The JFC chooses this apportionment by using inputs from his various subordinate commanders and comparing the requirements to the availability of air assets. If the ground commander exhausts his allocated CAS sorties, he may request additional sorties. FACs and other agencies pass detailed instructions on short notice to the aircrews. Specialized fire control, tactical air request, and tactical air direction nets are in place to plan, request, coordinate supporting arms, and direct aircraft. UHF and VHF channels are vulnerable to exploitation by the enemy thus creating the potential for the disruption of CAS missions.
Immediate missions are especially dependent on voice communication.
The FSCCs at all echelons constantly monitor a special parallel communication net for fire support deconfliction and approval. A standard nine-line brief contains the information to complete a CAS mission. Commanders use preplanned requests for anticipated CAS requirements. They allow detailed mission coordination and planning by the aircrews. Preplanned missions appear on the ATO and have an actual target, a location, and a target time.