 A similar service, Remote Airport Advisory (RAA), is provided at non-towered airports that do not have a FSS but nonetheless have a level of activity that is high enough to justify the service.At these airports communication is "remoted" to a nearby FSS.Terminal radar service area, or TRSA, is general controlled airspace wherein ATC provides radar vectoring, sequencing, and separation on a full-time basis for all IFR and participating VFR aircraft.