That's true, in the UK with its particular definition of an "air/ground" frequency. Which I still interpret as "the assigned frequency of an air/ground service".
But I did say it was a loose translation, didn't I? My original says "met toestemming van de verkeersleiding op een lucht/grond frequentie" if that is any help to you. "leiding" translates to "controller" for me, literally it would be "director" or "guide" or "manager".