A thundering fighter jet burst through the clouds, twisting and turning above the dumbstruck crowd.

"And that's just one of them," a commercial airline chief executive remarked, filming the daring display on his phone.

"Imagine the sound when there are 15 of those jets, all fighting in the sky at once."

Tens of thousands of people descended on the opening day of the biennial Paris Air Show, the largest and oldest of its kind in the world.

More than 2400 exhibiters from 50 countries displayed their wares throughout a meandering maze of stalls, with halls filled to the brim with parts and prototypes.

A clutch of international pilots gathered around an ejector seat, while a young man wearing a virtual reality headset tried his hand at landing a plane.

Trade delegates and aviation enthusiasts streamed through the turnstiles, as serious-looking men in expensive suits lined up nearby to have their photos taken inside a Lego spaceship.

More than 100 aircraft of all shapes and sizes were spread across the vast grounds of Le Bourget.

Travelling journalists waited behind a red velvet rope for their first glimpse inside a new passenger plane, while high-flying corporate types grinned at the words "profit hunter" emblazoned on a private jet.

In a place where people barely blinked at multi billion-dollar deals being struck, nobody batted an eyelid as a pair of scantily-clad Russian acrobats pranced around a helicopter display.

Across the aisle, air force engineers teetered atop a camouflaged combat plane.

The week-long affair pulls in 350,000 visitors from across the world, including plenty of ordinary punters.

On day one, a group of friends with broad American accents wandered between jumbo jets, clasping plastic beer cups and giant hot dogs in the French summer sun.

But the first few days were dominated by dignitaries and industry figures.

Fleets of golf buggies ferried airline executives between rows of corporate chalets.

Inside the air conditioned oases, trays of canapes were on heavy rotation and chilled champagne flowed like water.

"I'm just going to stay here all day," admitted one Chinese visitor.

"Why would I want to be anywhere else?"

A divergence in fortunes between the world's dominant plane makers was on full display at the 2019 event.

Airbus was quick off the blocks in confirming orders for hundreds of jets, and unveiling a single-aisle aircraft capable of flying long routes.

Meanwhile, its rival Boeing was stuck playing defence over the company's 737 Max planes, with the jets still grounded worldwide after two deadly crashes.

With the 50th anniversary of the moon landing fast approaching, the commercialisation of outer space was also a hot topic, with former astronauts and NASA officials tackling the topic in panel discussions.

Commercial carriers from across the globe were also jostling to cut the ribbons on their new fleets of planes.

For a few hours on day two, senior executives and cabin crews from dozens of airlines came together in a stiflingly hot hangar for the presentation of consumer awards.

With World War I aircraft suspended from the ceiling above, they took turns collecting their gongs.

The swarms of buggies reappeared as soon as the ceremony wrapped up, dispersing attendees around the showgrounds.

Some airline chiefs then escaped the show early to explore the city of lights, while another fighter jet took flight.

As their limousines snaked through the exit gates, two Parisian police officers leant against their squad car, staring up at the sky above.

* Reporter travelled to International Paris Air Show courtesy of AirAsia.

Australian Associated Press