The EU is being urged to relax airline rules that led to thousands of empty planes crossing Europe over the winter, prompting concerns over the effect on the climate and unnecessary waste of resources.
German airline Lufthansa said it would have to run 18,000 empty flights during the winter to keep its airport slots.
Its Belgian subsidiary, Brussels Airlines, expects 3,000 such trips by the end of March.
The so-called “use it or lose it” rule means that airlines must use 80 per cent of their allocated slots at airports or risk losing their take-off and landing rights to other carriers.
Although the EU reduced this to 50 per cent after air travel slumped during the pandemic, the threshold will rise again this summer, and critics say it is still too high given the unpredictable effects of the Omicron variant.
Travel chaos over Christmas led to thousands of flights being cancelled as Omicron case numbers surged in Europe, flight crew went off sick and border rules changed with little notice.
Lufthansa chief executive Carsten Spohr said the 18,000 trips were “empty, unnecessary flights just to secure our landing and take-off rights”.
The airline said it was running about 60 per cent of its flight schedule compared with 2019, and carrying about half as many passengers, as virus-related travel problems stretch into their third year.
Georges Gilkinet, Belgium’s mobility minister, described the empty flights as “environmental, economic and social nonsense”.
He said on Wednesday that he had written to the European Commission to demand that the rules be relaxed further to keep empty planes on the ground.
The EU needs to show more flexibility “given the significant drop in passengers and impact of Omicron numbers on crewing planned schedules”, he said. Traffic was well below 2019 levels even in the calmer autumn months.
Greta Thunberg, the Swedish climate activist, said mockingly that the EU hardly appeared to be in a “climate emergency mode”, despite its bold promises of environmental action. Brussels hopes to reduce carbon emissions from the transport sector by 90 per cent by 2050.
But a commission spokesman, Daniel Ferrie, said the reduced demand was already reflected in the adjusted 50 per cent threshold.
"The Commission expects that operated flights follow consumer demand and offer much needed continued air connectivity to citizens,” he said.
Brussels plans to raise the threshold to 64 per cent in this year’s April-to-November summer season, with high vaccination rates and a standardised EU health certificate cited as reasons for an expected recovery in air travel.
The commission said it hoped to take another step “towards the return to normal” this summer, although it said it would monitor the drop in flight bookings linked to Omicron.
Countries including France and Italy tightened travel rules because of the variant. But some governments have virtually given up on such restrictions, with Britain moving on Wednesday to restore the softer measures of last autumn.
Airline industry body IATA said it was now time for Britain to remove testing requirements entirely for vaccinated people.
“It’s clear that the extra measures had little or no impact on the spread of this new variant,” said IATA director general Willie Walsh.
