What is the purpose of the OBS function in the GPS system?

The OBS (Off-Bearing Switch) function in the GPS system is designed to allow the pilot to manually set and maintain a desired course without the system automatically adjusting the course based on the aircraft's current position or track. When activated, the OBS function enables the pilot to input a specific course to follow, which provides greater control over navigation, especially in situations where the desired track may not align with the GPS-provided route.

This manual setting is particularly useful during approaches, when pilots may want to navigate to a specific waypoint or maintain a particular course while entering or leaving a holding pattern. By giving pilots the ability to override the automatic navigation function, the OBS enhances situational awareness and allows for more precise navigation in complex environments.

Other answer choices entail functionalities that are not directly related to the OBS function. For example, tracking waypoints automatically is a primary function of the GPS system's navigation capability, which operates independently of the manual settings provided by the OBS. Similarly, initiating the descent phase of an approach or displaying current flight data pertains to other aspects of flight operation but does not specifically involve the observatory characteristics of the OBS function.