Quick enquiry. At MAN, the respective TWR and GMC VHF and UHF frequencies are fully cross-coupled so all stations, whether a/c, vehicles or ATC can all monitor one another. At LBA the same voice switch (Schmid) is used but without a full cross-coupling facility. This means that TWR can hear a/c and vehicles, vehicles can hear TWR and a/c but a/c can only hear TWR, with the result that vehicles' TX frequently gets stepped on by aircraft.
Seems a daft way of doing things. Can anyone shed any light on why this is ? Beats me.
Thankyou.
MC