Airlines have been ordered to comply with the law on passenger compensation for disrupted flights after Jet2 and Thomson Airways failed to win the right to appeal High Court rulings.
The Civil Aviation Authority also warned that fares could rise as a result of the Supreme Court ruling which airlines described as “surprising and disappointing”.
However, consumer groups welcomed the decision which they say will open the door to thousands of compensation claims.
CAA chief executive, Andrew Haines, said: “We acknowledge airlines’ concerns about the proportionality of the flight delay regulations and recognise that air fares may increase as a result.
“However, the court’s decisions in these cases bring legal clarity to this issue and we now expect airlines to abide by them when considering claims.”
Following the decisions in these two cases, airlines should not continue to put claims on hold, the regulator added.
“Where airlines have already put claims on hold, the CAA expects airlines to revisit them and pay compensation for any eligible claims,” it said.
“If passengers do experience a long delay or cancellation and wish to claim for compensation, they should contact their airline directly.”
British Air Transport Association chief executive, Nathan Stower, describing Friday’s ruling as “both surprising and disappointing” said: “UK airlines support the principle of passenger protection and always meet their legal obligations.
“However, the rules should be clear, affordable and proportionate for the sake of passengers and airlines. The current system fails those tests and this decision will further increase costs which ultimately are borne by all passengers.
“Vital reform of the EU regulation has recently stalled in Brussels due to disagreements between the Spanish and UK governments over Gibraltar. These differences must now be urgently resolved to allow the necessary reforms to proceed.”
But Martin Lewis, creator and founder of MoneySavingExpert.com, said the clarity of the ruling “is crucial for thousands frustrated by the airlines’ stubborn attitude on this issue”.
He said: “With the many thousands who have reclaimed through the free MoneySavingExpert template letters there has been a split reaction from the airlines.
“Some have paid out £100s or £1,000s in a couple of weeks, no problem. Others kick, spit and make excuses, or just ignore people’s legitimate rights.
“Many people stuck in a legal quagmire of delay and who felt forced to pay a company to reclaim when it should be a relatively simple procedure can get on with getting money back.
“Quite simply, the ruling states airlines are responsible for technical faults in all but extraordinary circumstances and that you can reclaim back at least six years.
“I would urge anyone who has been rejected on these grounds to pick up their pen and paper immediately and write back to reopen their case.”
Adeline Noorderhaven, UK manager of EUclaim, said: “We are delighted with the outcome of both these cases. This is an absolute ‘win’ for passengers and now thousands more consumers will be entailed to the compensation they deserve.”