Air Greenland operates government contract flights to villages in the Aasiaat region. These mostly cargo flights are not featured in the timetable, although they can be pre-booked. Departure times for these flights as specified during booking are by definition approximate, with the settlement service optimized on the fly depending on local demand for a given day. Settlement flights in the Disko Bay and Aasiaat Archipelago regions are unique in that they are operated only during winter and spring. During summer and autumn, communication between settlements is by sea only, serviced by Diskoline.