Airlines stand accused of “padding out” flight times to ensure they maintain punctuality and reduce the chances of having to pay out delay compensation.
Scheduled flight times are up to 35 minutes slower this summer than a decade ago, according to an investigation by Which? Travel.
A total of 76 out of 125 flights analysed by the consumer group take longer now than in 2008, despite advances in aircraft technology.
Airlines argued that slower flights were a result of congested skies, with air traffic controllers often keeping aircraft on the ground for longer and leaving them in holding patterns before landing.
Some routes to the Far East have been lengthened in recent years to avoid flying over dangerous countries.
It was also claimed that airlines were flying more slowly to reduce fuel consumption — bringing down the cost of fares.
Which? travel magazine editor Rory Boland said passengers were “likely to feel that schedule padding is another case of airlines pulling the wool over their eyes”.
He told The Times: “Longer scheduled flight times are likely to mean passengers spend more time sitting around at the gate or on the plane itself, just so the airline can pat itself on the back for being ‘on time’.
“It could also reduce the instances when an airline has to pay you compensation for a flight delay.”
Of British Airways flights analysed, 87% were officially slower than a decade ago, researchers found. The proportion was 82% for Ryanair, 75% for Virgin Atlantic and 62% for EasyJet.
The study, which used figures from the aviation data analysts OAG, showed that Ryanair’s flight from Stansted to Berlin Schonefeld now took ten minutes longer while EasyJet’s flight from Gatwick to Berlin took an extra 19 minutes.
BA flights from Gatwick to New York JFK, as well as Heathrow to Bangkok and Singapore, were scheduled to take 20 minutes longer this year on average.
The biggest time lag was on Virgin Atlantic’s Heathrow to Newark route, which takes 35 minutes longer. Of the Virgin Atlantic flights analysed, nine out of 12 were lengthier.
Despite this, BA, EasyJet and Ryanair were all less punctual last year than in 2009, with EasyJet recording a 10% fall in punctuality, according to the Civil Aviation Authority. Only Virgin Atlantic bucked the trend with a 9% rise, Which? said.
BA pointed out that routes to and from the Far East had been adjusted for security reasons, including the Malaysia Airlines aircraft shot down over Ukraine in 2014.
BA also said that air traffic control congestion was a factor. With European skies now much busier than 10 years ago, it said previous flight taxi times had been “too optimistic”.
A BA spokesman added: “Airlines know this airspace congestion is likely to happen, so may allocate an extra five minutes in their schedule publication times to reflect that busy environment.”
BA, Ryanair and Virgin Atlantic said that they were flying aircraft at slower speeds to reduce fuel consumption.
Ryanair suggested this efficiency allowed it to lower costs and that this was reflected in its cheap £12.99 London to Berlin fare.
The Irish budget carrier added that schedules were “adjusted up or down at the end of each season to reflect the average flight times recorded”.
BA said: “A wide range of factors beyond all airlines’ control impact flight times, including air traffic control strikes, air space management and security restrictions. We offer customers accurate information.”
Virgin Atlantic said: “There are many reasons why schedules may vary, for example congestion at airports, more economical flying regimes, stronger jet streams or different aircraft types.”
EasyJet said: “Our data shows Easyjet’s network punctuality was at 80% for 2017. Only 0.8% of our flights are delayed by more than three hours and we will always pay compensation when it is due.”
Passengers can claim up to €600 for flights that have been delayed by more than three hours under EU rules. Airlines are exempt from making payments for circumstances outside their control, such as bad weather.