What system is described as completely self-contained and capable of providing accurate positional data?

The Inertial Navigation System (INS) is described as completely self-contained and capable of providing accurate positional data because it relies on internal sensors, such as accelerometers and gyroscopes, to determine the position, orientation, and velocity of a vehicle or object. This type of system does not depend on external references or signals, which allows it to operate in environments where GPS signals may be unavailable or unreliable.

By continuously measuring its own motion and integrating that data over time, an INS can determine its current location without needing to receive any information from satellites or ground stations. This makes it highly effective for applications such as aerospace, maritime, and military navigation, where maintaining accurate positioning is critical.

In contrast, systems like the Global Positioning System and Satellite Navigation System rely on external satellites to provide their positional data, and the Ground-Based Navigation System typically depends on terrestrial signals. Therefore, the self-contained nature of the Inertial Navigation System is what allows it to provide accurate positional data independently.