Cold Equation / Live-Action Films

Cold Equations run in Live-Action Films.

• 633 Squadron: A Norwegian resistance member who knows about the operation is captured by the Germans. Ace Pilot Roy Grant has to bomb Gestapo HQ in Bergen before they can make him talk, and blow the whole mission.
• The trope is spoofed in Abbott and Costello Go to Mars. The spaceship has too much weight to take off so they have to leave behind...all the gorgeous space-babes that Orville is trying to sneak back to Earth.
• The Abyss: Bud and Lindsey are trapped underwater with one set of breathing equipment, which Bud is already wearing. Bud offers the gear to Lindsey, which would doom him. Lindsey presents what she calls "the logical option", which gives both of them a chance of survival: she drowns, and Bud drags her body to safety, and hopes she can be revived. Bud is the stronger swimmer, so Lindsey has to drown. Bud's initial response is "Fuck logic!", but he soon comes round.
• After the Dark is all about debating this trope, when a teacher sets the below-mentioned nuclear bunker scenario to his students.
• Alien (1979). After the xenomorph does some snacking, there are four crew members left.
  Lambert: I say that we abandon this ship. We get the shuttle and just get the hell out of here; we take our chances and hope that somebody picks us up!
  Ripley: Lambert, the shuttle won't take four.
  Lambert: Well why don't we draw straws then—
  Parker: I'm not drawing any straws. I'm for killing that goddamned thing right now.
• One of the pub crowd in An American Werewolf in London tells a joke about a plane full of U.N. representatives who need to lighten the load or they'll crash. Just tossing out the baggage and seats isn't enough.
  British Diplomat: God save the Queen! (Jumps out.)
  French Diplomat: Vive la France! (Jumps out.)
  American (Texan) Diplomat: Remember the Alamo! (Tosses out the Mexican.)
• Apollo 13, as in the Real Life incident, runs up against the Equation a few times, but the guys in mission control are able to ensure that Everybody Lives.
  • Once the explosion happens and the mission switches to "get them back home", the overarching concern is how they get three men to survive for four days in a lunar module designed to sustain two people for a day and a half — the biggest issues are power and carbon dioxide. Thankfully, with rationing of the former and a clever solution for the latter, there turns out to be enough resources to pull it off without sacrificing anyone.
    Kranz: I don't care what anything was designed to do. I care about what it can do.
  • The Equation does get alluded to aboard the Aquarius when it comes to the carbon dioxide level being too high. When the crew is first alerted to the problem by Mission Control, Haise doesn't believe it at first having gone over the calculations thrice. Haise eventually figures out where his math went wrong — he only calculated for two people, i.e., he forgot Swigert, who on a normal mission wouldn't have been in the lunar module.
    Swigert: Maybe I should just hold my breath.
• Avengers: Infinity War: This is what Thanos thinks he's doing with his 'kill half of all life' plan. In his backstory, he suggested killing half his species as a desperate plan to prevent an overpopulation crisis, but his plan was rejected and everyone but him died. So now he's decided to push the solution on the entire universe as much to prove to himself that it would work as anything. Avengers: Endgame shows the results of this logic: massive environmental damage, as population control does not work that way.
  • Avengers: Endgame, for its part, reveals that Doctor Strange, in pushing for the one timeline where Thanos was stopped, had to have known it would involve the Heroic Sacrifices of Black Widow and Iron Man.
• Bird Box. Melanie has to row a boat down the river with herself and the children blindfolded so they won't be driven insane by the Brown Note Beings. But to get past the rapids, one of the children has to remove their blindfold and guide her. Her son volunteers, but it's implied Melanie will force the Girl to do it instead. In the end Melanie can't bring herself to do it and tries to row unguided, causing the boat to capsize—fortunately they all make it to shore.
• Chariot. Operation Chariot is a secret government program to save valuable or useful people in the event of a massive attack on the United States. Those on the list are kidnapped from their homes by government agents, regardless of whether they might want to stay and die with their families.
• Destination Moon (1950). The rocketship loses reaction mass landing on the moon, so someone has to stay behind even after they've thrown out every piece of equipment they can unbolt. While the Science Heroes are arguing over who gets to make the Heroic Sacrifice, the Plucky Comic Relief sneaks outside and laconically tells the others to take off without him. Fortunately someone realises how to dispose of an extra piece of equipment so they can all return safely.
• Doomsday Machine features an absolutely bonkers zig-zagged version of the trope. The Earth has been destroyed, and the only survivors of humanity are the seven astronauts aboard the spaceship Astra, en route to Venus to establish a colony there. The oldest astronaut notices an increase in radiation, and calculates that it's not fatal—but at their current speed, it'll sterilize them all by the time they reach Venus. He also calculates that they can avoid this fate if they jettison part of the Astra, most of their equipment... and four of the crew members. He uses the ship's computer to calculate which of them should die, but before he can announce the results, two other astronauts get killed in an accident with the airlock. Sick of all this dying, the Astra's captain decides to disregard the calculations: they'll jettison everything except the crew, accelerate as much as possible, and hope for the best. But part of the ship gets stuck as they're jettisoning it, so Daniel and Georgiana (who had been marked for death in the original equation anyway) go to manually un-stick it, knowing they'll be left behind in the process. And then in one final, bizarre twist, Daniel and Georgiana survive by finding an abandoned but still functioning spacecraft from a prior mission to Venus, while the three designated survivors aboard the Astra all die when the ship is destroyed off-screen. ^note The final twist appears to be the result of the filmmakers having to cobble together an ending five years after the rest of the movie was filmed, without access to the original actors or sets. Daniel and Georgiana wear face-concealing spacesuits and barely talk for this entire sequence, to obscure the fact they're suddenly different actors.
• Dune (2021): Discussed when Duke Leto Atreides leads a rescue operation using 3 vehicles to try to evacuate 21 spice harvesters from an approaching Sand Worm. The vehicles each only have room for six more people, so Leto's men say they'll have to leave three behind. Fortunately, Leto's son Paul comes up with the idea to dump their shield generators, making enough room to save them all.
• Dunkirk: A group of soldiers conceal themselves on a Dutch trawler that's washed up on the beach. The tide comes in, but the boat doesn't float so they start arguing that someone should get off. Rather than ask for volunteers they try to force a French soldier off at gunpoint, then when a British soldier tries to object they declare he'll be next, because he's not a member of their regiment. It becomes a moot point because the trawler floats off at that point, but the German see this and start riddling it with gunfire, causing it to sink.
• The Final Destination films are built around the idea of people being slated to die at particular moments in time, and Death coming back for them (in the order in which they would've died naturally) when somebody, thanks to a premonition of a coming disaster, manages to save themselves and some of their friends. Final Destination 5 raises the idea that somebody marked for death can kill somebody else and gain the time that their victim had until they were fated to die. Nathan accidentally kills Roy and so gets passed over in Death's order, causing Peter, who is next in line, to try and kill Molly (the one person in their group who didn't die in Sam's premonition of the disaster) in order to claim the time that she had left. The ending reveals that Nathan only bought himself a couple of weeks, because Roy's autopsy revealed a massive aneurysm in his brain that would've burst "any day now" had he not died sooner — meaning that the film ends with Nathan getting squashed.
• Five Came Back: A plane has crashed in the jungles of the Amazon. The pilots fix it, but due to one of the engines being damaged beyond repair, the plane can carry only five people. Unfortunately there are ten people in the party, and it's a Cold Equation because the sound of drums has revealed that The Natives Are Restless, and they're headhunters, and they're about to attack.
• Flash Gordon (1980) has first Zarkov then Flash himself attempt to sacrifice himself to stop Ming. "It's a rational transaction; one life for billions."
• A Discussed Trope in I Am Mother with the Ethics course that A.I. robot Mother gives to the human Daughter she is raising in a bunker After the End. One of the questions on the practice exam is whether a doctor should let one of their patients die so that their organs can be donated to five other patients who need organ donors; if the doctor should save the patient but let the other five die; or if the doctor should let themselves die and give up their own organs for the patients. Daughter points out that sacrificing someone to save the others depends on the type of people they are, because it would be a Senseless Sacrifice if these people are murderers/bad people. Mother finds her answer interesting. This foreshadows The Reveal that Mother brought about the extinction event herself in the hope of raising more ethical humans under her guidance.
• I, Robot: Spooner was once in a car accident that almost resulted in both him and a young girl drowning in a river. The robot that first arrived didn't have time to save both of them, and chose to rescue Spooner because it calculated that Spooner had a 45% chance of survival while the girl only had 11%. Spooner doesn't seem to object to the notion that only one of them could have survived, but resents the robot (and all robots, by extension) for choosing to save him instead of the child, who did not survive.
  Spooner: That was somebody's baby. 11 percent's more than enough. A human being would've known that.
• Defied in the 2022 film The Ice Road. When a bunch of trapped miners start to run out of air, the Jerkass of the group stirs up dissonance in the group by trying to convince the rest to kill the miners who got wounded in the explosion that caused the cave-in (and they don't know if they will survive long enough for rescue even without the oxygen issue), but the leader of the group prevents a riot by pulling out a Zippo and threatening to blow everybody up with the methane that got trapped in with them if they take one step closer to the wounded. The rescue does come, but it cut it really close to the wire.
• The Imitation Game: Referred to as "blood-soaked calculus." After the team has cracked the German Enigma code, they realize that they can't act on every decoded message as the Germans will realize their communications are compromised and come up with a new code, prolonging the war. The decision is made to identify key German operations to counter but leave the rest alone, meaning that they will knowingly allow allied soldiers to walk into certain death in order to end the war more quickly and save more lives in the long run.
• In Interstellar, Cooper does a Heroic Sacrifice by detaching himself from the spaceship to ensure Brand's safe onward travel to Edmunds planet. Apparently, resources weren't enough for both of them to survive.
• The Last Days on Mars (2013). Campbell, Irwin, and Rebecca escape the Mars expedition base in the solar-powered land Rover, but as it's night the Rover doesn't have enough power to reach the landing zone where a Drop Ship will pick them up. They could walk the rest of the way, but their infected colleagues are coming after them and Rebecca has been wounded in the leg. She's a suspected Zombie Infectee, so Irwin suggests they leave her behind. Campbell refuses, but then Irwin remembers there's another Rover nearby they can use instead. The Take a Third Option trope is defied however when Irwin steals the Rover after unsuccessfully trying once more to persuade Campbell to abandon Rebecca.
• Lifepod (1993), set in an escape pod ejected from a sabotaged spaceship with limited air, food and water. Stating that their odds of survival would increase if one of them dies, a blind passenger tries to cut his wrists. He's actually the saboteur, and did it knowing the others would stop him.
• Marooned (1969 — made before the Apollo 13 disaster). The crew of an Apollo mission is left stranded in Earth orbit with no means to deorbit and a dwindling oxygen supply. Both an emergency rescue mission and a passing cosmonaut eventually help the crew, but not before Mission Control calculates that there's only enough left to save two of the crew. The mission's commander decides to sacrifice himself.
• The Meg: Jonas' career as a deep sea rescue specialist was spoiled by one when he was forced to decide between going back into a sunken nuclear submarine to save his best friends (which would've risked the lives of everyone down there), or return to the surface with the eleven people they had already rescued by then. He chose the latter, something he has never forgiven himself for even years later.
• Morning Departure: When Lt. Cdr. Armstrong discovers that there are not enough breathing sets to allow all of the crew to escape to the surface, he has to decide which of the remaining crew will be allowed to leave, and which will have to stay and wait for a rescue that might never come.
• Pitch Black: As the spaceship Hunter-Gratzner is Coming in Hot, its pilot Carolyn Fry starts to purge the cargo compartments. She then decides to purge the passenger compartment as well, but her navigator jams the airlock door open between themselves and the compartment to stop her. Much of her subsequent heroism is atoning for this action.
• This is evoked at one point in Red Planet, and one of the three still-alive crewmen decides to try and reach the old Russian module alone. The second crewman later dies protecting the third one.
• In the 1955 war movie The Sea Chase, John Wayne plays a German captain trying to evade British warships to get back to Germany, but one of his sailors is dying of gangrene poisoning. He could save him if he surrenders to the British, but he might be executed for war crimes thanks to their Token Nazi Crewmember murdering British civilians. The sailor hears their argument, smashes open a nearby pistol cabinet and shoots himself. Everyone rushes in to find the captain standing over the dead man holding the pistol
• Seven Waves Away (aka Abandon Ship) a 1957 film starring Tyrone Power, has the survivors from a torpedoed ship in an overloaded lifeboat. The captain tries to keep it afloat by ruthlessly throwing out those who can't survive and keeping those he feels can, making no moral judgments on who is worth saving. Inspired by the Holmes case (see Truth in Television).
• Starflight One (1983). Disaster movie involving a hypersonic passenger plane that gets stuck in orbit. Most of the passengers are successfully evacuated and the crew intends to try and achieve reentry, but they're running out of oxygen (the plane is only meant to pass through space for a short time before returning to Earth). A Corrupt Corporate Executive on the ground half-heartedly suggests that if there were three less passengers... The pilot demands this jerk be thrown out of the control room, and he is.
• The story of Stowaway (2021) is based on the Trope Namer, so the usage of this trope is not surprising. Being a realistic sci-fi, the spaceship is built with enough spare resources to bear the extra crew member, but the breakage of the carbon-dioxide scrubber results in oxygen shortage.
• Sunshine (2007):
  • Icarus II is damaged on its mission to reignite the sun, but the crew realize there is still enough oxygen to get there if one of them dies. A scientist who's lapsed into depression after indirectly causing the death of The Captain (and soon the rest of them even more indirectly) is an obvious candidate. All but one of the crew vote to kill him (their mission is, after all, to save the entire human race) only to find he's already killed himself. Or he was killed by a stowaway whose presence makes the whole question moot.
  • When there's only one spacesuit to cross back to the Icarus II, the other crewmen immediately start putting Capa (the only man who can fire the payload that is their mission) into the suit, ignoring the protests of their acting commander.
  • The Master Computer takes control of the spacecraft from the astronauts because it has been programmed to prioritise the mission. Exposure to sunlight has started a fire in the garden that provides their oxygen, so the computer turns the Icarus II so the heatshield is fully facing the sun, killing the captain who is on the heatshield doing repairs. The astronauts try to re-establish manual control to prevent this, but the captain refuses to give his permission.
• 3 Godfathers: Robert, Pedro, and the little baby they're carrying are desperately trying to cross a salt flat in the Thirsty Desert in order to reach the town beyond. When Pedro falls and breaks his leg, a frantic Robert suggests either fixing him a splint or fixing up a travois and dragging him. Pedro calmly points out that either way, they'll be too slow and all three of them will die of dehydration before they make it across. So Robert has to leave Pedro behind.
• Threads. After a nuclear attack devastates Britain, the Sheffield emergency council argue over whether to distribute food to people in irradiated zones who are going to die anyway, or horde it as currency to conscript the survivors to work on clean-up operations.
• In The Time Travelers, Councilman Willard points out that the four time travelers cannot be brought on to the rocket to Alpha Centauri because the number of passengers has been precisely established. Adding four extra people would require extra air and provisions, which would reduce the amount fuel they could carry, which would cause them to miss their rendezvous with the planet. The time travelers will have to remain on Earth and either find a way to survive in the caves or attempt to rebuild their time portal.
• In Titanic (1997), this is the reason given why the lifeboats don't go back to try to save those in the water after the Titanic sinks: if they go, they'll be mobbed by people trying to get on the boat, causing the lifeboats to sink and killing the passengers aboard them.
• The Transporter has one in the opening sequence. Frank is hired to be the wheel man for a bank robbery, with the express and very clear agreement that there will be three men at 254 kilos. The gang shows up with four men. Frank refuses to budge, since he has planned for a very precise amount of fuel to optimally carry three men plus himself and not one smidgen more. The gang's left with the choice of kicking out one man to make weight or sitting still and waiting to be caught. There's nothing tying Frank to the gang, so he's perfectly willing to cool his heels. Finally, the gang leader shoots one of the accomplices and throws his body out, at which point Frank springs into action and proves himself and his ways worth every penny.
• When Worlds Collide (1951). A rocket ship is built to escape The End of the World as We Know It, but it can only take forty people selected by a Lottery of Doom with the exception of some reserved seats, such as the jerkass financier who's funding the rocket's construction on condition that he be taken along. When the girlfriend of one winner has to stay behind he decides to stay as well, so it's arranged for both to go. Then the protagonist is also brought in as back-up pilot. Therefore when the rocket is about to take off the scientist who thought up The Ark idea stays behind and forces the financier to stay with him, so the rocket will have enough fuel.
• Woman in the Moon (1929). After a struggle punctures the oxygen tank, the two male crewmembers draw straws to see who gets to return to Earth on the rocket. The Dirty Coward gets the short straw and breaks down sobbing, so the hero makes the Heroic Sacrifice and stays behind on the Moon instead.