What is the role of a wet compass in aeronautical navigation?

The role of a wet compass in aeronautical navigation primarily involves indicating the aircraft's heading. This instrument is essential for pilots as it provides a reference to maintain or alter the aircraft's course. The wet compass operates based on the Earth’s magnetic field and uses a freely suspended magnetized needle that aligns itself with the magnetic north, thereby allowing pilots to navigate accurately.

While the other options mention important navigation tasks, they are not functions of the wet compass. Groundspeed is calculated by combining time and distance measurements, altitude is measured using altimeters, and wind direction is typically determined through weather instruments or by taking wind readings during flight, not by the wet compass itself. Therefore, the wet compass is integral for maintaining the correct heading in flight, making it a fundamental tool for navigational accuracy.