Passengers who have been stranded abroad or forced to pay out for a new ticket because of 'no show' clauses could sue airlines, following pressure by Which? Travel.
The Civil Aviation Authority (CAA) has warned that the practice, where airlines reserve the right to cancel a flyer's return flight if they miss the outbound leg, is unfair.
Airlines including British Airways, Virgin Atlantic and KLM still have the little-known clause in their terms and conditions. In some cases, they are effectively able to double their money by reselling the seats they cancel, with no refund given to passengers.
In a report released last week, the Civil Aviation Authority (CAA) concluded that the policy of automatically cancelling a passenger's return flight if they fail to show up for the outbound journey is 'disproportionate'.
It also said that passengers might, in some circumstances, be able to sue the airlines for denied boarding.
However, the regulator stopped short of taking any enforcement action to prevent passengers from getting ripped off by the practice.
Which? believes this decision puts the interests of airlines ahead of their passengers, and is urging the CAA to put an outright ban on the clause.
One passenger, Ben Smith, ended up forking out £1,600 in addition to the cost of his original ticket, after medication caused him to oversleep and miss his flight to the US. When he arrived at the airport, he was told that he would have to buy another outbound ticket - but not that his return ticket would also be cancelled.
He told us: 'Had I known the situation with my return being cancelled I would have booked another round trip ticket. In all, I had to spend £700 getting to New York and then £900 getting home, on top of the £700 my ticket originally cost me. I am struggling financially as a result of these fares.'
BA's terms and conditions state that passengers may have to pay the difference between their original fare and a new return ticket, but Mr Smith was not informed of this.
A spokesperson for British Airways responded: 'Many of our tickets allow customers to make changes to their flights if they inform us before they travel. We believe that being upfront with customers is essential, so we work hard to give them the information they need when travelling with us, and ensure that our terms and conditions are very clear on our website. This policy is common practice in the industry and designed to stop the abuse of our fares.'
Another passenger, Laura Kidd, had to buy a new return flight from Seattle to Heathrow for nearly £700 after she was unable to take her scheduled outbound flight because of work commitments.
The musician from Bristol says she didn't receive any notification from Virgin Atlantic and only found out as she checked in for her flight back to Heathrow. She said that sorting the issue out was an 'awful, lonely experience'.
Virgin Atlantic apologised to Ms Kidd and said: 'We always encourage customers to get in touch as soon as they think they are going to miss their flight. If they arrive too late at the airport we will rebook them on the next available flight and their inbound flight won't be cancelled.
'If a customer can't make their flight due to a legitimate change in circumstances, we will not cancel their inbound flight if they get in touch with us before the flight. If the customer can't contact us before they miss their flight they will need to contact us as soon as they can and if there has been a legitimate change in circumstances we will reinstate their inbound ticket.'
In December 2018, Which? wrote to nine carriers, including British Airways and Virgin Atlantic, informing them that 'no show' clauses potentially breach both the Consumer Rights Act and the Unfair Terms in Consumer Contracts Directive. We believe it creates a significant imbalance between the airline, who stands to profit, and the passenger, who is forced to pay out considerable sums of money to rebook.
Both Thomas Cook and Channel Islands airline Aurigny agreed to scrap the clause entirely. Flybe also pledged to make changes in response to Which?'s letter.
Since then Emirates and Virgin have agreed that passengers won't have their return flights cancelled if they miss the flight due to 'unusual and unforeseeable events' outside of their control. However, the onus is still on the flyer to be aware of this rule and contact the airline within 24-hours of missing the flight (in the case of Emirates) or before the return journey (for Virgin).
While Which? welcomes these changes, we believe they do not go far enough.
Caroline Normand, Which? director of advocacy said: 'It's totally unreasonable for an airline to cancel a passenger's return flight, often without warning, simply because they've missed the first leg of their journey.
'Airlines have been able to cash in with this tactic for too long - leaving people miserable, stranded and hundreds if not thousands of pounds out of pocket. If airlines are not going to do the right thing and stop this disgraceful practice on their own, the Civil Aviation Authority should step in and ban these rip-off clauses.