Interference COMMS

Fading is caused by two signals arriving at the same time. In RNav, you may have come across this in the context of night effect with NDBNDB —Non-Directional Beacons, where signals from other NDBNDB —Non-Directional Beacons can reach into other's "area" giving two signals. In comms the cause is more straightforward: two aircraft transmitting at once. If they are talking to the same controller, they are by definition on the same frequency, so their signals will interfere.