http://tvtropes.org/pmwiki/pub/images/ventilation_shaft.jpg
[[caption-width:217:[-Why this trope doesn't work in RealLife very often: most ventilation shafts aren't people-sized.-] ]]

->''2. My ventilation ducts will be too small to crawl through.''\\
-- The EvilOverlordList

->"Oh yeah, no one would think of looking for us in THE VENT!"\\
-- '''Cale Tucker''', ''TitanAE''

->"Now I know what a TV dinner feels like."\\
-- '''John [=McClane=]''', ''DieHard''

It's the only move on the part of a villain that's stupider than LockingMacGyverInTheStoreCupboard (or any room with [[BedsheetLadder a bed]]). When heroes find themselves trapped in a room with all doors and windows locked, the quickest exit is always through the ventilation duct. Covers require little or no effort to remove, openings are always within reach, they're always able to support the weight of a person even though they were only designed to carry ''air'', they are wide enough in diameter to easily allow a human being to pass comfortably through, are totally soundproof, and there's never a lack of light or chance of getting lost unless the plot calls for it.

Air vents also work excellently in reverse for breaking ''in'' and infiltrating a facility, as well.

You'd think the bad guys would eventually learn to design thinner air ducts, or post guards around the openings instead of at regular doors, or line their ducts with barbed wire and broken glass. It even appears near the top of the EvilOverlordList. At least some are smart enough to equip their prison with a surveillance camera, which the hero [[InsecurityCamera simply has to smash]] before making the getaway.

In the event there are no convenient air ducts available, you may be forced to take the AbsurdlySpaciousSewer. TheAlcatraz ''always'' has at least one or the other.

On some occasions, because of the fact that a woman is crawling along a surface and the camera is pointing along the shaft, you [[MaleGaze can get an "interesting" view]].

This is practically a DiscreditedTrope by now, and requires some effort to [[JustifiedTrope justify]] if it's to be used seriously. Which is why it's such a shock that [[TruthInTelevision it's actually happened at least once in real life]]. Frank Morris and his accomplices escaped from Alcatraz by breaking out the grills in their cells and climbing through a maintenance corridor, up to the large ventilation duct that led them to the roof. This escape was later reproduced by ''{{Mythbusters}}''. However, on another occasion, ''{{Mythbusters}}'' did test more standard metal ducts, such as one would find in most buildings, and found climbing around in them impractical at best, along with being very noisy and certain to attract attention. (At least, if you've got magnets attached to your hands and knees....)

One area where the trope isn't discredited is the world of VideoGames: Expect almost any game set inside a complex to contain an ample supply of vents, many of which mysteriously just connect two rooms with no fans, grates, branches, or actual ''ventilation''.

Some large universities (MIT and [=Caltech=] in particular) have longstanding "steam tunnel spelunkers" clubs, who often use air ducts (among other things) for exploring, getting around campus quickly, or pulling off pranks. Readers of this trope should be advised that [[DontTryThisAtHome this is *extremely* dangerous]], not to mention illegal -- steam tunnels are usually hot, cramped places that are frequently criss-crossed by scalding-hot (badly-insulated) piping, and explorers face trespassing charges (and possible academic sanctions) if they're discovered within.

However, most attempts to sneak in or out via air duct aren't very successful since people tend to be fairly large and ducts tend to be fairly small. There have been numerous cases where enterprising criminals have attempted to rob a store by sneaking through the ducts end up getting stuck. The usual ending is the embarrassed criminal being rescued by the fire department and is promptly handed over to the authorities.

However, air ducts sometimes need to be large -- very large -- so there is truth to this trope. In many underground mines, more tons of air are moved per year than ore, and ventilation systems are massive. The tunnel under the Hudson River was only made possible by the construction of a custom ventilation system on a scale then unprecedented. Underground settings require massive ventilation passages - including, in mines, entire shafts cut solely for the purpose of providing ventilation (as an extra layer of safety, the vent shafts are designed to double as secondart emergency exits, in the event that the main tunnel is blockedby a cave-in or otherwise inaccessible).

----
[[foldercontrol]]

!!Examples

[[folder:Anime & Manga]]
* ''NeonGenesisEvangelion'': Asuka, Rei, and Shinji were forced to use this route to get into the Geo-Front during a power outage when none of the doors would open. Later in the episode, we are treated to the sight of ''HumongousMecha'' escaping via (humongous) air ducts.
** The air vent entrance also {{lampshaded}} the MaleGaze when Asuka kept kicking Shinji for "looking ahead".
* Mokuba Kaiba once escaped from the Big 5 this way in ''{{Yu-Gi-Oh}}!''
** At least he's a fairly small KID, more likely to fit and all that.
* [[JustifiedTrope Justified]] in ''FullMetalAlchemist'': shrimpy Edward is the only character who can fit in the air vents, and even for him it's a tight fit.
** Which leads to further comedy as Ed has a complex for being TheNapoleon.
* {{Subverted}} with glee in ''{{Mnemosyne}}'': Slender (though busty) ActionGirl Rin Asougi decides to infiltrate an empty research laboratory by going through the ducts. She predicts the [[LaserHallway LASERS]] and makes them visible by filling the cramped ventiliation duct with smoke from a cigarette, and then proceeds to slip under the lasers... until her butt catches the laser, setting off all the alarms. Cue Rin's capture and... {{Squick}}.
* In ''{{Monster}}'', [[spoiler:Johan and Anna/Nina's mother escapes through a rather small-looking air vent not just pregnant but ''in labor'']].
* Mamoru and Volfogg do this in ''GaoGaiGar'' when their base is taken over by a computer-hacking Zonder. Mamoru is a nine-year-old, but Volfogg is a ''Robot that transforms into a police car''.
* ''PrettyCure'' episode 10. Nagisa needs to get into a store being robbed so she can meet Honoka, since [[WonderTwinPowers they have to be together to transform]]. Extra points for doing it in the course of about five seconds with no equipment.
* Integra does this to hide from her uncle in ''{{Hellsing}}''.
** Seras and Walter also use this to avoid a confrontation with the Valentine brothers.
* In ''ShugoChara'', Kiseki and Yoru escape from a locked room this way. [[JustifiedTrope Justified]] since the Shugo Charas in that series are small enough to fit in normal air ducts.
[[/folder]]

[[folder:Comics]]
* An example of a villain using this trope is found in Marvel's 1990s series ''{{Sleepwalker}}'', when {{serial killer}} Jeremy Roscoe, after freeing himself from his restraints, climbs into the ducts to escape the prison hospital where he was being held. Probably not as bad as some of the other examples, since by that time the alarms were already activated and Roscoe's only concern was getting out by the fastest route possible.
* ''{{Spider-Man}}'' does this every now and again. In an interesting variation, however, he usually does it when he's breaking ''into'' a place, rather than trying to escape.
** In the ''{{Spider-Man}}'' game for the Playstation, Spider-Man has to escape from an underwater base using the air ducts... ''which are big enough for him to web-swing through''. Talk about shoddy design....
* Kei tries this in ''The DirtyPair'' series ''Biohazard''. But she gets stuck when her full, child-bearing hips won't fit. Mmmm.
** It's a ShoutOut to one of the TV episodes. Also contains Yuri's wonderful 4th-wall-leaning (slash) LampShadeHanging from her outside POV: "Been hitting the cheesecake a little too hard, hmm?"
* Subverted in ''[[{{YTheLastMan}} Y: The Last Man]]'' when Agent 355 and Yorick are breaking into a hotel in Sydney (surrounded by barbed wire and armed security due to the increase in drug-related crime after the plague).
-->'''Agent 355:''' You said we'd be able to use the air conditioning vents. They're six inches by four inches.\\
'''Yorick:''' Yeah, well, I overestimated the amount of... air this place might need...
* In a ''{{Dilbert}}'' strip, Alice tells naive intern Asok "You must climb through the Jeffries tubes to reach the furnace before it fries us all!" He gets stuck half-way in, but that was her plan: "Today, Asok learns that life is not like ''StarTrek''."
** With Asok's lower body handing out of the vent, Alice puts up a sign that reads "Spank the Intern $.50"
* In a series of ''GetFuzzy'' strips, Bucky tried this tactic to reach the ferret in the next apartment. While he fit fine (because he's a cat) he ended up getting lost and having to call for help... and Satchel mistook the voice coming out of the walls for God. HilarityEnsues.
* Reed Richards of the ''FantasticFour'' does this now and again as well. Justified in that he can shapechange.
* [[{{Batman}} Scarecrow]] escaped out of Arkham Asylum this way. Justified in that the villain has always been a skinny britches. And it's [[CardboardPrison Arkham Asylum]].
[[/folder]]

[[folder:Fan Works]]
* This is the method that [[spoiler:Draco]] uses to get the Death Eaters into Hogwarts in ''AVeryPotterMusical''.
* This [[http://www.fanfiction.net/s/4471204/6/I_Think_Some_Serious_Physics_Just_Happened chapter of a]] ''KimPossible'' {{fanfic}} has a nice {{deconstruction}} of the trope when Ron, dropped into the real world, sneaks into a library through the airvents and naturally gets dirty while crawling through them. Then he starts to wonder why the vents in the [[SupervillainLair supervillains' lairs]] were never less than spotless. Who was cleaning them? How? Why?
** It's often a good idea to clean out ventilation systems to increase air-flow efficiency, reduce allergens, and stop a significant layer of dust accumulating on everything in the building every night. Particularly in warehouses with the giant ventilation systems that someone could actually crawl through.
[[/folder]]

[[folder:Films -- Animation]]
* ''ToyStory 2''. Naturally, ducts are much more convenient when you're eight inches tall.
* In ''Film/SkyBlue'', Shua flees Ecoban through the air vents after going through the AbsurdlySpaciousSewer system.
* Subverted in ''[[EdEddNEddy Ed Edd N Eddy's]] [[TheMovie Big Picture Show]]''. Taking refuge in Eddy's Brother's room, the Eds try to get out the window. It's bricked in, as shown in a previous episode. ("My brother's a whiz at laying bricks.") While Edd tries to find anouther way out, he trips over a rug, revealing a heating duct. Eddy quickly pries open the grate, jumps in, and... more bricks. [[spoiler:Then Ed finds the "In Case Of Movie Break Glass" case.]]
[[/folder]]

[[folder:Films -- Live Action]]
* Used quite famously in ''DieHard'': the villains quickly realize the hero John is using the ventilation system, and come perilously close to catching him inside. Also lampshaded in that John [=McClane=] is rather muscular and the vents are small; he remarks, "Now I know what a TV dinner feels like."
* Used, more realistically than usual, in ''SkyHigh''. One character's power (glowing in the dark) comes in handy here, allowing the others to see. And only the character who can become a rodent can reach the place needed to save the day. [[WhatKindOfLamePowerIsHeartAnyway Lame power? What's a lame power?]]
* Subverted in ''TheBreakfastClub''. After John Bender is locked in a broom closet by Principal Vernon, he tries to escape through an air duct, which collapses just as he is muttering the punchline to an obscene joke to himself (and [[FourthWall the audience]], of course).
** Mind you, it still gets him out of the closet.
** And it was ceiling tiles, not an air duct. Most dropped ceilings (or whatever you call them) DO have enough room to wiggle through, but the tiles are even weaker than sheet metal and will not hold the weight of even a thin adult. Er, OrSoIHeard.
** Dropped ceiling tiles are, essentially, half-inch thick cardboard. The grid that holds them up isn't that secure either, seeing as its only job is to hold up the tiles. However, it's possible to get around above the ceiling (in a school or house) by using the joists, pipes and such to support your weight.
*** Except they normally have even less room than an air duct.
* Minor subversion in ''{{Serenity}}'', when the Captain must get a wrench and properly remove the duct cover before executing the trope to get past a locked door.
** And played for laughs later on at the end, when Simon and Kaylee are taking the "unresolved" out of their [[UnresolvedSexualTension UST]]. They begin removing their clothes, then start kissing, then they fall down out of sight... and the camera pans up to show [[CovertPervert River]] watching from an air duct overhead.
*** [[CeilingCling Ceiling]] River is watching you procreate.
* Subverted in ''TheFifthElement'', where the villain sweeps the ceiling with a machine-gun, perforating Milla Jovovich, who is hiding in the ceiling duct.
** Played straight earlier, when she escapes from the cloning lab by running through rather massive air ducts to get outside.
* Subverted in ''TheBoondockSaints'', when the brothers break into Copley Plaza Hotel to assassinate Russian mobsters, but get lost ''and'' break the vent... granted, they happen to near-fall into the correct room. Agent Smecker than explains how this trope is only ever seen in "bad television":
-->'''Smecker:''' Little assault guys, crawling through the vents, coming in through the ceiling -- that James Bond shit never happens in real life! Professionals don't do that!
* Played with in ''{{Mr And Mrs Smith}}'', where assassin Jane Smith's place of work has security lasers everywhere to keep intruders out, ''including the vent system'', as Mrs. Smith is the owner of the company and has used such tactics herself in the past.
* Used in ''{{Tenacious D in the Pick of Destiny}}'', complete with a rooftop airvent to enter through and enough lighting inside to see. The shaft does however break apart and fall through the ceiling once two people are inside it, crashing to the floor below and alerting the guards.
* In ''Film/{{Alien}}'', the ''monster'' actually uses the air duct escape against the protagonists, and then in ''{{Aliens}}'' Ripley and the marines use ducts to escape the monsters (which likewise use the ducts to invade).
** It's only explained in the movie's extended director's cut, but the character of "Newt" earned that nickname because she was so good at playing hide-and-seek in those same ducts.
* In ''DesperateMeasures'', the villain Peter [=McCabe=] is capable of taking an entire medical facility over by himself once he gets to the control room, able to lock and open doors at will and talk via the police intercoms to the movie's main character, Frank Connor. An agent attempts to listen into [=McCabe=] and Connor's conversation by situating himself in an air vent above the control room and lowering a small mic, but he is soon found out by [=McCabe=]. He shoots into the ceiling and waits until he sees blood drip from the bullet holes in the ceiling. When asked by Connor what happened, he simply replies "Just a rat, Frank. Just a rat."
* In ''Film/MissionImpossible'' TheMovie, Tom Cruise's character infiltraits CIA headquarters this way (along with Jean Reno), which leads to the famous "dangling in the ultra-secure white room" scene.
** In ''MissionImpossible III'', Tom Cruise escapes IMF headquarters like this. Given they are the masters of the air vent entry, you would have thought they'd had better security, but no.
*** He didn't so much "escape" as "get into another office in the same building that shared the vent system".
* A variation happens in the Italian movie ''{{Diabolik}}'' (featured on the last episode of ''[[MysteryScienceTheater3000 MST3K]]''), where the title character scales up a castle wall using a pair of devices consisting of three hand-activated suction cups attached to a handle. Of course, Mike and the Bots have a field day with it.
-->'''Servo:''' Diabolik's only two feet down the tower, moving as fast as he can...
** Another ''MST3K'' film, ''FutureWar'', subverts this trope. A minor character climbs into a air vent to avoid a rampaging killer cyborg. The vent promptly collapses through the ceiling under the weight of her average-sized body and she gets killed.
* Subverted in the ''JamesBond'' film ''{{Goldeneye}}''. TheDragon pursues Natalya Simonova into a breakroom and, seeing the air vent cover pulled down, opens fire into the air vent. After she's left, Natalya emerges from a cabinet, having used the air vent as a DecoyHidingPlace.
** Double-subverted way back in the film ''[[DrNo Dr. No]]''. When Bond tries to escape his cell through the vent, he gets electrocuted when he touches the grill. However, he tries again by using his shoe to push it out and succeeds in escaping. As a nice touch, he experimentally taps the grill at the other end with his feet to make sure ''it'' isn't electrified.
*** And, as noted in ''IrregularWebcomic'', in the book, it was [[spoiler:a deliberate obstacle course set up by Dr. No, complete with viewports for entertainment]], so the red-hot surfaces and tidal wave of water serve a purpose. Other than, of course, to provide a wet, shirtless Sean Connery. [[FanService Mmm... wet, shirtless Sean Connery...]]
* Used and subverted in ''TheNegotiator'', where the SWAT team uses small vents for running fiber-optic cameras and larger vents for team members. When the title character barricades himself into an office, one of the precautions he takes is to close off the vents as best he can with available materials.
** Later played straight in his attempt to escape the office building.
* One of the scenes in ''{{I Now Pronounce You Chuck and Larry}}'' involves the main characters (who are firemen) having to rescue a would be thief that got stuck trying to sneak through an air duct.
* In the appalling ''{{Santa Claus Conquers the Martians}}'', the creepily jolly St. Nick and some Earthling kids escape from a spaceship's ''air lock'' through the ventilation duct -- employing Santa's long-established ability to fit through chimneys.
** MST3K adds an appropriately Bondian line "So, Mister Claus, you have a nasty habit of surviving!"
* ''{{Sneakers}}''. One of the team infiltrates an enemy-controlled building through the ventilation system, and tries to get out the same way after the job is completed.
* Subverted and [[LampshadeHanging lampshade hung]] in ''{{Harold and Kumar}} Go to White Castle'', when [[spoiler:Kumar calls in an incident as a diversion and crawls through a heating duct to get Harold out of jail, making a racket, having an argument with Harold (who doesn't want to escape) while still in the duct, getting stuck in it and eventually causing the duct to collapse, falling onto a table and hitting his head on a file cabinet]]. He does manage to [[spoiler:grab the bag of weed and get Harold out]] due to [[LampshadeHanging lampshade-hung]] [[PoliceBrutality police brutality]], though.
* Fully embraced in ''JurassicPark'' as Grant and others use some ridiculously large vents to escape from a velociraptor. This was hilariously pointed out in the [[AlternateDVDCommentary Rifftrax commentary]].
** ... Those weren't air vents. They were crawling on top of those perforated ceiling panels (drop roofs) offices have to keep sound from bouncing around, and do indeed have a couple feet of space in them in Real Life. (Although look at the troper tales for why they still aren't normally an option.) One of the obstacles, in fact, was an actual air vent, which was a realistic size.
* The ''SuperMarioBros'' movie includes a scene where the main characters and mooks sled through a gigantic air vent.
** Actually, that was a frozen-over drainpipe. It's one of the few places where anything in the plot resembles vaguely anything in the game.
* Referenced in ''TwelveMonkeys'' when the staff of a mental hospital find Cole has vanished from his restraints, in a locked room. Their eyes turn to the tiny airvent way up on the high ceiling. After all, there's no other way out. Unless he was snatched through time....
* Slightly altered in ''{{Crossfire}}'', where the main characters are able to escape an army of policy by crawling through an air duct of a building.
* Parodied in ''[=~Top Secret!~=]''. While incarcerated in Flugendorf Prison, Nick Rivers tries to escape through the air vent system. He ends up sticking his head out of a medicine cabinet and a toilet before finally sliding back out through the vent into the cell. Watch it on [=YouTube=], [[http://www.youtube.com/watch?v=eLU4HCWeZjI starting around 5:50]].
* In ''{{Resident Evil}}: Extinction'', one of the Alice clones jumps into an air vent to escape a replica of the Laser Grid deathtrap from the first movie. Milla Jovovich ends up in Air Vents a lot, as noted by ''{{The Fifth Element}}'' examples above.
* Inverted in ''MenInBlack II''. The worms get to the power control of MIB headquarters through the air vents.
* ''{{Daylight}}'' has Sylvester Stallone get into a caved in tunnel through a air vent. Since the air vent was meant to supply air to an entire car tunnel, it's huge size is justified. However, the architecture of the system is still not completely realistic.
* In ''PaulBlartMallCop'' Blart attempts to use an air duct to escape from some {{mooks}} but only ends up completely giving away his position by all the noise and all the dents showing up, leaving him open to attack. In the end the air vent just breaks loose anyway, proving to not be a stable place to climb in in the first place.
* In ''[[{{DEBS}} D.E.B.S.]]'', Lucy Diamond uses the air vents to infiltrate the building in which Endgame is occurring, but it turns out that Homeland Security has been briefed about the possibility that spies could enter illegally through such routes.
* I can't believe no one's mentioned Yoda's escape through the vents in ''[[StarWars Revenge of the Sith]]''. Justified, of course, by Yoda's small size.
* The 1998 American ''{{Godzilla}}'' movie has this, where Audrey Timmonds and Animal Palotti are sneaking through the vents of Madison Square Gardens in order to escape Godzilla's babies. Also subverted in the movie, since it turns out the vent can't hold their weight after all.
* In ''TheBrothersBloom'', Penelope tries to escape from the police using a ventilation duct.
[[/folder]]

[[folder:Literature]]
* JamesBond escapes confinement in ''Dr. No'' through some ductwork, but he soon discovers that it was a purposefully-built series of hazardous obstacles (poisonous spiders, extreme heat, etc.) intended as a DeathTrap. It's not explained that it's a DeathTrap in TheMovie, though, so it doesn't really make sense.
** That's because it wasn't a DeathCourse in the movie, just a shaft guarded by a BoobyTrap that Bond is able to bypass.
* Justified in the sci-fi book ''{{Footfall}}'', as the aliens are twice human size and deliberately put the captured humans to work cleaning the spacecraft's air ducts. Their prison cell also doesn't contain a handy air duct, forcing them to escape before using the ducts to evade.
* In ''IllegalAliens'' by Nick Pollotta and PhilFoglio, abducted humans on an alien ship hide in the air vents, because all the movies say that's what you do in that situation -- only they aren't air vents; they're conduits for a horrifically deadly gas weapon, which the aliens are preparing to flood throughout the ship, because they can't locate the humans....
* Something similar to the above happens in ''ArtemisFowl: The Arctic Incident''. Artemis has to crawl through a duct filled with fuel for the building's plasma weapons. Before his helmet runs out of air. Without being able to see where he's going. Knowing full well that if anyone turns on the plasma cannons, he's literally toast. Not to mention that once he gets out, he has to be sprayed with anti-radiation foam or he'll likely develop cancer.
* Subverted in Christopher Brookmyre's ''{{One Fine Day in the Middle of the Night}}''. After an earlier discussion after action movie tropes, one of the heroes spots the "Holy Grille" as the way out when they're held hostage. Unfortunately, he didn't reckon on the fact that crawling through metal ductwork is incredibly noisy, so everyone hears him as he tries to squeeze through.
* Justified in ''[=~Ender's Shadow~=]''. Bean uses the air ducts to explore and reconnoiter, but he can only do it because he designed a specialized workout to develop the muscles he needs to pull himself through at odd angles, and because he's really, ridiculously small. Eventually he grows too big to use the vents anymore.
** He also, later on, uses the bigger vents in the commander's room to [[spoiler:trap Achilles and force him to surrender]].
* Works better in ''[=~Mrs. Frisby and the Rats of NIMH~=]'' than in most stories due to the escapees being rats.
** Well, right up until the system starts ventilating. This is one of the scenes that, legend has it, convinced Disney to pass it by as an animated adaptation. Something about having a large part of the party wiped out faster than the RedshirtArmy, and without even an enemy to credit for it. They also need help in opening the grilles, too.
* Parodied in ''{{The Adventures of Samurai Cat}}'', in which a cruise ship's air vents "... appear to have been ''designed'' for covert transportation." -- "That would explain the moving walkways and vending machines."
* Lyra crawls around in the dropped ceiling in Bolvangar in PhilipPullman's ''[[HisDarkMaterials Northern Lights]]''. Being a twelve-year-old girl, she's smaller and lighter than most {{Action Hero}}es, but [[spoiler:she gets caught anyway, and almost transformed into a soulless abomination. She's only saved because the BigBad had a special interest in her, and was present]].
* Used in the ''HonorHarrington'' spinoff ''Crown of Slaves'', but half-subverted by the simple expedient of using it realistically. Crawling around in them is murderously hard work, characters without detailed schematics get badly lost, and it proves almost impossible to remove a grille without the proper tools.
* Referenced in TerryPratchett's ''OnlyYouCanSaveMankind'':
-->"I saw a film where there was an alien crawling around inside a spaceship's air ducts and it could come out wherever it liked," said Johnny reproachfully.\\
"Doubtless it had a map," said the Captain.
* In JohnCWright's ''{{Fugitives of Chaos}}'', Vanity finds an accessible air vent. On the other hand, she has an ability to find secret passageways that weren't there before she looked.
* In SandyMitchell's ''CiaphasCain'' novel, ''Cain's Last Stand'', the air vents are exactly the place genestealers like to hide.
* Used in the last two books of TimothyZahn's ''{{Dragonback}}'' series; the (less-than-subtle) justification is that large air vents are actually standard design in capital ships, so that in the event of a hull breach emergency air supplies can be funneled to the compromised areas in large amounts, buying the occupants time to reach emergency air masks and so on.
* Slightly altered in ''{{Harry Potter and the Chamber of Secrets}}'', using the castle sewer-pipes for the monster to invade from -- and for the heroes to find -- the titular chamber.
** Hogwarts Castle has got to have the most gigantic pipes ever seen... particularly for being built by wizards.
*** My impression was that only one pipe was built that way - [[spoiler: a basilisk, such as Slytherin's monster, can't get through a normal drain pipe to get to Myrtle's bathroom, hence the bigger one under the sinks.]] The other pipes would be normal.
* Comes up in several variations (breaking in, breaking out, air ducts, hanging ceilings...) in places in the ''{{Vorkosigan saga}}'' by {{Lois McMaster Bujold}}, particularly the short story "Labyrinth" -- where it involves problems like ducts forking or being blocked by grilles, and the others being only passable by the rather less than five-foot-tall main character, not his companions.
* In {{Graham McNeill}}'s ''{{Warhammer 40000}}'' novel ''Storm of Iron'', this is how Hawke [[spoiler:escapes a launching rocket and a Chaos SpaceMarine]].
[[/folder]]

[[folder:Live Action TV]]
* ''{{Buffy the Vampire Slayer}}'' and Xander use this method to [[spoiler:escape from vamp Jesse and his new friends in the electrical tunnels]] in "The Harvest".
** In "Out of Mind, Out of Sight", Marcie Ross lives above the school's music room in a space accessible only by climbing up through the drop ceiling.
** In the episode "School Hard" Buffy gets out of a locked classroom and gets the drop on Spike by crawling though the space above the drop ceiling (she is at least shown traversing a wooden catwalk).
*** Subverted in "Gingerbread", where Xander and Oz can fit into the vents but become lost.
* ''[[TwentyFour 24]]'' enjoys playing around with this. Sometimes played straight and other times, the villains are quick to seal them to prevent the cliché from happening. One notorious use of air ducts was seen in a fifth season episode, as agent Jack Bauer uses duct tape to seal a shaft and prevent nerve gas from seeping into a safe room.
* ''StarTrek'' has the "Jefferies Tube" tunnels criss-crossing the ship and was actually designed for human access, but is quite often used in this way.
** Dr. Helen Noel saved the day this way in ''StarTrekTheOriginalSeries'', episode "Dagger of the Mind".
** ''StarTrekTheNextGeneration'' had a few DieHardOnAnX episodes where the Jefferies Tubes come in handy this way.
** ''{{Enterprise}}''. The ship is taken over and everyone is locked in their rooms. Hoshi, being the smallest person on board (and of course, a regular) manages to wriggle out through the vents. Presumably, Hoshi is the one called upon when something in the vent needs fixing.
*** Or she was chosen so we could have a gratuitous {{Fanservice}} moment where her [[ShirtlessScene shirt gets pulled off]]. Especially since the ducts didn't seem that narrow anyway.
*** If anything, that was at least acknowledging that the Jefferies Tubes would be guarded by the bad guys. That vent existed solely during construction and was closed off upon completion, it was never intended for people to pass through.
* In an episode of ''StargateAtlantis'', Zelenka crawls through a vent to turn the city's power back on. And in ''{{Stargate SG-1}}'', the aforementioned team uses this trope ''every'' time they're on a Go'aould mothership.
* Subverted on ''{{Undeclared}}'', where Steven, finding himself trapped in a room, attempts to crawl through an external ventilation duct, which breaks from the wall and falls as soon as he enters.
* Justified in the ''TheXFiles'' episodes "Squeeze" and "Tooms", since the killer -- Eugene Victor Tooms -- is a mutant whose power is to be capable of squeezing through tiny openings.
** Used with absolutely no justification in "Ghost in the Machine". Though there is a slight subversion when Scully learns firsthand the downside of trying to climb through the airducts when an [[AIIsACrapshoot insane [=AI=]]] controls the ventilation system...
** A conspiracy theorist trying to spy on a defense contractor's meeting in "Three of a Kind" gets caught when the duct audibly flexes under his weight.
* In the second season of ''{{Lost}}'', this was a legitimate way of getting around in the Swan station. Kate used the ventilation ducts to escape imprisonment in the food storage room in the episodes "Adrift" and "Orientation", and in the episode "Lockdown", Ben (then going by the alias of "Henry Gale") could escape from being locked inside ''by blast doors''.
** Locke later sealed the vents to put an end to this kind of thing, which didn't work out so well later once he and Jack found themselves locked inside.
* LampshadeHanging in the ''DoctorWho'' episode "The Satan Pit"; when Rose suggests escaping through the maintenance ducts, Security Officer Jefferson replies "I appreciate the reference but there's no ventilation. No air, in fact, at all. They were designed for machines, not life forms." They're able to escape through them anyway, though, by manipulating the air-pressure controls to "flood" certain ducts.
** According to ''Doctor Who Confidential'', the reason Jefferson says he appreciates the reference is [[ActorAllusion because the actor playing him was actually]] '''in''' one of the ''Alien'' films -- Danny Webb was in ''Alien 3''.
** Lampshaded again in the ''DoctorWho'' audio adventure ''The Apocalypse Element''.
--->'''Evelyn:''' There must be some other way. An inspection hatch, or even, God help us, a ventilation shaft!
** Used straight in "The Ark in Space" (realistically: Sarah is the only one small enough to fit and even she get stuck) and "The Tenth Planet" (hilariously: Ben has a ''map'', albeit one drawn by the man who designed the ventilation system).
** Beefy science teacher Ian Chesterton uses one in "The Aztecs" while the First Doctor makes time with a local lady.
** Used by the Fourth Doctor and company in Tom Baker's second Dalek story "Destiny of the Daleks" -- notable for the Doctor pausing to mock the Daleks' inability to follow them...
--->'''The Doctor:''' If you're supposed to be the superior race of the universe, why don't you try climbing after us? Bye bye!
* ''{{The Suite Life of Zack and Cody}}'': Zack and Cody easily spend more time traversing the Tipton's air vents than just using the hallways and doors. So far, Max and Zack are GenreSavvy to the air vent appeal.
* ''NedsDeclassifiedSchoolSurvivalGuide'': Many ASimplePlan requires use of the school's elaborate, labyrinthine air ducts, which eventually gave out in the GrandFinale.
* Spoofed on ''ArrestedDevelopment'': in one episode, George Sr. finds an entrance to the air ducts behind the refrigerator and attempts to escape house arrest. Not only does he fail to find a way out of the house, Buster pushes the refrigerator back into place and traps him inside.
* The master of air duct navigation is clearly the ''MissionImpossible'' jack-of-all-trades Barney Collier. And one of the few times he wasn't doing it, he was coaching the woman who was.
* Justified in ''{{Farscape}}'' where the diminuitive Rigel often uses air ducts and service tunnels to travel when the ship is being invaded or he's feeling particularly paranoid.
* ''MyNameIsEarl'': Earl engineers a jail break using this method. Unfortunately, the duct collapses in the warden's office.
* The unaired pilot ''I-Man'' subverts and [[LampshadeHanging lampshades]] this one: Scott Bakula references it as an escape plan... and then finds out that the room only has a regular air vent.
* ''{{Mythbusters}}'' tested this trick along with a variety of other cat-burglar techniques. Jamie used the common technique of using powerful hand-held magnets to climb the vertical shaft, only to cause a ''thunderous'' sound as they connected to the vent walls, defying the point of it being a "stealth" technique. Adam, on the other hand, used vacuum "cups" on his hands and feet that would grip the vent. While this achieved the silent ascent the equipment lacked reliability (breaking down several times during the course of the show) and it was tricky to use. Adam himself said that he wouldn't trust his life to such machinery.
** "What's this? Thor, the God of Thunder, is breaking into my building!"
* The Australian series ''{{Escape from Jupiter}}'' features a moonbase and space station/makeshift rocket that both feature large air ducts. Of course, they're also likely some sort of Jefferies tubes -- just built in case of need for extended residence.
* Famously {{Lampshaded}} in ''{{Mystery Science Theater 3000}}'':
-->'''Joel:''' You know, it's funny how movie directors always make air vents big enough to crawl around in.
* {{Lampshaded}} and subverted in an episode of ''BurnNotice''. When trapped in an office building, Michael wryly notes that air vents are viable escape routes... if you happen to be size of a four year old. He does state, however, that instead of using air ducts, you can instead use the sub-ceiling of an office building to escape danger.
* Lampshaded and subverted in the ''[[TheMiddleman Middleman]]'' episode "The Clotharian Contamination Protocol":
-->'''Wendy:''' We're coming from an isolation chamber in a secret headquarters built by an organization so covert we don't even know who they are, yet somehow we have vents large enough to crawl through, with accessible registers everywhere. Was this building designed by TV writers or what?
::The Middleman explains that the "[[DieHard Nakatomi Protocol]]" specifically enlarges the vents and turns off the surveillance.
* Hiro and Ando attempt one on ''Series/{{Heroes}}'', but their captors show up at the cell before they make it into the vent.
* Not "escaping" anything, but the "steam tunnel spelunkers" aspect shows up on ''{{NUMB3RS}}'', when it is revealed that Larry had been ''living'' in the tunnels on campus for awhile.
* On the ''{{Friends}}'' episode "The One With the Birth", Phoebe, Susan and Ross get locked in a janitor's closet in the hospital. Phoebe tries to escape through the vent but gets stuck, while Susan and Ross just get let out by the janitor.
* {{Lampshaded}} in ''DarkSeason'' episode 5 where Marcie escapes and says, "A ventilation shaft. Marvellous, I'm a cliché!"
* Not an escape, but in the ''RedDwarf'' episode "Duct Soup", the crew spend most of the episode crawling around the ship's exceptionally large heating ducts to fix the thermostat. This, unfortunately for them, includes a badly claustrophobic Lister and the ducts being washed down and then air-dried...
* This troper has seen the air duct trope used to get Robin Hood out of a Norman castle in the TV series ''{{The New Adventures of Robin Hood}}'' (only 90% sure about the name since it's a long time ago). The series was a bit on a ''Hercules'' and ''Xena'' level of authenticity but (sadly) not meant as a spoof.
* The old ''{{Voyage to the Bottom of the Sea}}'' series was rife with this trope, especially in the later seasons, when it seemed every third episode had a villain or Monster of the Week or regular character evading a villain or MotW getting into the ventilation system at some point. Played straight for the most part, although somewhat subverted in that the ducts themselves were quite roomy, and the vents were about a yard square or more in size, hinged like a door with a latch that anything brighter than a rock could operate, allowing convenient access.
* ''BattlestarGalactica'', "Blood on the Scales". Chief Tyrol spends most of TheMutiny crawling through shafts [[spoiler:to get to the FTL drive]]. Unlike some examples of this trope, these are shown to be narrow, unpleasant (especially when going past the urinals), and bloody tiring to crawl through -- when Tyrol is caught at one stage, he invites his captor to shoot him then and there as he's too exhausted to clamber out and be taken prisoner.
* Lampshaded on ''{{Leverage}}'': "Looks like Parker's going to have to climb through the air duct again..." Somewhat justified in that Parker is a) a master thief with an extensive knowledge of building layouts, and b) petite.
* Used on ''{{Primeval}}'' when Abby and Connor needed to get to a certain floor in a skyscraper. Since taking the stairs/lift would have been incredibly dangerous (there was fog coming out of an anomaly that obscured the floor, and moving in the fog were giant worm things that were hard to see), they had to use the air vents.
* In one episode of ''Las Vegas'', some bad guys take over the Montecito security centre. Danny [=McCoy=] uses the airvent system to try and get some intelligence on them. Right after the audience starts wondering why the hotel with "the best security on the strip" has such a gaping security hole, the vent collapses, conspicuously dumping Danny in the middle of Security. On his own desk, I believe.
[[/folder]]

[[folder:Video Games]]
* ''{{Battlefield 2142}}'' The Titans have vents on the top that provide an alternate way to enter, however, unless the other team if full of idiots, they are usually boobytraped or being guarded by someone armed usually with a shotgun or a LMG.
* ''FinalFantasyVII''
* ''ChronoTrigger'', and initially without weapons, as a FakeDifficulty. This can be avoided by putting Ayla in your party, as she fights with her bare fists. The other two in your party, however, will just watch and not even try to help, even if they know powerful magic, or are a metal killing machine.
* ''MetalGearSolid''
* ''The Chronicles of Riddick: Escape from Butcher Bay'', in which the ducts were used so widely they actually had directions scribbled inside them.
* A few ''LegendOfZelda'' games.
** Especially hilarious in ''The Wind Waker'', when Link is thrown into the same room, every time he gets seen.... and they never leave guards in front of the room, neither do they check on HOW exactly he always escapes: There's a fairly obviously placed easy-to-reach air-vent in the room....
*** Well, the Moblins are portrayed as idiots.... They've probably forgotten about him by the time he's caught again. They dump him in the same cell simply because it's empty. They aren't even smart enough to notice a SUDDENLY-OUT-OF-PLACE BARREL. (Unless you actually move it while they're looking at the barrel, that is.)
**** Though at least in that case, the "air-vent" is at least just a tunnel-like hole in the rock walls, instead of an actual duct made out of flimsy, noisy sheet metal.
* ''{{Grandia}}'' had this, including a side-trip to the women's locker-room...
* ''DukeNukem 3D'' did this so often that there is a small monster almost designed to be placed in the vents. In the expansion pack, the game has a nod to the famous air vent scene in the first ''MissionImpossible'' movie.
* [[LampshadeHanging Lampshaded]] in ''{{Half-Life}} 2: Episode 1'' by mentioning that Freeman used to participate in races to break into Dr. Kleiner's office when he locked his keys inside. Naturally, the air vents are now full of headcrabs.
** And subverted in the same game, where one vent you crawl through collapses, landing in a room filled with ExplodingBarrels and laser-tripwire mines.
* Slightly subverted in ''{{Half-Life}}''. At one point, the character is forced to crawl through an airvent. In a scripted scene, soldiers below hear the player, yell "He's in the ventilation system!" and shoot into the air duct, causing it to collapse. Note that some of ''Half-Life'''s vents have ladders in them, suggesting that they may have been designed to allow people to go through them.
** When? During "We've Got Hostiles" or "Surface Tension"? The first is avoidable if you crawl very very slowly and quietly; and the second, I think, collapses anyway. They do hear you in the vents anyway; there's one sequence where they hear you in the pipes and throw in a grenade in which you must OutrunTheFireball.
*** "Surface Tension." You round a corner and break a grate, and the grunts below in a garage start shooting at the vents. The vent will collapse but you can back away from the collapsing part and then toss grenades or snarks down at them.
* ''DeusEx'' often includes alternate paths through air vents, which usually double as maintenance tunnels, complete with ladders and hinged grates. However, unlike Duke Nukem, there's also always a straight way.
** ''{{BioShock}}'' does this too.
* Mildly subverted in ''DeusEx: Invisible War''; all the vents are comfortably navigable, but inevitably are patrolled by small, spider-like security bots armed with electrical shock-based weapons. According to characters, the bots are to combat any vermin that might enter the vents.
* ''{{Secret of Evermore}}'' had an escape through the ventilation system take up an entire ''dungeon''. Fortunately, to make up for the confusion of navigating the vents, the game followed the trope pretty well by having no enemies inside them.
* ''GoldenEye'' began one level with the player infiltrating a Russian base via the air vents.
** Which reappeared in ''PerfectDark''. Gunfire in toilets. Always classy.
* ''[[FirstEncounterAssaultRecon F.E.A.R.]]'' requires you to travel through air ducts several times per level in order to advance deeper into the facilities you're penetrating, whose covers are quite easily bashed in. Strangely, despite the game's horror atmosphere and the obvious darkness and claustrophobia factors, you are never once subjected to any sort of scare sequence within one.
** ''Except'' one. During one particular part, you turn the corner, and Alma does the spider-crawl towards you -- before vanishing a foot away from you.
** Alma seems to use this, popping out of an air vent right in front of you on one occasion. While you're utterly defenseless. On a ladder.
* Played straight in ''[=~Resistance: Fall of Man~=]'' when Parker uses a vent that pops open to escape from the conversion center, leaving Hale to find his own way out.
* Apparently, design standards in the ''{{Metroid}}'' universe include a provision that all facilities and spacecraft must have access tunnels, air shafts, or other openings big enough for Samus Aran's Morph Ball form. (Expanded and partially subverted in ''Zero Mission'', wherein [[spoiler:after losing her armor, Samus must negotiate said tunnels on her hands and knees, which is dead slow, and Space Pirates can also use the tunnels, largely negating their escape value.]])
* ''{{Aliens}} Versus {{Predator}} 2'' (the game, not the movie) featured liberal amounts of duct crawling. The first few levels of the [[SpaceMarine Marine]] campaign required constant duct crawling, including a situation where Frosty has to jump into a duct vent that a Xenomorph recently launched out of in order to avoid being eaten. The Alien campaign, however, was almost entirely composed of duct jumping for most of the early half of the game.
* Though technically not an air vent, one mission in ''CallOfDuty 2'' involves a group of Russian soldiers infiltrating a German-held railway station via a long, damaged fuel pipe. The Germans are quick to catch on, though, and if he player isn't careful he can get caught by gunfire or hand grenades.
* ''PaperMario: The Thousand-Year Door'' has Mario go through air ducts twice in the course of plot in order to eavesdrop. He may also go through a third in order to gain an item.
* One level of ''[[TwentyFour 24]]: The Game'' has Kim Bauer, armed only with a taser, having to crawl through ducts to get around a room full of bad guys. She has to move very slowly, though, or they'll hear her and shoot.
* The titular characer of the ''SlyCooper'' series can do this in all his games. He usually does to break into places, though.
* The only reason the title character's client in the third case of ''Apollo Justice: AceAttorney'' is accused of the murder is that it's a LockedRoomMystery and he's the only one small enough to fit through the vents (where they found his fingerprints). [[spoiler:He did escape the crime scene through the vents, but didn't commit the murder.]]
* Lots of duct-crawling goes down in ''BeyondGoodAndEvil''. Jade makes use of air vents once or twice in order to break into a few facilities, but Double H tends to do it whenever he and Jade [[LetsSplitUpGang split up]] in order to follow her. He literally ''slides out of one'' during the third boss fight, [[BigDamnHeroes rocketing to the rescue.]]
* The online game ''{{Infantry}}'' has a "Bug Hunt" map, allowing players to play as humans or aliens, the aliens granted the advantage of traveling by air ducts and even launching ambushes from them.
* In episode one of ''[[HomestarRunner Strong Bad's Cool Game For Attractive People]]'', Strong Bad must use the air vent to sneak past The Poopsmith while infiltrating the King of Town's castle. However, unlike some other examples here, you can get caught if you aren't careful.
* Partially subverted in ''[[WildArms1 Wild ARMs]]'': only Hanpan, the little mouse sprite belonging to one of the main characters, is small enough to navigate the air vents.
* While the player of ''DeadSpace'' never actually enters one himself, the ship in which the game takes place is blanketed with large, easy access vent shafts that the "necros" use to move around at will. This allows them to bypass security lock downs and quarantines with impunity, rendering them useful only apparently as an obstacle to the player.
** In the RailShooter prequel "Extraction" you do get to crawl through the vents and similar locales several times, but it's lampshaded that they are tight, cramped and hard to move quickly in. The fact you only face Leapers and Crawlers in them only makes it worse.
* ''Thirteen'' or 'XIII' has this a lot. Justified in that the player tends to machine gun all the bad guys ahead of time so there's nobody left to hear him clunk clunk through the shafts.
* This happens alot in ''Batman: Arkham Asylum''. Whenever opening doors, stealth or jumps are impossible, a conveniently placed vent will always be there to be busted open to save the day, and help you proceed.
* During Wolverine's escape from the Weapon X facility in the ''X-Men Origins: Wolverine'' game, he has to crawl through ventilation shafts a few times to avoid attention (thanks to his healing factor being temporarily disabled). In one of them, a guard down below yells about hearing something and starts riddling the shaft with bullet holes. Another guard tells him to stop being jumpy, and that it's ridiculous that Wolverine would be up there.
* ''ShadowComplex'' uses vents where Metroid uses morph ball tunnels.
* In the ''{{Myst}}'' universe we have a justified version of the mine example: D'ni is an underground city, and it's Great Shaft is a huge air exchange shaft, but it's also used as the primary method of reaching the surface (or vice versa)
[[/folder]]

[[folder:Web Comics]]
* Subverted in ''[[http://freefall.purrsia.com/ff800/fv00770.htm Freefall]]'', when Sam finds out the hard way that the air ducts on his ship are not ''quite'' big enough for him to hide in.
* Justified in ''SchlockMercenary'', as Schlock is a carbosilicate amorph -- he can squeeze through air vents no matter ''how'' small they are -- well, except for his eyes (standard [[TheSimpsons Simpson]]-sized eyeballs) and his plasgun (big).
* Justified in ''GunnerkriggCourt'', as the Enigmaron fortress that Antimony infiltrates is a [[HardLight simulation]].
* Used in this ''[[http://ubersoft.net/comic/hd/2007/11/secret-weapon Help Desk]]'' comic, the reasoning behind such large vents is questioned and explained as ContractualGenreBlindness in [[http://ubersoft.net/comic/hd/2007/11/bureaucracy-evil the next strip]].
* Subverted in ''{{Casey and Andy}}'': Casey sneaks in through the airvents, but is met by [[EnemyMime the Mime Assassin]] inside the air vents, as the villain had been expecting the plan.
** Of course, the ''C&A'' villain Lord Milligan follows the Path of the Villain as a religion and deliberately follows every cliché. Including having giant air ducts.
* Wonderfully subverted in [[http://cad-comic.com/comic.php?d=20080421 this]] ''CtrlAltDel'' comic, given that it [[spoiler:LEADS TO THE DEATH OF THE MAIN CHARACTER! Thus ending this ChooseYourOwnAdventure storyline.]]
* Subverted in ''QuestionableContent'' when Raven attempts to enter Coffee of Doom through the airvent and gets stuck. She's not the [[TheDitz sharpest of minds]], though.
* Used in [[http://www.sluggy.com/daily.php?date=011004 this]] ''SluggyFreelance'' strip to sneak into Aylee's office. [[JustifiedTrope Justified]] since Bun-Bun, a [[TalkingAnimal mini-lop rabbit]] is the only one who can make it through.
* Averted in ''DeadWinter''. Lou's plan for getting into the store for supplies involves this method, but Monday objects on the grounds that he won't fit. Apparently he's tried before.
* {{Lampshaded}} by the DeadpanSnarker in the improvisational comic ''The Omega Key'' on [[http://www.drunkduck.com/The_Omega_Key/index.php?p=229585 this page]], where he finds it suspiciously convenient that he (a ''6'10"'' man) can fit in an air duct. (He was right, as the destination turned out to be a trap.)
[[/folder]]

[[folder:Web Original]]
* Used to escape a dead-end in ''{{Survival of the Fittest}}'' by John Sheppard, Vera Lang and Kyrie Joseph, as killer Harry Tsai was hot on their heels and it was the only way out of the building they had run inside.
* ''TechInfantry'' has a sequence where a space station is captured by rebels, and they lock Xinjao O'Reilly, the chief engineer on one of the space docks, in [[LockingMacGyverInTheStoreCupboard a tool storage closet]] with his engineering crew. They [[LampshadeHanging hang a lampshade]] on what a stupid move this is, grab a bunch of tools, and escape into the maintenance passageways between bulkheads. They make life very difficult for the rebels controlling the station for a while.
[[/folder]]

[[folder:Western Animation]]
* This is a favorite route of the girls in ''TotallySpies!'' for breaking in, clearly thanks to MaleGaze.
* ''KimPossible'' and Ron infiltrated this way in TheMovie. They do it quite a lot during the series.
* ''{{Recess}}'': T.J. often uses this route to break himself and occasionally others out of detention.
* ''TeenTitans'' is an exception; Titans Tower's quarantine lock-down system apparently ''does'' seal off openings to the air ducts, as seen in the episode "Haunted". (Of course, Robin got into the vents anyway...)
** Subverted in the same series: Cyborg is attmepting an Air Vent Infiltration in the episode "Wavelength" when the walls roll up and the thing rotates, dumping him into an arena and a battle with Bumblebee which he very nearly loses. He should've thought twice about even coming across a vent ''big enough'' for his 6-foot, 200-pound chassis.
* ''{{Ben 10}}'' did this a couple times, though it's [[JustifiedTrope justified]] by the fact that, both times, Ben was transformed into an alien form that was five inches tall and gave him greatly enhanced brainpower.
* In a ''{{Jem}}'' episode, Jem, Aja, and Shana do this to escape a locked room.
* ''{{Spider-Man The Animated Series}}'' constantly had Spidey doing this. During the Venom arc, after Peter finds the symbiote and experiences drastic changes to his personality, he considers but chafes at using the trope, saying "That's the old Spidey thinking." He instead goes for the direct approach: kicking the steel door down and barging into Kingpin's meeting.
* The ''TransformersGeneration1'' episode "The Ultimate Doom, Part 2" introduced ventilation ducts large enough for Transformers to stand inside. Of course, they're on Cybertron, where everything is of the same scale as Transformers are to humans, but why would they need air anyway?
** And pulled again in ''TransformersAnimated'', episode "Decepticon Air". Optimus Prime crawls through the ducts (it seems to be a squeeze, letting him homage DieHard as well) of a spaceship -- maybe the air circulates to keep the energon from heating up and getting unstable? He does use it as a makeshift bomb, after all.
* Peter and Brian do this in an episode of ''FamilyGuy'', complete with a ShoutOut to ''DieHard''.
* Subverted in ''{{Futurama}}''. Fry and Bender try to escape from a brig through a steam pipe vent. Unfortunately, the steam pipe is full of steam. At least they got a good steam out of it.
** Also {{Lampshaded}} in TheMovie. While trying to destroy a "Death Star", Al Gore's head in a jar flies a through an air vent actually ''labeled'' "Achilles' Vent", lasers a-blasting, successfully destroying it.
* {{Lampshaded}} and subverted in an episode of ''{{Buzz Lightyear of Star Command}}'', when Emperor Zurg chews out the designer of his latest evil lair for making the air ducts big enough for heroes to fit through.
* Subverted in ''[=~Avatar: The Last Airbender~=]''. The Gaang was stuck in a room and the only exits were air ''tubes'', so they tried to get Momo through it. However, Momo ate too much, and couldn't fit.
** Momo later ''did'' crawl through some tubes in Roku's Temple, though it wasn't actually an "escape".
* Parodied in the 100th episode of ''TheSimpsons''. Santa's Little Helper gets into the school ventilation shafts, and only a greased Scotsman can catch him....
-->'''Groundskeeper Willie:''' Lunchlady Doris... d'ye have any grease?\\
'''Lunchlady Doris:''' Yes. Yes we do.\\
'''Groundskeeper Willie:''' '''''Then grease me up, woman!'''''\\
'''Lunchlady Doris:''' ... Okee-dokee.
** "There's nary an animal that can outrun a GREASED SCOTSMAN!"
* ''{{Chip and Dale Rescue Rangers}}'' uses this in a few episodes, but more-likely as a way ''in'' rather than out. Then again, the use is probably justified as the Rescue Rangers themselves are only around 10 cm tall.
* In ''{{Sat AM Sonic the Hedgehog}}'', most episodes that contain Robotropolis have the main characters in an air duct at LEAST once. Robotropolis is perhaps Air Duct Central, essentially one giant factory bathing in its own heated (polluted) air. Lots of cool (polluted) air has to be moved around to keep the place from overheating somehow. By the way, Robotnik hates this trope:
-->'''Robotnik:''' [[TranquilFury Tell me, Snively, how did the hedgehog get past all my security]]?\\
'''Snively:''' Through an air duct, Dr. Robotnik.\\
'''Robotnik:''' An ''air duct?'' Then SEAL IT OFF!!
* In the ''CodeLyoko'' episode "Canine Conundrum", Yumi and Ulrich escapes from the Gymnasium (besieged by robot dogs) this way. Although there is a joke, previously, about the adult teacher, Jim, being too fat to follow them.
* Given her size, Jade from ''JackieChanAdventures'' utilizes these at times to get around places when no one else can. The episode "The Day of the Dragon" feature both her and the Dark Hand using the air vents to escape Section 13.
* [[LampshadeHanging Lampshaded]] on ''[[WolverineAndTheXMen Wolverine and the X-Men]]'': Wolverine and Gambit are trying to break into a secret lab to steal back a power inhibitor collar, and Wolverine suggests taking advantage of this trope. Gambit counters with: "No, that's only in the movies. In RealLife, the vents are too thin."
* Parodied and subverted in ''BatmanBeyond'': The protagonist enters a vent large enough to walk in, but the subsequent sections keep getting smaller and smaller.
* ''DannyPhantom'': In the episode "Doctor's Disorders", the only way to save the hero so he can stop the villain is to go ''in'' by the way of an air vent.
* The ''[[DennisTheMenaceUK Denis the Menace]]'' cartoon does this in one episode when he's trying to flee with Gnasher from a large mobile mall that has arrived in Beanotown and hypnotising everyone into buying useless junk. Whilst crawling, they find the office of the mad scientist behind the plot, and instead of escaping Dennish decides to bring him down instead.
* Subverted and played with in ''[[BatmanTheBraveAndTheBold Batman: The Brave and the Bold]]'': Batman is infiltrating a parallel Earth, disguised as his evil counterpart Owlman. He's allied himself with Red Hood, the heroic counterpart of [[spoiler:the Joker]], who is being tortured by Silver Cyclone, the evil version of Red Tornado. Batman sneaks through the air vents to free Red Hood and escape after his cover is blown by the evil Atom. [[spoiler:This might have worked... EXCEPT Silver Cyclone apparently had a tracking device or something on Batman, because the moment he realizes that Red Hood has been in contact with someone, he remembers that Owlman has been acting strangely and his computer immediately tells him Batman's location, in the air vents, proving that he's a spy. Silver Cyclone then powers up the fan to slice "Owlman" to pieces. Of course, this is the goddamn {{Batman}} we're talking about, so he blows up the fan. But still, the AirVentEscape turned out to be ''not'' the best idea.]]
** Averted in "Menace of the Conqueror Cavemen!", as the air vents are cramped. They also shake and make a good deal of noise when Batman and Booster crawl through them. Fortunately Kru'll isn't paying much attention.
* In an episode of ''Max Steel'', the only entrance to a highly-secured building is through the air vents. The only way in is by careful timing to avoid being sliced by a giant fan; the vents end two-thirds of the way up the wall in a room where the floor is littered with explosive devices, and not only do the air vents have cameras, they're also equipped with flamethrowers the big bad of the episode can activate at will.
* ''RobotChicken'' {{Lampshaded}} this in an ''IronMan'' spoof. Two {{Mooks}} guarding The Mandarin's lair are able to instantly determine the deafening banging and screeching noises they hear are from Iron Man trying to sneak through the air ducts.
* ''JonnyQuest'' episode "Mystery of the Lizard Men". Jonny crawls though an air duct to escape from the title oppponents.
* ''{{SpongeBob SquarePants}}'', "Truth or Square": after getting [[LockedInAFreezer locked inside the Krusty Krab freezer]], the gang makes their way out through the restaurant's labyrinthian ventilation system.
* Subverted in JimmyTwoShoes, "Jimmy in the Big House", where Jimmy and Beezy disguised themselves as pandas to try to get Cerbee, Jimmy's pet, out of the prison for animals but Cerbee already escaped and they are imprisoned themselves. Until Cerbee tries to get Heloise, the one who built the prison, to let her understand that they are in trouble; Jimmy and Beezy tries to get out by going through air vents. Suddenly, a screen pops out and it's a video message from Heloise who lets them know that they have made it far in escaping but in her prison, there is NO ESCAPE! As a result, they are blown out of the air vents by the fans at high speed and back to where they were. Finally, Heloise breaks them out by breaking in.
[[/folder]]

[[folder:Real Life]]
* There are personal anecdotes in [[TroperTales/AirVentEscape Troper Tales: Air Vent Escape]].
* This was attempted in 1994 by Cleveland Indians pitcher Jason Grimsley to try to switch out teammate Albert Belle's corked bat before the umpire could find out he was cheating. Going through 10 feet of ducts and a false ceiling, he might have even gotten away with it if he hadn't replaced it with [[http://www.mentalfloss.com/blogs/archives/7338 an autographed bat]].
* Averted in real life: [[http://en.wikipedia.org/wiki/Sensitive_Compartmented_Information_Facility Sensitive Compartmented Information Facilities]], a.k.a. [=SCIFs=], where top-secret intelligence information is handled in the United States have a list of regulations on construction of air vents, including grates to prevent entry and deliberate metal disconnects to avoid sound transfer.
[[/folder]]

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