Timing a Rocket Attack

Hey Folks,

I'm sure there is an easy answer for this, but I heave searched the forum and not had much luck. Here goes: how does a player time a rocket attack against a given target? To further clarify - how does someone know how long a rocket will take to target before you launch it? Is there a way to know my rocket will take 2 mins (for example) from my launch point to the target before I actually hit the launch button? I am playing against an opponent that has timed his rocket attacks perfectly to catch my aircraft in transit or refueling, hence massive aircraft losses. I cannot figure out how he times it so well within the game.

Any help is greatly appreciated!

Thanks!