Airlines are currently expected to fly at least 50% of their flights or risk losing the slots used at airports to take off and land the following year.
Pressure is mounting on the European Commission to ease rules that require empty "ghost" planes to fly in order to retain their take-off and landing slots at airports.
Airlines are currently required to use 50% of their places to ensure they keep them, but with bookings plummeting due to the arrival of the Omicron variant, businesses are calling for flexibility from Brussels this winter.
Lufthansa has already warned that 18,000 flights, or 5-6% of all their routes this winter, will be "unnecessary" flights, essentially with too few passengers to be profitable.
The company has already announced the withdrawal of 33,000 flights in the coming weeks and months but says it cannot cut any more.
In pre-pandemic days, airlines were obliged to fly 80% of their flights in order to retain them the following year.
But once 2020 began and COVID hit, the European Commission suspended this rule due to the collapse in air traffic.
The 50% rate was introduced in February last year.
Now though, Brussels is under pressure once again to further reduce the percentage for airlines.
"Whereas in almost all other parts of the world, climate-friendly exceptions have been found in times of pandemic. The EU does not allow this in the same way," said Lufthansa Group CEO Carsten Spohr in the Frankfurter Allgemeine Zeitung.
"The Brussels rules are detrimental to the climate and are exactly the opposite of what the European Commission wants to achieve with its 'Fit for 55' programme."
One source told Euronews: "We need to change the rules from now on because the winter period only lasts three months, and we cannot cancel new flights,"
The EU executive is also facing pressure from member states.
Belgian Mobility Minister, Georges Gilkinet, wrote to the European Commissioner for Transport, Adina Vălean, earlier this week to ask for a reduction in the rate.
According to one Belgian diplomat, Gilkinet is asking for the rate to be reduced from 50% to 30%.
So far, the Commission is resisting the pressure, saying it will not relax the rules.
"The overall reduced consumer demand, as a result, is already reflected in the much-reduced rate of 50% compared to the usual 80% rate used," said European Commission spokesman Daniel Ferrie on Wednesday. "These rates, together with the justified non-use exceptions, offer airlines much-needed protection on their slots during the current difficult period."
In December last year, Brussels announced that from March 28 it will raise the rate for the summer period to 64%, based on the expectation that demand will pick up.