What’s bright pink and will play a crucial role in a $500 million battle for your attention on holiday flights?

“Barbie,” the movie that ruled the summer, is now ruling the skies. It’s no accident it is playing on American, United, Delta, Southwest and other major U.S. airlines. It became available in time to add it to their December lineups, and they pounced.

Holiday classics like “Elf,” beloved action franchises like “John Wick” and binge-watching favorites like “Succession” aren’t just in-flight entertainment. Airlines see them as tools to make you love them a little more.

Gone are the days when carriers showed a single movie to a plane full of passengers from tiny monitors under the overhead bins. Today they have teams carefully curating the choices we have when we fly. Airlines worldwide spend an estimated half a billion dollars a year on movies, television shows, live TV, podcasts and music, according to Anuvu, which helps United, Southwest and other airlines select the right mix of content.

People won’t book a flight because “Barbie” is showing, but they will book if they think they’re getting a good value, says Mark Muren, managing director of product, identity and loyalty for United. That’s where a primo mix of seatback-screen options comes into play.

Airlines take this question seriously. In a major about-face, United is outfitting all of its planes with seat-back screens. They are now on about half of its fleet. The airline took pricey seat-back entertainment systems off planes years ago as more travelers brought their own devices. United Chief Executive Scott Kirby has said the screens will make passengers “pick United more, and more often.”

Delta already has seat-back screens on most of its planes. JetBlue Airways built a business around screens at every seat when it began flying in 2000. Southwest has no screens, and American only has them on long-haul flights. Both still offer robust entertainment options for travelers to watch free on their own devices.

Delta says 80% of its passengers interact with the seat-back screens, higher than its mobile app. Movies are tops, followed by 18 channels of live TV and series like “Yellowstone.”

Movie nerd nirvana

Ekrem Dimbiloglu, Delta’s managing director of in-flight entertainment and connectivity, oversees a team of five employees. Their job is to devise the best mix of entertainment options each month for as many fliers as possible. The airline features about 1,000 pieces of content on its flights, including 300 movies. It changes 20% to 25% of the lineup every 30 days, in part so frequent fliers don’t get bored.

Delta Studio employees keep an eye on new releases a year out and attend film festivals like Sundance. They have had their eye on “Barbie” for about a year. Dimbiloglu calls the airline’s staff movie expert a savant.

“You can tell her Ryan Reynolds and she can tell you every movie he’s been in, what year it came out, how the movie performed,” he says.

Being a movie or streaming buff is only half the equation. The people on the team also must know how to mine Delta’s data to get a vibe on fliers’ tastes.

“It’s not [about] what they want to watch,” he says. “They need to understand what our customers are consuming and want to consume.”

Muren says the people on United’s in-flight entertainment team tend to be artistic, into pop culture and experts at analyzing customer data.

“It’s definitely a part of the airline business that is not super airline-y,” he says.

Picking the movies is the fun part. The hard part comes at the end of the month when technicians have to make sure they get on each plane. Manually. At Delta, that means boarding 840 planes with devices preloaded with the content, usually overnight.

Now showing

Blockbusters like “Barbie” are no-brainers. People who haven’t seen them are happy to find them and people who loved them are happy to rewatch them. Think “Top Gun” and “Top Gun: Maverick.”

“It’s not a big emotional commitment to watch it,” Muren says. “Lots of points during the movie, you can be semi-distracted.”

Romantic comedies are also popular. “We see a lot of grown men watching chick flicks on planes,” Muren says.

TV shows popular at home are popular on planes. Right now, that means “Yellowstone” and its spinoffs, “1923” and “1883,” “Abbott Elementary” and even “Chernobyl,” among others.

The real joy for Muren and Dimbiloglu comes from discovering the gems: lesser-known films and shows that passengers come to love.

“People will take time on a plane to go deeper, explore some genres they might not explore at home,” Muren says. He says some of the best movies he’s watched on planes were new to him. They include “Beautiful Boy,” a 2018 drama starring Steve Carell and Timothée Chalamet.

Dimbiloglu puts “Past Lives,” a romantic drama starring Greta Lee, in this category. Delta knew it had to have it on its flight after it premiered at Sundance in January, he says. It’s been a hit. (It also scored five Golden Globe nominations this week.)

Indie films and TV shows are a big trend in in-flight movie-watching right now, says Estibaliz Asiain, senior vice president of media and content for Anuvu.

“All these movies that are not mainstream are suddenly becoming very big,” she says.

Just because the airlines want a movie doesn’t mean it ends up at your seat. Netflix shows aren’t available on planes, unless you download at home on your own device.

One 2023 blockbuster you won’t see on planes, at least yet, is “Taylor Swift: The Eras Tour.” The movie, released in theaters in October and available to stream starting Wednesday, isn’t on any airline’s coming movie schedule, at least publicly.

“That’s one of those opportunities that my team is actively looking into,” says Delta’s Dimbiloglu, who calls himself a big fan of the singer. “If we can have it on board, we would like to.”

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Write to Dawn Gilbertson at dawn.gilbertson@wsj.com