When a commander/observer calls in support like explosive mortars, smoke mortars, strafing run, whatever... It should be visible on the map for friendlies to see. For strafe run it would be a transparent colored rectangle covering the direction of the strafe or if it was mortars, perhaps a general large transparent colored circle to represent the possible radius of the rounds. If big colored UI areas on the map isn't your thing, perhaps just simple map markers indicating incoming support to a specific area.
This would improve information flow for ally decision making and tactics, strategy and lessen team killing.
However, enemy support would not be visible just like how it is now.