EasyJet boss Johan Lundgren has admitted he "can't guarantee" passengers will not suffer more disruption this summer.
The chief executive said the airline has introduced "a number of measures" to avoid a repeat of the chaos seen during the Easter and jubilee periods, when thousands of flights were cancelled. The summer holidays for most schools in England and Wales start this week.
Schedule reductions across the airline industry will "help" but factors "outside our control" could affect flights, Mr Lundgren warned.
READ MORE: Spain warning for Brits as Foreign Office updates advice
Mr Lundgren said: "We're operating up to 1,700 flights a day. We're doing it with the level of operational performance that you would have seen in 2019.
"But having said that, we can't guarantee that there won't be things that sit outside our control that could affect our customers, as they will affect any other airlines' customers as well. We are absolutely focused on this. This is the key priority for us apart from the overriding objective to deliver safe operation."
Mr Lundgren said one of the key risks to reliability is air traffic control providers imposing restrictions. He said: "It only takes one or two people in the tower to be sick and then you have flow restrictions coming into play.
"Flow restrictions could ultimately lead to cancellations."
Asked if he is concerned some passengers could switch to Ryanair, which has not cancelled as many flights in recent months, Mr Lundgren replied: "Every airline has had cancellations. We deeply apologise for those events that took place when we had day-on-day challenges.
"But we've taken the right actions in order to correct that, and hope to continue to deliver a great operation for the rest of the summer."
Receive newsletters with the latest news, sport and what's on updates from the Liverpool ECHO by signing up here
Holidaymakers heading to Spain now need extra documents to travel
Change of flight fees for easyJet, TUI, Ryanair, Jet2 and British Airways
Flight attendant issues warning to people who fall asleep on planes
Sock trick and nine other hacks to help stay cool in heatwave at night
Four heatwave habits that break the law including swimming and driving barefoot
