Which statement correctly describes how the INS uses data to predict position?

• A. It uses WSN-7 inputs in combination with GPS to predict the ship's position
• B. It replaces GPS position entirely with inertial data
• C. It uses star trackers to determine position
• D. It calculates only heading, not position

Answer: (B)

An INS predicts position by relying on its own motion sensors—accelerometers and gyroscopes—to perform dead reckoning. It integrates measured accelerations to get velocity and then integrates velocity to obtain position, allowing the ship’s position to be estimated without external aids for a while. In practice, GPS updates are used to correct this inertial estimate and limit drift, but the fundamental capability is to use inertial data to forecast position. The other statements don’t reflect how an INS works: it isn’t about combining a separate feed with GPS to predict position, star trackers aren’t typically used on ships for position fixes, and the INS provides both position and heading, not just heading.