The number of flights using British skies on one day is set to reach an all-time high of 9,000 on Friday.
More than than six per minute are expected, exceeding the previous record of 8,854 set on 25 May 2018.
A bank holiday, school half-term, the Monaco Grand Prix, and Cannes Film Festival have added to the spike, air traffic controller Nats said.
The record may soon be broken again, with flights to the Champions League final in Madrid on 1 June contributing.
Prices for flights from the UK to the Spanish capital have soared to more than £1,300 return since Liverpool and Tottenham both qualified for the final.
The UK's busiest airspace is over south-east England, where four of the country's five main airports are.
Nats' head of service performance, Wendy Howard-Allen, said demand for air travel was "increasing all the time".
"We've been planning for this busy summer period for a number of months - preparing for the worst and hoping for the best," she said.
"With many events coinciding at the end of May and in early June, it's important to realise the impact this will have on air traffic."