Definition

A Multifunction Control and Display Unit (MCDU), sometimes called a Multipurpose Control and Display Unit, is a device that serves as the heart of an aircraft's Flight Management System (FMS). The MCDU includes a keypad and a liquid-crystal display that allows a pilot to enter and modify flight plans. The MCDU also serves as the control head for the radios; presents flight information such as fuel consumption, time elapsed, and time to go; and allows input of engine thrust ratings and other data. MCDU functions also include communications via the Aircraft Communications, Addressing, and Reporting System (ACARS).

Description

In most installations, an aircraft will have two MCDUs: one for the captain and one for the first officer. The MCDUs are usually fitted into the center console, and each pilot can enter data independently. This also provides redundancy; normally, the failure of one MCDU will not affect the operation of the other.

MCDU keypads include function keys that allow selection of pages for radios, flight plan, aircraft performance, fuel planning, etc. Line select keys on either side of the display screen allow for more specific selections within certain functions. Alphanumeric keys allow for entry of data.

System architecture can vary with aircraft model, but generally, MCDUs work through modular avionics units or other such electronic units. Communications busses connect the MCDUs with air data computers, flight control systems, the FMS, and other aircraft systems.