Which instrument is primarily used for lateral navigation in a VOR system?

The course deviation indicator is the primary instrument used for lateral navigation within a VOR (VHF Omnidirectional Range) system. This instrument provides pilots with feedback on their aircraft's position relative to the desired flight path defined by aspecific course or radial from the VOR station.

When a pilot sets a course on the aircraft's nav radio to orient towards a VOR station, the course deviation indicator displays information on whether the aircraft is flying to the left or right of that course. It features a needle that moves left or right, allowing the pilot to make necessary adjustments to stay on the intended path.

This capability is essential for navigation as it ensures that the aircraft remains on course during flight, thereby improving safety and efficiency in navigating airspace. None of the other instruments listed, such as the attitude indicator or airspeed indicator, serve this specific function of guiding lateral navigation. The attitude indicator deals with the aircraft's orientation, while the airspeed indicator monitors speed, making them irrelevant for lateral navigation in the context of a VOR system.