How Amazon’s The Aeronauts pulled off its terrifying balloon-climbing action sequence

Months ahead of the release of Tom Harper’s old-school adventure-drama The Aeronauts, the conversation swirling around the film had more to do with release strategy than actual content. Amazon Studios, which funded the film, initially planned for an exclusive IMAX rollout ahead of a wide theatrical release. But in America, at least, that plan was scrapped in favor of a smaller rollout, and a release to Amazon Prime Video in time for the holidays.

That’s an unfortunate fate for a film that clearly plays best on big screens. The Aeronauts’ story, about a pair of pioneering 19th-century balloonists played by Eddie Redmayne and Felicia Jones (and based on a variety of real-life explorers), is expressly shot to draw wonder from the scale of the wide-open sky. It’s a lush, gorgeous film with strong acting and breathless action. The film’s currently playing in theaters — in some American markets, it opens in 70mm on Dec. 20, as well as on Amazon, while Britain is getting a wider-scale release — but its action will also play well for families watching at home over the holidays.

Ahead of the theatrical run, Polygon spoke to Harper about some of the film’s stunts and effects, the difficulties of location scouting for terrific clouds, and about the film’s rocky release.

Polygon: What was behind the scaled-down theatrical release for the film?

Tom Harper: I think it’s just changing times. I certainly know, as a parent of two young boys, it’s hard to get to the cinema. I watch a lot of films and TV through streaming services, and through traditional TV as well. Aeronauts is designed for a big-screen experience, and I hope people choose to see it on the big screen. At the same time, I know that’s not always possible, and it’s expensive, and people are busy. So the most important thing is, I want audiences to see it, however they choose to see it.

There’s a variety of ways you can choose to see it, even in the theaters — in a normal cinema, in IMAX, we’ve got a 70mm print of it. They’re all slightly different experiences. That’s the day and age in which we live. We have all these choices, and ultimately, I think that’s a good thing. But still, if I got my way, I would control exactly how everybody sees everything. Even if they’re watching on TV, I’d go around to their house and put their TV settings exactly how I want them to see it. [Laughs] But you have to give away some of that control at some point, and accept that people are going to make their own choices.

Photo: Amazon Studios

I’ve interviewed people who’ve made Netflix films and are just excited about the platform’s international reach. Some people feel getting their film to a hundred countries at once is better than a big-screen experience. How do you personally balance that choice?

That’s a very hard question to answer. I think it’s pinned, frankly, on the film as well. Amazon enabled us to make this film, and I don’t think it would have been possible to have it financed by a conventional studio, because this is not based on an IP, it’s not a superhero movie. It was quite an original, ambitious, expensive movie to make. So if I’m really honest about it, I’m just happy and delighted that I got to make this film, and that it’s going to be seen by so many people. It didn’t follow the exact path I would have chosen, but it never does. Everyone’s going to get to watch it worldwide. More than 800 million people will have access to it for Christmas, and that’s a wonderful thing.

Is it still getting a much broader release in Britain?

It is. It’s getting a full theatrical release there. I think that actually came down to a contractual — I think the UK bought it first, and that’s why they were able to retain it in theaters. Are there differences in the audiences? I do think there are. Clearly there are differences in audiences all around the United States, let alone the UK. But when we’ve tested movies in the UK and the US, they come out surprisingly close. I think our sensibilities are more similar than I would have imagined. Films like that you think are extensively very British, like Downton Abbey, for example, are doing incredible business in the US. So I think our tastes are similar.

Was the film shot on IMAX cameras?

We didn’t actually shoot in IMAX. We shot in dual aspect ratio, on 65mm cameras. There were various artistic reasons for doing that, but it came down to a creative decision as an instigator, rather than a business decision. We wanted it to feel like the story was opening up when you got into the sky. That will be consistent on the Amazon Prime release, because TVs are mostly built for the 16:9 aspect ratio nowadays. Everything we shot on the ground is is 2.39:1, and then when you go up into the air, it opens up to 1.85:1. So that actually transposes to Amazon Prime very nicely. And if you see it on IMAX, as you can in a few places in the US, the UK, and in China, it’ll be replicated there. And the 70mm print is a slightly different aspect ratio. So again, there’s a whole variety of different formats you can choose.

The film’s crispness and color are particularly striking. What was important to you in creating the film’s look?

We were looking for the immediacy of what it would be like to be up in the atmosphere, and what it must have felt like to them that first time. All our choices came down to trying to make it feel as real as possible. So we did shoot a lot of the film for real, with the actors in a balloon. We tried to use as much real footage as possible. For example, we shot all the background plates in helicopters in South Africa and New Orleans, trying to get the best cloudscapes. Even when they’re going through the storm — we obviously couldn’t put Eddie and Felicity in the middle of a thunderstorm in a balloon. But we did pour enormous amounts of water on them, and throw the balloon around. And we did put the cameras into clouds. Where we couldn’t do it for real, we tried to replicate events as closely as we possibly could.

What’s involved in location scouting for clouds?

The most ridiculous amount of planning and stress. Even though the film is about learning to scientifically predict the weather, we’re still not that good at predicting the weather. It’s not an exact science, particularly long-term weather forecasting. And if what you want is a great big storm, that’s a really hard thing to do. We shot all that stuff on what’s called an array camera. You shoot 360 degrees in a helicopter. They’re very specialist cameras. To get that many of those cameras into one place, and get the right helicopter and gear, those have to be shipped from all over the world. You have to know where and when you’re shooting weeks in advance. So you’re looking at the long-term forecast, and you go, “Okay, there’s this place in South Africa that’s very good at a certain time of the year for taking the moisture from the sea, funneling it up a mountain, and producing these great billowing towers of cumulonimbus clouds.” We used a lot of experts.

What else gave you headaches on this film? What was the hardest part to get down?

Flying the balloon with the actors was the hardest thing to to orchestrate. Usually, when you get in a balloon, it’s just the pilot, the balloon, and the passengers. You check the weather a couple of days in advance, and you pick it up and you go. But with filming, there are so many more variables. You need the cameras and the catering, the stunt people and the health and safety people and insurance getting sorted. That’s a huge amount of planning and mobilization when you don’t know what the weather will be like. It presented huge challenges. But we did it, and I think the film really benefits as a result. If we hadn’t filmed real balloons, I don’t think it would be the same experience.

Photo: Amazon Studios

Who do you go to these days to build a giant weather balloon from the 1800s?

There aren’t many people! You need six months’ lead time to build a balloon. And because of the nature of getting films financed, it’s quite hard to get all the money that far in advance. We went to someone called Per Lindstrand, an aeronautical engineer who flew with Richard Branson. They flew around the world together. We went to him, and he built us a period gas balloon, I think the first netted gas balloon that had been built in 50 years, or something like that. It was absolutely wonderful just seeing it, inflating it, and taking off for the first time. It was unbelievable.

Was there just the one balloon?

Yeah, just the one.

Films are so used to having redundancy in props, in case something goes wrong. Was that as nerve-wracking as it sounds?

We were confident in what we were trying to do, as much as it was logistically challenging. This is all tried and tested technology, and we were working with real experts who knew what they were doing. And the equipment is incredibly resilient. You know, to this day, they still use wicker baskets for balloons, because they’re just the best. They absorb the impacts the best, and they bend and shift. We had one balloon, but we did have three baskets, and duplicates of various bits of the equipment. But also, it’s not like a helicopter, where you’ve got thousands of working parts for things to go wrong. It’s literally a big balloon, and if you get a hole in it, you sew it up. It’s not rocket science. The science is genuinely “fill it with gas, throw out sand to go up, let out gas to come down.” That’s it!

For the sequence where Felicity’s character Amelia climbs up the side of the balloon, I understand that you used a stunt person and shot that sequence in the air, with her actually making the climb. What was it like shooting that sequence?

Really fun. [Laughs] The stuntwoman’s name is Helen Bailey, and she’s fearless. I’d seen a picture of someone standing on top of a balloon, so I knew it was possible. I didn’t know if it was possible for us, and to insure it. I think the last time someone did it, they had a parachute. We did it on harnesses. She did it three times, with me in a helicopter filming, and it was amazing.

How much time did you spend in helicopters on this film?

Too much. They give me the heebie-jeebies. Again, they have thousands of moving parts. You have one pilot, and if they have a heart attack, or something goes wrong with the equipment, you’re dead. People crash in helicopters all the time. If my pilot had a heart attack in a balloon, I’d give a damn good go at landing it, you know? You let out some gas, you throw out some sand. I reckon I could do that! I’m not saying I’d do it well, but I could get myself down! Whereas in a helicopter, that’s it! So yeah, I try not to go in helicopters wherever possible.

The characters here are amalgams of different historical figures, and the balloon trip is an amalgam of several balloon trips. What was important to you to preserve from the historical record?

The essence of the wonder of flight, and what it meant for these characters to go up in the balloon. Really what I found most inspiring in reading about these characters was the genuine desire to see the world differently, and to advance humans’ knowledge of the world. They went to extraordinary risks to do that. I find that really inspiring. There are so many remarkable things we can achieve as humans if we work together, and sometimes that’s forgotten about. We do have great challenges, but it’s also important to celebrate the great things we do in the pursuit of improving everybody’s lives. I know that’s a bit lofty.

Eddie Redmayne has played a lot of determined but fragile nerds, and Felicity Jones has played a lot of tough but vulnerable women. Were there specific roles you’d seen them in that made you want them for this film?

Yes and no. The reason you call someone for a role in the first place is because there are aspects of their their work or their personality that you think will transfer to your character. With most directors and companies, most anybody, you can see a pattern in their work. I think that’s true of Eddie and Felicity. But I do think there are things in this film that pushed them. Some of that’s character-based — two actors in a pretty large-scale action movie, basically confined in an 8-foot-by-8-foot space is an immense challenge, and it relies on the chemistry between them. I think they really enjoyed working with each other, daring each other to take risks, and pushing each other. And I think you you really get that in the film. Can you maintain an audience’s focus and keep it compelling over 90 minutes in such a small space? Not many people could do such a great job of that.

The ice on the balloon during the climb to the top is one of the most striking effects in the film. How did you achieve that look?

It’s like you want me to tell you how we did a magic trick! It’s actually mostly wax. There’s a company called Snow Business, and they specialize in ice and snow. They’re very successful. They do it for all the movies. We had very specific needs, so we experimented with different levels of ice and sparkle.

As with so many movie scenes, it starts off with getting the real thing and analyzing what it looks like. We took their clothes, made them moist, and froze them to see how ice crystals would form on them. Then it’s, “Let’s take those pictures of that. Now how can we recreate that in a way that’s sustainable, and will match continuity? How can we create that with resins and waxes?” Felicity had 19 different versions of her costume at different stages, and we’d never be able to get those costumes to freeze the same way every single time. So we had to be able to maintain the consistency with artificial ice. It was the same with the balloon — we started with pictures of real balloons and what high-altitude flights do to different materials, then analyzed them, trying to recreate those effects.