Apparatus for a communications system of a moving platform comprising a plurality of systems, at least one platform application, and a communications module comprising at least one wireless communications link and configured to effect wireless data communication, wherein said apparatus comprises a communications planning module configured to: —receive data representative of a communications requirement between said platform and a recipient node; —identify a communications link for supporting said communications requirement; —determine, using attribute data representative of a position and/or orientation of said platform relative to said recipient node, a distance and direction of said recipient node with respect to said platform; —receive data representative of prevailing emissions control restrictions including an upper emissions limit defining a maximum transmission power permitted N to be utilized by an on-board antenna or portion of aperture antenna; —determine a best achievable transmission power, within said upper emissions limit, of said identified communications link taking into account at least said distance of said recipient node with respect to said platform; and —cause the transmission power of said identified communications link to be set to said best achievable transmission power.