Inventive technology is directed to a control method for a terminal device in a non-terrestrial cellular data communication network. In an embodiment, the network includes at least one airborne or spaceborne base station moving along a flight trajectory for connecting the terminal device to the network. The method includes steps of: providing flight trajectory data for the base station in a memory element of the terminal device; providing terminal location data in a memory element of the terminal device; using a data processing unit, determining at least one time slot during which a wireless communication channel between the terminal device and the base station is estimated to be available, based on the flight trajectory data and on the terminal location data. The method also includes scheduling a data reception or transmission between the terminal device and the base station during the determined time slot.