Radio Nav Aids is an aircraft radio navigation instrument simulator. A huge world wide database of DME's, VOR's and VORTAC's is built in. Both a VOR (VHF Omni-directional Range) and HSI (Horizontal Situation Indicator) can be simulated. Both also have a classic 7-segment simulated DME (Distance Measuring Equipment) displayed consisting of slant distance, groundspeed and ETA.