnight, your airline should help you with accommodation. Alternatively, you can book this yourself, but keep costs reasonable and keep your receipts to improve your chances of a refund. If the delay is more than five hours, you can choose not to travel and receive a refund.What are your rights if your flight is cancelled?Simon McCulloch, chief growth officer at Staysure, on what affected travellers should know: ‘Your airline should be your first port of call. Under UK261 regulations, in the event of a cancellation, you’re entitled to a full refund or an alternative flight. Depending on the circumstances, your airline may also have obligations to provide assistance during a lengthy delay.’This kind of disruption may be covered under travel insurance policies, for things like reasonable additional accommodation, transport costs, missed connections, certain expenses caused by a lengthy delay and potentially cancellation/abandonment, depending on the policy wording.’It’s worth checking your policy’s definition of ‘travel delay’, ‘missed departure’, ‘abandonment’ or ‘travel disruption’ as cover levels vary.’ You’ll need to check with your airline to see if you can get compensationHe also advises you keep receipts for any costs you incur as a result of the delay.Will you receive compensation?Anton Radchenko, aviation expert and CEO of AirAdvisor, says: ‘On compensation, the NATS failure is outside airlines’ control, so it is likely to count as extraordinary circumstances. Most directly affected passengers should therefore not expect the usual £220 to £520 payment. ‘However, NATS disruption is not a magic phrase that allows every later cancellation to be rejected automatically. The airline should be able to explain how the incident affected that particular aircraft, crew or route and what reasonable measures it took. If the cancellation was actually caused by a separate operational problem within the airline’s control, fixed compensation may still be payable.’I expect the main disputes from this incident to concern later flights described simply as ‘knock-on disruption’, as well as replacement travel, hotels and meal expenses. Passengers should therefore treat fixed compensation, rerouting costs and care expenses as separate parts of their claim, which means a rejection of one does not automatically defeat the others.’