Basic Trope: Air ducts are used to escape a prison cell, sneak around enemies or just move around.
- Straight: Bob uses the vents to get out of his cell.
- Exaggerated:
- Bob escapes through the vent... along with every other prisoner in the prison.
- The ducts are bigger than the hallways people are supposed to walk around in, and end up being used as such.
- Downplayed:
- The air ducts are too small for Bob to get through, but not his pet monkey. Now if only Bobo will do something useful with his freedom.
- Bob doesn't use the vents themselves because they're too small, but the crawlspace above the paneled ceiling where the ducts are located is large and sturdy enough for him to traverse above the normal room.
- Justified:
- The ducts are large to funnel large amounts of air and reinforced to survive an earthquake.
- Bob is an air-conditioning engineer, or otherwise knows how to get out safely through unconventional means from a building.
- The characters are small animals, allowing them to fit into spaces humans could not.
- Bob is a Pint-Sized Kid.
- The air-vent is a repurposed servant passage way.
- Inverted: Bob's captors seal him inside the air vents, reasoning that he'll never find his way out.
- Subverted:
- The ducts turn out to be too small for Bob to fit through.
- Upon seeing an air vent is open, a guard leaves his patrol to investigate, allowing Bob to sneak past in a cardboard box.
- Double Subverted:
- The ducts are too small for Bob to fit through, but that's only because they're the local ducts. The central vents, needing to handle lots of air, are much larger.
- Bob then abandons his cardboard box after finding some larger air vents, and escapes through them.
- Parodied:
- Air vents are the main form of transportation in the facility; corridors are essentially unused, making them the sneaky way of getting around.
- The air vents are a network of huge tunnels, complete with water fountains and maps of the building.
- Zig Zagged: The local vents are too small, but the central vents are large enough. However, the vent cover on them is too tightly secured. Luckily, another large vent runs just under the floor.
- Averted: Bob never even considers the ducts.
- Enforced: The director wants his movie to be Troperiffic.
- Lampshaded:
- "Oh, great, am I going to have to crawl through the vents?"
- "If I ever run a prison, I'll secure the vents"
- "Why is it always ducts?"
- Invoked: "The tracker is installed. We should let Bob escape, but it needs to be hard so he thinks he's gotten away." "Let's put a conveniently large vent leading to his room."
- Exploited:
- An Incredible Shrinking Man uses the airvent to sneak around specifically because no normal-sized man can fit through them, and thus his entrance will be completely unsuspected.
- Alice's makes the Airvents to her Elaborate Underground Base obvious and man-sized, specifically so they make an obvious point of entry and thus she'll know exactly when she's being attacked through them.
- Defied: "Go in the vents? That's the first place they'll look for escapees!"
- Discussed: "I happen to know that this building has extra-large, reinforced air vents, specifically installed to provide the inhabitants with a means of emergency exit." "Fantastic! How do we-" "Yeah, they aren't hooked up to the prison cells. These guys aren't morons."
- Conversed: "You just wait and see; he'll go into the ducts eventually."
- Deconstructed: Bob comes close to being badly injured by a fan he tries to jump through. He realizes he has no idea how to find his way around, and starts panicking that he'll be trapped for ever. However, the ductwork transmits the sound of his movement throughout the building, and his captors catch him in minutes.
- Reconstructed: Bob only uses the ducts after exhausting every other option, and is careful to stick to the larger, stronger vents. Knowing he won't be able to sneak through them for very long, he uses them just to get into the nearest corridor.
The way back to Air-Vent Passageway is too heavily guarded. Looks like we'll have to go through... oh, how did you guess?
