The Control Display Unit (CDU) is the pilot interface to the Flight Management Computer (FMC). The FMC integrates with the Flight Mamangement System (FMS) of the aircraft.
Historical Context - What is a CDU, FMC & FMS ?
The first true FMC was introduced in 1984 with the release of the Boeing 737-300. In its most basic description, the CDU can be described as a computer that can store flight and navigation data and perform detailed and comprehensive assessments of the stored data, providing the pilot with up date information that is relative to safe and accurate flight. The CDU interacts with the autopilot, flight director, auto-throttle and internal reference system (IRS).
The navigation database is used to store route information which the autopilot will fly when in LNAV mode. When given data such as YMHB & KSEA, it takes inputs from the fuel summation unit to give a gross weight and best speeds for take off, climb, cruise, descent, holding, approach, etc. These speeds can all be flown directly by the autopilot & auto-throttle in VNAV mode.
Flight Management System (FMS)
The integrated system, of which the FMC is just one component, is known as the Flight Management System (FMS) The FMS can be defined as being capable of four dimensional area navigation (latitude, longitude, altitude & time) while optimizing performance to achieve the most economical flight possible.
An aircraft will only have one FMC installed, however, dependent upon company regulations, air safety and routing (flying over water), many operators will have two CDU's installed for redundancy. Think of the CDU as a keyboard to the FMC which in turn is a component of the FMS.
This said, the acronyms FMC and CDU are often interchangeable.
Flight Deck Solution's PRO Mx CDU
The CDU manufactured by Flight Deck Solutions (FDS) is an outstanding piece of simulation engineering. The unit is well built, solid and replicates a real B737 style CDU 1:1.
The CDU body and bezel (front plate) is manufactured from high grade metal while the rear section that houses the electronics is plastic. A USB and VGA cable connects to the video card output on the computer. The connections to the cable are located on the rear of the unit which allows easy connectivity to the computer. The CVU has been painted in the correct Boeing grey colour and the paint has been applied professionally in several thin layers; the paint does not chip or wear off with use. Importantly for those using genuine aviation parts, the unit is DZUS complaint and drops into the rails in the MIP with perfect precision. FDS includes four DZUS fasteners to allows connection to the rails.
High Fidelity Dimable Keyboard
The keyboard used in the CDU is made from high definition injection-molded plastic and the keys are dimpled and back-lit. The keys are very tactile and when depressed an audible click is heard ensuring you know the key has been depressed.
For night operations, the unit has a knob that can be rotated to dim the back-lighting brightness level of the keys. A functional metal carry bracket, that folds out from the edge of the bezel is also included. This replicates the carry handle observed in the real CDU.
Functionality - Software (Sim Avionics & ProSim737)
It's important to understand that the functionality of the CDU is not generated by software that comes bundled with the unit, but by the avionics suite you have chosen to use. Therefore, I have chosen not to discuss the various options that each software suite may or may not replicate. In the real world, airline companies have the opportunity to purchase specific options they believe are relevant to their flight operations. This said, many of the variations have been replicated in both software suites.
I have used the CDU with Sim Avionics and ProSim737; both software suites provide excellent functionality and work flawlessly with the unit.
The CDU is used throughout a flight; therefore, reliability is expected. The solid construction of the FDS CDU has not let me down and after endless pressing on keys they still function as you would expect them to.
The unit does not ship with navigation data included. The navigational database which includes STARS and SIDS, Runways, airports and the like must be purchased separately from Navigraph and then installed into your avionics software suite. Download and installation of the database is very easy and most of the install is automated.
The benefit of being able to regularly update the navigational database is obvious.
LEFT: The CDU at night with the only illumination being from the actual CDU unit.
I have left the best feature of the CDU to last – the display. WOW is the only word to describe the display.
The display is a colour VGA display unit sporting 800 x 600 resolution. What this means is that the script on the display is VERY clean, VERY readable and VERY sharp. Being a colour display means that differing colours (white, green and magenta) can be used for the fonts that your avionics software generates. The use of colour helps distinguish between functions that are activated or in stand-by mode, not to mention enhancing the units display readability.
I was very impressed that you can easily read the display during daylight; often reading a display screen is problematic during the daytime, especially when you are reading the screen at an angle such as you do with the CDU. The screen used by FDS delivers optimal results during daylight use.
Setting up the CDU using Sim Avionics was relatively painless. You must designate which CDU you are installing (Captain, First Officer or Instructor), edit a few lines in the .ini file to ensure it recognises the correct CDU, and configure the display location. The only teething issue I had was ensuring that the monitor display window size was correctly positioned on the screen for the location of the CDU. It took quite a few attempts to get the position "just right".
The set-up with ProSim737 is equally straightforward, however, to ensure correct operation you must install and enable additional software supplied by ProSim737. Installing and initiating the software is relaticvely painless, however, it's important to follow the provided instructions to ensure troublefree operation.
Mabual and Tuition
A manual explaining the functions of the CDU and/or tutorial is not included. In my opinion, FDS should develop a video tutorial that runs you through the basic functions of the unit including a simulated flight. This said, there are several dozen excellent tutorials that can be watched on U-Tube that provide basic and advanced CDU use. If you navigate to the video ection on this website, you will find a number of CDU training videos. A basic manual explaining the install and set-up procedure is included.
I'd strongly recommend purchasing Bill Bulfer's FMC Guide. This guide will allow you to get the most from the CDU. I'll be reviewing the FMC Guide in a future post.
I have nothing but the highest praise for this unit and in my opinion this is the BEST piece of reproduction flight simulation equipment I have owned or used.
My Rating 10/10
Please note that this review is my opinion only and is not endorsed.
A short video depicting some of the more commonly used keystrokes of the Flight Deck Solutions CDU. I have not used any particular sequence. The video is mainly to show the screen resolution and the uptake speed after depressing a key. Double click video to view full screen. Note that this video is using the Sim Avionics software suite. ProSim737's software provides slightly different options.