An Inertial Navigation System (INS) requires continuous signals from satellites or ground navigation aids to estimate the aircraft’s movement.

### Why this is right An Inertial Navigation System (INS) is described as self-contained. It uses onboard gyroscopes and accelerometers rather than requiring continuous external navigation signals. ### The concept The INS measures acceleration and rotation along the aircraft’s axes. Starting from a known position where the system has been aligned, it combines motion measurements with elapsed time to estimate speed, heading, distance, and position. Because sensor errors accumulate, the estimated position becomes less accurate over time. This distinguishes INS from GNSS, which relies on satellite signals for position measurements. ### The other options - **True**: this would describe a system dependent on external signals, not the self-contained inertial system in the material. ### Terms - **Inertial Navigation System (INS)**: an onboard system that estimates movement and position from measured acceleration and rotation. - **Gyroscope**: a sensor that measures rotation. - **Accelerometer**: a sensor that measures acceleration. ### Remember INS measures its own motion; GNSS uses satellite signals.