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Mission Statement 

The purpose of FLAPS-2-APPROACH is two-fold:  To document the construction of a Boeing 737 flight simulator, and to act as a platform to share aviation-related articles pertaining to the Boeing 737; thereby, providing a source of inspiration and reference to like-minded individuals.

I am not a professional journalist.  Writing for a cross section of readers from differing cultures and languages with varying degrees of technical ability, can at times be challenging. I hope there are not too many spelling and grammatical mistakes.


Note:   I have NO affiliation with ANY manufacturer or reseller.  All reviews and content are 'frank and fearless' - I tell it as I see it.  Do not complain if you do not like what you read.

I use the words 'modules & panels' and 'CDU & FMC' interchangeably.  The definition of the acronym 'OEM' is Original Equipment Manufacturer (aka real aicraft part).


All funds are used to offset the cost of server and website hosting (Thank You...)

No advertising on this website - EVER!


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If you see any errors or omissions, please contact me to correct the information. 

Journal Archive (Newest First)

Entries in FMC Guide (1)


FMC Guide by Bill Bulfer - Review

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.

Historical Context

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. 

Learning CDU Functionality can be Frustrating if not Adequately Trained

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.

Software Variations

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.

Invest in Education - FMC Guide

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.