Motion-capture apes overran cineplexes this year. Photo-realistic animated worlds teemed with fighting pandas and an adventurous young reporter. But one of 2011’s most jaw-dropping sequences comes courtesy of the human special-effect himself, Tom Cruise, and the craftspeople behind director Brad Bird’s Mission: Impossible — Ghost Protocol. In it, Cruise’s spy Ethan Hunt and his squad (Jeremy Renner as Brandt, Paula Patton as Jane Carter and Simon Pegg as Benji Dunn) find themselves in Dubai’s Burj Khalifa — the world’s tallest building.

Complications force Hunt to travel several storeys above the team’s 119th floor command centre — from outside the building — using electronic gloves that allow him to climb glass. The dizzying experience is made all the more vertigo-inducing by being shot in IMAX. And, yes, that really is Cruise doing the climbing.

Here’s a breakdown of how that scene came together, with script excerpts by Josh Appelbaum and André Nemec.

Gregg Smrz, stunt coordinator: We were in meetings, and they said, “Tom’s not going to climb that building. The studio will never allow that.” I said, “Tom’s going to climb the building, I guarantee it.” When you’re on top and you look out, people are going to think it’s CG [computer-generated], and it’s not. You have to see it to believe it.

BURJ KHALIFA: 119TH FLOOR

A window panel is removed and pulled inside the room by Brandt and Benji. Ethan picks up the gloves.

Tom Peitzman, co-producer, visual effects producer: Special mounts had to be made for the 65mm IMAX cameras, special safety had to be put in place, because in a building that’s 800m tall [2,723 feet], you couldn’t run the risk of anything falling. Being in a building that high, it almost gave you the sense you were in an airplane, watching Tom Cruise outside, actually doing it.

Tom Cruise: We were dealing with a lot of issues — not only the height issue but also the temperature issues and the winds. It can get so hot up there that it could burn me, so we had to really play with different kinds of rubber, different kinds of materials.

Smrz: We rehearsed in Prague and never rehearsed in Dubai. We flew into Dubai and climbed the building. Kind of like a military operation, where they’re gonna go in and rescue the hostages; they’ve never been there, they rehearse on a set, then they go in there. The only difference was, Don’t Look Down.

Ethan steadies himself on the glass, and gets his first real feel for the gloves — the only things keeping him from a 2,000-foot plummet.

Gary Rydstrom, sound designer, sound re-recording mixer: The sound of that scene hinges on the gloves Ethan’s wearing. You have to believe they’re really going to hold him up on the outside of the building. The key we found that made it natural and believable were these thumps from an MRI machine. They make these magnetic thumps... an electronic sound, a sense of power.

Ethan climbs. Stops. He turns to see a massive sand storm, several hundred feet high, racing toward the city.

Mike Meinardus, special effects supervisor: Believe it or not, when you get to 147 floors, you’d think it would be really windy, but it was completely, most of the time, still. So we made a special 120mph wind machine, custom-built, that went on an arm that stuck outside the window, to blow on his clothes and hair.

BURJ KHALIFA: 130TH FLOOR

Ethan fumbles the laser cutter. As he tries to catch it, he inadvertently twists his right hand — disengaging the glove. And Ethan falls!

Peitzman: That was done on the building, 154 storeys up. I remember [Cruise] wanting to do it countless times because he thought his timing wasn’t right. I’ve got a lump in my throat the whole time he’s doing it.... That’s Tom doing it. He’s literally falling two-and-a-half storeys.

Smrz: I can only imagine how sore he was. He never complained. He would hang up there for hours. He climbed, I want to say, five days in a row! As far as bruised ribs, there’s just no way around it.

Ethan charges out the window, dangling from a length of server cable, running down the side of the building.

Peitzman: In one shot, we’re looking up, he’s running toward us, he jumps over the camera and then is running down away from us. I’ll never forget lying on the platform, watching Tom running down directly at us, 60 storeys above us. It was unbelievable.

Ethan runs along the side of the building — in the opposite direction — swinging himself like a pendulum…. Ethan lets go … arms outstretched, he reaches for the opening [back into the command centre].

Cruise: Some of the crew couldn’t even go on the floor [of a room where the window had been taken out] just because of the height issue, it was too much for them. When I’m swinging from the building, I have crosswinds, and, when you see the shot, you’ll see that I’m actually flying.

Smrz: I think it was 1,717 feet. I said, “There’s nowhere to attach a cable. I can send you out, but once you’re out, you’re coming back just as hard.” He was impacting the building pretty hard as it was.