Nearly 200 million seats have been removed as airlines cut 13,000 flights globally in May due to rising jet fuel prices caused by the conflict in the Middle East. The cuts come ahead of the UK half-term holidays at the end of the month.
Jet fuel prices have more than doubled since the beginning of the war - one tonne was trading at $831 (£610) in late February, and by early April, it hit a high of $1,838 (£1350).
Many airlines have already pushed up ticket prices, but Wizz Air's chief executive has said that some European flight prices were falling as airlines try to attract hesitant customers.
The trade body for British airlines, however, said they were operating as normal and not currently facing supply issues, but welcomed the government's contingency plans which will prevent them from losing take-off and landing slots if they cancel flights. The cancellations for May represent just 1% of global flights, and UK flights to popular summer destinations remain unaffected according to the travel agents' trade body Advantage Travel Partnership.
Airlines have said they are not currently experiencing fuel supply problems, but experts have cautioned that disruption to deliveries because of the Iran war may bring shortages within weeks. In mid-April, the head of the International Energy Agency (IEA), which advises 32 member governments on energy supply and security, warned that Europe would face jet fuel shortages by June unless more can be secured from elsewhere.
In the UK, the government is preparing several concessions, including allowing airlines to cancel flights at busy airports like Heathrow well in advance, without the risk of losing valuable take-off and landing slots.
The UK imports about 65% of the jet fuel it uses, a significant portion of which comes from the Middle East under normal circumstances. But the closure of the Strait of Hormuz - a key route for oil and liquefied natural gas - means those supplies cannot get through.