What is the normal FMGC mode of operation?

The normal mode of operation for the Flight Management and Guidance Computer (FMGC) on the A320 is Dual. In this mode, the FMGCs work in tandem to provide redundancy and enhance aircraft safety and performance. Each FMGC operates simultaneously, ensuring that if one system fails, the other can take over seamlessly without loss of data or functionality. This dual operation allows for continuous monitoring and accuracy in navigation, performance calculations, and flight management tasks.

Operationally, the dual mode ensures that any discrepancies between the two systems can be detected and addressed by the crew. This is vital for maintaining situational awareness and navigational integrity, which are critical for safe aircraft operations. The design philosophy of having two FMGCs also allows for cross-checking of data, which helps to ensure reliable flight management and guidance, especially in complex flight scenarios.

In contrast, the other operational modes either do not provide the same level of redundancy (as in Independent mode) or are not typically used as standard practice during flight operations. Thus, Dual mode remains the standard for ensuring the highest safety and efficiency in flight management on the A320.