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). The FMS can be defined as being capable of four dimensional area navigation (latitude, longitude, altitude & time) while optimising performance to achieve the most economical flight possible.
Learning CDU functionality can be frustrating if you’re not trained
Many virtual aviators blunder through the CDU line detents trying to understand how and when to use it – often with failure. 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; learning to correctly use a CDU is not achieved overnight.
Although there are several training guides available on the Internet, many fall short of being comprehensive. One of the issues is that each CDU can be slightly different to another. The reason for this is that various airline companies will have certain options enabled or disabled.
Precision Manual Development Group (PMDG) produces a very good section in one of their manuals (PMDG B737 FMC Guide) dealing with CDU usage. Tom Metzinger and Fred Clausen have also documented an excellent tutorial that addresses the operational functionality of the PMDG style CDU unit (similar to, but not exactly the same functionality and set out in the FDS CDU.
To read these guides, navigate to the Training and Documents Section in this website.
Invest in Training – FMC Guide
If you’re serious about your virtual flying or have a bent for technology, I’d strongly recommend you purchase Captain Bill Bulfer’s FMC Guide. The guide is a real world guide meaning that it’s designed for real B737 pilots. The guide not only provides detailed information on a vast array of FMC commands, screens and nuances, but also depicts many of the options (variabtions) that each CDU can depict.
The guide is a high quality production with clear and a concise guidance. It can be purchased either in colour (recommended) or in black and white.
Like anything, what you get from your simulator is what you put in. With a good working knowledge gained from study, you will soon discover that the shooting that STAR approach after a procedural turn with altitude and speed restrictions isn’t that difficult to fathom.
With this guide in your hand, you will be able to correctly operate the CDU.
To purchase a copy you can either navigate to either of the below sites:
I'll 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 my opinion only and is not endorsed.