APPARATUS FOR SYNCHRONIZING FLIGHT MANAGEMENT COMPUTERS WHERE ONLY THE COMPUTER CHOSEN TO BE THE MASTER RECEIVED PILOT INPUTS AND TRANSFERS THE INPUTS TO THE SPARE

A method and apparatus for choosing which flight management computer (FMC) of two FMCs will function as a master FMC (11) and which will function as a spare FMC (13) in maintaining data commonalty and synchronization between the master FMC (11) and the spare FMC (13) is disclosed. The status of a control switch (15) having FMC select and auto positions is scanned to determine the state of the switch. If the switch (15) is in an FMC select position, the related FMC is chosen to be the master FMC and the other FMC is chosen to be the spare FMC. If the switch is in the auto position, the failure status of the FMCs is evaluated. If one of the FMCs has failed, the other is chosen to be the master FMC. If the FMCs are both operating, the health of the FMCs is evaluated. If both FMCs are healthy, one is chosen to be the master FMC and the other is chosen to be the spare FMC, in accordance with a predetermined protocol. If the health of one of the FMCs has degraded, the other FMC is chosen to be the master FMC. Only the master FMC receives pilot data, which is forwarded to the spare FMC. The master FMC maintains object managers and sends changed data to the spare FMC when a data change occurs. The spare FMC stores the changed data within its own object managers.