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This glossary is written for virtual airline and flight simulation use within Virtual Air Canada Airline. It is not intended as a real-world aviation reference.
The Control Display Unit (CDU) is the primary cockpit interface for the Flight Management System (FMS). It consists of a screen displaying alphanumeric data and a keyboard with line-select keys used to enter, modify, and review FMS data. Through the CDU, flight crews program the route, enter performance data (weights, cost index, cruise altitude, and wind forecasts), set departure and arrival procedures, and monitor the computed flight plan. The CDU is the means by which the crew communicates intent to the FMS, which in turn drives the autopilot and autothrottle along the computed lateral and vertical profiles. On aircraft with dual or triple FMS installations, each pilot position has its own CDU, and both units are linked to the same FMS databases. CDU data entry is typically done during preflight and cruise using the INIT, ROUTE, PERF INIT, and DEP/ARR pages. Errors in CDU data entry - such as an incorrect cost index, wrong cruise altitude, or a missed waypoint - can affect fuel consumption calculations, speed scheduling, and the accuracy of the computed vertical profile. Airlines train crews extensively in CDU procedures because FMS input errors have been a contributing factor in several serious incidents and accidents.

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In Virtual Airline Operations

At Virtual Air Canada Airline, correct CDU programming is a fundamental part of pre-departure preparation. The SimBrief OFP provides all the data needed to populate the FMS - route, weights, cost index, alternate, and cruise level. Taking the time to enter this data accurately before departure and cross-checking the FMS route against the OFP is consistent with the AOPS standard operating procedures and reflects real-world practice for professional flight operations.
  • FMS - Flight Management System
  • CI - Cost Index
  • CDA - Continuous Descent Approach