Cannes, France - Tom Cruise's film crew on his latest Mission: Impossible epic feared the star was about to die after he appeared to pass out on the wing of a stunt plane over South Africa.

The 62-year-old, who does his own stunts and was flying the biplane alone, was laid out flat on the wing after spending 22 minutes out of the cockpit – 10 more than safety guidelines allowed, his director Christopher McQuarrie told a masterclass at the Cannes film festival, where Mission: Impossible - The Final Reckoning is premiering Wednesday.

"When you leave the cockpit of the plane, it's like stepping onto the surface of another planet," McQuarrie said.

"The wind is hitting you in excess of 140 miles an hour coming off the propeller. You're breathing, but only physically – you're not actually getting oxygen," said the filmmaker, who has shot the last four movies of the franchise.

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"Tom had pushed himself to the point that he was so physically exhausted, he couldn't get back up off the wing. He was laying on the wing, his arms hanging over the front. We could not tell if he was conscious or not."

Cruise, a trained acrobatics pilot, had agreed on a hand signal to show if he was in trouble, McQuarrie said.

"You can't do this when you're unconscious," the director told an audience at Cannes, with Cruise sitting beside him nodding sheepishly.

To make matters worse, the plane had only six minutes of fuel left. But the star finally stirred.

"We watched Tom as he pulled himself up and stuck his head in the cockpit so that he could replenish the oxygen in his body and then climb up into the cockpit and bring the plane safely down to land.

"No one on Earth can do that but Tom Cruise," he said to rapturous applause.

Asked about how he dealt with the fear, Cruise pointed to the years of preparation that went into the movies, which he compared to the workings of "a Swiss watch."

But in the end, "I like the feeling [of fear]. It's just an emotion for me. It's something that is not paralyzing."

"I'm like, 'Oh, that's exciting'... I don't mind kind of encountering the unknown," insisting that "this is what I dreamed of doing as a kid."

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It was far from the only scare the pair had on the $400 million epic, the eighth in the franchise known for its dizzying set pieces and heart-stopping action scenes.

The movie, one of the most expensive ever made, had to struggle through Covid-19 lockdowns and two Hollywood strikes.

But the wait appears to be worth it, according to the Hollywood Reporter, which quoted critics emerging from the first press screenings calling it "astonishing," "jaw-dropping," "just insane," and the "best action movie of the summer."

The film is being released in India, Australia, and South Korea this weekend, with audiences in Europe and the Middle East having to wait until May 21 and those in North America until May 23.