Britain's Farnborough airshow flew into view Monday under a sweltering heatwave, as US planemaker Boeing basked in the glow of the first gigantic order in global aviation's first get-together since Covid.

Visitors flocked to air-conditioned chalets and exhibition halls to escape the intense heat on the first day of one of the world's biggest civil and defence shows, while queues snaked for ice cream vans under dizzying air displays.

Tens of thousands of visitors are expected at this year's event, which coincides with Britain's first-ever "extreme heat" red alert that has been declared for both Monday and Tuesday, when temperatures set to soar further.

At Farnborough, US titan Boeing and its European arch-rival Airbus will battle for supremacy as they declare their latest multi-billion-dollar jet orders
At Farnborough, US titan Boeing and its European arch-rival Airbus will battle for supremacy as they declare their latest multi-billion-dollar jet orders AFP / Christof STACHE

"People who come to visit are really happy to visit. Some of the stays are a little longer than they would normally be because it's pretty relaxing inside," said John Paul Frasier, adviser for Canadian manufacturer De Havilland Aircraft, speaking to AFP inside its business chalet.

"It's pretty challenging and we know that tomorrow is going to be a little bit warmer."

The business terraces were meanwhile deserted as some plucky visitors -- clad in hats, shorts and sunglasses -- headed to the tarmac to watch the commercial and military jets soar across the skies.

The order of 100 737 MAX jets by Delta is a major vote of confidence in the plane that suffered two crashes
The order of 100 737 MAX jets by Delta is a major vote of confidence in the plane that suffered two crashes AFP / JUSTIN TALLIS

"It the hottest I've seen, we just have to power through," said Aaron Rutter, vice president of sales at Lisi Aerospace, with beads of sweat dropping from his forehead as he watched Boeing's new 777X jumbo jet make a series of twists and turns across the sky.

"There a few crazy (ones) of us out there. It's all relative," added Rutter, who hails from Arizona and kept his black jacket on.

Britain's Prime Minister Boris Johnson spoke at the Farnborough Airshow
Britain's Prime Minister Boris Johnson spoke at the Farnborough Airshow POOL via AFP / Frank Augstein

This is the first Farnborough since 2018 because the 2020 edition was cancelled as the Covid health emergency ravaged the aviation sector.

Boeing fired the first shot on Monday in its traditional orders battle with European rival Airbus, clinching a $13.5-billion deal for 100 MAX planes from Delta Airlines in a huge vote of confidence for the crisis-hit jet -- and for the industry's broader recovery from Covid.

Delta lodged its first-ever order for medium-haul MAX 10 aircraft, with options for 30 more of the fuel-efficient planes as it seeks to replace its ageing fleet and cut emissions.

The blockbuster deal marks a huge turnaround for the MAX jet which had suffered two deadly crashes in 2018 and 2019.

The South Korean Black Eagles aerobatic team wowed the crowds at the airshow
The South Korean Black Eagles aerobatic team wowed the crowds at the airshow AFP / JUSTIN TALLIS

Delta, which has 222 Airbus aircraft due for delivery, was until now the only large US airline that had not yet ordered MAX jets.

The MAX 10 is the largest version of Boeing's new generation of single-aisle aircraft, and competes with the commercially-successful Airbus A321.

Delta boss Ed Bastian added that the aircraft would help it improve fuel efficiency and secure a "more sustainable future for air travel".

The news comes as airlines worldwide seek to replace ageing fleets with fuel-efficient planes that emit less carbon dioxide.

Airbus and a number of major airlines signed letters of intent to explore the possibility of capturing CO2 emissions from the air and storing them underground.

Boeing revealed also that Japanese airline ANA had agreed to purchase 20 of its smaller MAX 8 jets -- worth $2.4 billion -- plus two 777-8 freight planes.

Outgoing British Prime Minister Boris Johnson opened the prestigious five-day event as the aviation sector plots its post-Covid recovery.

The event coincides with fast-moving political turmoil in Britain after Johnson's recent announcement that he is stepping down as Conservative party leader, sparking a divisive contest to replace him also as prime minister.

"This government believes in aviation and its power to bring jobs and growth to the entire country," Johnson said Monday in opening remarks, before alluding to his exit from Downing Street.

"After three years in the cockpit... I am now handing over the controls seamlessly to someone else. I don't know who," he added, sparking laughter from delegates.