I`ll try to explain myself.
Missle performance is about it's energy. When you launch from high altitute and speed you give your missile some extra potential and kinetic energy which increase it's range. If to speak precisely when you launch to target that is below you your missle has advantage of potential energy. When you launch "upwards" it has disadvatage because missile has to waste energy to gain altitude.
Next, actual effective launch range is largely defined by target course, spead and delta-altitude. Head-on engagements have longer launch distances: target approaches you helping your missile to get to it. So, you launch range can be bigger than actual missle kinetic range. The situation is reversed when you shoot at target's tail - effective launch range is reduced dramaticly. Modern fire control systems keep track of target motion parameters and provide pilot an actual effective launch distance to prevent waste of missiles. AFAIK Russians FCSs event forbid weapon release it target is not within engagement envelope.
Speaking of the game, I would expect two things:
1. Realistic missile energy model.
2. AI shooting only if target is within weapon's engagement envelope.
