�����ԹϺ���

Hollywood has a sadistic streak when it comes to the wilderness. If the industry sends its biggest stars into the woods, it usually submits them to the most horrific, bone-crunching, organ-twisting experience possible, including amputation (), bear mauling (), cannibalism (), insanity (), and poisoning (). For the silver screen, the conscience-clearing, horizon-gazing moments of Zen that most of us associate with outdoor recreation seem to be the exception (), not the rule.

This is the canon that The Mountain Between Us will join when it hits theaters on Friday. The part-survival, part-romance film was directed by  and features two massive stars—Idris Elba and Kate Winslet—making it this year’s most-hyped addition to the genre. It was filmed mostly on location above 10,000 feet in British Columbia’s Purcell Mountains. The extreme environment, just west of the Canadian Rockies, made for what Abu-Assad told �����ԹϺ��� was one of the most harrowing film shoots of his career. He had a team of wilderness experts and a helicopter on hand to help him keep the cast and crew alive. But the characters’ actions on camera didn’t always adhere to best survival practices. After all, playing it safe often doesn’t make for the most riveting drama.

And riveting the movie is, if a little predictable. It opens with Winslet’s character, a hyperactive journalist, rushing home to her wedding, and Elba’s character, a stern-faced brain surgeon, headed to perform a life-saving operation. After finding out their flight from an Idaho airport is canceled, the strangers agree to split commission on a two-seater plane to get them across the Rockies to their connections. Midway through their trip, the pilot dies from a stroke, and they find themselves surviving a heart-stopping crash into Utah’s Uinta Mountains. Suddenly, they are stranded alone on a snowy peak, bruised and shaken up, fashionably if not practically garbed, and with only a few almonds and a lot of snow to suck on.

This is where the survival fun begins. In the interest of keeping our unlucky protagonists honest, we took a search-and-rescue expert to a screener of the film to spot-check their wilderness decision-making. Art Fortini is vice president of the and a former president of the in the San Gabriel Mountains outside Los Angeles. Here’s what he has to say about how Winslet and Elba fared. (Spoiler Alert: the movie's plot is discussed in depth below.)

Formulate a Plan

After surviving the crash, our two heroes start smart. “You want to formulate a plan. Don’t just run off,” says Fortini. “Take stock of your situation, the equipment you have, and where you are.” It’s no surprise that Elba’s steely surgeon character knows this. He immediately and ably tends to an unconscious Winslet’s busted leg, assesses their bleak surroundings, and stays sheltered in the hull of the plane. What then? He keeps busy by organizing supplies and checking injuries, which likely helped keep his stress at bay. Nice work, doctor.

Make Yourself Visible from the Sky

“You want to make yourself big from the air,” Fortini says, noting that Elba wisely spelled out “S.O.S.” in the snow after making sure Winslet was in stable condition. “You should make the letters as big as possible. They’ll be coming in helicopters or a small fixed-wing; they’ll see it.”

Build a Fire (But Be Careful)

Elba builds a small fire in the hull of the plane—something worth doing, Fortini says, but very cautiously: “Depends how much of a draft you have. If you have a yellow flame, you’re creating a lot of carbon monoxide, and even if you don't, you still have to make sure there’s enough airflow.” We’ll give Elba the benefit of the doubt and assume there was enough fresh air coming into the hull.

Stay Put

By far, the most important rule for when you’re stranded in the wilderness—whether on broken skis or in a crashed plane—is staying put. It’s a tactic Winslet and Elba completely botch. Winslet wakes up panicked and immediately insists on leaving the mountaintop to find a road. “They had shelter; they left it. Not a smart move,” says Fortini. “They definitely had people waiting on the other end. The authorities will get notified, and a search will ensue. We usually find you.” Even if the emergency transmitter on your plane is disabled in the crash, the aircraft will be on some airport’s radar in the lower 48. And that radar will have recorded where they went dark—even if there’s no mayday transmission and the plane veers far off its flight plan. According to the Federal Aviation Administration, it takes only around seven hours on average to find a downed plane with a functioning electronic locator transmitter (plenty of time before dehydration kicks in), and 40 hours with a busted one (a little sketchier, but if you have water, you’ll still be okay).

Don’t Walk on Ice

Another big, technical challenge the pair face is hypothermia. At one point, they unwittingly walk onto a sheet of ice covering a river that is hidden beneath snow. Winslet falls through, and then Elba tries to step out onto the same ice that failed to support his willowy companion. There are a number of things to keep in mind in this situation, Fortini says: “It is a profoundly bad idea for Elba to walk out onto the ice to try to rescue her because in real life he’d end up in the water, too. If you must, you want to crawl out, so your weight is more evenly dispersed, and move carefully. Tie yourself to an anchor on land, if possible.” Winslet, to her credit, actually got dunked into a frozen British Columbia river, according to Abu-Assad—with a wetsuit and temporary barriers protecting her from the cold current, that is. Still, she one-upped her Titanic co-star Leonardo DiCaprio’s icy death in an .

Stay Warm

Elba gets absurdly MacGyver-y when treating Winslet for hypothermia, fashioning a saline IV out of household items he finds in an abandoned cabin. (Which they eventually leave, again violating the “stay put” dictum.) An IV in the backcountry is a medically dubious strategy, and maybe not advisable for anyone who isn’t a brain surgeon like Elba’s character, but something like it could plausibly have saved Winslet’s life in a real-world version of the same scenario. If you’re not a medical expert with an IV, stick to stripping off wet clothes, getting in a sleeping bag, and placing bladders or bottles filled with hot water on the major arteries in your neck, armpits, and groin.

“You get dehydrated from hypothermia. If you heat up too quickly, especially in the arms and legs, which aren’t critical to survival, your blood vessels dilate, you’re short on fluids, and the blood you need in your core goes to your arms and legs,” says Fortini. “Elba may have avoided that by injecting enough fluid into Winslet's arm, but there still might not have been enough to sustain the vital organs. The other key is you want the IV fluid to be isotonic—the same amount of salt as in your blood. If it’s just freshwater, you might just pee it right out. You could lose sodium and get hypernatremia, and then you’re in a world of hurt.” (While careful to note that he is not a doctor, Fortini is a rocket scientist by day, when not doing volunteer SAR, so he’s still smarter than you.)

Stick Together

Do the pair eventually get rescued? We won’t spoil it. But we will say that Fortini thinks in real life after leaving the crash site they would have had a sliver of a chance to beat hypothermia and starvation and make it out alive. The best survival choice they made in the entire movie, he adds, was to stick together.