Flight management system is an integration of four major systems: flight management computer system, digital flight control system, autothrottle and inertial reference system. The basic function includes automatic flight control, performance management, precision navigation and system monitor. It is designed to allow crew access to the total range of its performance, navigation and advisory data computation capability at any time and in any flight control mode. The computer unit can be a standalone unit providing computing platform and various interfaces to other avionics. The control display unit provides the primary human/machine interface for data entry and information display.