The Control Display Unit (CDU) is the pilot interface to the FMC (Flight Management Computer). It’s one of the more complex items that real and virtual aviators need to the master.
First introduced on the B737-200 in 1979 as the Performance Data Computer System (PDCS), the Flight Management Computer (FMC) was a technological step forward in in-flight navigation The PDCS was trailed on two in-service 737-200 series aircraft and crew reports indicated a fuel saving of 2.95% and an increase in trip time (based on a 71 minute trip). As a result, the PDCS became a standard fit and over time was developed to be reincarnated as the FMC will see today in the later 737 series aircraft.
The FMC is only one component of the Flight Management System (FMS) which is defined as being capable of four dimensional area navigation (latitude, longitude, altitude & time). The FMS contains the navigational database.
Many virtual aviators blunder through the CDU line detents trying to understand what they do; often failing. For the most part, the uninitiated will blame buggy software for the aircraft’s sudden dive or climb in response to a CDU command. The algorithm behind the functionality of a CDU is not simplistic – it is complex, and mastering the CDU is not achieved overnight.
LEFT: Random page from the FMC Guide. Click image to enlarge.
Real-world pilots attend lengthy pre-flight classes to understand the use of the CDU, and although there are several training guides available on the Internet, many are not peer-reviewed and fall short of being comprehensive.
One of the reasons that learning the CDU can be tiresome, is that the software that provides the intelligence behind the Flight Management System, has over time been upgraded to take into account technological advances. This is in addition to there being several software variants available. Software variants have been developed to cater towards individual airline options; an airline may want, or not want a particular function available to its flight crews.
Precision Manual Development Group (PMDG) produces a very good section in one of their manuals that deals with CDU usage (PMDG B737 FMC Guide). Tom Metzinger and Fred Clausen have also documented in their excellent tutorials, a segment on using the PMDG style variant CDU (PMDG use the latest sioftware version).
To read these guides, navigate to the Training and Documents Section in this website.
If you are serious about your virtual flying or have a bent for technology, I strongly recommend you purchase Captain Bill Bulfer’s FMC Guide.
LEFT: Page from FMC Guide discussing fixed waypoints. Click image to enlarge.
The guide is a real-world guide designed for real B737 pilots, and not only provides detailed information on a vast array of FMC commands, screens and nuances, but also examines many of the options relating to specific software versions.
The guide is a high quality production and has been written in a style that provides clear and a concise guidance. It can be purchased either in colour (recommended) or in black and white.
Like anything in life, you get out what you put in. With a good working knowledge gained from the study of this text, you will soon discover that the carrying out a procedural turn with altitude and speed restrictions, before flying a complex STAR and approach is not that difficult to fathom.
The information in this guide will allow you to be confidently and correctly operate the CDU.
To purchase a copy you can either navigate to Leading Edge Publishing.
I will be reviewing another of Bill Bulfer's text in the near future - The B737 Cockpit Companion.
My Rating 10/10
Please note that this review is not endorsed.