MCDU

MCDU stands for Multipurpose Control and Display Unit. It is the primary input/output interface used to interact with an aircraft’s Flight Management System (FMS), most commonly on Airbus airliners such as the A320 family. The MCDU is typically mounted on the glareshield and comes in pairs (MCDU 1 and MCDU 2) to provide redundancy. Each unit consists of a compact keyboard and a small display, with a set of line-select keys (LSKs) adjacent to the screen to select options shown on the current page.

The MCDU provides the crew with control over the navigation and performance aspects of the FMGS (Flight Management and Guidance System). Pilots enter or modify the flight plan by routing waypoints, airways, SIDs and STARs, and direct-to routes. It also accepts performance data such as cruise altitude, target speeds, thrust settings, and fuel and wind information. The MCDU retrieves data from the aircraft navigation database and from sensors and systems aboard the aircraft, and it communicates with the FMS to compute lateral and vertical flight paths (LNAV and VNAV guidance) and to support autopilot and autothrust operations.

User interaction is page-based; pages include functions such as INIT/REF for initialization data, F-PLN for the flight plan, PERF for performance, PROG for progress and constraints, and others. LSKs on either side of the display allow selection of items, confirmation, or entry of commands. In normal operation, both MCDUs are available, with redundancy ensuring that input can be made from either pilot’s side, and the active MCDU provides the data used by the FMS to guide the aircraft.

The MCDU is central to planning and execution, but it relies on up-to-date navigation data, wind and performance information, and proper crew input to ensure accurate and safe flight guidance.