What are 'ghost flights' and why are they causing so much uproar right now?

Their seats lie empty, their emergency-landing videos stay unwatched and their meals remain unmicrowaved as they glide like phantoms through the skies, as if blighted by some terrible airborne curse.

But there is no curse. Not unless you count the curse of runway overcrowding or the climate impacts of running empty flights.

For they are the “ghost flights” of the aviation industry: Chartered to fly around the world – sometimes just around an airport – simply so airlines can hang on to takeoff and landing slots.

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And now, a U.K. parliamentary petition has been launched waging war on this “shocking waste of resources and a needless source of emissions." At the time of writing, it had amassed more than 4,000 signatures.

“Airlines have been flying planes empty to retain their landing slots,” the petition states. “These ‘ghost’ flights are a shocking waste of resources and a needless source of emissions."

“At a time of climate emergency, we need to drastically reduce our fossil fuel use, and in the context of our steadily dwindling carbon budget, it beggars belief that planes fly empty."

“U.K. regulation states that airlines must use their landing slots more than 80% of the time in order to keep them. This was suspended at the outset of the pandemic but is now 50%, with plans to return to 80% by March 2022.”

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What are 'ghost flights'?

According to EU regulations, carriers must maintain a certain percentage of their scheduled flights, or risk losing the slots to another company — a practice known in the flight business as “keeping slots warm."

Normally, airlines must stick to the 80:20 rule, meaning they must fulfill at least 80% of their allocated runway time.

During the pandemic, however, that was reduced to a 50:50 rule. But as the travel industry clambers back to its feet after two years of restrictions, that is expected to return to 80:20.

Last week, Lufthansa Group, which owns Lufthansa, Swiss International Airlines, Austrian Airlines, Eurowings and Brussels Airlines, stirred anger after it admitted 18,000 flights would be flown empty this winter, including 3,000 Brussels Airlines routes.

“We will have to carry out 18,000 extra, unnecessary flights just to secure our takeoff and landing rights,” said chief executive Carsten Spohr.

What's all the fuss about?

In reaction to Lufthansa's ghost flights, last week Ryanair responded by calling on the European Commission to force Lufthansa to sell seats on empty flights at low fares.

Chief executive of Ryanair, Michael O’Leary, said at the time that “Lufthansa loves crying crocodile tears about the environment when doing everything possible to protect its slots."

“If Lufthansa doesn’t want to operate ‘ghost flights’ to protect its slots, then simply sell these seats at low fares, and help accelerate the recovery of short and long haul air travel to and from Europe.”

Lufthansa argued that customers were not being kept away by a reluctance to provide cheaper fares but by pandemic travel restrictions.

Related: How pilots deal with sudden airspace closures

For the aviation industry, the argument for the "use it or lose it" rule is that it keeps the industry competitive by incentivizing airlines to fly routes, trade them or hand them back so other carriers, including new market entrants, can use them instead.

“The slot rules help maximize competition by keeping airfares low while increasing their choice of destinations and airline," Gatwick airport’s chief commercial officer, Jonathan Pollard, told The Independent. “Restoring the slot rules would be a clear signal that the U.K. government is getting fully behind the recovery of the  U.K. aviation sector.”

But the flights aren't just causing airline industry squabbles. They have also long caused anger among environmental groups, with Greenpeace dubbing them “absurd and revolting."

It may make financial sense, campaigners say, but environmentally, it's nonsense.

Aviation is, after all, responsible for around 2.4% of global CO2 emissions while, alongside other gases and the water vapor trails produced by aircraft, the industry is responsible for around 5% of global warming.

“A short-haul flight on a 737 emits approximately 18 tons of CO2 per hour — that is almost twice what an average European citizen emits in an entire year," Catherine Livesley, founder of No Fly Travel Club, told EuroNews.com. "It seems incomprehensible that we actively require airlines to produce these colossal emissions simply to secure landing slots — even at 50% of normal capacity.

Then there is air pollution in towns and cities across the world. According to the World Health Organization, 99% of the world population is exposed to unhealthy levels of air pollution — of which air travel is a major contributor — leading to 4.2 million premature deaths worldwide.

"Absurd and revolting," tweeted Greenpeace on Jan. 10. "These unnecessary ghost flights need to stop now."

For the current petition to receive genuine government attention it will need to hit the 10,000 signature mark, at which the government will formally respond to it. If it reaches 100,000 signatures it will be considered for debate in Parliament which could prompt further actions.

TPG will continue to monitor this story and provide additional updates on how this could affect travel in the U.K. and potential resolutions to the problem.