What does the INS continuously calculate?

• A. The aircraft's position and navigation information
• B. External weather data
• C. Ground-based radar guidance
• D. Satellite ephemeris updates

Answer: (A)

An inertial navigation system continuously determines where the aircraft is and how it’s moving by using the data from its onboard sensors. It measures linear acceleration and rotational rate with accelerometers and gyros, and then integrates those signals over time to estimate velocity, position, and attitude. This process provides ongoing navigation information, essentially a dead-reckoning of the aircraft’s state, even without external inputs. Other items like external weather data, ground-based radar guidance, or satellite ephemeris updates come from different systems and aren’t what the INS is computing. GPS or other updates may later correct drift, but the INS’s core ongoing output is the aircraft’s position and navigation information.