Sorry, I just realise I confused the terms 'aeronautical station', which - in ICAO terminology - means ground station, and 'aircraft station'. The respective definitions, as given in ICAO Annex 10, Volume 2, Chapter 1, are:
Aeronautical station [...] A land station in the aeronautical mobile service. In certain instances, an aeronautical station may be located, for example, on board ship or on a platform at sea.
Aircraft station [...] A mobile station in the aeronautical mobile service, other than a survival craft station, located on board an aircraft.