Since the beginning of 2018, 8.33kHz radios became mandatory. Although it has been communicated via various channels that there are significant differences with the old simple 25kHz radios, this still is not clear to a very large number of pilots.

The problem is the following: in contrast to the 25kHz radio, the frequency on the screen of an 8.33 one is not the actual frequency the radio uses. Additionally, there is now an overlap between frequencies.