Or better simulate it properly, with dialing in target area barometric altitude above sea level into the slant range unit, in the mission editor in aircraft's setup. Actually its a CCIP, its just so inconvenient and inaccurate in RL nobody used it in combat conditions(its ok for ideal conditions of test range). It calculates impact point from a difference of own and target's pre-dialed altitude, current pitch, speed and selected weapon's ballistic coefficient. A little mistake in altitude setup, or target drove away, or weather changed - and all the setup goes down the drain.