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Missile Lock-On

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When you're firing a missile (either from a hand-held launcher or from a vehicle), there's this technology that allows you to "lock on" your target so that your missile could reliably chase it. Usually accompanied by crosshairs and the iconic tone of "Beep.... beep.... beep, beep, beep, beeeeeeeeeeeeeeeeeeep". A screen that actually says "Lock On" is optional. The target, if they're aware (whether by looking or by radar), may attempt to do High-Speed Missile Dodge or use their point defense system to get rid of it.

This trope is common both in films and video games that involve fire-and-forget weapon systems. While representation in media may be more or less accurate to real life, most of the associated tropes for both the person aiming and the person being targeted have their basis in real world technology.

Subtrope of Homing Projectile; not all homing projectiles need locking-on first. Compare Player-Guided Missile, where the launcher is more hands-on on guiding the missile's flight path akin to a high-speed RC plane; i.e it's far from "fire-and-forget".

Not to be confused with Camera Lock-On, which is a Video Game Trope about keeping the camera pointed towards an enemy. If this is happening to you in a video game, that's a form of Crosshair Aware.


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    Anime & Manga 
  • Almost all Macross series feature a sequence of the protagonist trying to line up a shot. Or ten.
  • We also see Area 88 pilots waiting for the tone before launching missiles.
  • Sentou Yousei Yukikaze: What separates them from the rest of the trope is that the lock-on tone is taken directly off an F-15J fighter jet from a JASDF airbase for added realism.

    Films - Live Action 
  • Star Wars: An New Hope: Targeting computers come up for both lasers and proton torpedoes, especially during the Death Star run. Even though they lock on they can't hit the target, until Luke shuts off his compiuter and uses the Force to hit the target.
  • Used a lot in the many aerial combat sequences in the movie Top Gun. The F-14s can also detect when an enemy fighter achieves missile lock, as demonstrated when Cougar loses his shit at a MiG locking onto him (even though it doesn't fire, the idea that it could have scares the hell out of him).
  • Iron Man uses this somewhat, though it doesn't exactly seem to take him long. He is also on the opposing side in Iron Man 2 when he is chased by War Machine and the Hammer drones.
  • Used at the climax of Down Periscope: the Stingray needs to hit a dummy ship to win the wargame, while at the same time avoiding another sub that's hunting them. They don't have time to acquire a "shooting solution" and have to shoot from the hip just before the Orlando gets a solution on them.

  • Both the locking-on and locked-onto variants are ubiquitous throughout the Star Wars Expanded Universe, especially in books dealing with pilots in some form or another (read: most of them). Notable in that missiles can be fired blind or on a proximity detonator to avoid giving the enemy any warning, but it's very difficult to actually hit anything doing that.
  • Occurs repeatedly in Gerald Seymour's In Honor Bound, which is essentially a book-length duel between a Soviet Mi-24 pilot and a British officer wielding a Redeye missile launcher. As the Redeye is one of the less advanced heat-seeking missile launchers, so making sure the firer (and their target) are in the correct position to get a missile lock is an ongoing problem.
  • The mechanics of the FIM-092 "Stinger" missile launcher feature into one of the plots of The Cardinal Of The Kremlin by Tom Clancy: the mujihaddeen fighter known only as the Archer uses them to devastating effect on Soviet gunships in Afghanistan, and the book points out how the missile works, by going into detail about the heat-seeking warhead. The heat-seeking nature of the missile becomes important when they're used against guard towers equipped with electric heaters to protect against cold: while not the intended use, the missiles work just as well.

    Tabletop Games 
  • While BattleTech fiction occasionally mentions this happening (and not necessarily just for missiles — "lock-on" tones for lasers have been described before), a special case exists in the actual board game in the form of Streak missiles, which will not even launch unless they get a lock. A failed to-hit roll with a Streak launcher simply results in no missiles actually being fired from that launcher that turn at all, both conserving ammunition and preventing needless heat buildup. They're also virtually guaranteed to hit with the entire salvo if they do launch; anti-missile systems can still take down a few and sometimes a missile will expend itself against partial cover, but no roll on the cluster table is required in and of itself.

    Video Games 
  • Present in every game in the Ace Combat series using the exact same system that was presented in Top Gun.
  • ANNO: Mutationem: The Tunguska missile launcher is capable of locking onto enemies and even with large single targets, it causes a significant amount of damage and armor destruction after firing multiple shots.
  • Metal Gear:
    • Stinger missiles feature in most of the games and feature the traditional lock-on behavior, with potential targets being marked with a diamond that the crosshairs must be aimed at until it turns red to indicate a lock on. The missiles were first introduced in Metal Gear 2: Solid Snake, where they functioned more as rockets:. To hit the target, you had to fire the missile as it was making a turn, as otherwise the target was too fast and could evade the missile. There was no lock-on, per se, but firing at the right time instead guaranteed a hit.
    • For both the first two Metal Gear Solid games, you get the Stinger in order to fight flying bosses or the eponymous Humongous Mecha. Of course, you can use them on regular guards if you're feeling so inclined. There are also Stinger specific missions in the VR training add-on missions.
    • The Stinger returns in Metal Gear Solid 4: Guns of the Patriots as well as the Javelin, although that functions with fly-by-wire manual aiming to differentiate it functionally from the Stinger.
  • In Ghost Squad, the boss fight against the helicopter in the Mansion mission equips the player with rocket launchers. Each player has a crosshair that will slowly converge on the target the longer it's aimed at, together with the usual rising beeps and lock-on prompt.
  • The Call of Duty: Modern Warfare games both feature missile launchers in both the single player and multiplayer modes. The Javelin includes a targeting screen that highlights potential targets with green boxed that turn red when locked onto. The AT4 and Stinger missiles have no screen, and use only the lock-on tone to indicate when a target is being acquired and then locked onto. The RPG is dumb-fire only. For the other end of things, when you are controlling the AC-130 killstreak in multiplayer, you will hear the lock-on warning when you're being fired upon by missile-wielding enemy.
  • The move Lock-On in Pokémon is based off of this, enabling the user to (usually) guarantee a hit on the next turn.
  • The Wing Commander series used this a lot. Heat-seekers could only lock on if you were behind the target, whereas with Image-Recognition missiles you just had to point at the target for long enough. Torpedoes were an interesting case; they were anti-capital ship missiles that took a very long time to lock on, even though capital ships were very slow moving and couldn't dodge. The explanation was that the torpedo had to synchronize with the enemy ship's shields in order to punch through. Wing Commander: Prophecy further complicated things by requiring the torpedo to target and strike a specific weak spot, such as the engines.
  • Very common in the Colony Wars series, and you also have countermeasure beacons when you're the target of enemy missiles, although the reaction time to use them is punishingly low.
  • The Naval Ops series uses this for ship-launched missiles. An AEGIS system allows you to lock on to multiple targets.
  • Grand Theft Auto: San Andreas has this feature, Color-Coded for Your Convenience, on the handheld Stinger missile, the Hydra V/STOL jet fighter and the Hunter attack helicopter.
  • Halo:
    • Halo 2's Rocket Launcher, though it only worked on vehicles. It was discontinued for Halo 3, and games from Halo: Reach onward have it only work on air vehicles (except for a few Halo 5 versions which can also lock on to ground targets).
    • Halo: Reach introduced the Plasma Launcher, which does have this for all targets. The Sabre fighter also uses it, but since that took place in space, you never find out if it could lock on to terrestrial targets...
    • 2's Rocket Launcher also had a slightly peculiar lock-on mechanism in so far as you didn't have to keep your target in your reticle. In fact, you didn't even need a line of sight - you only needed to have the target in your reticle when you started holding down the right trigger, which would start the lock-on process. This means that you could hide behind a large rock, pop out for a split second to start the lock-on, go back behind the rock (breaking line-of-sight to the target), wait the 2 seconds until lock-on was completed, and finally release the right trigger to fire the rocket. Combined with the rocket's very small turning radius, this means that you didn't have to pop out from behind the rock to launch the rocket; looking straight up was enough for the rocket to hit the target even if it was pretty close already.
    • The various rocket/missile pods/turrets also usually have lock-on capability, though usually only on air targets.
    • Halo 5: Guardians introduces the Hydra, which fires micro-missiles that can lock on to even infantry.
    • In Halo 4, the Mantis Mini-Mecha's missiles/rockets can only lock on to air targets, and only in the campaign at that. In Halo 5: Guardians, the lock-on is also available in multiplayer, and the campaign version can even lock on to multiple ground targets at once. The ONI Mantis in 5's Warzone mode can also lock on to ground targets.
    • In most Halo games, you get an audible warning when someone has locked on to you. Halo 5, with its abundance of guided anti-vehicle weaponry, has removed this feature.
  • All guided missiles in Warhawk take time to lock on, represented by a shrinking box around the target.
  • After Burner has instant lock-on missile (instead of a beep you hear "FIRE!") Move the cursor over an enemy, launch. Repeat.
  • Resident Evil 5 has the LRT laser guided system. The launcher itself doesn't actually do anything, however targeting the boss it is used against long enough results in a converging crosshair and a beep when lock on is made. Pulling the trigger result in a space satellite firing a powerful condensed beam into the boss.
  • Rockets and normal torpedoes in Star Wars: Battlefront II take some time to acquire target lock, but homing missiles have an instant lock-on.
  • In most of the Star Fox series Arwings and Landmaster tanks can lock on and fire homing bombs and charged laser blasts.
  • The homing missiles in the Descent series make a distinctive sound to their target as they home in. Just one pulse of that sound is enough to make most veterans of the game twitch their fingers to instinctively dodge. Even worse in Descent 3's multiplayer, where players could assign pre-recorded audio taunts to keys. Guess how many people made one of their sounds the homing missile lock-on noise?
  • Much like the Wing Commander example, the FreeSpace series has this with aspect-seeking missiles and torpedoes - here justified as analyzing the target's armor to ensure maximum damage. Heat-seeking missiles ditch the lock-on time in exchange for being more susceptible to a High-Speed Missile Dodge. Both kinds of missiles can also be distracted with "countermeasures", electromagnetically active chaff designed to confuse the seeker head.
  • In League of Legends Urgot's Acid Hunter blades normally fire straight forward, but if someone's been struck with his acid they home in on them. Catelyn's ultimate is a sniper shot that can't miss one she's started lining it up, but can be intercepted by another champion.
  • Armored Core series does this too with their missile weapons. This continues until Armored Core 4 where missile lock is indicated by a visual cue, without the beeping.
  • In the MechWarrior series, guided missiles require a couple seconds to lock on, at which point they will track an enemy until they hit or run out of fuel. Mechwarrior Living Legends accompanies it with a BEEP BEEP BEEP siren when hostile missiles are inbound with your radar engaged. Using the Target Acquisition Gear allows for stealth missile attacks, as the TAG laser is invisible to the visual spectrum and doesn't give lock warnings.
    • One curious use was a weapon called the NARC Beacon. On its own, it does no damage, it just sticks on the enemy's mech if you hit. However, once it's active, it automatically directs all of your (and your allies') subsequent missiles towards the target unless they're explicitly locked to a different foe.
  • Battlezone (1998) and its sequels have a wide variety of flavors for lock-on missiles; some given lock-on tones to the user, but enemies never hear a warning. In both games, TAG missiles fire a tracer dart, then Macross Missile Massacre, Shadowers/Comets/Hornets use visual/radar/infrared targeting (respectively) to lock on and then fire. In the sequel, Fire-And-Forget and Swarm (combat) missiles go for the first they detect after being dumbfired, while Swarm (assault) missiles sequentially lock missiles and fire them in succession; from a single rocket to Macross Missile Massacre. It's possible for NSDF, ISDF, and CCA units to avoid certain locked missiles if they have the proper stealth system fitted on their tank, though Scions have to suck it up and tank the damage.
  • In the original PlanetSide, the Terran Republic's empire specific anti-vehicle weapon could lock onto targets, but the crosshair had to remain on the target or the missiles would lose the signal. In the sequel, all factions have access to generic anti-vehicle, anti-air, and combined rocket launchers that require a variable amount of time to lock (based on distance) but are fire-and-forget and can only be avoided with flares or some radical evasive actions. The TR Striker and NS Coyote missiles are completely fire-and-forget; simply spray wildly in the direction of a target and the missiles will robotech into anything that gets in their detection radius.
  • The Unreal series has had by tradition a lock-on function on the rocket launcher, activated when the user holds the crosshair on the enemy for at least one full second. Better yet, the launchers in the series can load up multiple rounds (up to six), for a person-scale Roboteching Macross Missile Massacre.
  • Activating the Tenta Missiles in Splatoon 2 will bring up a targeting reticle that shows the location of all enemies on the stage, and it allows you to lock on to up to five targets.note  After you've locked on to your targets, a barrage of missiles will be unleashed upon each of them.
  • Knuckles Chaotix has the Blitz Badniks, which fire 6 bursts of homing missiles at Knuckles and his friends when they're in range.

    Real Life 
  • For varying types of targeting systems and varying types of missiles, this can be true to varying extents.
  • Radar-guided missiles don't have any audible lock-on tone. They are guided initially by the aircraft's radar and after launch by their own, which locks on in different ways (and don't have a characteristic lock tone).
  • For some aircraft, the characteristic beeping that warns of a missile lock-on comes from a radio pulse detector. Slow beeps indicate a "scan", usually from a stationary radar installation sweeping over you as it turns; rapid beeps indicate "tracking", where the radar on board another plane attempts to pinpoint you, while the continuous tone, indicating "lock", is due to the radar pointing straight at you. Unfortunately, some modern air-to-air missiles only require the aggressor to achieve the "tracking" stage for it to find you, meaning you may already be dead meat even though the continuous tone hasn't yet sounded.
  • There are times where aircraft (or ships, or whatever have you) from two unfriendly nations encounter each other, but don't want to fight each other. One might be testing the other to see if they will take a stand, or they might be trying to intentionally bait them into starting a confrontation. There are various threatening maneuvers that can be done to try and convince the other guy to blink firstnote , but the generally-accepted be-all-end-all is to attain a missile lock and hold it without firing on the target, signaling to them that you have them dead-to-rights if they don't disengage. From time to time you will hear about US Navy pilots doing this to aircraft from various other countries which try to get too close to their aircraft carrier.
    • This is also used in training exercises and war games with pretty much the same meaning. Often the planes/ships/submarines aren't equipped with missiles or torpedoes, but the lock-on indicates that if they were they could take down their opponent.
  • The lock-on tone for the American AIM-9 Sidewinder series of air to air missiles isn't a beep, but a growling-razor type of sound. The louder, and more constant the growl, the more solid the lock. Coupled with "SHOOT!" that appears on a pilot's HUD this is an indication that the pilot has achieved weapons perameters, can safely launch his missile, and guarantee a hit/kill.
    • In versions of the Sidewinder up until the AIM-9P, the growl comes from the electrical activity of the seeker head, so the pilot is literally hearing what the seeker is seeing. The AIM-9X (and its predecessor, the prototype AIM-9R) use an imaging seeker head, so the growl is simulated.