Bailiffs are reportedly being sent into airline offices because carriers are failing to pay passengers compensation for flight delays and cancellations.
Thousands of court rulings ordering compensation have been ignored by airlines, including EasyJet and Tui Airways, according to BBC Radio 4 programme You and Yours.
EasyJet said it is changing its policies about claims, while Tui Airways has launched an investigation.
Bailiffs are arriving at the offices of leading UK airlines, and staff are paying on-the-spot with debit and credit cards, an investigation by You and Yours found.
If staff fail to pay up the bailiffs can remove and sell office equipment and furniture.
In one case, bailiffs boarded an aircraft belonging to a small European airline and prevented it from taking off until the owners paid up.
EU rules state that passengers who have had their flights cancelled or delayed three hours or more, are entitled to compensation of around £500, depending on the flight.
But when they put their claims in, many passengers have found the airline ignores them.
As a result, some passengers have turned to lawyers to get compensation, but they have also been ignored.
Tui Airways and EasyJet now have thousands of unpaid County Court judgments against them.
When You and Yours searched official records, there were so many outstanding court orders against EasyJet and Tui Airways that the official websites crashed.
New court judgments are being registered against Tui Airways at a rate of around 20 a day.
Some passengers have turned to solicitors, including Bott and Co, which acts on behalf of flight delay clients and in some cases sends in bailiffs to recover compensation.
The law firm claims that some of the UK’s largest airlines have failed to pay more than £4 million in court judgments to over 10,000 delayed passengers.
Solicitor Coby Benson said: “In 2017 we had to issue court proceedings on 73% of our Thomson [Tui] cases – around 3,000 in total on behalf of 7,000 passengers. Many of our customers have tried to recover compensation direct from the airline but been ignored or fobbed off so they have had no other choice but to come to us for help.”
He told the BBC: “Passengers shouldn’t have to go to lawyers at all to get what they’re owed.
“The airlines ignore solicitors who present a formal letter for compensation, then ignore the court proceedings and finally they ignore the judgement against them as well.”
He added: “The airlines think they can bury their heads in the sand thinking that the problem is going to go away, but that’s not the case”.
Bott and Co, which describes bailiffs as “a last resort” said they have been sent to airline offices “dozens of times”.
Tui Airways told You and Yours: “We’re extremely concerned and disappointed by the volume of these [judgments].”
It added: “We are conducting a full and thorough investigation to understand what has happened and to resolve the situation.”
EasyJet said: “Historically, we have chosen not to defend all EU261 County Court cases in certain circumstances.”
However, the budget airline added: “We have recently reviewed that approach and this is no longer the case.”
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