In Working Order

If the alien's transmogrifier has been captured--and was not destroyed in a huge explosion--you will almost certainly want to turn it on the enemy. This could, in principle, be difficult. Alien technologies are, well, alien, and it might be hard to figure out how they work, or do basic maintenance and troubleshooting, let alone repair major damage. After all, Americans have trouble figuring out how to operate a rice cooker with Japanese instructions, let alone an alien spaceship.

Luckily, a corollary of Ragnarok Proofing comes to the rescue. Captured alien technologies always work, and are usually very intuitive for humans to use. This is true even in emergencies, even after the working parts have been seriously damaged, and even after thousands or millions of years. Pretty handy, huh?

See also Black Box, Possession Implies Mastery.

"Justin: Luckily one of those aliens dropped this thing and I was quickly able to figure out how to operate their advanced technology... Justin: It's a switch."
 * Deconstructed in the novel Gateway by Frederik Pohl. Humanity finds a hollowed out asteroid orbiting within the inner Solar System. Exploring, they discover it contains almost a thousand ancient and abandoned faster-than-light alien starships of varying size, some working, many not. They find out how to make the ships go, but they have absolutely no idea how to direct them and can only select the preprogrammed destinations. They also have no idea how the ships work, how to fix them, what they run on or how much of what they run on is left. The 'prospectors' who take their chances on these ships for wealth and glory occasionally come back rich, more likely come back empty handed, often come back dead, or in most cases never come back at all. The corporation that runs the operations only makes this lethal lottery more dangerous with their futile attempts at 'reverse engineering.' Much of the novel concerns the underlying terror of not knowing where you're going, on a starship whose technology you can't understand.
 * The Mothership Zeta mission in Fallout 3. Your character can use the guns the aliens dropped, and their shock sticks, and even explode their various engines, dismantle their Death Ray and even fight another alien warship. And then in the end you get to keep the spaceship! You don't get to fly it anywhere else though (leave the DC Wasteland? Never!)
 * Like most weapons, alien weapons will degrade with use. Fortunately, they're just as easy to repair with spare parts (taken from spare weapons) as human-made weapons.
 * Averted (and explained) in Command & Conquer 3: Tiberium Wars. One of the intelligence reports for GDI details how one of the Scrin tripods was captured: after a commando had blown up one of its legs with plastic charge, an engineer moved in and established control over it, using a computer program originally used to decode the Tacitus back in Firestorm. It works just as easily for The Brotherhood.
 * In Gundam Seed, weapons designed for mobile suits of one side have energy and data interface plugs that can only work with Humongous Mecha of that side. Some mobile suits are built later during the series that have a "Universal plug" that can allow weapons of all sides to work with that suit.
 * In the Fantastic Four's battle with Galactus, the Human Torch retrieves a weapon called the Ultimate Nullifier, from another dimension and before the dawn of time, etc. It fits nicely in a human hand and is operated by a single trigger.
 * As seen later in Quasar, he was lucky the darned thing didn't eat him. It operates mostly mentally.
 * In Total Recall, the switch that vaporizes the frozen atmosphere of Mars fits nicely into a human palm, has no interlocks, and works immediately after a million years. (Apparently the aliens were not concerned that a pebble would fall on the switch...)
 * Handwaved in the novelization by having the system specifically set up by the aliens for the humans to use once they've reached Mars.
 * Interestingly, at least one of the mutated humans had a hand that would exactly fit the activator.
 * Miyazaki's Laputa: Castle in the Sky, though not involving aliens, uses the same trope.
 * There is an entire sub-genre of stories in which an alien spacecraft has been shot down and crash-landed, but it's still flightworthy, and an ace human pilot figures out how to fly it again...very very fast.
 * In Battlestar Galactica, the reboot. Especially ridiculous as said pilot was able to out fly another, albeit slightly less hotshot, pilot comprehensively and yet no one else could even figure out how to get the thing moving without her.
 * Just because it wasn't explicitly stated. Starbuck flies a craft that, not only was "alien", but designed to operate without a pilot at all.
 * In Independence Day. Here it has been studied for the past 40 years - but not by the person who piloted it. And the ones who did study it got the directions reversed. Note that the craft has a convenient joystick when the aliens could control a human brain by touch.
 * Funny. This troper thought that the scientists installed that.
 * No, it's pretty obvious that it was the original. What the scientists did install was a high-powered radio transmitter to interface with the Mothership computer (shown in the extended version), and that handy little nuke launcher.
 * More or less in Battlefield Earth. It's technically old Human technology being used by Primitive Screwheads After the End, not alien. But then, it's almost worse... At least alien ships would have the justification of being made by futuristic engineers for ultimate reliability and ease of use- not 20th century lowest-bidders targeting 20th century Air Force Academy graduates!
 * Stargate. Once reverse-engineered somehow, any tech can be used as-is, even the titular piece of Lost Technology from The Ark of Truth, which was buried for about 50 million years.
 * The reverse engineering does at least take a while, sometimes several years, and a lot of alien tech turns out to have a psychic component.
 * And then there's the fact that the Ancients had exactly the same body type as humans (to the point where your husband/wife could theoretically be an unascended/descended/whatever Ancient and you wouldn't even know), so it's perfectly logical that anything designed for them to use themselves could be operated by any human (unless it's genetically keyed, in which case it can "only" be used by any human with the ATA gene). Good thing they're friendly (read: don't give a ____ about anything that's not ascended), right?
 * Played in crossover fic XSGCOM. Humans are specialy designed to be able to use Ancient technology because
 * Averted in Tabletop RPG Cthulhu Tech: for the expressed purpose of avoiding this trope, the alien Migou design their guns and mecha to require no less than six limbs to operate.
 * In the the remake of The Tomorrow People, the kids use a crashlanded spaceship has headquarters. While it cannot fly, it can act as homing beacon for Tomorrow People, heal them when they nearly drown, enhance their telepathic abilities, and whip up the best orange juice known to man.
 * Subverted in Cowboys and Aliens. Zeke finds what appears to be an alien sidearm, and uses it to destroy a random alien object as a test. Turns out the sidearm is actually a welding tool, and the random object is an alien grenade. Its alternate modes of fire are also amusing.
 * Averted and yet played straight in the first season of the new Doctor Who. From a stash of alien weapons gathered by a collector of such items, all but one are hopelessly broken, and the Doctor identifies one as hairdryer. The last one is in perfect working condition, though, and doesn't even need fiddling with the sonic screwdriver to work.
 * Niven's Known Space stories also use this pretty heavily, but with a good justification: The Thrintun and Tnuctpin artifacts are all held within Slaver stasis fields, which prevents them from aging.
 * In the show Aquila two school kids find a small alien ship, with a dead Roman Centurion in it, it's perfectly tuned for humans but the downside is that its controls are in Latin, later they figure out that you can change the language to English thus making it a lot easier to control. So it's an alien vessel, tuned for humans, been underground for at least 2000 years plus however long it was before the Centurion found it and it can be configured for modern languages, neat.
 * In the X-COM series, it is in your best interest to quickly research alien items, and THEN this is in full effect. You can manufacture them after that, but why should you if you can just take them from the hands of dead aliens? Even so, some items like armor can only be used to research human-usable equivalents, and it's taken a tad far in some cases. For example, every alien enemy fought in-game that can carry weapons and grenades is at least vaguely humanoid, and certainly has an opposable thumb fairly similar to ours (and it works pretty well, so why should we be the only ones to evolve it?). The fluff is even explicit about the fact that most of them are genetically engineered and/or selectively bred to be more obedient than smart, so AK47 levels of simplicity to operate would be a necessity. Your troops still can't pick one up from a dead alien grunt and use it until they've been researched.
 * At least one fanfic Hand Waves this by claiming alien weapons were DNA-locked to their owners. What the scientists were doing was to add humans to the list of permitted users (and while they were at it, they also added iron sights), and the questionably-canon "Data Cannisters" suggest that the alien grenade had some weird psionically-activated arming system that nobody could figure out and which had to be stripped out and replaced with a mechanical timer.
 * UFO Aftermath takes this one step further: research descriptions suggest that the scientists have added a stock, a grip and a trigger to the plasma gun so that it can be used by humans. Also, alien armor won't work for humans due to their environmental systems (Reticulans need lower gravity and more oxygen) so they had to build that from scratch.
 * Similarly, the Wargot weapons in Aftershock require a little additional modification for human or cyborg use, as the Wargot inexplicably possess an additional 'finger' on their elbow-equivalents, in order to operate an additional trigger system. It's never really explained why, but it could well be an attempt to avoid this trope.
 * The mass relays and the Citadel itself in Mass Effect. Oddly,.
 * Justified, as the
 * Another example of this is
 * The existence of this trope is a plot point in the Halo series, with the Forerunner technology that apparently can only be used by humans.
 * Averted with Covenant weapons: While humans can use them, they never quite figure out how to reload the battery-powered ones.
 * Real Life: The US Air Force ran a program during the Cold War codenamed Constant Peg, which basically involved Soviet aircraft, primary of the MiG-21 and MiG-23 varieties, acquired from a number of sources (e.g. Egypt, which changed sides in the late 1970s) for analysis and pilot training. The pilots had to write their own checklists and one piece of advice was "You can touch the shiny switches, but don't touch the red or rusty ones". A number died in accidents.
 * Averted and then played straight (for laughs) on the pilot of Megas XLR. The Earth's last defense forces capture the Glorft's new superweapon prototype, the Avatar, and take some time to rebuild it into the MEGAS, which they can use. In the ensuing conflict, Megas is beheaded and then teleported back in time to the 1930s where it sits buried in a scrapyard for about 70 years. Coop has to rebuild the control panel from scratch, but he has no trouble at all interacting with partially alien technology from hundreds of years in the future, or adapting it to video game controllers or the dashboard of a Plymouth Barracuda. He even adds new weapons of his own design. Somewhat justified in that Coop is a Genius Ditz.
 * And subverted in that only Coop is capable of piloting MEGAS after all he's done with it.
 * Lampshaded in Wizards of Waverly Place episode "Wizard for a Day":


 * In the Kamen Rider Decade/Kamen Rider Double Crossover movie, Double takes control of a Super Shocker mammoth mecha simply by docking his modular motorcycle's front half into the mecha's forehead (and for extra points, that spot was previously occupied by a laser cannon).
 * In the Planet Hulk storyline, basicly the whole planet of Sakaar is built on this. Every piece of technology the natives have is salvaged from crashes and wreckage that's fallen through a wormhole. Subverted, though, in that quite a bit of it is beyond their ability to reproduce.
 * Lampshaded in at least one episode of Invader Zim. Dib was hacking into an Irken ship and said "I sure hope the Irkens happen to have the same Operating System as I do."
 * Somewhat inverted in Galaxy Quest: the aliens designed their technology after what they saw in a low-budget TV show because they thought it was real, then track down the actors to help them use the technology when they get into some trouble with another alien race.
 * Their pilot learns to drive the ship by... watching clips of himself, as a kid actor, pretending to drive their ship. The friendly aliens built the controls intuitively matching what they thought he was doing, and didn't bother making a manual. (These are also the aliens who built a fully functional black box Deus Ex Machina without having the slightest idea what it did, or even what it was supposed to do.)
 * Warhammer 40000: Da Orkz are the master of this trope. They can pretty much use anything made by other species. An example of this would be the Looted Leman Russ Tank, originally belonging to the Imperial Guard. Subverted, though: it's not that da orkz understand how to operate it, they work because da orkz simply believe that they work. Which also means nobody else can use anything made by da orkz, because they shouldn't work at all.
 * Timothy Zahn's Spinneret book deals with a human colony planet with no metal whatsoever. It doesn't take long before it's discovered that alien machinery has been sucking up all the metal for purposes that become clear later. Said machinery is at least a hundred thousand years old, but works almost perfectly - a few ancillary machines have seized up, but the bulk of the system does its job as well as it used to when humans were still busy carving stone tools.