EasyJet has blamed the government for security delays that are increasing the number of flights being cancelled.
Chief executive Johan Lundgren said the airline is waiting for the Department for Transport to give permission for about 100 new members of staff to start work.
He said there have been delays in processing security checks for new airline crew that are urgently needed as existing staff call in sick with COVID-19.
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EasyJet has cancelled hundreds of flights in recent days, mainly on routes serving Gatwick Airport – impacting many Britons who made travel plans around Easter.
The airline said 6% of its flights in the last week did not run as planned.
Mr Lundgren said it is “too early to tell” how long the flight disruption will continue.
“You would expect however, that the spike that we’re seeing in COVID infections that really exists here in the UK and also in (other) parts of the network, is going to come down, but this is something that we don’t see yet,” he added.
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While cancellations were mainly due to coronavirus, Mr Lundgren said the government is also taking too long to vet new recruits.
“There’s this delay of the clearance from the DfT [Department for Transport] for people to get their IDs,” he said.
“There’s a backlog there and we’re waiting currently for about 100 cabin crew to get their IDs.
“There’s a three-week delay on that. That has had an impact. If that would have been on time, we would have seen less cancellations.”
Mr Lundgren said it was “absolutely not” fair to accuse the company of selling flights it could not deliver.
“We were having in some cases up to 20% of absence, and you wouldn’t expect any airline at any point in time to be able to cover that,” he said.
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“That is unfortunate for people who have been affected but I would like to reiterate that those cancellations were made pre-emptively.
“People got notice on that in the beginning of last week. The majority of them had the opportunity to rebook to flights that we have on the same day, however unfortunate that is.
“We’re carrying up to 260,000 customers per day, so I think it’s important to put that into context.”
EasyJet cancelled at least 23 flights to or from Gatwick on Tuesday, affecting destinations such as Berlin, Milan, Valencia and Venice.
Labour’s shadow transport secretary Louise Haigh accused the government of being “missing in action” while “Brits are facing travel chaos”.
She said: “They were warned about staffing shortages, and yet the Tories have comprehensively failed to take action to tackle the security backlog hampering recruitment.
“They need to get a grip, do their jobs, and act to ease the disruption by prioritising the huge backlogs in security checks so airport staff can safely begin work.”
EasyJet said more bookings for summer flights were made during the past six weeks than in the same period in 2019, before the pandemic.