What are user-defined waypoints?

• A. Official GPS database entries that cannot be edited.
• B. Waypoints automatically generated by the navigation system.
• C. Waypoint location and other data which may be input by the user; this is the only GPS database information that may be altered by the user.
• D. Altitude constraints at each waypoint.

Answer: (C)

User-defined waypoints are points you create yourself by entering coordinates or selecting a known location, and you can edit their location and other data. They are stored in your GPS as custom points, separate from the official navigation database, and you’re allowed to modify both the location and the associated information for these points.

This differs from official GPS database entries, which are part of the published database and are not typically editable by pilots. They also aren’t automatically generated by the system—that’s a different, non-user-generated type of waypoint. Altitude constraints at each waypoint are not what defines a user-defined point; they’re just additional data that may be associated with a route or procedure, not the core idea of creating and editing a custom point.