[[quoteright:217:http://static.tvtropes.org/pmwiki/pub/images/ventilation_shaft.jpg]]
[[caption-width-right:217:Why this trope [[RealityEnsues doesn't work]] in RealLife.]]

->''"Buildings always seem to house gigantic vertical shafts where the hero can hide and access any other room in the entire building, and where the enemy never seems to look for them."''
-->-- [[http://www.avforums.com/threads/the-hollywood-rule-book.32262 "Hollywood Rule Book"]], Vanity Fair

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. Air vents also work excellently in reverse for breaking ''in'' and infiltrating a facility, as well. 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 allow an adult to pass through, there are no internal obstacles like bracing or [[DeadlyRotaryFan blowers]] (except for the occasional DeadlyRotaryFan blocking the branching corridors), they are free of normal sheet metal's dangerously sharp edges, they are totally soundproof, and there's never a lack of light or chance of getting lost unless the plot calls for it.

And the escapee always emerges without having picked up so much as a speck of dust.

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.

This is practically a DiscreditedTrope by now, and requires some effort to {{justif|iedTrope}}y 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 ''Series/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 (even more so if you've got magnets attached to your hands and knees...). Perhaps the only way this trope is justified is if the character in question has some kind of shrinking or SuperSmoke power, in which the physical limitations of an air duct are less of a concern.

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]] '''[[DontTryThisAtHome extremely]]''' [[DontTryThisAtHome dangerous]], not to mention illegal -- steam tunnels are usually hot, cramped, and frequently criss-crossed by scalding-hot 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, plus the fact that air can bend at ninety degree angles and fit through grates much more readily. There have been numerous cases where enterprising criminals have attempted to rob a store by sneaking through the ducts and end up [[StupidCrooks getting stuck]]. The usual ending is the [[StupidCrooks embarrassed criminal]] being either pulled or cut out of the duct by the fire department and then promptly handed over to the authorities.

Compare AbsurdlySpaciousSewer for a similar trope which takes place beneath buildings rather than in them.
----
!!Examples

[[foldercontrol]]

[[folder:Anime & Manga]]
* {{Justified|Trope}} in ''Manga/FullmetalAlchemist'': shrimpy Edward is the only character who can fit in the air vents, and for him it's a tight fit. Which leads to further comedy as Ed has a complex for being TheNapoleon.
* Like the opening of season 1, the opening of season 2 of ''Anime/GhostInTheShellStandAloneComplex'' is all about showing off the awesome skills of Section 9 while providing a reason for the unit's reactivation. The regular SWAT unit attempts an assault on the Chinese embassy through the air vents, but spectacularly fails with one officer dead and another being added to the terrorists' hostages. Seeing these poor results, his superiors immediately give Aramaki the green light to send in his team and get the job done.
* ''Anime/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. The air vent entrance also {{lampshaded}} the MaleGaze when Asuka kept kicking Shinji for "looking ahead." Later in the episode, we are treated to the sight of ''HumongousMecha'' escaping via (humongous) air ducts.
* Mokuba Kaiba once escaped from the Big 5 this way in ''Anime/YuGiOh'' At least he's a fairly small kid, more likely to fit and all that.
* In ''Manga/YuGiOhR'', Jounouchi and Honda avoid some {{Mooks}} this way. Lampshaded by Jou, who complains about how claustrophobic it is and keeps getting accidentally kicked in the face by Honda.
* {{Subverted|Trope}} with glee in ''Anime/{{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 ventilation 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}}.
* Ryō and Saeko sneak into a jewel exhibit this way in ''Manga/CityHunter''. Ryō gets a heel in his forehead as a reward for his overly ardent MaleGaze.
* In ''Anime/{{Monster}}'', 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 ''Anime/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''.
* ''Anime/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.
* ''Anime/{{Hellsing}}''
** Integra does this to hide from her uncle.
** Seras and Walter also use this to avoid a confrontation with the Valentine brothers.
** Walter actually makes a point of reminding Integra that she used the vents to hide, so it's possible that they were deliberately designed with the purpose of allowing people to move throughout the mansion and avoid enemies in mind.
* In ''Manga/ShugoChara'', Kiseki and Yoru escape from a locked room this way. {{Justified|Trope}} since the Shugo Charas in that series are small enough to fit in normal air ducts.
* Done once in ''Manga/RaveMaster'' though by a creature who must be light, because he floats when he sleeps, and something that [[CallASmeerpARabbit may be a small dog]].
* {{Justified|Trope}} on two occasions in ''Manga/DanceInTheVampireBund''.
** Akira making it through the massive vents and tunnels of the underground city beneath Tokyo Landfill #1 to escape the assassins hunting him makes sense (and he finds himself reminding his [[UndeadChild prepubescent rescuers]] that he is not as compact as they are).
** In an inversion from volume 7, after a ManchurianAgent locks down Mina's skyscraper-cum-palace the only person who can get to the security center via the way-to-small-for-anything-remotely-human vents is [[BattleButler Vera]] (who turns into mist and is obliged to [[FullFrontalAssault leave her clothes behind]]).
* ''Manga/FrankenFran'' has to cut off at least half her body in order to pull off a vent escape.
* In ''[[Anime/MobileFighterGGundam G Gundam]]'''s second episode, Domon sneaks through the ducts of Madison Square Garden and ambushes Chibodee's boxing opponent so he can take his place. In the 2010 manga re-telling, the sequence is PlayedForLaughs instead: Domon ''intends'' to go to Chibodee and challenge him, but [[IdiotHero ends up in the opponent's room because he got lost]]. [[RefugeInAudacity He then tries to play himself off as an autograph hound.]] It doesn't work, and after knocking the guy out he decides to take his place.
* In ''Manga/AxisPowersHetalia'', '''Paint it White!''': Italy, Germany, and Japan pull one of these in order to escape the aliens currently chasing them. May or may not be {{justified| trope}} because they were in an alien mothership, with air vents about the size of an average person. They DID fall through at one point, and Germany got quite a few scratches to the face.
* While searching an enemy ship in ''Manga/FairyTail'' the Exceeds (who are about the size of a cat) are shown crawling through an air vent, wondering about the necessity of it and complaining about how narrow it is. When they ask why they're in there instead of searching the rooms like a normal person, Happy says [[RuleOfCool "No particular reason"]].
* In "Turnabout Prophecy" of the ''Franchise/AceAttorney'' manga, this is averted. The ventilation pipes themselves are too small to crawl in, but it is possible to crawl in the area where the pipes are.
* Amusingly {{Downplayed|Trope}} by [[{{Meganekko}} Jody Hayward]] in ''Anime/ElCazadorDeLaBruja''. She uses the vents to sneak into [[BigBad Rosen]][[TheChessmaster berg's]] office only to find that her hips are slightly too large to fit through them.
* Successfully done by Tsukiyo in ''Manga/TheWorldGodOnlyKnows'', but small as she is she still couldn't have pulled it off normally. Rather, she was shrunk down to the size of a doll and it was still a pretty tight fit.
* In ''Manga/{{Akira}}'', Kaneda tries to escape custody through the ventilation duct. He doesn't get far though.
* In ''Manga/JoJosBizarreAdventure Part 2: Battle Tendency''. Despite attempts to contain him, HumanoidAbomination Santana simply decides to leave through the grated air vents, via ''pulverizing every bone in his body and flattening himself'' until he can slip through. Thereafter, the Nazi research team does not live long enough to learn that EvilIsNotAToy.
[[/folder]]

[[folder:Comic Books]]
* An example of a villain using this trope is found in Marvel's 1990s series ''{{Sleepwalker}}'', when SerialKiller 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.
* Franchise/{{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.
* Kei tries this in ''The LightNovel/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 ''ComicBook/YTheLastMan'' 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...
* Reed Richards of the ''ComicBook/FantasticFour'' does this now and again as well. Justified in that his powers are to stretch his body to any length, and width.
* ''Franchise/{{Batman}}''
** Scarecrow escaped out of Arkham Asylum this way. Justified in that this villain has always been a skinny britches. And it's [[CardboardPrison Arkham Asylum]].
** Used again in the 1980s FrankMiller envisioning of Batman. True, this time it was an arranged "escape" -- with both Batman and Commissioner Gordon in on the act of breaking a villain out of an ''ordinary'' holding cell. However, this time the prisoner is the hulking Mutant leader, a man built enough to take on Batman in hand-to-hand combat. (The breakout was so that Batman could have a rematch, after also arranging for the entire Mutant gang to be on hand to watch their leader get taught a lesson in messing with the Batman.)
* ''ComicBook/MsTree'' makes an AirVentPassageway escape as part of her DieHardOnAnX plot in the "New Year's Evil" story.
* In ''Webcomic/{{Dreamkeepers}}'', Namah and Mace (And Whip) are both partial to this trope.
* In ''[[ComicBook/MickeyMouseComicUniverse Mickey Mouse and the Chirikawa Necklace]]'', Mickey and Atomo Bleep-Bleep escape a deathtrap through an air vent. May be justified in that they are very small, especially compared to the {{dogfaces}} that inhabit the ElaborateUndergroundBase.
* Recently used in a Bash Street Kids strip in ''TheBeano'' which saw Fatty, Plug and Smiffy crawl into a vent in an attempt to steal a key off Teacher.
* Subverted in "Earthquake",an issue of ''PaperinikNewAdventures'': Paperinik must get around a closed door. Being GenreSavvy, he tries to go in an airvent remarking: "This Always works in movie!" Being a PintSizedPowerhouse he can crawl in, but his large shield gets stuck.
** Played straight in a issue of its sequel.
* Discussed by ComicBook/{{Catwoman}}, who [[JustifiedTrope explains]] that extra and unnecessarily large vents and crawlspaces are common in Gotham as a result of the widespread corruption that allows contractors to get paid for extra construction on municipal buildings, then further cautions that most of these are undependable and poorly made since they're just there to justify extra budget allocations and the contractors weren't concerned with their use and upkeep.
* Played with in ''ComicBook/{{Diabolik}}'': depending on the {{Genre Savvy}}ness of the victim, their house may have or have not vents sufficiently large, resulting in Diabolik and Eva (extremely agile people) either climb in themselves or [[DangerouslyGenreSavvy use a remote-controlled robot]] to reach the safe or vault.
[[/folder]]

[[folder:Comic Strips]]
* In a series of ''ComicStrip/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.
* In a ''ComicStrip/{{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 ''Franchise/StarTrek''." With Asok's lower body handing out of the vent, Alice puts up a sign that reads "Spank the Intern $.50".
** Similarly, the boss has to hid in the ducts when his security clearance is revoked. He gets stuck and is presumed dead, resulting in the construction of a 'totally cool device to increase the duct pressure and propel his carcass into the stratosphere'.
[[/folder]]

[[folder:Fan Works]]
* This is the method that Draco uses to get the Death Eaters into Hogwarts in ''Theatre/AVeryPotterMusical''.
* [[http://www.fanfiction.net/s/4471204/6/I_Think_Some_Serious_Physics_Just_Happened One chapter]] of the ''WesternAnimation/KimPossible'' {{fanfic}} ''I Think Some Serious Physics Just Happened'' has a nice {{deconstruction}} of the trope when Ron, dropped into the real world, sneaks into a library through the airvents and naturally [[RealityEnsues 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.
** Or there might simply be enough traffic in the ventilation system of the average villain lair to prevent dust gathering... Let's face it, those bases usually last a month or three, and see twenty-odd people getting around by air vents in that timeframe.
* In another ''Kim Possible'' fanfic, ''To Bebe or not to Bebe'', Kim and Ron are captured by a surprisingly competent villain who not oly has air vents too small to crawl through, but also took all their equipment and destroyed it rather than leave it out to pick up when they escape.
* A [[TroperCriticalMass necessary reference to]] ''FanFic/NobodyDies'': Terrifying!Rei's favorite method of StealthHiBye is to drop out of [[strike:NERV's]] ''any'' ventilation system. ''He~eeey.'' OhCrap. Running now. Later revealed to be a trait common to all Lilith-based Nephilem, as when [[spoiler:Shinji is temporarily turned into a Nephilem, he suddenly gets good at zipping through vents too]]. Kensuke is picking it up as well, due to his... "friendship" with Rei.
* Used in the ''VideoGame/{{Portal 2}}'' fanfic ''FanFic/TestOfHumanity'', though it's more of an "incinerator exhaust pipe escape". Subverted in that [[spoiler:[[BigEater Wheatley]] is too fat to fit all the way through and ends up stuck, causing the pipe to explode from the built-up pressure.]]
* In ''Fanfic/FalloutEquestriaPinkEyes'', the main character Puppysmiles is just a little filly, meaning it's easier to crawl around in tight spaces. She uses this to enter a locked-down fortress to search for her mom.
* Examples from Fanfic/{{the Calvinverse}}:
** Calvin ends up using one of these in ''Fanfic/RetroChill''.
** Inverted in ''Fanfic/CalvinAndHobbesTheSeries'': Andy and Sherman are ''captured'' by a [[TurnedAgainstTheirMasters possessed]] air vent.
* ''Fanfic/QueenOfAllOni'': Drago uses the air vents to break into Section 13. He calls it a cliche, and expresses disappointment that the Section 13 of the present isn't on the same level as the one in his time.
* ''FanFic/EarthAndSky'': After [[spoiler: Chrysalis]] is arrested and thrown in the dungeon in Los Pegasus, she slips free of her chains by [[spoiler: molting to filly-size]] and then crawls out through a vent. [[JustifiedTrope Even then, it only works because, as Luna points out,]] [[spoiler: [[JustifiedTrope her carapace hasn't hardened yet]]]], [[JustifiedTrope allowing her to squeeze through the tight space.]]
* ''FanFic/HitmanMiami'': In chapter 8, the only way into the target's office, apart from a locked steel door, is a six-inch wide vent in the ceiling, which Agent 47 uses to drop monkey chow into the room in order to lure in a KillerGorilla, then a grenade to kill the gorilla.
* In the ''VideoGame/{{Portal}}''[=/=]''WesternAnimation/MyLittlePonyFriendshipIsMagic'' crossover ''FanFic/BetterLivingThroughScienceAndPonies'', Chell uses some vents to get back inside the Enrichment Center. Justified in that her small pony body fits better.
* In ''FanFic/BlueSky'' it's not exactly air vents, but climbing in the chaotic crawl spaces of the facility.
* The absurdly spacious ones in Arkham are viciously lampshaded in the ''Franchise/{{Batman}}'' fic ''FanFic/BruceHasAProblem''; evidently they were originally dog runs put in by a director who thought dogs would have mental healing properties, abandoned when the director died in a dog-petting accident. They were then repurposed as vents by another director, who was looking to cut costs to fund a step pyramid he was building.
* In the ''WesternAnimation/MyLittlePonyFriendshipIsMagic'' fanfic series ''FanFic/HarpflankAndSweets'' -- in the headquarters of the heroes, no less.
* Used for infiltration in the ''Franchise/MassEffect'' fic ''FanFic/MassesToMasses''. Subverted when Ian's weight brings it down, resulting in Melanis lecturing him on how this trope doesn't work in real situations.
** [[{{ThisIsReality}} "This is real life, not the vids."]]
* In the ''Series/StargateUniverse'' fic ''FanFic/{{Scribblings}}'', Chloe and Rush both make use of a variant of this: Chloe turns it into a prison for Eli and Rush turns it into a nest.
* In the ''VideoGame/SuperSmashBros'' fic ''FanFic/SmashGeneration'', this is how Midna went to see who was in the Mansion, and also how Pear, Riley, BJ and Popo evaded escape.
* This is Eric's favorite method of travel in the ''Series/{{Glee}}'' fanfic FanFic/SpahVerse, both at Dalton and McKinley.
* In the ''VideoGame/{{Persona}}''[=/=]''VideoGame/SuperSmashBros'' crossover ''Fanfic/SSBTheReturn'', Melody uses these to get around the school.
* In the MegaCrossover ''FanFic/SuperNetworkWars'' [[IdiosyncraticEpisodeNaming episode]] 27, some members of the Nueva Liga Filipina have to crawl through this in order to stop the poisons from being administered into the food of the [=VIPs=] at the 12th ASEAN Summit.
* Occurs in ''Anime/BubbleGumCrisis'' fanfic ''FanFic/TheBubblegumZone''.
* In the ''Literature/HarryPotter'' [[AlternateUniverse AU]] series ''FanFic/TheDarknessSeries'', Harry uses this when doing spy work at Riddle Manor [[spoiler: [[JustifiedTrope in snake form.]]]]
* The ''WesternAnimation/ChipNDaleRescueRangers'' fic ''[[FanFic/TheMidnightverse Diamonds In The Desert]]'' is practically about this.
** Also from the same series, Zipper gets into and out of the National Institute for Mental Health via air vents in ''Lost And Found'', and the Rangers use the air-conditioning vents to get into Mr. Jacob's penthouse in ''Last Date''.
* The heroes use these to break into the base in the ''WesternAnimation/TheAdventuresOfJimmyNeutron'' fanfic ''FanFic/TheOtherSideOfTomorrow''.
* Occurs in the ''Franchise/StarWars'' [[AlternateUniverse AU]] ''[[FanFic/ThePadmeAUs The Part to Be Played]]''.
* Part of the caper plans in the ''FanFic/UndocumentedFeatures'' fic ''Hellbringer and the After-School Special Mission Force #1: "The Bad Bank Caper"'' -- as Lain Iwakura says, "Oh, good... I was -hoping- we'd be hitting all the cliches on this job."
* This is how Carlos leaves the VILE base in the ''[[Literature/WheresWally Where's Waldo]]''[=/=]''Franchise/CarmenSandiego'' crossover ''FanFic/WhereOnEarthSpies''. He's a small dog, so it works.
* Used by the protagonists of ''Fanfic/YuGiOhForever'' during the last part of the Dueltropolis arc, to sneak on board the ARK.
* Calvin and Hobbes use this to infiltrate a base in ''Fanfic/TroubleIsland''.
* Justified in ''Fanfic/MassEffectHumanRevolution'': Ventilation passages in Krogan battle barges are huge because they're really meant for defenders to outmaneuver boarders.
* ''Fanfic/{{Equestrylvania}}'': In Book 2, after Rainbow Dash and Shatterstom are captured by [[spoiler: [[TheQuisling Rose Blade]]]], he has the former locked in a bathroom that's been converted into a holding cell/torture chamber; after getting free of her chains, she gets out of the room this way. Somewhat subverted, as it's a cramped fit, and Rainbow Dash is constantly worried that she's going to make noise and alert the {{Mooks}} below.
[[/folder]]

[[folder:Films -- Animation]]
* ''WesternAnimation/ToyStory2''. Naturally, ducts are much more convenient when you're eight inches tall.
* ''Disney/LiloAndStitch'': This is how Stitch escapes from the prisoner bay after breaking out of his cell. Justified because he's small and fast, and all the guards know he's there, they just couldn't shoot him in time.
* In ''Animation/SkyBlue'', Shua flees Ecoban through the air vents after going through the AbsurdlySpaciousSewer system.
* Subverted in ''WesternAnimation/EdEddNEddy'''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 another way out, he trips over a rug, revealing a heating duct. Eddy quickly pries open the grate, jumps in, and... more bricks. Then Ed finds the "In Case Of Movie Break Glass" case.
* Done by [[ColdSniper Trig]] in ''WesternAnimation/StarshipTroopersInvasion'', where she has to strip out of her power armor to get into the vent. She also [[LampshadeHanging mentions]] that Bugspray would never fit when he wants to go with her.
* Franchise/WallaceAndGromit's ''WesternAnimation/TheWrongTrousers'' has air ducts to a museum big enough to stand in. They were realistically loud though, insofar as a pair of remote-controlled, vacuum-soled robotic trousers can be realistic.
* Lampshaded near the start of ''WesternAnimation/TitanAE'' when Korso tells Cale to head for the vents. Cale responds sarcastically that no one would think to look for them there.
* ''WesternAnimation/TheSecretOfNIMH'' carries this over from the book it's based on. The rats make it out fine, however all but two of the mice are blown away to their deaths.
[[/folder]]

[[folder:Films -- Live-Action]]
* ''Franchise/DieHard''
** Used quite famously in the [[Film/DieHard first film]]: 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." Plus, he gets really dirty.
** In the [[Film/DieHard2 second film]], [=McClane=] crawls through a ventilation shaft on directions from the janitor to reach an area where he believes mooks are waiting to attack an airport SWAT team escorting the engineer to a backup radio system to establish contact with planes circling the airport. [[CassandraTruth He turns out to be right, but gets there after the SWAT officers have been taken out permanently]].
* In ''Film/{{Dawn of the Dead}}'', the main characters use the mall's air vents to access the stores that are locked with gates.
* In ''Film/{{Masterminds}}'', Ozzy has an extended sequence where he dodges the hostage-takers in air vents. Done realistically in that the school is huge but only covered by a small group, the ducts are barely large enough for him to fit in the first place, and he makes enough noise that they can follow him once they stumble upon his location.
* Used, more realistically than usual, in ''Film/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 ''Film/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]]).
* Minor subversion in ''Film/{{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.
* ''Film/TheFifthElement''
** Subverted when the villain sweeps the ceiling with a machine-gun, perforating Leelo, 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 ''Film/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 ''Film/MrAndMrsSmith'', 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 ''Film/TenaciousDInThePickOfDestiny'', 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.
* As evidenced in ''Film/Halloween5TheRevengeOfMichaelMyers'', Michael does not take too kindly to this trope. He proceeds to relentlessly stab the outside of the air vent when a would-be victim (his niece) tries to escape through one.
* ''Franchise/{{Alien}}'':
** In ''Film/{{Alien}}'', the ''monster'' actually uses the air duct escape against the protagonists
** In ''Film/{{Aliens}}'', Ripley and the marines use ducts to escape the monsters (which likewise use the ducts to invade). Likewise the aliens bypass the walls and doors by sneaking through the ceiling plenum ''à la'' ''Film/TheBreakfastClub'', correctly using the structure to carry their weight and cross the lay-in-ceiling.
** 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 ''Film/DesperateMeasures'', the villain Peter [=McCabe=] can take a 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."
* ''Film/MissionImpossible''
** TomCruise's character infiltrates the CIA headquarters this way (along with JeanReno's), which leads to the famous "[[MissionImpossibleCableDrop dangling in the ultra-secure white room]]" scene.
** In ''Mission: Impossible III'', Ethan 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". The vent Ethan crawls out of is in a room with pamphlets for the Virginia Department Of Transportation, his cover job, implying that he uses that room frequently and either knows of -- or set up -- that opportunity, should he ever need it.
** In ''Ghost Protocol'' there's an offhand comment that "infrared sensors" prevent Ethan from infiltrating the server room in the Burj Khalifa, so he has to get there by [[OhCrap climbing up the outside of the world's tallest building]]. Played straight later on in the movie when Brandt has to enter another server room through the heat vents, which of course are rather hot and contain a DeadlyRotaryFan he has to leap onto and hope his metallic suit will keep him suspended above a remote-controlled robot with a large magnet. As a RunningGag in the movie is the failure of the various gadgets the IMF team is equipped with, this plan does not fill him with confidence.
* A variation happens in the Italian movie ''Film/DangerDiabolik'' (featured on the last episode of ''Series/MysteryScienceTheater3000''), 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. 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, ''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.
* ''Film/JamesBond''
** Subverted in ''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 ''Film/DrNo''. 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. One part of the vent had red-hot surfaces and Bond gets swamped by a huge wave of water at one point. As a nice touch, he experimentally taps the grill at the other end with his feet to make sure ''it'' isn't electrified.
* Used and subverted in ''Film/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 ''Film/INowPronounceYouChuckAndLarry'' involves the main characters (who are firemen) having to rescue a would be thief who got stuck trying to sneak through an air duct.
* In ''Film/SantaClausConquersTheMartians'', 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. ''Series/MysteryScienceTheater3000'' adds an appropriately Bondian line: "So, Mister Claus, you have a nasty habit of surviving!"
* ''Film/{{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. Though somewhat subverted in that he is caught as the guards are smart enough to look and find him.
* Subverted and [[LampshadeHanging lampshade hung]] in ''Film/HaroldAndKumarGoToWhiteCastle'', when 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 grab the bag of weed and get Harold out due to [[LampshadeHanging lampshade-hung]] PoliceBrutality, though.
* Referenced in ''Film/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 air vent 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 ''Film/TopSecret''. 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.
* ''Franchise/ResidentEvil''
** ''Film/ResidentEvil''. After leaving the Red Queen's chamber the 2nd time, at one point the surviving team members go through air vents to evade the zombies.
** In ''Film/ResidentEvilApocalypse'', Alice escapes Nemesis via a random spacious disposal chute.
** In ''Film/ResidentEvilExtinction'', 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.
* In ''Film/MenInBlack II'', the worms get to the power control of MIB headquarters through the air vents.
* ''Film/{{Daylight}}'' has Sylvester Stallone get into a caved-in tunnel through a air vent. Since the air vent was meant to supply air to a car tunnel, its 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. It doesn't help that Paul is a little on the heavy side (played by KevinJames).
* In ''Film/{{DEBS}}'', 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.
* ''Franchise/StarWars''
** The famous [[TheWallsAreClosingIn trash compactor scene]] from ''Film/ANewHope'', which is a subversion because in that case, attempting to escape [[FromBadToWorse led to an even worse situation]].
** Yoda's escape through the vents in ''Film/RevengeOfTheSith''. Justified by Yoda's small size.
** Played straight in ''Film/ThePhantomMenace'', when Obi-Wan and Qui-Gon do this flawlessly to escape the Neimoidians' ship. "They've gone up the ventilation shaft!"
* The 1998 American ''Film/{{Godzilla|1998}}'' 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.
* Memorably parodied in ''Film/TheBrothersBloom''. Penelope needs to smuggle a MacGuffin out of a church while the police are thoroughly distracted. She fits in the air vents well enough, but they are not concealed in the least, and the clamor she makes attracts the police to her. The duct has very little support, so it breaks open ''right in front'' of a SWAT team, and she picks herself up into a FightingStance.
* In ''Winning London'', Riley and Brian help the hostages escape using the air vents.
* In ''Film/FourteenOhEight'', protagonist Mike Enslin attempts to escape from the titular room by crawling through the air duct... only to discover that one of the room's many long-dead occupants has taken up residence there as well. He manages to escape the ghoul by quickly backtracking out of the vents, but the attempted escape in the first place didn't do anything, as most of the airvents leading to different rooms simply lead to various memories he's had throughout life, making it a pointless effort to begin with, not that he knew that until he tried.
* ''Film/TwentyEightWeeksLater'' has Andy using this to escape a room in which the ranks of the infected are growing exponentially. Partially justified in that Andy is supposed to be only around ten or eleven and therefore is small enough to fit inside the vent with little trouble.
* Subverted in the ''Film/DayOfTheDead'' remake, as one of the zombies catches the heroes trying this and actually follows them into the vent.
* Subverted in the B-movie ''Film/ChoppingMall''. The teens attempt to escape the shopping mall's malfunctioning killer robots through the airvent. Only the girls get in before the guys are forced to flee for their lives. The girl end up abandoning this plan when it seems the computer has turned on the heat, forcing them to leave the vent and re-enter the mall.
* Done in the Lorenzo Lama vehicle ''Snake Eater II: The Drug Buster'': as Lama's character [[FanService wiggles his denim-clad gluteal region]] through the mental asylum's air duct, he meets two characters going ''in'' -- a hired woman, and a pizza delivery guy!
* ''Film/{{Inception}}'' had the group breaking into an ice fortress using a air vent system. Justified since they had created those air vents to be big enough to let people move around.
* The famous ''Film/TheShawshankRedemption'' escape although instead of an air vent, it's a sewage pipe.
* In ''Film/ToySoldiers'', the main characters use the air vents to get from the bathroom to the headmaster's office.
* The cast of ''Film/ThePool'' try to do this, but the killer will have none of that nonsense.
* Played with in ''Film/EightLeggedFreaks'', when a character narrowly escapes the giant spiders by diving into a rooftop air duct into a mall's ventilation shafts... only to slide helplessly down a ''slanted'' vent, then get trapped when the grill at the bottom won't come loose.
* In ''Film/TheJourneyOfNattyGann'', Natty escapes from a reform school via ''some'' kind of vent which she gets into by removing a grate from the bottom of the bathroom wall.
* ''Film/ThePoseidonAdventure''
** Used as a means of navigation in the remake. Handled a bit more realistically than most examples of this trope: the ducts are wide enough to crawl through without very much effort, but one character does get stuck in a compressed section and has to be helped out. Another one suffers from claustrophobia, and the heroes nearly drown due to the rising water because it takes a ''lot'' of effort to get the panel on the other side open.
** Also used in the sequel to the original movie, ''Beyond the Poseidon Adventure,'' complete with internal lighting fixtures.
* In ''Film/{{Colombiana}}'', Cataleya sneaks through a prison's air vents, helped by the fact that she is ''very'' skinny. She had to disable the vents' fans before starting her journey.
* Done in ''Film/IronSky'' by James Washington when escaping from the Nazis on their Moon base (ItMakesSenseInContext). We're not shown how he actually get into the vents, all so that we can be treated to a {{pun}} by Klaus Adler, when he comments to Renate that she is a "knockout"... just as a vent cover is falling on him from the ceiling. Slightly justified in that the Nazis never expected to be invaded or infiltrated. And all their technology is of the SchizoTech variety.
* ''Who's Harry Crumb'' has the titular detective attempt to spy on his client's GoldDigger wife and her lover (whom he suspects to be the kidnappers of the client's daughter) by pretending to be a repairman and crawling in the vents, which are big enough to accommodate someone the size of JohnCandy. Subverted in that he actually can't get a good look inside the room due to the awkward positioning of the airholes, so he resorts to using a camera (and then doesn't bother to look at the pictures to find out that the kidnapper is [[spoiler:his boss]]). When the kidnapper turns up the A/C, Harry is rapidly propelled along the vents to the point that he literally flies out at the end.
* Played completely straight in ''Film/BlueStreak'', where Logan manages to hide a huge diamond right before the cops find and arrest him. Years later, he is released from prison and comes looking... only to find out that the building is now a police precinct.
* In the HBO Movie ''Deadly Voyage'' (depicting the murder of 8 African stowaways on a Europe-bound cargo ship), the 9th stowaway manages to to escape from the ship and his would-be killers by shimmying up one of these. Made all the more harrowing by the fact that movie is based on a true story and that this isn't AdaptationDisplacement--this is EXACTLY how the man was able to get away.
* ''WrongfullyAccused'' uses this. Leslie Nielsen uses the vents to get into the hospital's computer room.
* ''Film/GingerSnaps'': Used by Ghost and Brigitte in the second film. Somewhat justified since they are both skinny teenage girls.
* The starship in ''Film/GalaxyQuest'' has a spacious duct system plus a team of fanboys able to navigate the heroes across. Justified as the starship is based on one used in a TV show, so this trope would come into play.
* ''PoliceAcademy'': Several officers use this method (among others) to infiltrate a building held by criminals.
** The obese officer "House" lampshades it when he complains about having to take the stairs (when one infiltration team got to take the elevator [[JanitorImpersonationInfiltration while disguised as maintenance personnel]]) and is reminded that he was offered the vents.
** In ''2'', Mauser co-opts Lassard's plan to take the Scullions by surprise via the air vent on top of the zoo enclosure's roof. Unfortunately for him, he chooses [[TheKlutz Fackler]] to help him. HilarityEnsues.
* In ''Film/TheThieves'', Yenicall escapes from Park's hotel room by crawling through the ceiling crawlspace.
* Subverted in ''Film/{{Outpost}}'' [[spoiler:when the last remaining team member escapes through an air vent, only to end up in the testing chamber where he's swarmed by its undead occupants.]]
** But played straight in ''Outpost: Rise of the Spetsnaz'' where a powerfully-build Russian escapes from the underground lab by climbing a convenient ladder in a vertical air vent. There are no locks or bars whatsoever, in a secret military installation where prisoners and zombies are confined, targeted by American spies and Soviet commando groups.
* ''The Killing Room'' (2009). Several volunteers are locked in a room for a psychological experiment, only to be killed off one at a time. One man is able to smash through the ventilation duct in the ceiling. The researchers react calmly as this has all happened before (in fact, the protagonists had heard someone scrambling through the duct earlier). He reaches a roof duct, but is blocked by a steel grill. Two labcoated researchers with clipboards are shown standing over another rooftop duct [[NightmareFuel from which can be heard a woman screaming]]. They walk over to the other grill, hit the man with knockout gas and drag him back to the Room.
[[/folder]]

[[folder:Literature]]
* ''{{Duumvirate}}'' The small kids who live in Northberg Educational Facility discover that they can go anywhere they want in the air vents. And the child-sized "secret" areas they lead to.
* 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.), complete with viewports for entertainment, intended as a deliberate obstacle course set up by Dr. No.
* Justified in the sci-fi book ''Literature/{{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 ''Illegal Aliens'' 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 ''Literature/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 toast. Once he gets out, he has to be sprayed with anti-radiation foam or he'll likely develop cancer.
* Subverted in Creator/ChristopherBrookmyre's ''Literature/OneFineDayInTheMiddleOfTheNight''. 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 ''[[Literature/EndersGame 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 outflow vents anymore, but by then [[spoiler:is the commander of Rabbit Army]] and so has access to the larger inflow vents.
* Works better in ''Literature/MrsFrisbyAndTheRatsOfNIMH'' 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 ''Literature/TheAdventuresOfSamuraiCat'', 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 ''[[Literature/HisDarkMaterials Northern Lights]]''. Being a twelve-year-old girl, she's smaller and lighter than most {{Action Hero}}es, but 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 ''Literature/HonorHarrington'' spinoff ''Crown of Slaves'', but used more realistically than many examples. 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. Additionally, the ducts in question are on a space station and are deliberately designed to be large enough to crawl through since they double as maintenance access passages.
* Referenced in Creator/TerryPratchett's ''[[Literature/JohnnyMaxwellTrilogy Only You Can Save Mankind]]'':
-->''"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.''
* Pratchett also pokes fun at the trope in ''Discworld/GoingPostal'' when, after a character fails to tunnel out of his jail cell, a guard remarks that the last guy in that cell -- who happened to be unusually small and nimble -- managed to squeeze through a tiny drain in the floor. Unfortunately, it didn't lead to the river like he thought.
-->"He was really ''upset'' when we fished him out!"
* Used and lampshaded in JohnCWright's ''[[Literature/ChroniclesOfChaos Fugitives Of Chaos]]'', Vanity--who has the power to find-slash-create hidden passages--finds an accessible air vent.
* In SandyMitchell's ''Literature/CiaphasCain'' series:
** In ''Cain's Last Stand'', the air vents are exactly the place genestealers like to hide.
** In other books, following a close call in ''Death or Glory'', Cain makes a point of always acquiring the access codes to the maintenance conduits whenever he travels by ship. In one occasion where he didn't find the time to do so, Jurgen brought to his attention the fact that he was in a civilian ship, therefore its maintenance conduits didn't require access codes.
* 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. Although humans can't fit through them as it is, so it can almost be call a lampshading. Shontine/K'da ships are actually ''designed'' for the stealthy, compressible K'da to be able to move through in case of hostile takeover, and a human sourly remarks that he outgrew the ability to navigate even big ships' navigation ducts when he was seven. When a K'da takes to those vents for the first time she gets thoroughly lost; in a later escapade she's almost caught when her tail twitches in shock enough to thump a vent.
** Played with in Zahn's {{Blackcollar}} novel ''The Backlash Mission'', where the air intakes for a huge underground military base are large enough an adult human can walk through them, in order to accommodate the massive inflow needed and the filtering equipment to keep out poison gas attacks. Since even with the vents camoflaged, this is an insanely large security risk, the intakes are designed with a very large kill zone of automated defenses, which are described as completely undefeatable and possibly viable for centuries without maintenance. [[spoiler: They actually were completely undefeatable. But with the base abandoned, there was no one to stop someone from spending months ''tunneling around'' the killbox.]]
* Slightly altered in ''Literature/HarryPotterAndTheChamberOfSecrets'', using the castle sewer-pipes for the monster to invade from -- and for the heroes to find -- the title chamber. Hogwarts Castle has got to have the most gigantic pipes ever seen... particularly for being built by wizards.
* Comes up in several variations (breaking in, breaking out, air ducts, hanging ceilings...) in places in the ''Literature/VorkosiganSaga'' by LoisMcMasterBujold, 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 Creator/GrahamMcNeill's ''TabletopGame/{{Warhammer 40000}}'' novel ''Storm of Iron'', this is how Hawke escapes a launching rocket and a Chaos SpaceMarine.
* In the ''WomenOfTheOtherworld'' short story "Chaotic" in the anthology ''Dates From Hell'', Hope flees from a werewolf into an office, and finds herself in a dead end. She tries to escape through the air ducts, but she makes too much noise when moving and has to freeze when the werewolf enters the room. He finds her immediately. Later, after the pair has teamed up, they both move around through the air ducts, which are noisy, painful, cramped, and dusty. Still later, the bad guy enters a room looking for Hope, and while he's investigating the unscrewed air vent the good guys come out of their real hiding places and get the jump on him.
* Averted in Creator/RobertAHeinlein's ''Literature/RedPlanet'' when one of the good guys proposes taking a vent grille off of a wall to get to the room on the other side. His friend points out that there will certainly be a similar grille on the other side, fastened by screws they won't be able to reach.
* In ''LuckyStarr and the Oceans of Venus'', Bigman Jones sneaks through the air ducts in order to prevent a psychically-controlled man from opening the gates and flooding the UnderwaterCity. The Venusian leader points out that air ducts "aren't as big as all that," but the trope is slightly {{Justified|Trope}} because, as Bigman [[GaggingOnYourWords painfully]] replies, "[[TheNapoleon I'm not as big as all that, either]]."
* Deconstructed in ''Literature/BlackDogs''. The ventilation in question is portrayed as tough, claustrophobic going in the dark, with Lyra, the protagonist, suffering several minor injuries, and a high chance of her falling and breaking her neck. Or breaking something else that renders her unable to escape, and dying slowly over several days.
* Subverted in the final book of the ''{{Sten}}'' Series, by having the hero nearly get stuck in a claustrophobic moment.
* Both played straight and subverted in Creator/JohnRingo's ''[[Literature/PaladinOfShadows Choosers Of The Slain]]''. They need to sneak into the secure facility of one of the bad guys, so (played straight) they pick the slimmest girl on the team, as the men on the team are too large especially wearing all their weapons. Subverted because they knew she would get stuck half-way down when the air vents narrowed, so her sole job was to get to that point and release a small robot (an R2-D2 toy they had picked up in a toy store and then modified to include surveillance and communications gear) which could go the rest of the way.
* Used by Cammie and Macey in the third book of ''TheGallagherGirls'' series to get back into a building, though in this case it was still for escape rather than infiltration.
* Subverted and lampshaded in ''[[Series/StarTrekDeepSpaceNineRelaunch Star Trek: Section 31: Abyss]]''. After escaping her cell, Ezri Dax goes up into an air vent, which (contrary to what the holonovels of her youth would have her believe) is very dirty, dark, small and has creepy things living in it. (She is, however, successful in using the air vents to move throughout the base to important rooms.)
* Subverted in ''LightNovel/ACertainMagicalIndex''. In Volume 17 of the novels, Touma asks if he could use the ventilation ducts in the plane, but the flight attendant says that the ducts are too small. Instead, Touma asks for some hot tea and coffee to pour down the duct, causing thermal expansion and make the terrorist on the other side think that there's someone crawling through the ducts. As a result, the terrorist on the other side gets some boiling hot tea to the face when he checks the ducts.
* Used in ''Literature/AgeOfFire'', where the two dragon siblings escape from a raid on their home cave by escaping through naturally formed air passageways.
* In short story "[[http://www.baenebooks.com/chapters/0743471741/0743471741___3.htm In the Bone]]", the protagonist uses air ducts which were too small for his alien opponent but nonetheless navigable by the smaller human form. Some of the ducts are indeed too small for the human.
* Justified in ''WitchAndWizard''. In order to free innocent children being persecuted by the government for being witches and wizards from prison, the protagonist Wisty infiltrates one of the prisons through the air vents..... but she turns herself into a mouse first.
* Played with in ''TheVampireFiles''. Jack can justifiably play this straight if he assumes a gaseous form (gas, after all, being what air vents are ''designed'' to let through). However, he's a bit claustrophobic and can't shake the feeling of being trapped while traversing a ten-inch-square conduit.
* ''The Disreputable History of Frankie Landau Banks'' features the steam tunnel and pranking variant, as it is set at a school similar to MIT/Caltech mentioned above. It should be noted that this does not occur without consequences: one character gets a moderately-to-severe burn from the exposed pipes.
* Somewhat altered in ''[[The39Clues The 39 Clues: The Dead of Night]]'', in which Phoenix Wizard and Reagan Holt try to escape the Vespers' prison by climbing up a dumbwaiter shaft. Justified, since the characters are children.
* Averted and lampshaded in SergeyLukyanenko's ''Literature/{{Competitors}}'', when Valentin and Lena are confined to quarters in a SpaceStation. When Valentin suggests escaping via the air vents, Lena laughs that he watches too many movies and points out that the vents are barely a foot wide. Valentin's suggestion to set off the fire alarm has Lena point out that this would cause the quarters to be depressurized to contain the fire.
* ''Under Alien Stars'' by Pamela F. Service has a crew from a hostile alien race take over a hotel, placing their prisoners on one floor. They remember to seal the edges of the air vents, but don't know or don't care about the garbage chutes descending past each floor.
* In MichaelFlynn's ''Literature/SpiralArm'' novel ''In The Lion's Mouth'', Bridget's first guess is such an escape before she deduces that in fact Ravn hid {[Invisibility Cloak}}s in the ventilation system, and then escaped, invisible, with her companion as soon as the door opened.
* ''[[Literature/TimeMachineSeries The Rings of Saturn]]'': The space pirate base has an extensive air ventilation system, extensive enough that a MadScientist was able to live alongside the inhabitants and move around the base for years without their knowledge.
* ''Literature/SixtyEightRooms'': The two kids manage to fit easily in the Museum's air vents as they have been [[IncredibleShrinkingMan shrunk down to five inches]]. Getting up to the vents was much harder.
* ''Literature/CannonFodder'': Kelsey says she escaped from Black Jack's base in this way, but we never see it happen.
* Attempted by Rolas in "[[Literature/TheRedVixenAdventures Captive of the Red Vixen]]", after he figures out that his ShockCollar is only tied to the door to his cell, but he finds a note from his captor and a trap waiting for him at the grille above the lifeboats.
* Averted in ''Literature/GetBlank'' when Blank uses a false ceiling, rather than any kind of duct, to get around.
[[/folder]]

[[folder:Live-Action TV]]
* ''Series/TheATeam'': Several episodes, including one where Murdock escapes from a locked room, with his hands bound no less, through a ventilation shaft. Hannibal and B.A. boost him into the shaft while Face distracts the guard.
* ''Series/BuffyTheVampireSlayer''
** Buffy and Xander use this method to 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). Also worth noting, Spike notices, and in a singsong voice says “some-one's-in-the-cei-ling”.
** Subverted in "Gingerbread", where Xander and Oz can fit into the vents but become lost and only reach the rest of the cast after the monster of the week is already dead. "We're here to rescue you..."
* ''Series/TwentyFour'' enjoys playing around with this. Sometimes played straight and other times, the villains are quick to seal them to prevent the cliche 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.
* ''Franchise/StarTrek'' has the "Jefferies Tube" maintenance tunnels criss-crossing the ship. They're actually designed for human access, but are quite often used in this way.
** Dr. Helen Noel saved the day this way in ''Series/StarTrekTheOriginalSeries'', episode "Dagger of the Mind".
** In "The Trouble With Tribbles", Scotty speculates that the tribbles got into the food processors on the ''Enterprise'' via the actual air vents. Spock realizes that the grain the ''Enterprise'' is guarding on the nearby space station is in storage compartments with similar vents, prompting Kirk to beam over and leading to the episode's CrowningMomentOfFunny.
** ''Series/StarTrekTheNextGeneration'' had a few DieHardOnAnX episodes where the Jefferies Tubes come in handy this way.
** ''Series/StarTrekEnterprise''. The ship is taken over and everyone is locked in their rooms. Hoshi, being the smallest person on board (and 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 the MirrorUniverse episode "In A Mirror, Darkly", the crew of Mirror NX-01 Enterprise pursue a [[TheDreaded Gorn]] through the Jeffries tubes of an Original Series vessel.
* In an episode of ''Series/StargateAtlantis'', Zelenka crawls through a vent to turn the city's power back on, although in this case the air vents are the same size as you'd find in the real world so he did have a very hard time moving around.
* In ''Series/StargateSG1'', the eponymous team uses this trope ''every'' time they're on a Goa'uld 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.
* ''Series/TheXFiles''
** Justified in 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.
* ''Series/UnnaturalHistory'' subverts this. Jasper tries to think of a creative way out of the room he's trapped in, and the camera focuses on a air vent duct. The next shot show him struggling futilely to pry the vent free.
* ''Series/{{Lost}}''
** In the second season, this is a legitimate way of getting around in the Swan station. Kate uses 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") can 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.
* ''Series/DoctorWho''
** {{Deconstructed}} in the episode "The Satan Pit"; Rose suggests escaping through the maintenance ducts, to which Security Officer Jefferson replies: "[[ActorAllusion I appreciate the reference]][[note]]Danny Webb, who plays the role, also appeared in ''Film/{{Alien 3}}''[[/note]], 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.
** Lampshaded again in the ''AudioPlay/BigFinishDoctorWho'' 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" (albeit realistically: Sarah Jane Smith is the only one small enough to fit and even she get stuck).
** Played straight in "The Tenth Planet". Ben even has a ''map'', albeit one drawn by the man who designed the ventilation system.
** Also played straight in the Third Doctor episode, "Invasion of the Dinosaurs", where Sarah Jane is locked in a closet and escapes through an air duct.
** 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 Doctor and companions use one of these to escape from Area 51 in the animated special ''Dreamland''. The Doctor lampshades their captor's [[JustifiedTrope Justified]] GenreBlindness.
-->'''The Doctor:''' I love 1958, no one's seen ''Film/DieHard''. Or ''Film/{{Alien}}''. Or ''Film/DieHard2'', or ''Film/{{Aliens}}'', or ''[[Film/DieHardWithAVengeance Die Hard 3]]''...
** The frequent use of this trope in its [[Series/DoctorWho parent show]] is [[LampshadeHanging lampshaded]] in ''Series/TheSarahJaneAdventures'' story "Death of the Doctor".
-->[[spoiler: '''The Doctor:''']] Ventilation shafts, that takes me back. And forward.
** The Cybermen's Cybermat devices could infiltrate target installations by going through ventilation ducts. Justified, since Cybermats are about the size of a rat.
* ''Series/TheSuiteLifeOfZackAndCody'': 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.
* ''Series/NedsDeclassifiedSchoolSurvivalGuide'': Many ASimplePlan requires use of the school's elaborate, labyrinthine air ducts, which eventually gave out in the GrandFinale.
* Spoofed on ''Series/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.
* ''Series/MissionImpossible''
** The master of air duct navigation is clearly the jack-of-all-trades Barney Collier. And one of the few times he wasn't doing it, he was coaching the woman who was.
** Somewhat justified and subverted in some episodes, particularly early ones. In one they had to employ a contortionist (played by Eartha Kitt): only she was small and limber enough to crawl through the ducts, and they even gave her a CoolTool so she could unfasten, from inside the duct, the screws that hold the grille on from the outside. At other times they sent a miniature remote controlled hovercraft and a small trained dog through vent ducts and similar. But most of the time, yeah.
* Justified in ''Series/{{Farscape}}'' where the diminutive Rigel often uses air ducts and service tunnels to travel when the ship is being invaded or he's feeling particularly paranoid.
* ''Series/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 {{Lampshade|Hanging}}s this one: Scott Bakula references it as an escape plan... and then finds out that the room only has a regular air vent.
* ''Series/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. It was so ridiculously loud that ''everyone on set'' - including Jamie- broke up laughing after the first step. Adam, on the other hand, used vacuum "cups" on his hands and feet that would grip the vent. Though it wasn't nearly as noisy, it was far from silent, and 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.
-->'''Adam:''' Why, Thor, the God of Thunder, is trying to enter my building!\\
'''Tory:''' Somebody needs to check that air conditioner!
* The Australian series ''Series/{{Escape from Jupiter}}'' features a moonbase and space station/makeshift rocket that both feature large air ducts. They're also likely some sort of Jefferies tubes -- just built in case of need for extended residence.
* ''Series/MysteryScienceTheater3000''
** Famously {{Lampshaded}}:
-->'''Joel:''' You know, it's funny how movie directors always make air vents big enough to crawl around in.
** And later, ''much'' later parodied in the episode ''Film/IWasATeenageWerewolf'' as an ''Alien'' parody where Tom Servo attempts to fight an invading alien, armed to the teeth, by going after it in an air vent; but gets stuck and after a few moments of nervous singing, bursts into tears. He does free himself soon afterwards, no thanks to Mike and Crow.
* ''Series/BurnNotice''
** {{Lampshaded}} and subverted in an episode. 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.
** His mother remembers he crawled through an air vent so he can go to the theatre and watch ''Star Wars''.
** Justified in a later episode (and spelled out in the narrative) that they were in a medical experimentation lab and the ventilation system had to be sufficiently large to facilitate a quick full air turn around in the event that something bad happened allowing him to climb to a higher floor in the building (in the narrative he says that normally it's not possible to use the airvents due to their size and lack of strength as well) (the system ventilated through the roof, he cut through it to get onto the second floor).
* Lampshaded and subverted in ''Series/TheMiddleman'' 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 subversion being that normally the vents are only a few inches in diameter, but they expand during an alert for this exact purpose. The Middleman explains that the "[[Film/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 ''Series/{{Numb3rs}}'', when it is revealed that Larry had been ''living'' in the tunnels on campus for awhile.
* On the ''Series/{{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 ''Series/DarkSeason'' episode 5 where Marcie escapes and says, "A ventilation shaft. Marvellous, I'm a cliche."
* In the ''Series/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...
* The air duct was used to get Robin Hood out of a Norman castle in the TV series ''Series/TheNewAdventuresOfRobinHood''. The series was a bit on a ''Series/{{Hercules|TheLegendaryJourneys}}'' and ''[[Series/XenaWarriorPrincess Xena]]'' level of authenticity but (sadly) not meant as a spoof.
* The old ''Series/VoyageToTheBottomOfTheSea'' 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.
* ''Series/{{Battlestar Galactica|Reimagined}}'', "Blood on the Scales". Chief Tyrol spends most of TheMutiny crawling through shafts 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.
* ''Series/{{Leverage}}''
** Lampshaded: "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.
** Played with in one season three episode, when Parker encounters difficulties trying to do this as there are lasers blocking her path. Why it wouldn't be cheaper to simply make the ducts too small to crawl through is never addressed.
* 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 ''Series/LasVegas'', 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. [[FridgeBrilliance Given that his predecessor, Ed Deline, had a bit of a mischievous streak, it's entirely possible he rigged the whole thing up]].
* This is used on several episodes of the first season of ''ThePretender''. During the first season finale Jared does this to break into and escape the Centre.
* On ''Series/{{Smallville}}'', Clark travels through the LuthorCorp air ducts when he is BroughtDownToNormal. In a later episode, this is also part of Jimmy's spy tactics.
* Along with many, many other tropes, this one is parodied in ''Series/{{Spaced}}'' when Mike and Tim are trying to escape from the offices of Dark Star comics: "Ah, the air vent. Simple, classic."
* In ''Series/{{Chuck}},'' there was once an ''incredibly'' roomy network of air vents, with ''lights.''
** Averted, however, in a season one episode, where Chuck crept around the area between the ceiling tiles and the high Buy More roof, and had to clamber over the air ducts while he was in there.
* Roomy air vents were used in at least one episode of ''Series/ISpy'', one of the more 'realistic' 1960s spy shows.
* Contra Security of ''Series/BreakingIn'' has large roomy air ducts... with booby traps. Knowing Oz, he may have had them built that large just to trap intruders inside.
* In an episode of ''Series/LawAndOrderSpecialVictimsUnit'', Elliot hides inside an air vent in order to spy on a woman holding hostages in autopsy. Then his phone goes off...
* ''Series/{{Seinfeld}}'', when George uses an air vent to break into his office after his boss tries to get him to resign by barricading it.
-->'''George:''' (on phone) Hello Margery, George Costanza. How are you sweetheart? Listen, can you give Mr. Thomassoulo a message for me?... Yes. If he needs me, tell him "''I’M IN MY OFFICE!''" Thanks.
* In ''TheSecretWorldOfAlexMack'', the eponymous heroine did this a few times, and at least once escaped captivity via the plumbing. It helped that she could turn into a liquid.
* ''Series/{{JAG}}'': In "Sightings", Harm and Meg escape the oncoming Colombians by climbing through an air vent.
* In ''[[Series/LoisAndClark Lois & Clark: The New Adventures of Superman]]'''s DieHardOnAnX episode "Fly Hard", Jimmy Olsen manages to escape unseen into the air vent system when terrorists initially take over the Daily Planet. Once he exits the system, however, it doesn't take long before he's found and neutralized.
* 1960's ''Series/{{Batman}}'' episode "A Riddle A Day Keeps The Riddler Away". Batman and Robin use air ducts to infiltrate a building where the Riddler is holding a kidnapped king hostage.
* Still shows up regularly in ''Series/{{Supernatural}}'', with Sam and Dean playing RockPaperScissors to see who'll go down in the ductwork. (It's always Dean. Dean is really bad at RockPaperScissors.) Although it was [[TheBigGuy Sam]] who crawled through the vent to the old cell block in [[Recap/SupernaturalS02E19FolsomPrisonBlues "Folsom Prison Blues" (S02, Ep19)]].
* ''Series/{{Alcatraz}}'': Rebecca uses a air vent to sneak into a bank during a hostage situation in "Cal Sweeney".
* Done by the entire main cast in ''Series/{{Pixelface}}'' when the zombies from Claireparker's game invade the console. Of course, the vents aren't designed to take that much weight and they end up crashing through the ceiling.
* Subverted in ''Series/TwentyOneJumpStreet'' episode "Gotta Finish the Riff." Aoki sneaks into the high school through a heating duct, and is doing fine until, at the worst possible moment, [[spoiler: he suddenly falls through the ceiling into the room where the bad guys are]].
* Played straight in Season 5 of ''Series/TrueBlood''. Turns out when you can shift into a fly, air vents are quite accommodating.
* In ''Series/{{Community}}'', [[spoiler: Señor Chang]] moves into the air vents for a while. And is joined by a monkey.
* ''Series/{{Psych}}'' plays it straight with the sheer size of the ducts, but compensated by making the ensuing chase loos awkward and ridiculous.
* Played with in one episode of ''FallingSkies'' where three characters are trapped in the basement of a hospital. Only the smallest character can fit through the vents (barely) so he goes to get help in clearing the hallway so the others can escape. [[spoiler:The alien creatures infiltrating the hospital, being much smaller than humans, have no such problem.]]
* Played with but ultimately averted in part two of the ''Series/TheIncredibleHulk'' episode Prometheus, where the blind girl who is leading Banner (stuck in a demi-Hulk state that severely limited his intelligence) suggests to him that he remove the grating covering an air vent to escape the underground government research facility they're trapped in, but they don't get the chance to actually try it before they're caught. Possibly double-subverted when they wind up escaping through a large ventilation shaft to the surface anyway.
* ''Series/{{Hustle}}'': Sean and Emma break into a gallery via the vents in "Eat Yourself Slender".
* On ''Series/{{Nikita}}'', this is used in "Innocence" ([=3x02=]) to place a bomb beneath its target. Realistically, it's incredibly hard to get in-it required some serious gymnastics-and claustrophobicly small once you are, and that's for a brainwashed 12-year old ex-gymnast ChildSoldier. Nikita doesn't even ''consider'' following, instead opting to intercept her after she exist the vents.
* In ''Series/{{Helix}}'', Once he escapes from isolation, Dr. Peter Farragut, a research scientist infected with TheVirus, holes up inside the vent systems at the arctic research facility where he works, and {{Exploit|edTrope}}s their extensiveness to make his way around the facility once his RFID chip has been disabled. {{Lampshade|Hanging}}d by Major Balleseros during an attempt to trail Peter:
-->'''Balleseros''': "Now I know what a TV dinner feels like."
-->'''Alan Farragut''': Didn't think you were old enough to remember that one.
-->'''Balleseros''': ''Film/DieHard''? Sure, saw it in third grade.
-->'''Alan Farragut''': ''Ouch.''
* ''Series/TheWorstYearOfMyLifeAgain'': Used by Alex in "Maths Test" to break into Norris' classroom to either steal (the first time round) or retrieve (the second time) the test papers. Neither time ends well.
[[/folder]]

[[folder:Other Sites]]
* [[http://scp-wiki.net/scp-932 SCP-932 ("Night Feeder")]]. During the containment breach described in Incident Report 932-02 SCP-932-06 escaped, apparently by somehow getting into Site-09's air ducts. While in the air ducts it reproduced, creating SCP-932-07 and SCP-932-08.
[[/folder]]

[[folder:Tabletop Games]]
* ''Dune: Chronicles of the Imperium'' main rules, adventure "Instrument of Kanly". The agents of House D'murjzin enter and exit the 35th floor of the Adici Enterprises corporate headquarters through an air vent.
* ''TabletopGame/{{Traveller}}''
** FASA's Classic supplement ''Action Aboard: Adventures on the King Richard''. A paragraph details how the air ducts can be used to move around the ship.
** ''Challenge'' magazine #32 adventure "A World On Its Own''. One way for the {{PC}}s to get into the starport is to go through the service ducts for air circulation and electronics lines. The only problems are that most of the ducts are barely large enough for human beings and the chance of getting lost.
* ''TabletopGame/{{Paranoia}}'' 1E supplement ''Acute Paranoia'', adventure "Outland-ISH". When the Troubleshooters are trying to get to ISH sector their High Programmer opponent tries to stop them by putting a convoy of vehicles across their path. They can get around this by finding and using an air vent passage.
* Chaosium's ''ComicBook/ElfQuest'' RPG main rules, adventure "The Dying River". The elf {{PC}}s can get inside the troll tunnels by finding one of the airholes that the trolls use as a ventilation system.
* ''Encounter Critical'' supplement ''Asteroid 1618''. Small creatures can pass through The Vanishing Pyramid's ventilation system, but they must roll well or either get lost and and exit in the wrong room or have to fight off packs of Raider Rats. If they survive they can scout out the contents of 2-8 rooms before having to roll again.
[[/folder]]

[[folder:Video Games]]
* In the ''Franchise/{{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....
* ''[[VideoGame/{{Battlefield}} 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.
* ''VideoGame/FinalFantasyVII'' in numerous places, most notably in Shinra tower when the player eavesdrops on the evil corporate meeting from a ventilation duct connecting to a bathroom.
* ''VideoGame/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.
* Frequent in the ''Franchise/MetalGear'' series.
** In ''VideoGame/MetalGear2SolidSnake'', said vents are occasionally guarded by the [[MemeticMutation memetically infamous]] Poisonous Zanzibar Hamsters.
** One of the first areas in ''VideoGame/MetalGearSolid'' has an otherwise level air duct with a lowered section in it. Said lowered section is ''flooded'', which would render the duct useless for ventilation. Perhaps justified given the Shadow Moses base shows many signs of poor maintenance.
** Very blatant in ''Portable Ops'', which opens up with Snake escaping from a prison by crawling through the air vents.
* ''VideoGame/EscapeFromButcherBay'', in which the ducts were used so widely they actually had directions scribbled inside them. ''Assault on Dark Athena'' continues this.
* ''VideoGame/{{Grandia}}'' had this, including a side-trip to the women's locker-room...
* ''VideoGame/DukeNukem3D'' 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 ''Film/MissionImpossible'' movie.
* ''VideoGame/HalfLife''
** Subverted in ''VideoGame/HalfLife1''. 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. Whether or not you're in it is a matter of timing.
** In another instance, the guards hear you and toss a satchel charge in for an OutrunTheFireball sequence. Some of ''Half-Life'''s vents have ladders in them, suggesting that they may have been designed to allow people to go through them. Mr. Freeman crawls through the vents wearing what is a [[PoweredArmor high-tech suit of platemail]]. But considering how [[ElaborateUndergroundBase deep]] the Black Mesa facility stretches, perhaps it is not quite unrealistic that it would use people-sized vents.
** {{Lampshade|Hanging}}d in ''VideoGame/HalfLife2: 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.
* Some ''VideoGame/{{Counter-Strike}}'' maps feature this. E.g. on cs_assault, there is a large air vent that leads from the hangar roof to the room with the hostages. Appropriately, walking through it makes a lot of noise and it can be shot through to kill whoever is inside.
* ''VideoGame/DeusEx''
** The game often includes alternate paths through air vents, which usually double as maintenance tunnels, complete with ladders and hinged grates. One of the {{NPC}}s even explicitly suggests it as a stealth route in the first mission, saying that "these 20th century buildings always have ventilation shafts". However, unlike ''VideoGame/DukeNukem'', there's also always a straight way.
** Mildly subverted in ''VideoGame/DeusExInvisibleWar''; 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.
** And just because it was such a big part of the first game, in ''VideoGame/DeusExHumanRevolution'', air vents abound, often leading to rooms with a couple of neat little bonuses, or an easy way around the guards. This is even lampshaded in an early conversation, where someone asks if the reason you took so long getting to his office is if you got stuck in an air duct.
%%* ''VideoGame/BioShock1'' does this too.
* And so does ''VideoGame/SystemShock''. The second game almost starts with one, and the first game had whole maintenance tunnels in addition to vents.
* ''VideoGame/SecretOfEvermore'' had an escape through the ventilation system take up a ''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.
* ''VideoGame/GoldenEye1997'' began one level with the player infiltrating a Russian base via the air vents.
* Which reappeared in ''VideoGame/PerfectDark''. Gunfire in toilets. Always classy.
* ''VideoGame/FirstEncounterAssaultRecon'' 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 ''VideoGame/{{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 ''VideoGame/{{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 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.) More accurately, it seems all maintenance robots (which use the tunnels) are the same size as the Morph Ball.
** There's a prevailing theory (with some canon evidence) that nearly all modern technology is based on that of the [[{{Precursors}} Chozo]] unless stated otherwise and most races are too afraid to tinker with the design fundamentals unless their whole project blows up. Naturally, the Chozo would have no problem making their vent shafts just the right size for their PowerArmor warriors to take a shortcut through.
* ''AliensVsPredator 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 ''VideoGame/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.
** In the final act of ''ModernWarfare'', you infiltrate Zakhaev's [[YeOldeNuclearSilo missile base]] through the vent system.
* ''VideoGame/PaperMarioTheThousandYearDoor'' 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 ''Series/TwentyFour: 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 character of the ''Franchise/SlyCooper'' series can do this in all his games. He usually does to break into places.
* As lampshaded by [[WebVideo/TheSpoonyExperiment Spoony]] in his review of the ''VideoGame/TheThing'' videogame, at one point Blair acquires access to another room by walking hunched through a four-foot-wide air duct.
* Lots of duct-crawling goes down in ''VideoGame/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 ''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 launching ambushes from them.
* In episode one of ''VideoGame/StrongBadsCoolGameForAttractivePeople'', 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 ''VideoGame/{{Wild ARMs|1}}'': only Hanpan, the little mouse sprite belonging to one of the main characters, is small enough to navigate the air vents.
* ''VideoGame/DeadSpace''
** The ship in which the game takes place is blanketed with enormous, easy access vent shafts that the Necromorph enemies use to move around at will. This allows them to bypass security lockdowns and quarantines with impunity, rendering such measures useful only as an obstacle to the player. This continues into the design of the space station where the sequel is set, and protagonist Isaac Clarke gets to crawl through a few special engineer-only vents himself to get from place to place.
** 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.
* ''VideoGame/{{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 a lot in ''VideoGame/BatmanArkhamAsylum''. 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. Sort of justified by the fact that Arkham Asylum is famous for having horrible security. Also, many of the buildings in Arkham are very old, so the vents are likely from an old ventilation system.
* During Wolverine's escape from the Weapon X facility in the ''VideoGame/XMenOriginsWolverine'' 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.
* ''VideoGame/ShadowComplex'' uses vents where Metroid uses morph ball tunnels.
* In the ''VideoGame/{{Myst}}'' universe we have a justified version of the mine example: D'ni is an underground city, and its Great Shaft is a huge air exchange shaft. But it's also used as the primary method of reaching the surface (or vice versa).
* ''VideoGame/VampireTheMasqueradeBloodlines'' has a series of air vents (with ladders leading to them, no less) in the garage in the Downtown area. During the mission for Fat Larry that takes you there, a stealthy character can make good use of them and avoid combat entirely- a good idea, as the enemies there are heavily armed and quite numerous.
* In ''VideoGame/RatchetAndClank'' you never actually climb inside the vents, although Clank would certainly be small enough to have one of his missions in there, but at one point you break into a building by climbing on the outside of external air vents with Magnet Boots.
* In ''VideoGame/GoldenSunTheLostAge'', Felix and gang sneak into the Great Gabomba Statue, a clockwork statue worshipped as a god by a stereotypical Subsaharan African-like tribe, through the ventilation shaft, since the original builder's entrance has been sealed with a big rock.
* Most of the air vents in ''Videogame/TeamFortress2'' are inaccessible and just for decoration, but there are a few in Hydro that are big enough for players (even the Heavy Weapons Guy) to stand up in. Custom-map-made-official Turbine has a system these that's more of a cramped hallway than a vent.
* Valve [[LampshadeHanging hangs a lampshade]] on this trope in ''VideoGame/Left4Dead2'' with the ever-epic lines of Ellis; In Dark Carnival, he says "if there's one thing video games have taught me, it's that good shit comes from crawlin' through vents". (Unlike in ''VideoGame/HalfLife'' the vents do not lead to anything particularly important, however.)
* Both played straight and subverted, for unsettling effect, in ''VideoGame/HeavyRain'', where Ethan Mars is guided by a serial killer through series of Se7en-style trials. One of them involves deliberately crawling into something that resembles both a system of wide air ducts and a dangerous exhausts vent (it sounds stupid, but looks appropriately menacing). The vent system is one foot high and branching, it's absolutely dark and hard to breathe there, and its floor is ''covered with broken glass''.
* This is how VideoGame/{{Rayman}} escapes the [[SpacePirate pirate's]] [[CoolAirship prison ship]] in ''Rayman 2''. Considering that was an air vent, which is never really explained. Judging by its size, it's more likely to be where the smaller warships are sent from, if not from the deck.
* Sam Fisher of ''VideoGame/SplinterCell'' has an odd ability to encounter ridiculously large vents with grates off to get into areas that would otherwise be unreachable. Somehow, a guy carrying a large gun as well as a few pounds worth of other weapons and gadgets doesn't make enough sound to alert anyone. There's a particularly bizarre instance in the first game where Sam makes his way into a walk-in freezer. Given that the vent in question is connected to a regular part of the building, it means the vent is just wasting coolant.
* The demon in ''[[VideoGame/{{Reincarnation}} Reincarnation: Riley's Out Again]]'' does this to get around the school without being spotted by humans. but it's so "[[ScrappyLevel tedious and unfun]]" that later versions added an option to skip the sequence altogether. He's seen doing it again in a mini later in the series.
* Also used in ''In the Name of Evil,'' but thankfully without the maze.
* Used in a level in ''VideoGame/{{Geist}}''; Raimi [[GrandTheftMe possesses]] a dog to get through the vents. It appears to be a boxer-type dog, and can't stand up in the vent.
* ''VideoGame/ArmoredCore'' has the player chase after terrorist mechs who have escaped through air tunnels. In two-story tall mechs. It's sort of [[JustifiedTrope justified]], as these are the vents that are supposed to serve an underground city. Just don't [[FridgeLogic think about how that would actually work]].
* ''VideoGame/MirrorsEdge'' features a number of extremely large (and life-saving) air vents. Lampshaded in one instance when Faith does this and a guard can be heard below exclaiming "Wow, the rats must be ''huge'' in here!"
* Occurs at least once in most of the ''VideoGame/MedalOfHonor'' games, such as the last level of Mission 2 in ''Allied Assault''.
* Twice in ''SyphonFilter 2'', first in the Pharcom Expo Center, then in the Agency Biolab.
* ''VideoGame/PajamaSam 4'' has the titular character doing this at the end of the game, even though it simply leads to the ceiling of the same room.
* Phil does this to escape his room at the beginning of ''VideoGame/RiddleSchool 5''. He's a child, so the size issue isn't relevant.
* ''Franchise/MassEffect''
** While Shepard never has to enter a vent in ''VideoGame/MassEffect2'', there are a few instances or references of vent use in the game.
*** Thane Krios uses one during his recruitment mission. You can actually hear a clunk while he's in there before he makes his big entrance.
*** During the suicide mission, the chosen Tech Expert has to move through a duct, while the player has to fight off the Collectors in order to open the valves for him/her/it. That instance should probably count as a subversion, in that the game makes very clear how ''very'' dangerous it is, and that the tech expert would have died, hideously, were it not for Shepard's help. At some points you can see them and the ducts are actually tall enough to let them ''walk through''.
*** Most disturbingly, during Thane's Loyalty mission, Captain Bailey mentions Duct Rats, homeless children who travel in the Citadel's ventilation system. Played straight, as some of the vents can lead to [[DeadlyRotaryFan razor sharp fans]], [[NotTheFallThatKillsYou sheer drops]], [[StewedAlive protein vats]], [[ContinuousDecompression depressurized vents]], or being [[ThrownOutTheAirlock spaced]].
** Used by Liara in ''VideoGame/MassEffect3'' to escape from some Cerberus troopers. True to their real-life counterpart, they are extremely noisy - the player can hear the vents being banged around by Liara and the Cerberus troops clear across a large parking garage. While the vents are very large, the troopers have trouble getting around in their bulky armor; they repeatedly try to shoot her, but aren't able to aim and just further ventilate the shaft. There's a little boy on Earth in a smaller vent at ground level. The sound of him moving around in there is actually the only reason Shepard detects him.
** During the Citadel DLC, [[spoiler:temporary ally Maya Brooks has to crawl through the vent of a casino to disable the door to the panic room, all the while avoiding alarms until Shepard disables them.]]
* A series of maintenance tunnels in ''VideoGame/ThePerilsOfAkumos'' prove to be this. A separate series of air vents also prove plot-relevant.
* ''VideoGame/{{Portal 2}}''
** A variant on this: At one point, Chell uses the ductwork of old Aperture [[spoiler:to apply conversion gel in otherwise unreachable locations. She also uses access shafts and tunnels at some points.]]
** The Perpetual Testing DLC features a clip of an AlternateUniverse Cave warning people not to do this aboard his PrisonShip.
--> Cave: "Attention, test prisoners attempting to escape through the air ducts. I don't know what nonsense you learned on TV, but in real life, air ducts just go to the air conditioning unit. It's also pretty dusty, so if you have asthma chances are you're gonna die up there. And we'll be smelling it for weeks, because, again, air ducts aren't some secret escape hatch; they're how we ventilate the facility."
* ''[[MaxPayne Max Payne 3]]'' subverts this when Max scrambles into an air duct just big enough to fit him to escape a room full of tear gas. After awkwardly maneuvering himself along for a few moments, he finds out the hard way that just cause it ''fits'' him doesn't mean it can ''support'' him...
-->'''Max''': I was trying to work out what direction I was headed in when I discovered some more Brazilian architecture not designed for the "American physique".
* {{Dishonored}} uses this trope in a quite realistic way : you can use air ducts to infiltrate buildings and, in one case, to escape captivity, but you need a special power that allows you to possess a rat to do so.
* ''VideoGame/{{Messiah}}'' has vents big enough for Bob (who is the size of a baby) to crawl through. There are also smaller vents, which you can explore while you're possessing the body of a rat.
* ''VideoGame/{{Monaco}}'', being largely an homage to heist films, features air vents as a very convenient way to get around each floor unnoticed, assuming they go where you need them to. Hilariously, not only will nobody hear you as you walk through them, but if an NPC decides to enter one, they can ''pass directly through you'' without so much as raising any suspicion. If you play as The Cleaner, you'll even knock them out as they pass by.
* The [[{{HoldTheLine}} base-defense mission]] in ''XCOM: Enemy Within'' has the aliens using air vents to gain access to part of the XCOM base. [[{{JustifiedTrope}} Justified]] in that the aliens coming through the air vents are either Sectoids or Thin Men; the former are very small, while the latter are incredibly flexible.
* ''VideoGame/ContagionMonochrome'' has them in the Escape map, Roanoke Police Department. Zombies can use them as shortcuts to get through different parts of the map.
[[/folder]]

[[folder:Visual Novels]]
* ''VisualNovel/ApolloJusticeAceAttorney'':
** The only reason the title character's client in the third case 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). He did escape the crime scene through the vents, but didn't commit the murder.
** Also, the air vents were used by Lamiroir to get from one side the stage to the other quickly for her part in the magic act in the middle of her song. They are stated to be large enough for her to walk, albit hunched over and there was staff waiting at either end to help her.
[[/folder]]

[[folder:Web Comics]]
* ''Webcomic/{{Angels 2200}}'': Loser uses one when they attempt to "rescue" Quetz
* [[http://freefall.purrsia.com/ff800/fv00770.htm Subverted]] in ''Webcomic/{{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. He might have succeeded if he had ditched [[StarfishAlien his encounter suit.]]
* Justified in ''Webcomic/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 SphereEyes) and his plasgun ([[HandCannon big]]).
* Justified in ''Webcomic/GunnerkriggCourt'', as the Enigmaron fortress that Antimony infiltrates is a [[HardLight simulation]].
* Used in a ''[[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]].
* ''Webcomic/CaseyAndAndy''
** Subverted: 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.
** The ''C&A'' villain Lord Milligan follows the Path of the Villain as a religion and deliberately follows every cliche. Including having giant air ducts.
** They try the air vent route multiple times, and the mime-assassin is in there every single time. Including the last time, when they were finally expecting it, and had someone outside the vent stab through it.
* Wonderfully subverted in [[http://www.cad-comic.com/cad/20080421 a strip]] of ''Webcomic/CtrlAltDel'', given that it LEADS TO THE DEATH OF THE MAIN CHARACTER! Thus ending this ChooseYourOwnAdventure storyline.
* Subverted in ''Webcomic/QuestionableContent'' when Raven attempts to enter Coffee of Doom through the airvent and gets stuck. She's not the [[TheDitz sharpest of minds]], though.
* In ''Webcomic/RoninGalaxy'', Taylor and Rin use the floor's ventilation ducts to [[http://www.roningalaxy.com/comic/page-78/ escape the brothel.]] They're both relatively small people, so it may be justified.
* ''Webcomic/SluggyFreelance''
** Used in [[http://www.sluggy.com/daily.php?date=011004 a strip]] to sneak into Aylee's office. {{Justified|Trope}} since Bun-Bun, a [[TalkingAnimal mini-lop rabbit]] is the only one who can make it through.
** Used again in [[http://www.sluggy.com/daily.php?date=001217 another strip]]. Also {{Justified|Trope}}, since it's done by Rudolph the Reindeer, who has picked up all the tricks Santa uses for shimmying up and down chimneys.
* Averted in ''Webcomic/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.)
* In ''Webcomic/{{Drowtales}}'', the air vents are too small for an adult Drow. But for a child...
* In ''Webcomic/ElGoonishShive'', Noah uses air vents in the process of hunting a magical creature and the trope is discussed in the commentary.
* Trigger from ''Webcomic/FarOutThere'' is [[http://faroutthere.smackjeeves.com/comics/1067778/page-151-hey-at-least-its-not-all-going-to-waste/ very good at these]].
* ''Webcomic/NerfNow'' on [[http://www.nerfnow.com/comic/735 air ducts in games vs. reality]]. No inescapable death trap is complete without one!
* [[http://permanentinc.thecomicseries.com/comics/11 Malum Industries]] of PermanentInc have air ducts built [[InvokedTrope intentionally wide enough to crawl through]].
* ''Webcomic/{{Banished}}'': To escape from the Boscis base, Rak and Timbo follow a Mammazon out this way.
* Justified in {{Curvy}} when used by a native of [[PlanetOfHats Candy World]] who is actually a ''liquorice''-based organism: she can squeeze into places a normal human wouldn't be able to. In fact, in the immediately previous page she's seen squeezing through the bars of a prison cell.
* In ''Webcomic/TheMotleyTwo'', the spaceship "Hiroja" has vents big enough that the characters can sneak around the entire ship with impunity. Perria Makara, who snuck aboard undetected, even sleeps quite comfortably in the vents (near the heating unit).
* ''[[Webcomic/MetroidThirdDerivative Metroid: Third Derivative]]'': Samus with the Morph Ball up until [[TheCorruption Phazon corruption]] damaged her Varia Suit and required emergency repairs destroying the Morph Ball in the process.
* In ''Webcomic/{{Outsider}}'', Jardin [[http://well-of-souls.com/outsider/outsider031.html lampshades the lack of handy vents.]]
[[/folder]]

[[folder:Web Original]]
* Used to escape a dead-end in ''Roleplay/SurvivalOfTheFittest'' 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.
* Shelton and Ridgeway successfully do this in ''Roleplay/DarwinsSoldiers: Schrodinger's Prisoners''. It's also subverted in the third RP when Hans suggests this as a way to get into Pelvanida and James points out how that wouldn't work.
* ''TabletopGame/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.
* Played straight in ''Literature/MagicalGirlHunters'' when sneaking into the Mashihaishi Ultra building. The confusing layout is lampshaded with Yoi asking directions of other people traveling through the same vent system.
* ''{{Mercs}}'' has this done by Varisa and Creed to sneak around the ship during the "Hijack" episode. At one point, one of the mooks tracks Varisa by the banging noises in the ductwork and ambushes her when she comes out.
* ''[[http://www.youtube.com/watch?v=hRTP2IZ2nOo& Duct Hunt]]'', a parody of the ''Franchise/MetalGear'' series made by Creator/RocketJump, deconstructs almost every aspect of this trope, including the way some players tend to use it in ''Metal Gear''.
* Kai tries to use one of these in the first episode of the WebVideo/{{Chronicles of Syntax}} to get out of the school. It doesn't quite work out how he expected.
-->'''Kai:''' Okay, this thing is ''definitely'' getting smaller. I might just hyperventilate myself into a coma down here. They'll find me years later, turning to dust in the fetal position. Can I even get into the fetal position? I don't care. Just keep moving. Just keep moving forward...
[[/folder]]

[[folder:Western Animation]]
* ''Franchise/{{Transformers}}''
** ''WesternAnimation/TheTransformers'' episode "The Ultimate Doom, Part 2" introduced ventilation ducts large enough for Transformers to stand inside. Spike, Bumblebee & Brawn go through a ventilation shaft that takes them to Decepticon HQ. 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 ''WesternAnimation/TransformersAnimated'', episode "Decepticon Air". Optimus Prime crawls through the ducts (it seems to be a squeeze, letting him homage ''Film/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.
** ''WesternAnimation/BeastWars'': Cheetor goes through the ventilation shafts of the Predacon ship after having been accidentally transported to ''The Darksyde'' in "Equal Measures".
* This is a favorite route of the girls in ''WesternAnimation/TotallySpies'' for breaking in, clearly thanks to MaleGaze.
* ''WesternAnimation/KimPossible'' and Ron infiltrated this way in TheMovie. They do it quite a lot during the series.
* ''WesternAnimation/{{Recess}}'': T.J. often uses this route to break himself and occasionally others out of detention.
* ''WesternAnimation/TeenTitans''
** Exception; Titans Tower's quarantine lock-down system apparently ''does'' seal off openings to the air ducts, as seen in the episode "Haunted". (Robin got into the vents anyway....)
** Subverted in the same series: Cyborg is attempting 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.
* ''WesternAnimation/{{Ben 10}}'' did this a couple times, though it's {{Justified|Trope}} 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 ''WesternAnimation/{{Jem}}'' episode, Jem, Aja, and Shana do this to escape a locked room.
* ''WesternAnimation/SpiderManTheAnimatedSeries'' 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.
* Peter and Brian do this in an episode of ''WesternAnimation/FamilyGuy'', complete with a ShoutOut to ''Film/DieHard''. They don't make it all the way in stealthily, though, Peter's large girth causes the vent to give out and dump them right in the middle of the prom.
* ''WesternAnimation/{{Futurama}}''
** Subverted: 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 sauna out of it.
** {{Lampshaded}} in ''[[TheMovie Bender's Big Score]]''. While trying to destroy a [[Franchise/StarWars "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.
** In ''[[TheMovie Bender's Game]]'', Fry and the other travel around [[BigBad Mom's]] factory through a tube that sends chickens to the enslaved Nibblonians. It works, but they have to shove their way through a lot of chickens.
* {{Lampshaded}} and subverted in an episode of ''WesternAnimation/BuzzLightyearOfStarCommand'', 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 ''WesternAnimation/AvatarTheLastAirbender''. 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".
* ''WesternAnimation/TheSimpsons''
** Parodied in the 100th episode. Santa's Little Helper gets into the school ventilation shafts, and only a greased Scotsman can catch him....
-->'''Groundskeeper Willie:''' "Lunchlady Doris...'ave ye got any grease?"
-->'''Lunchlady Doris:''' "Yes. Yes we do."
-->'''Groundskeeper Willie:''' (tears off his clothes) "Then grease me up, woman!"
-->'''Lunchlady Doris:''' ... "Okee-dokee."
-->'''Groundskeeper Willie:''' "There's nary an animal that can outrun a GREASED SCOTSMAN!"
** This is how Homer spies on Mr. Burns meeting with terrorists, and would be caught if it wasn't PlayedForLaughs:
-->'''Homer:''' ''(scribbling on pad)'' I love spying.
-->''(terrorist picks up a bar of uranium; radioactive gas boils off the surface of the rod)''
-->'''Burns:''' "Don't worry about those fumes. They'll be sucked into that air vent."
-->''(Homer moans from fumes, drops pad out of vent and onto the floor)''
-->'''Burns:''' "This place is falling apart." ''(walks over, picks up pad and shoves it back into the vent)''
** In one of Homer's daydreams where terrorists take over the plant, Homer jumps from a standing position into a vent on the ceiling, then comes out in Burns' office to beat the terrorists up.
* ''WesternAnimation/ChipNDaleRescueRangers'' uses this in a few episodes. Then again, the use is probably justified as the Rescue Rangers themselves are only around 10 cm tall.
* In ''WesternAnimation/SonicSatAM'', 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 ''WesternAnimation/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 ''WesternAnimation/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.
* {{Defied|Trope}} in ''WesternAnimation/{{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: "Heh, only in the world of cinema. [[ThisIsReality In real life, they never hold]]." It certainly doesn't help that Wolverine's metal skeleton makes him about three times as heavy as a normal person.
* ''WesternAnimation/{{X-Men Evolution}}''
** Subverted, with the vent being only a few incles long, big enough for people to climb into, having a ladder inside, and Blob gets stuck. However, it also has a large amount of security lids which Cyke was able to close to keep Mystique from escaping.
** Played with in another episode. When the group is testing out the security of the mansion, Wolverine is able to go to many parts of the mansion through the vents, and suggests something be done about them.
* ''WesternAnimation/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 ''ComicStrip/{{Dennis the Menace|UK}}'' cartoon does this in one episode when he's trying to flee with Gnasher from a large mobile mall that has arrived in [[TheBeano 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 Dennis decides to bring him down instead.
* Parodied and subverted in ''WesternAnimation/BatmanBeyond'': The protagonist enters a vent large enough to walk in, but the subsequent sections keep getting smaller and smaller.
* ''WesternAnimation/BatmanTheBraveAndTheBold''
** Subverted and played with: Batman is infiltrating a parallel Earth, disguised as his evil counterpart Owlman. He's allied himself with Red Hood, the heroic counterpart of 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. 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. This is the goddamn Franchise/{{Batman}} we're talking about, so he blows up the fan. But still, the AirVentPassageway escape 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.
* Justified in ''WesternAnimation/TheBatman'' when Ragdoll uses it; he is the most flexible person to have ever lived, and the air vent only needs to be big enough for his head to fit in, as many air vents are in RealLife.
** Also played straight in the episode "The Butler Did It" when Alfred has to escape from a room to warn Bruce. He pronounces it "quite a sticky wicket."
* In the ''WesternAnimation/BatmanTheAnimatedSeries'' episode "The Cat and the Claw, part one", ComicBook/{{Catwoman}} uses the air vents to escape from the Multigon offices.
* In an episode of ''WesternAnimation/MaxSteel'', 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.
* ''WesternAnimation/RobotChicken'' {{Lampshaded}} this in an ''ComicBook/IronMan'' spoof. Two {{Mooks}} guarding The Mandarin's lair are able to instantly determine that the deafening banging and screeching noises they hear are from Iron Man trying to sneak through the air ducts.
* ''WesternAnimation/JonnyQuest'' episode "Mystery of the Lizard Men". Jonny crawls though an air duct to escape from the title opponents.
* ''WesternAnimation/{{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 the ''WesternAnimation/JimmyTwoShoes'' episode "Jimmy in the Big House", when [[IdiotHero Jimmy and Beezy]] tries to get out of prison by going through air vents. Suddenly, a screen pops out and it's a video message from [[EnfanteTerrible 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. In this case, it's probably [[JustifiedTrope justified]] since Heloise probably made the vents that big just to [[ForTheEvulz crush prisoner's hopes for escaping]].
* ''WesternAnimation/StarWarsTheCloneWars''
** Ahsoka once escaped Griveous this way.
** Ventress used the airvents to infiltrate and sabotage a Republic Star Destroyer unnoticed.
** Cad Bane infiltrated the Jedi Temple through the airvents. Doubles as AbsurdlySpaciousSewer.
** Ahsoka Tano and Barriss Offee escape from mind-controlled Clone Troopers by jumping into the air vents. Later in the episode, Ahsoka uses the same vents to travel to the coolant control room and the bridge while she's running from Barriss.
** Aura Sing used these to attemp the assasination of Padmé.
** Subverted and lampshaded in "The Citadel". With the entry point the Jedi wanted to use blocked, Anakin and Obi-Wan muse how to get in, and Ahsoka points on the ventilation hatch. Anakin argues that they're too small to gain acess, but in response Ahsoka points out, that they might be too small for Anakin, Obi-Wan and the clones, but she might be able to squeeze through -- which she is, although barely. In the next episode Obi-Wan's entire team tries to escape the Citadel in absurdly spacious airvents. However these had lethally effective security doors, and the warden at least had enough [[DangerouslyGenreSavvy common sense]] to send at least one drone in the airvents.
** In "A Test of Strength" Hondo Ohnaka proves he is DangerouslyGenreSavvy by immediately recognizing the trick and having smoke bombs dropped into the vents to flush out the occupants.
* In season 1 finale of ''WesternAnimation/ExoSquad'', after taking their attempt to use [[BigBad Phaeton]] as a hostage fails, [[TheSquad Able Squad]] escapes the Brood Chamber via the air ducts. Typhonus responds by sending troops into the tubes; why the tubes were made big enough for Neosapiens to walk around in isn't explained. Then he reroutes the ventilation so the tubes are flooded with poisonous "volcanic gas". Exactly why someone would build a ventilation system that allows that isn't explained either.
* ''WesternAnimation/SpaceGhost'' episode "The Space Piranha". Jan and Jace infiltrate an enemy base using the ventilation system.
* Sam and Max, and Sam's granny Ruth, try to reach the prison warden this way in the ''WesternAnimation/SamAndMaxFreelancePolice'' episode "Christmas, Bloody Christmas" -- only, instead of the air vent, they go through the prison's ''water duct'', and end up in the shower room.
* ''WesternAnimation/TheAmazingSpiez'': The title team use this technique in episode "Operation Spy-Sitter".
* ''WesternAnimation/{{Birdman}}'' episode "The Quake Threat". When Birdman is trapped in an ElaborateUndergroundBase, Avenger the eagle breaks in through an air vent to save him.
* Zadavia stages one on Deuce's ship during the ''WesternAnimation/LoonaticsUnleashed'' episode "In Search of Tweetums, Part II".
* ''WesternAnimation/{{Archer}}'' is fond of this. Somewhat surprisingly, it's always played straight.
* Played straight in ''WesternAnimation/TheProblemSolverz'' episode "Badcat", when the solverz travel through a vent to reach Bad Cat's lair on the top floor of his casino.
* The strangely clean air ducts of the SHIELD Helicarrier are lampshaded in the ''WesternAnimation/{{Ultimate Spider-Man}}'' episode "For Your Eye Only" which, as a spy movie parody with nods to ''Film/DieHard'', has Spidey using air ducts rather frequently.
* ''WesternAnimation/YoungJustice'': In "Homefront" - the DieHardOnAnX episode - Robin and Artemis spend a lot of time trying to avoid the Reds by crawling through the ducts; with varying degrees of success.
* ''WesternAnimation/GravityFalls''. "The Inconveniencing": Dipper uses the HVAC vents to get into the abandoned Dusk 2 Dawn convenience store.
* ''WesternAnimation/{{Dogstar}}'': After Boombah locks the crew of the Valiant in their cabins in "Robbie", Simone has to crawl through the vents to reach the bridge.
* This is Lee's usual mode of transportation around the school in ''WesternAnimation/{{Detentionaire}}''. He started doing it to keep out of Principal Barrage's way and off the security cameras, and by now has spent enough time in the vents to know his way around very well and be able to get from one end of the school to the other as fast by vent as he would using the hallways. Other characters have used air vents as well, though not to the same extent as the protagonist. The air vents of A. Nigma High also happen to house a red snake/lizard/dragon monster called a Tazelwurm, who could kill you in a second and is also the school mascot. [[spoiler:He turns out to not be as dangerous as he looks, though.]]
[[/folder]]

[[folder:Real Life]]
* To this day, criminals will attempt this trope at any number of buildings where they can find a suitable opening. The difficulty they will encounter is that ducts don't stay the same size or shape all that often. The added difficulty of straight up-and-down ducts will see many criminals slipping and falling to become wedged or even killed by the fall. Even worse for some criminals is they may attempt this on holidays or weekends to avoid being heard clambering through the ventilation. When they become trapped, they must wait days without food or water in extremely uncomfortable positions for somebody to discover them.
* In RealLife, small animals tend to be more successful at this trope than humans (they're small enough to get inside easily, they're light enough that the ducts can support their weight and they don't make as thunderous a noise while they move around). Depending on the animal, they can still be very loud as claws or nails make a racket running on metal.
* During and around TheDungAges, a popular way to infiltrate a stronghold was to climb through the privy chute. This had varying outcomes; either they made it, and incidentally killed Edmund II by [[AssShove puncturing his arse]], or they got stuck and died in there, or they suffocated and ''then'' died in there. After such sieges, those chutes had to be cleaned elaborately and swept through because of all the stuck-up cadavers.
** According to some sources, this was how Finnish Cudgel War leader Jaakko Ilkka escaped from his imprisonment in the Turku Castle.
* 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.
* Successfully done by serial killer Ted Bundy. While in prison awaiting trial on one of many murders he was suspected in, he climbed through the roof of his cell (he had dieted and lost enough weight to make this possible), crawled across the floorboards into the adjoining warden's apartment (the warden and his wife were out at a New Year's Eve party), and simply walked out of the apartment into freedom. He was caught several weeks later, but not before adding several more victims to his list.
* When Kingsley Ofosu and 8 other Ghanians stowed away on a Europe-bound cargo ship, he escaped from the ship's murderous crew (the other stowaways were not so lucky), by shimmying up one of these.
* [[http://www.thetelegraph.com/news/jail-27519-film-crew.html Quantay Adams]] managed to escape from a jail by going into the subceiling ''and'' out through a vent. It was harder than it sounds; after getting a hacksaw blade to get through the ceiling, he had to both time the guards, evade the cameras-including the one ''in his cell''-and get to his accomplice outside. His grand total of freedom? ''Seven hours.''
* On a G4 special one of the famed Bioware doctors mentioned how as a child his teacher locked him in the closet for misbehaving, he climbed from the closet into the drop ceiling ''BreakfastClub'' style. After crawling back into his classroom he positioned himself over where the teacher was standing and dropped a lugie on them.
* Attempted unsuccessfully by Jamie Minor. She tried sneaking into her workplace by the air ducts but got trapped.
* Russian President Boris Yeltsin was thought to have done this once during a stay in Washington D.C. in order to evade security (the security aimed at protecting him) so that he could go out for a night on the town unburdened by bodyguards. In reality the president only unscrewed the vent as a decoy and or prank then used an unlocked window to "escape".
* Inverted -- if only just -- in real life basements containing an "[[http://www.escapewindows.net/ egress window]]". This is ''intended'' to assist folks in their escape in the event of a house fire or emergency, but many folks often leave it open to get some air circulation going. Furthermore, many people are too large to make proper use of them.
[[/folder]]
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