Air-Ground-Air (AGA) activity is also called Air-To-Ground. It is a TETRA radio service. It is intended to give communication between radio users operating from airborne resources and ground based operatives including radio clients. The airborne resources regularly will be comparatively small in number operating comparatively rarely. they are operational, their viability is profoundly esteemed. The AGA service is given by deploying an overlay network of Radio Cells or “Air Cells” that gives the user with communications regularly from 150 m upwards.