What type of signal does a Flight Management Computer (FMC) use for approach guidance?

The Flight Management Computer (FMC) relies on both GPS and inertial data for providing approach guidance during a flight. This integration is crucial because GPS offers precise positional information based on satellite signals, while inertial data provides continuous tracking of the aircraft's position and motion using onboard sensors.

By combining these two types of signals, the FMC can deliver highly accurate navigation information, especially during critical phases of flight such as approaches to landing. The use of both data sources helps ensure reliability and improves the aircraft's ability to maintain the desired flight path, even in circumstances where one source of data may be less effective or temporarily degraded.

This dual dependence on GPS and inertial data distinguishes the FMC's functionality, especially in complex environments such as near airports where precision in approach and landing is paramount. Other options do not capture the comprehensive approach the FMC utilizes for effective navigation and guidance.