IATA’s Director General said the European Commission had “missed an open goal” by setting this winter’s slot use threshold at 50 per cent.

The International Air Transport Association branded the decision “out of touch with reality”, and argued that the Commission had “ignored the advice and evidence presented by EU member states and the airline industry, which had made the case for a much lower threshold”.

In normal times the “use it or lose it” rules require airlines to operate at least 80 per cent of allocated slots, or face losing their right to the slot in future seasons.

A waiver to these rules was put in place following the devastating effects of the Covid-19 pandemic on demand for flights, but a recent EC announcement means that airlines operating at slot-regulated airports between November 2021 and April 2022 must use at least half of slot allocations.

IATA also said that there was “no alleviation to hand back slots at the start of the season allowing airlines to match their schedule to realistic demand or enable other carriers to operate”, adding that “the rule on ‘force majeure’, by which the slot rule is suspended if exceptional circumstances related to the Covid pandemic are in effect, has been switched off for intra-EU operations”.

The association said that the changes would “restrict the ability of airlines to operate with the agility needed to respond to unpredictable and rapidly changing demand, leading to environmentally wasteful and unnecessary flights”.

IATA said that regulators in the UK, China, Latin America and Asia-Pacific had “put much more flexible measures in place”, and argued that the EC’s justification for the decision based on intra-EU traffic recovery this summer “flies in the face of significant evidence of the uncertain outlook for traffic demand this winter, provided by key EU member states as well as IATA and its members”.

The association estimates that international travel will only reach 34 per cent of 2019 levels by the end of 2021.

“Once again the Commission has shown they are out of touch with reality,” said Willie Walsh, IATA’s Director General.

“The airline industry is still facing the worst crisis in its history. The Commission had an open goal to use the slots regulation to promote a sustainable recovery for airlines, but they missed.

“Instead, they have shown contempt for the industry, and for the many member states that repeatedly urged a more flexible solution, by stubbornly pursuing a policy that is contrary to all the evidence presented to them.

“There is a rich irony that only a week after the Commission released its ‘Fit for 55’ carbon emissions plan, it publishes a slots regulation that may force airlines to fly regardless of whether sufficient demand for that route exists.

“Transport Commissioner Valean said ‘We need to act with ambition for our planet, but without punishing our citizens or businesses.’ Clearly, this decision on slots fails to meet these conditions.”