Complex sentence: A TACP always includes at least one Joint Terminal Attack Controller (JTAC) qualified to control attack aircraft; it sometimes includes an Air Liaison Officer (a qualified aviator), primarily in an advisory capacity.
Split into simpler sentences: A TACP always includes at least one Joint Terminal Attack Controller (JTAC) qualified to control attack aircraft. It can also include an Air Liaison Officer (a qualified aviator), who works primarily in an advisory capacity.