When I was researching a couple of military campaigns for use in GURPS I was struck by how long it would take to get fire or air support.
Minutes.
In a game that is famous for resolving combat in seconds.
I think that says a lot that, in the real world, that real troops in contact were able to fight for five to twenty minutes waiting for support to arrive. Sometimes even more minutes while the aviators got themselves aligned with the situation.
I think I know how to make it work, but it will impact the player's expectations about modern combat.
I bumped into it before when trying to explain that the 3e rules let far too many hits happen unless you tossed in some of the, unpopular, optional rules.
They'd become accustomed to the world acting like a shooting range and the bad-guys being the paper targets.
Extending the ranges that contact begins at would go a long ways towards making the entire battle last longer in game time rather than table time.
I see running it in combat turns in small spurts to simulate the pulse of the battle.
I don't see a chance to test my idea any time soon, but...