Originally Posted by
mrmum
You will of course, have to be within line of sight of your nearest GA airfield to hear both sides of the transmissions.
Not necessarily - while if you have line of sight it obviously should work, as long as you're relatively close and the airfield has a powerful enough transmitter you may still pick it up anyway. For example at just over 2nm as the crow flies, with no direct line of sight (buildings + trees etc) I can pick up transmissions from the tower, though not from aircraft on the ground.