Yesterday I was being ATC controlled by SCHOOL in EGGB Birmingham, I think, and I had AI traffic switched on. I got text messages in the top of the FlightGear simulation window like "Birmingham Ground, ready to taxi B1484" or something. Right now I am at London Heathrow, and getting tons of such messages. Following a picture:
To come back to the ATC controlling in Birmingham, I asked the ATC controller whether he were doing a solo session on ATC-pie because of these messages (I was the only one being ATC controlled at that time in that area). He said, no, and he said something about "airport ATC". Where do these messages come from (they stop appearing when I switch AI traffic off), and can I get such ATC too ?
If it matters : I have RGAtc installed, but disabled, and no other ATC plugins (SpokenATC, ATCChatter, …)
EDIT:
By now, I found out that this "airport ATC" responds even to me when I switch to the correct radio freq and use the standard phrases which can be selected by pressing -, then numbers.