Surprise Vehicle

The gang is standing on a cliff's edge when they are startled by a helicopter which rises, roaring, into view... and yet that roaring helicopter somehow didn't make any noise until they saw it.

This is not restricted to helicopters: any roaring vehicle that should have made noise before appearing is a Surprise Vehicle.

It doesn't count if the audience hears the vehicle, but the character is too deep in thought or wearing headphones.

In Real Life, combat aircraft do something similar to this, though at much longer ranges, typically using the terrain for cover. A common method of invoking this trope is for a spotter to "paint" the target (preferably from a safe concealed place) so the pilot can reveal himself only when he is the best position to attack with immediate surprise.

Often a case of Gunship Rescue.

See also See No Evil Hear No Evil, Rule of Perception and Look Both Ways.

Anime & Manga

 * Ghost in The Shell Stand Alone Complex 1st Gig, first episode ("Section-9"). After the Major captures a terrorist on top of a building, a helicopter carrying Batou rises up from below the edge of the building.
 * Happens frequently on Najica Blitz Tactics, thanks to Najica's ever-so-handy remote-controlled helicopter gunship. Might be partially justified by it being a low-noise Stealth Chopper specifically designed for the kind of secret missions she engages in, but still...
 * Mahou Sensei Negima does this with the reveal of, which provides a way for Negi to get to Nodoka in time to save her from a group of bounty hunters.
 * Repeated with the same vehicle during the Governor's Ball.
 * In the first episode of Hanaukyo Maid Tai La Verite, a helicopter appears right next to the two main characters with no noise warning of its approach.
 * Pokémon Diamond and Pearl: Galactic Battles episode "Unlocking the Red Chain of Events!" When Ash, Dawn, and Brock confront Galactic Admin Jupiter, she escapes via a helicopter which appeared from below the side of a building without having made any noise beforehand.

Comic Books

 * A Black Helicopter surprises Wallace this way in Sin City comic, Hell and Back.

Film

 * Blue Thunder. The title helicopter appears from below the side of a bridge to save a woman being (unjustly) pursued by the police. Watch it here. The helicopter actually had a "whisper" mode that could be turned on to make it quieter than normal. Apparently, it was not a good idea to use it all the time. It most likely reduced the performance in exchange for sound reduction.
 * Undercover Brother. As the title character is fighting Mr. Feather, The Man's helicopter rises up from behind a wall.
 * Star Trek V. On the planet where "God" was imprisoned, the Klingon Bird-of-Prey rose up over a hill to rescue Kirk.
 * Aliens. When Ripley and Newt are about to be attacked by the Alien Queen in the atmosphere processing plant, the dropship rises up from below the edge of the platform they're on.
 * Though the processing plant was loudly exploding around them, so not hearing the ship coming can be excused.
 * Thelma and Louise had a helicopter rising up over a cliff.
 * Charlies Angels had a helicopter rising up over a castle.
 * The Humongous Mecha from Terminator Salvation that was able to sneak up on people despite its earthquaking footsteps and the deafening Scare Chord noises that its gears made every time it moved.
 * Three Ninjas
 * Alex Rider
 * In True Lies, Arnold's character manages to pull off a Surprise Harrier Jet.
 * Narrow Margin. Roger Ebert tore this movie a new one over this trope.
 * Down With Love
 * In Avatar a humunguos tree-dozer SUDDENLY appears in the middle of the forest and starts wreaking terrible chaos and destruction all around it.
 * Sky Captain and The World of Tomorrow. Dex suddenly appears in one of Totenkopf's hoversleds to save the heroes from pursuing robots.
 * Buckaroo Banzai. When Buckaroo is about to be run over by a truck, a ladder suddenly appears swinging from the sky. Buckaroo grabs hold and is lifted away by a Blue Blaze Irregular helicopter.
 * In Back to The Future Part II, Marty's Suicidal Gotcha is aided by Doc's flying DeLorean.
 * The Spy Who Loved Me. Stromberg's attack helicopter appears from behind a low wall at the edge of a cliff with no warning. Watch it here.
 * The first Final Destination has the stealth bus to end all stealth buses.
 * Timerider: The Adventure of Lyle Swann. Lyle Swann is trapped against the edge of a cliff with the bad guys closing in. A helicopter suddenly rises up from below the cliff edge, scaring the fertilizer out of his pursuers.
 * This happens in the final scene of The Mist. The main character is saved by the U.S Military but he never heard the rolling of the tanks which are rather hard to miss as they make plenty of noise as they literally shake the Earth as they move about. A fog shouldn't effect the clarity of sound, only sight.
 * Toy Soldiers: Two mooks fail to notice a lurking attack helicopter within a few feet of them until it rises up to the same level as them.

Live Action TV

 * The Sarah Connor Chronicles, Cameron steps out onto the street when SMACK. She gets hit by a car and her head goes through the windshield and she tells the people inside to remain calm.
 * Airwolf did this on more than one occasion.
 * Serenity did this in the Firefly episode "The Train Job".
 * In the season three episode "Not in Portland" of {Lost}, Juliet's husband is hit by a very quiet bus.
 * In NCIS, Gibs and DiNozzo are out in the desert with the local sheriff, when a helicopter simply arrives over them with no hint of sound. Fortunately, McGee was tracking it by satellite and gave them warning. Gibbs shoots it down.
 * All those times a helicopter is mistaken for a UFO, despite having a distinctive sound. Examples appear in Dark Skies, Airwolf, and The X Files'' (which managed to avoid the cliche for several seasons until the episode where Agent Dogget first appears).

Video Games

 * The Felreaver patrolling Hellfire Peninsula in World of Warcraft. It's a 50-foot tall demonic robot that shakes the ground with its footsteps and makes a sound not unlike a locomotive from hell, yet it still manages to suprise (and crush) unwary players who weren't paying attention to their surroundings. The game also has the dreaded Suprise Devilsaurs, which are even worse because they are actually quite sneaky (as sneaky as a T-rex can be).
 * And then a classic Good Bad Bug made the Fel Reavers into normal-size bears. Which still shook the ground with their footsteps and made the locomotive from hell sounds. So, screaming stealth bears.
 * The undermentioned stealth helicopter serves the protagonist of Deus Ex as a personal transport.
 * This happened in Final Fantasy VII with a giant airship that comes out of nowhere.
 * Used a couple times in Half-Life 2. The first time, a Combine Hunter-Chopper suddenly pops up from behind a flood control gate to continue hounding Gordon through the Canals. The other time happens later when a Strider suddenly jumps out of a large crater in the ground.
 * In Resident Evil 4, Ada makes her final exit this way, leaping off a cliff and then appearing inside a helicopter that rises up from out of sight.
 * Cyclonus makes his appearance like this in Transformers Prelude to Energon.
 * Averted in Ratchet and Clank: Going Commando when Ratchet asks if Clank hears something before the Thugs-4-Less Leader reappears in a helicopter.

Western Animation

 * The Amazing Spiez episode "Operation Spy-Sitter" had a WOOHP helicopter appear outside the window of the kids' house.
 * The Mighty Ducks animated movie had bored Tagalong Kid Nosedive come to the rest of the ducks rescue when they thought he'd stolen there only means of escape and left them stranded.

Real Life

 * Many helicopters, perhaps most famously the UH-1, are so loud that you know there is a helicopter nearby, but due to echoes, etc. it is sometimes difficult to know where it is unless you see it.
 * Rumor has it that the U.S. military was working on a stealth helicopter that would not only have a low radar cross section, but could also hide quietly behind terrain for minutes or maybe hours at a time, then pop up to fire antitank missiles when needed.
 * A popular urban legend/conspiracy theory is that the sinister Men in Black government agencies behind all the conspiracies have silent black helicopters that allow them to conduct operations without being observed.
 * This is a favorite trick in Blue Angel airshows. There are six Blue Angel fighters (all twelve-ton F/A-18s) aloft for the show, crossing in front of the stage in alternating directions. They get you nice and used to that, looking alternately to the left and right to spot the approaching aircraft as they approach in singles, pairs, and quads. Then a four-plane formation passes. Then you're told to look in one direction for a single approach. You do-VOOOM! The missing plane blasts overhead from the OTHER direction and hits its burners for giggles. Even though the plane is invariably a hundred feet up, half the six-foot-tall humans reflexively duck.
 * The Thunderbirds, the Air Force's F-16 flying team, does a similar stunt, going so far as to explain it as a relatively common tactic in air-to-ground operations. If the anti-aircraft gunners are looking the wrong way, it's much harder for them to shoot you.
 * Truth in Television where jet fighters in general are concerned (as anyone who's been to an airshow anywhere in the world will tell you) as the things are moving so fast you generally don't hear them until after they've past overhead.
 * Mind you, the above is only correct if the fighter in question is moving at trans- or super-sonic speeds, in which case you will not hear the noise until the plane is past, when you will hear a sonic boom.
 * Of course, even at subsonic speeds, you are still dealing with an aircraft traveling at hundreds of miles per hour. If they are using terrain-following tactics, or if the visibility is low, you will usually be surprised when they finally appear, regardless of if you could hear them or not. The way the sound of the jet engine bounces off of every available vertical surface (buildings, terrain, etc.) add to the difficulty in figuring out where they will appear.
 * The plane is a hundred feet above you so it will take about a tenth a second for the sound to reach you, giving the plane time to travel from dozens of feet away from directly overhead to directly overhead.
 * Some attack aircraft are designed with relative silence in mind. The American A-10 Warthog uses high-bypass turbofans (think of the big engines typical of airliners) rather than the low-bypass turbofans favored by most other combat aircraft because they trade raw power for reduced noice. Flying at low speed and low altitude towards a target, these planes have been known to induce puckering-level amounts of fear and surprise even in the troops that called them in, as the first sound they might hear of the plane is often the 30mm Avenger cannon opening up on the target at close range.