One of the most interesting and therefore popular things to monitor on a radio scanner are the airband transmissions. Listening to aircraft communicating with air-traffic control can be quite addictive, especially if you are able to hear transmissions from the tower of a busy airport.
Several years ago the geek factor for would be air-traffic controllers soared with the introduction of virtual radar systems. These units monitor the Automatic dependent surveillance-broadcast (ADS-B) that all modern aircraft now transmit in the 1090MHz band.
My younger brother who lives near Birmingham International brought a system a while ago and has great fun watching the approach of aircraft on 'radar' as they rattle the roof tiles on approach to BHX.
Not being a wealthy as my brother I have been looking for a cheaper alternative... and on Hackaday perhaps I have found one...or maybe not...
A simple decoder made from some salvaged parts from an old satellite receiver!
Until then I will have to make do with more low tech ACARS decoding.