Hi there,
I live under apporach to runway 26 at Luton and most bizz jets do not feature on SBS1 or RB. This is not a fault but due to most companies not having ADS-B fitted (ADS-B is the part of the kit that gives position reports thus enabling tracking). However, if you have the altitude showing and or a radio it is possible to tie up radio postiton reports giving call-sign and altitude and tieing up with the aircrft list. At this time only SBS1 gives altitude for non ADS-B aircraft but it has been requested (and accepted by Airnav) as a future requirement