When flight time matters

There are some scenarios in which winning initiative just isn't enough. Your character has to win initiative by a long shot. In a long range sniper shot the bullet can have a flight time of 3 to 5 seconds. That's one third to one half the duration of a combat round.

Winning initiative and taking the shot in the first second of the round does not ensure a kill fast enough to save your fellow party members. The enemy can be technically dead, but the bullet isn't there yet when he presses the trigger. When he is hit, his bullet is already on the way back to hit your character or some other party member.

Initiative mechanics set a sequence of events, but rarely specify how much time is between them. Sometimes it could be inferred that a certain amount of seconds are represented by a roll difference, but what if as a GM you roll once for all enemies? How is initiative modified by preparedness and skill? A better sniper should be able to adjust for variables in the bullets path a lot faster than an inexperienced one.

Same issues can be seen in fantasy settings. For example, the flight time of an arrow can be considerable as well, not only could the target fire back before getting hit, the target could move behind a friendly party member as is the case of close combat. Yet how many times have our archers fired at attackers tangled in mortal combat with a fellow party member without any regard for said party member's well being. In reality the two are moving around each other and not standing still in the position marked by the tokens. What could be a clear shot now may be an obstructed flight path a second later. But the arrow is already in flight!

Flight time matters a lot more in modern combat RPGs due to the nature of the weapons themselves and there much longer ranges when compared to medieval ranged weapons. Yet some of the issues apply to fantasy settings as well. How do you take flight time into consideration when running your game?