AKA TimeToImpact.

Because all kinetic weapons have a finite speed (along with most energy based ones) they take time to get from attacker to target. Even light takes 8 minutes to reach Earth from the Sun.

Sometimes this becomes a plot point. When a weapon takes over 30 seconds to reach a target, it allows things to happen. As in self-destructing the missile or attempting to.

May well involve a MagicCountdown.
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!!Examples:

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[[folder:Film]]
* In ''Film/TomorrowNeverDies'', Bond has to get an aircraft clear from an ArmsFair before a Tomahawk hits the place.
* ''Film/TheHuntForRedOctober'' has several scenes with torpedoes inexorably closing in on the sub. Usually includes the first officer stoically counting down the time to impact with his stopwatch.
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[[folder:Literature]]
* In ''[[Literature/AlexRider Eagle Strike]]'', [[spoiler:Alex has 90 minutes to stop the nukes launched by Cray near the end of the book.]]
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[[folder:Live Action TV]]
* In ''Series/BlakesSeven'' plasma bolts had running times, allowing the force wall on ''Liberator'' to be activated.
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[[folder:Real Life]]
* Torpedoes generally go around 50 knots. When launched at a target 2.5 nautical miles away, a torpedo will take 3 minutes to reach a target, allowing a sub time to "clear datum."
* Nuclear missile from the US to Russia, about half an hour. From Russia to the UK, about ten minutes. From Cuba to the southern US, under five. [[TheMoscowCriterion Welcome to nuclear strategy]].
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[[folder:Tabletop Games]]
* In ''TabletopGame/{{Harpoon}}'' missiles and torpedoes move set distances during engagement turns and may take over 10 minutes to reach a target.
* Torpedoes in ''BattlefleetGothic'' move a set distance (usually 30cm) every turn, which means that at long ranges they're more useful for limiting enemy movements than actually attacking.
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[[folder:Video Games]]
* Modern games often incorporate a tiny, practically invisible delay between firing and the slug hitting your target.
* Many a game involving HotSubOnSubAction.
* The first scene in the ''CallOfDuty 4'' mission "One Shot, One Kill" is a sniping mission. The target is so far away that the bullet will take over a second to reach him and your CO tells you that you need to account for the Coriolis effect in your aim.
** Later, during "Ultimatum," the bad guys launch [=ICBMs=] toward the Eastern Seaboard. "No Fighting in the War Room" becomes a TimedMission to take the control room and enter the missiles' destruct codes.
* In {{Portal 2}}, the portal gun works at the speed of light. In all of the test chambers save the finale [[spoiler: where you have to put a portal on the surface of the Moon]], the delay between trigger and portal open is negligible.
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