The chief executive of easyJet said COVID-related crew absence was a high as 20% at some of its bases, giving it no option but to pre-emptively cancel some flights, and it was too early to tell when the spike would ease.
"You would expect however that the spike that we're seeing in COVID infections that really exists here in the UK and also in parts of the network is going to come down, but this is something that we don't see yet," Johan Lundgren told reporters on Tuesday.
"And (until) that moment in time, we'll just continue to monitor the situation."
About 4% of flights a day were currently cancelled, he said.
(Reporting by Paul Sandle, Editing by Kylie MacLellan)