I know on IRL planes the marker beacon at 4-7 miles is 400hz continuous Morse code tone, 3500ft is 1,300hz, and 1000ft is 3000hz. The localizer (left/right deviation) is received up to 25 miles EOR, up to 2000ft alt. The LOC has a three-letter designator transmitted at intervals to identify each LOC on AM VHF carrier. Glideslope has no aural tones, and gives you up/down deviation. The GS channels is selected depending on what LOC channel is selected, so no ID tones have to be transmitted. So if your VHF radio is off then the tones you hear are more than likely an EOR indication for the Marker beacon. That is just IRL though, not sure about in game as it is still downloading on steam for me. Getting it because im curious how many of the avionics systems work compared to what I work on. From the videos Ive seen the Pod looks almost identical to the sniper pod I work with. Hope this answered your question and I didnt confuse you too much. :thumbup: