Aircraft systems and related methods are provided for extensible flight management capabilities. One exemplary system includes a multifunction computing module including a user interface, a first processing system, and a first communications interface supporting a first data characteristic, and a flight management computing module. The flight management computing module includes at least one avionics interface to receive operational data from an avionics system onboard an aircraft and having a second data characteristic different from the first data characteristic, a second communications interface communicatively coupled to the first communications interface to the multifunction computing module, and a second processing system coupled to the avionics interface and the second communications interface to convert the operational data to input data having the first data characteristic and provide the input data to the multifunction computing module.