The empty vessels are being flown so airlines can retain their landing slots, or approval from an airport to take off and land at a certain time.

According to flight data, which was obtained by a freedom of information request from the Guardian, 2,000 international flights departed from Heathrow, Aberdeen, Manchester, Stansted, and Norwich Airports nearly empty at the end of 2021.

Before the pandemic, airlines had to run 80% of their flights in order to retain their landing slots.

The rules were suspended during the COVID-19 pandemic with the crash in aviation demand and reintroduced in October 2021 at 50%.

But despite the lower threshold to keep a landing slot, the number of monthly ghost flights have not changed.

Flying is one of the most carbon-emitting practices, with global aviation accounting for 2.5% of all CO₂ emissions.

Ghost flights have been criticized by climate campaigners since the landing spot rules were put in place, but the issue came to light when it was uncovered 15,000 ghost flights left the U.K. from the start of the COVID-19 pandemic in March 2020 to September 2021.

German airline Lufthansa even spoke out against the practice in January 2022, reporting the airline wanted to cancel 33,000 flights, but after finding it would lose its take-off and landing spots, said it would still have to fly 18,000 “unnecessary” flights by March 2022 to retain them.

Anna Hughes at Flight Free U.K., a climate campaign group that created a parliamentary petition to end ghost flights, tells Fortune, “It’s so dispiriting for someone who is taking measures to reduce their emissions. For them to see that airlines are flying the planes anyway, you’re like, ‘Right, so what good is it me doing anything.’”

“The rules are archaic,” she adds.

Climate anger

Jenny Bates, transport campaigner for climate action group Friends of the Earth, tells Fortune: “It is just so obviously wasteful.

“If people see empty flights going around, they would think, ‘Well that’s really silly. Why shouldn’t I at least go and enjoy a holiday.’ That is essentially psychologically unhelpful, because the message is the opposite.”  

Tim Johnson, director of the Aviation Environment Federation, said in the Guardian that the while U.K. airline average occupancy grew to around 70% in November 2021, it is still well below the 86% capacity it was averaging before the pandemic began, and the number of ultra-low-occupancy flights has stayed the same.

“If changing market fortunes can’t solve this problem, then the government must act to do so,” Johnson said.

“Its recent claim earlier that aviation can be net zero by 2050 while accommodating a 70% increase in passenger numbers (from 2018 levels) stretches belief when there are such obvious examples of inefficiency in the current system. Fixing these should be a priority.”

The U.K.’s Department for Transport has avoided all blame in the practice, saying in a statement: “We acted swiftly [during the pandemic] to prevent empty aircraft needing to fly to retain their slots. However, some flights may operate with low passenger numbers for a whole range of reasons, including carrying key workers or vital cargo.”

Activist site Extinction Symbol tweeted in response to the number of ghost flights still flying: “Politicians won’t stop this because they only exist to serve their fossil fuel corporate paymasters, rather than protecting life on Earth.”

Leo Roberts, research manager at climate change think tank E3G, wrote: “A system that incentives moving high emitting assets around empty is batshit crazy.”