Control and Display Unit
The Control and Display Unit ( CDU ) or Multipurpose Control and Display Unit ( MCDU ) is the input device for the flight management system and other computer systems such as the central maintenance computer of modern commercial aircraft . It consists of a screen and an alphanumeric keyboard .
Before departure, all relevant data such as the destination airport , the planned flight route , the planned cruising speed , the empty weight of the machine and the amount of fuel, passengers and cargo are entered. The data calculated by the FMS , such as the starting speed, can be called up again via the CDU. The CDU is also used during the flight to enter changes to the route, holding patterns and the planned approach procedure , and to control the FMS.
The CDU is usually located between the pilots' seats . With larger machines, important devices are designed redundantly so that there are often at least two CDUs in the cockpit .