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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 Boeing 737 Flight Simulator (33)


Wind Correction (WIND CORR) Function - CDU

Wind Correction (WIND CORR)

The approach page in the CDU has a field named WIN CORR (Wind Correction Field or WCF).  Using WIND CORR, a flight crew can alter the Vref+ speed (additive) that is used by the autothrottle to take into account headwinds greater than 5 knots. 

LEFT:  OEM CDU showing WIND CORR display in Approach Ref page (click to enlarge).

The default reading is +5 knots.   Any change will alter how the FMC calculates the command speed that the autothrottle uses.  Any change is reflected in the LEGS page. 

It's important to update the WIND CORR field if VNAV is used for the approach or of executing an RNAV Approach, as VNAV uses data from the Flight Management System to fly the approach.   However, if hand flying the aircraft, or executing an ILS Approach, it's often easier to add the Vref additive to the speed window in the MCP.  Indeed, flight crews for the most part, other than when using VNAV, leave the WIND CORR as its default (+5 knots), and change airspeed by using the MCP or by using Speed Intervention (SPD INTV).

WIND CORR Explained

The ability to increase the Vref speed is very handy if a flight crew wishes to increase the safety margin the autothrottle algorithm operates.

Boeing when they designed the autothrottle algorithm programmed a speed additive that the A/T automatically adds to Vref when the A/T is engaged.  The reason for adding this speed is to provide a safety buffer to ensure that the A/T does not command a speed equal to or lower than Vref.   (recall that wind gusts can cause the autothrottle to spool up or down depending upon the gust strength). 

A Vref+ speed higher than +5 can be inputted when gusty or headwind conditions are above what are considered normal.  By increasing the +speed, the  speed commanded by the autothrottle will not degrade to a speed lower than that inputted.


WIND CORR is straightforward to use.   

Navigate to the approach page in the CDU (press INIT REF key to open the Approach Reference page).  Then double press the key adjacent to the required flaps for approach (for example, flaps 30).  Double selecting the key causes the flap/speed setting to be automatically populated to the FLAP/SPD line. 

It’s important to understand that this is the Vref.  This calculation ALREADY has the +5 additive added; this is the speed that the aircraft should be at when crossing the runway threshold.  

LEFT:  Virtual CDU (ProSim-AR) showing the difference in Vref between a +5 and +13 Knot Wind Correction change.  Vref altered from 152 knots to 160 knots (click to enlarge).

If the headwind is greater than 5 knots, then WIND CORR can be used to increase the additive from the default +5 knots to anything up to but not exceeding 20 knots. 

Type the desired additive into the scratch pad of the CDU and up-select to the WIND CORR line.  The revised speed will change the original Vref speed and take the headwind component into account.  If you navigate to the LEGS page in the CDU, you will observe the change. 

Note that the Vref speed displayed on the Primary Flight Display (PFD) does not change.  This remains at Vref +5.

For a full review on how to calculate wind speed, review this article: Crosswind landing Techniques - Calculations, or read the cheat sheet below.         

LEFT:  Wind calculation cheat sheet (click to enlarge).

Important Varibles - Aircraft Weight

To obtain the most accurate Vref for landing, the weight of the aircraft must be known minus the fuel that has been consumed during the flight.

Fortunately, the Flight Management System updates this information in real-time and provides access to the information in the CDU.  It's important that if an approach is lengthy (time consuming) and/or involves holds, the Vref data shown will not be up-to-date (assuming you calculated this at time of descent); the FLAPS/Vref display will show a different speed to that displayed in the FLAP/SPD display.  To update this data, double press the key adjacent to the flaps/speed required and the information will update to the new speed.

Interestingly, the difference that fuel burn and aircraft weight can play in the final Vref speed is quite substantial (assuming all variables, except fuel, are equal).  To demonstrate:

  • Aircraft weight at 74.5 tonnes with fuel tanks 100% full – flaps/Vref 30/158.
  • Aircraft weight at 60.0 tonnes with fuel tanks 25% full   – flaps/Vref 30/142.

 Important Points:

  • During the approach, V speeds are important to maintain.  A commanded speed that is below optimal can be dangerous, especially if the crew needs to conduct a go-around, or if winds suddenly increase or decrease.  An increase or decrease in wind can cause pitch coupling.
  • If executing an RNAV Approach, it's important to update the WIND CORR field to the correct headwind speed based on conditions.  This is because VNAV uses the data from the Flight Management System (FMS).
  • If an approach is lengthy, the Vref speed will need to be updated to take into account the fuel used in the aircraft.  


Autolands are rarely done in the Boeing 737, however, if executing an autoland, the WIND CORR field is left as +5 knots (default).  The autoland and autothrottle logic will command the correct approach and landing speed.


WIND CORR may or may not be functional in the avionics software you use.  It is 100% functional in the ProSim-AR 737 avionics suite (Version 2).


CDU – Control Display Unit
FMC – Flight Management Computer
FMS – Flight Management System (comprising the FMC and CDU)
Vref - The final approach speed is based on the reference landing speed
Vapp – Vapp is your approach speed, and is adjusted for any wind component you might have. You drop from Vapp to Vref usually by just going idle at a certain point in the flare


How To Calibrate Flight Controls Using FSX/FS10 and FSUIPC

Imagine for a brief moment that you are driving an automobile with a wheel alignment problem; the vehicle will want to travel in the direction of the misalignment causing undue stress on the steering components, excessive tyre wear, and frustration to the driver. 

Similarly, if the main flight controls are not accurately calibrated; roll and pitch will not be correctly simulated causing flight directional problems, frustration and loss of enjoyment.

Flight controls are usually assigned and calibrated in a two-step process, first in Windows, then either by using the internal calibration provided in the FSX/FS10 software, or using the functionality provided by FSUIPC.

In this post, the method used to assign and calibrate the main flight controls (yoke, control column and rudder pedals) in FSX/FS10 and FSUIPC will be discussed.  The common theme will be the calibration of the ailerons, although these methods can calibrate other controls. The calibration of the throttle unit will not be discussed.

Many readers have their controls tweaked to the tenth degree and are pleased with the results, however, there are 'newcomers' that lack this knowledge.  I hope this post will guide them in the 'right direction'.

STEP 1 - Registering Control Devices in Windows

All flight controls use a joystick controller card or drivers to connect to the computer.   This card must be registered and correctly set-up within the Windows operating system before calibration can commence.  

  • Type ‘joy’ into the search bar of the computer to open the ‘game controllers set-up menu’ (set-up USB game controllers).  This menu will indicate the joystick controller cards that are attached to the computer (Figure 1). 
  • Scroll through the list of cards and select the correct card for the flight control device.  Another menu screen will open when the appropriate card is selected.  In this menu, you can visually observe the movements of the yoke, rudder pedals and any yoke buttons that are available for assignment and use.  The movement of the controls will be converted to either a X,Y or Z axis (Figure 1).
  • Follow the on-screen instructions, which usually request that you move the yoke in a circular motion, stopping at various intervals to depress any available button on the device.  The same process is completed for the movement of the control column (forward and aft) and the rudder pedals (left and right).  Once completed, click ‘save’ and the profile will be saved as an .ini file in Windows.

FIGURE 1:  Game Controllers Menu in Windows (registering joystick controllers).

Registration is a relatively straightforward process, and once completed does not have to be repeated, unless you either change or reinstall the operating system, or recover from a major computer crash, which may have corrupted or deleted the joystick controller’s .ini file. 

STEP 2 - Assigning Flight Control Functionality in FSX/FS10

  • Open FSX/FS10 and select from the menu ‘Options/Settings/Controls’.  The calibration, button key and control axis tab will open (Figure 2).
  • Select the ‘Control Axis’ tab. When the tab opens, two display boxes are shown.  The upper box displays the joystick controller cards connected to the computer while the larger lower box displays the various functions that can be assigned.  The functions that need to be assigned are ailerons, elevators and rudders.
  • Select/highlight the appropriate entry (i.e. ailerons) from the list and click the ‘Change Assignment’ tab.  This will open the ‘change assignment’ tab (Figure 3).  Physically move the yoke left and right to its furthest extent of travel and the correct axis will be assigned.  To save the setting, click the ‘OK’ button. 
  • When you re-open the ‘Control Axis’ tab you will observe that the function now has an axis assigned and this axis is identical to the axis assigned by Windows when the device was registered.  You will also note a small box labelled ‘Reverse’.  This box should be checked (ticked) if and when the movement of the controls is opposite to what is desired (Figure 3). 
  • Save the set-up by clicking the ‘OK’ button.

FIGURE 2:  FSX/FS10 Settings and Controls Tab.

FIGURE 3:  FSX/FS10 Change Assignment Menu.

STEP 3 - Calibrating Flight Controls in FSX/FS10

The flight control functions that have been assigned must now be calibrated to ensure accurate movement.   

  • First, select and open the ‘Calibration’ tab.  Ensure the box labelled Eenable Controllers(s)’ is checked (ticked) (Figure 4).
  • The correct joystick controller card must be selected from the list displayed in the box beside the controller type label.

Whether simple or advanced controls are selected is a personal preference.  If advanced controls are selected, the various axis assignments will be shown in the display box.  The axis, sensitivity and null zone can be easily adjusted using the mouse for each of the flight controls (ailerons, elevators and rudders). 

Concerning the sensitivity and null zone settings.  Greater sensitivity causes the controls to respond more aggressively with minimal physical movement, while lesser sensitivity requires more movement to illicit a response.  It is best to experiment and select the setting that meets your requirement.

The null zone creates an area of zero movement around the centre of the axis.  This means that if you create, for example, a small null zone on the ailerons function, then you can move the yoke left and right for a short distance without any movement being registered. 

Creating a null zone can be a good idea if, when the flight controls are released, their ability to self-center is not the best.  Again, it is best to experiment with the setting.  To save the settings click the ‘OK’ button.  

FIGURE 4:  FSX/FS10 Settings and Controls.

This completes the essential requirements to calibrate the flight controls; however, calibration directly within FSX/FS10 is rather rudimentary and if greater finesse/detail is required then it is recommended to use FSUPIC.  

FSUIPC Software

FSUIPC pronounced 'FUKPIC 'stands for Flight Simulator Universal Inter-Process Communication, a fancy term for a software interface that allows communication to be made within flight simulator.  The program, developed by Peter Dowson, is quite complex and can be downloaded from his website.  FSUIPC allows many things to be accomplished in flight simulator; however, this discussion of FSUIPC, will relate only to the assigning and calibrating of the flight controls.

It is VERY important that if FSUIPC is used, the FSX/FS10 ‘Enable Controllers’ box is unchecked (un-ticked) and the joystick axis assignments that are to be calibrated in FSUPIC be deleted.  Deleting the assignments in optional; however, recommended.  The flight controls will only function accurately with calibration by FSX/FS10 or FSUIPC - not both. 

STEP 1 - Assigning Flight Controls Using FSUIPC

  • Open FSX/FS10 and from the upper menu on the main screen select Aadd Ons/FSUIPC’.  This will open the FSUIPC options and settings interface (Figure 5).
  • Navigate to the ‘Axis Assignment’ tab to open the menu to assign the flight controls to FSUIPC for direct calibration (Figure 6).
  • Move the flight controls to the full extent of their movement.  For example, turn the yoke left and right or push/pull the control column forward and aft to the end of their travel.  You will observe that FSUPIC registers the movement and shows this movement by a series of numbers that increase and decrease as you move the flight controls.  It will also allocate an axis letter.
  • At the left side of the menu (Figure 6) is a label ‘Type of Action Required’; ensure ‘Send Direct to FSUIPC Calibration’ is checked (ticked).  Open the display menu box directly beneath this and select/highlight the flight control functionality (ailerons, elevator or rudder pedals).  Check (tick) the box beside the function.

FIGURE 5:  FSUIPC Main Menu.

FIGURE 6:  FSUPIC Axis Assignments.

Calibrating Flight Controls Using FSUIPC

  • Select the Joystick Calibration’ tab.  This will open an 11 page menu in which you calibrate the flight controls in addition to other controls, such as multi-engine throttles, steering tiller, etc.  Select page 1/11 'main flight controls' (Figure 7)
  • Open the ‘Aileron, Elevator and Rudder Pedals’ tab (1 of 11 main flight controls).  Note beside the function name there are three boxes labelled ‘set’ that correspond to min, centre and max.  There is also a box labelled ‘rev’ (reverse) which can be checked (ticked) to reverse the directional movement of the axis should this be necessary.  The tab labelled ‘reset’ located immediately below the function name opens the calibration tool.  The ‘profile specific’ box is checked (ticked) when you want the calibration to only be for a specific aircraft; otherwise, the calibration will be for all aircraft (global).  The box labelled filter is used to remove spurious inputs if they are noted and for the most part should be left unchecked (not ticked).  The tab labelled ‘slope’ will be discussed shortly.
  • Click the ‘reset’ tab for the ailerons and open the calibration tool.  Move the yoke to the left hand down position to its furthest point of travel and click ‘set’ beneath max.  Release the yoke and allow it to center.  Next, move the yoke to the right hand down position to its furthest point of travel and click ‘set’ beneath min.  Release the yoke and allow it to center.  If a null zone is not required, click the ‘set’ beneath centre.

If a problem occurs during the calibration, the software will beep indicating the need to restart the calibration process.  The basic calibration of the yoke is now complete.  However, to achieve greater accuracy and finesse it is recommended to use null zones and slope functionality.

FIGURE 7:  FSUIPC Joystick Calibration (ailerons, elevator, rudder).

Null Zones

The null zone concept has been discussed earlier in this article.

If a null zone is required either side of the yoke center position, move the yoke to the left a short distance (1 cm works well) and click ‘set’ beneath centre.  Next, move the yoke 1 cm to the right and click ‘set’ beneath centre.  

As you move the yoke you will observe in the side box a series of numbers that increase and decrease; these numbers represent the movement of the potentiometer.  It is not important to understand the meaning of the numbers, or to match them.

Replicate the same proceedure to calibrate the elevators and rudder pedals (and any other controller devices)

To save the setting to the FSUIPC.ini file click ‘OK’

It is a good idea to save the FSUIPC.ini file as if a problem occurs at a later date, the calibration file can easily be resurrected.  The FSUIPC.ini file is located in the modules folder that resides in the FSX/FS10 route folder.  

Slope Functionality

Slope functionality is identical to the sensitivity setting in FSX/FS10.  Decreasing the slope (negative number) causes the controls to be more sensitive when moved, while a positive number reduces the sensitivity. To open the slope calibration, click the ‘slope’ tab.  This will open a display box with an angled line.  Manipulating the shape of this line will increase or decrease the sensitivity.

Slope functionality, like the null zone requires some experimentation to determine what setting is best.  Different flight controls have differing manufacturing variables, and manipulating the slope and null zone allows each unit to be finely tuned to specific user preferences.

Does FSUIPC make a Difference to the Accuracy of the Calibration ?

In a nutshell – yes.  Whilst the direct assignment and calibration in FSX/FS10 is good, it is only rudimentary.  FSUIPC enables the flight controls to be more finely adjusted equating to a more stable and predictable response to how the controls react.

Potential Problems

If using FSUIPC for axis assignment and calibration, remember to uncheck (not tick) the ‘enable controller’ box and delete the axis assignments in FSX/FS10 – only one program can calibrate and control the flight controls at any one time.  If FSX/FS10 and FSUIPC are both engaged simultaneously, spurious results will occur when the flight controls are used.

If the calibration accuracy of the flight controls is in doubt (spurious results), it is possible that the simulator software has inadvertently reassigned the axis assignments and enabled calibration.  

An intermittent issue does exist in FSX/FS10 in which the software occasionally enables the controllers and reassigns the axis assignment, despite these settings having been deleted (I am unsure why this occurs).  If a problem should occur with the accuracy of the calibration, before, re-calibrating the controls using FSUIPC, always check the calibration box and assignments in FSX/FS10 and ensure these settings have not inadvertently been enabled.  

Final Call

Many enthusiasts are quick to blame the hardware, flight avionics or aircraft package, when they find difficulty in being able to control the flight dynamics of their chosen aircraft.  More often than not, the problem has nothing to do with the software or hardware used, but more to do with the calibration of the hardware device.

The above steps demonstrate the basics of how to calibrate the flight controls - in particular the ailerons.  If care is taken and you are precise when it comes to fine-tuning the calibration, you maybe surprised that you are now able to control that 'unwanted pitch' during final approach.

Further Information and Reading

The following documents are invaluable in understanding FSUIPC and its advanced features.  In addtion, a link demonstrates how to calibrate the steering tiller.


List of B737 Carriers Worldwide - Interesting....

A Boeing B737 takes off or lands somewhere in the world on average every 5 seconds!

To date, the Boeing series of airliners is the most successful airliner the world has seen.    Boeing's success revolves around, amongst other things, the ability to be able to upgrade their aircraft from a basic overall design that has changed little since the first B727 rolled out of the hanger in the 1968, earmarked for the German airline Lufthansa.

So which nations place their trust in Boeing?  This link provides a list of worldwide carriers by nation.


Creating Waypoints on the Fly with the CDU

Often you need to inject into the flight plan an along track waypoint, that is defined by a distance from a known waypoint or navigational aid.  There are several ways to achieve this and each method is similar in operation, but is used in differing circumstances.  Depending upon the software version installed in the Control Display Unit (CDU), you can either use the LEGS or FIX page.

To Create a Place Bearing Waypoint and a Along Track Waypoint in the CDU

There are two methods that obtain similar results - a Place Bearing Waypoint (Points 1 through 3) and an Along Track Waypoint

  1. In the LEGS page, type into the scratchpad the waypoint name, vector and distance.  The distance is where the new waypoint will be created and is measured from the waypoint or navigation aid you are using as an anchor (LAV340/10).
  2. After entering the information into the scratchpad  (LAV340/10), upload to the CDU by key pressing the appropriate waypoint, where you wish the along track waypoint to be created.
  3. Clean up any discontinuity and execute.
  • LAV is the waypoint, 340 is the vector, in degrees, that the waypoint will be created, And 10 is the distance from LAV that the new waypoint will be created.
  • To insert the waypoint before the anchor waypoint, use the negative key - (LAV340/-10).  
  • To insert the waypoint after the anchor waypoint, do not use any identifier (LAV340/10).
  • Note that the / is after the vector, and the waypoint name and vector are joined with no spaces.

To insert an Along Track Waypoint the identifier and distance is typed into the scratchpad and up-selected.  For example, LAV/-10 or LAV/20.

If the target waypoint is already in the route, then it is not necessary to type the identifier into the scratchpad; rather, select the identifier from the route list and press the appropriate line select.  The software will automatically insert the selected waypoint into the scratchpad for editing.

If you want the new waypoint to be created along the current navigation track, type the vector that is displayed adjacent to the waypoint in the LEGS page of the CDU.  If you do not type a vector, then the location of the along track waypoint will be automatically assigned by the software, which may not be along your current track course.

In the example shown (LEFT), I have created an along track waypoint called LAV02 which is located the aircraft side of the waypoint LAV.  I also have created a circle around LAV (see instructions below).

The CDU software will create along track waypoints with generic names (LAV01, LAV02, LAV03, etc).  In the example, I have already flown over LAV01 and LAV02 is now the next waypoint.


METHOD 1 - How To Create a Circle around a Waypoint Using the FIX Functionality in the CDU

There are many reasons why you may want to place a circle identifier around a waypoint or navigational fix at a specific distance.  Least of which to highlight a distance from a waypoint so it can easily be seen on the Navigation display (ND).  Other reasons are to designate the distance from the runway threshold that the landing gear is to be lowered, or the beginning of the glideslope for an ILS approach.

  1. Press FIX on the CDU to open the FIX page.
  2. Type into the CDU scratchpad, the name of the waypoint or navigation aid (VOR, NDB, etc) and upload to the FIX page (in the example, LAV).  This will display a small circle around the identifier in the Navigation Display in green-dashed lines.
  3. Type into the scratchpad the distance you require the circle to be drawn around the waypoint.  For example, /15 and upload this to LSL1.

A quick way to insert a waypoint from a route into the FIX page is to press the waypoint name in the LEGS page.  This will automatically down select the waypoint to the scratchpad saving you the time typing the name.  Then select FIX and upload the waypoint from the scratchpad.

In the example shown (ABOVE), I have created a circle at a distance of 15 miles from LAV which can be viewed on the navigation Display (ND).    The straight, green dashed line displayed from LAV is the vector, which in this example is unimportant, as we are only creating a circle. 

The vector only becomes important when you want to create a waypoint that intersects the edge of the circle (see below).

METHOD 2 - How to Create a Single Along-Track Waypoint  (at the edge of the circle)

If you want to create an along track waypoint at the edge of the defined circle, and insert this waypoint in line with the aircraft's current navigation track (route), then the vector becomes more important. The vector will determine the bearing, from the waypoint anchor that the waypoint is created. 

A waypoint can be created anywhere along the circle, that is drawn at the nominated distance around the anchor waypoint.  The location of new waypoint is defined by the vector (bearing).  If the inserted waypoint is in line with aircraft's current navigation track, the vector shown in the FIX page or adjacent to the waypoint in the LEGS page should be used.  The new waypoint will be displayed before the anchor waypoint.  

  1. Open the FIX page and type into the scratchpad the waypoint or navigation aid identifier and up-select to the four digit space at the top of the screen (for example, LAV).  If the identifier is part of a route, open the LEGS page, select the waypoint from the route and press the appropiate line select button for the waypoint which will populate the scratchpad.  Then, open the FIX page and up-select from the scratchpad to the FIX page the waypoint. A dashed-green  coloured circle will be displayed around the waypoint in the Navigation Display.
  2. Type into the scratchpad the appropriate bearing vector and distance and up-select to the appropriate line (for example, 049/5 will generate a waypoint 5 miles from the anchor waypoint on a bearing of 049 degrees).  A dashed-green coloured circle will be drawn at 5 miles from the anchor waypoint, and the new waypoint will be shown along that line at the appropriate bearing.
  3. To place this new waypoint into the route, press the appropriate line select button adjacent to the entry and down-select this to the scratchpad.  The CDU software will automatically convert the entry to a format that can be inserted into the route.
  4. Open the LEGS page and up-select the waypoint to the location within the route that you wish the waypoint to appear.
  5. Finally, clean-up any discontinuity (DISCO).

In the example (BELOW), I have created the first, along track waypoint (ADM 01) as an entry point to an arc, directly in line with the navigation track of the aircraft, before reaching the anchor waypoint - ADMAR.  ADM 01 is at the edge of the defined circle.

METHOD 3 - How to Insert Additional Along-Track Waypoints Around the Arc of the Circle 

Another variable of the above theme, often used when executing an NDB Approach, is to create several along track waypoints that intersect a defined circle.  The waypoints which are created at a set distance from an anchor waypoint or navigation fix, create an arc.

First, ensure you have a circle created around the waypoint at the distance required (FIX page).

  1. Select the anchor waypoint for the arc from the LEGS page and download to scratchpad.
  2. Type in the scratchpad as seperate entries: ADMAR100/15, ADMAR130/15, ADMAR160/15, ADMAR190/15 and so forth and up-select to the appropiate line select in the route.  This will create an arc 15 miles from ADMAR at the different bearing locations. 
  • If you want the first waypoint to be along your navigation track, use the vector for this initial waypoint as indicated in the LEGS page of the CDU.
  • The above can also be generated from the FIX page using the methods outlined in Method 2.

In the example (LEFT), I have created a number of along track waypoints, separated each by 30 degrees, that intersect the circle 10 miles from ADMAR.  With a little imagination, it is easy to uncover several uses for such funtionality: terrain avoidance, approach protocols, etc.  Click image to enlarge.

It is important to note that user and along track waypoints are given generic names by the software (ADMAR01, ADMAR02, ADMAR03, etc). 

To ensure that the waypoints are sequential when displayed (01,02,03,04,05, etc), upload the new waypoints to the LEGS page, to the same waypoint name that was used to create the along track waypoint.   In this example it is ADMAR.

Understanding the CDU

What I have described above is but a very brief and basic overview of some functions that are easily performed by the CDU.

CDU operation can appear to be a complicated and convoluted procedure to the uninitiated.  However, with a little trail and error you will soon discover a multitude of uses.  It is important to remember, that there are often several ways to achieve the same outcome, and available procedures depend on which CDU software you are using.

I am not a professional writer, and documenting CDU procedures that is easily understood is challenging.  If this information interests you, I strongly recommend you purchase the FMC Guide written by Bill Bulfer.  Failing this, navigate to the training section of this website and download some of the FMC tutorials.


Anchor Waypoint – The waypoint from which additional waypoints are created from
CDU – Control Display Unit
FMC – Flight Management Computer
Target Waypoint – The waypoint that has been generated as a sibling of the Anchor waypoint
Waypoint – Navigation fix, usually an airport, VOR, NDB or similar


Construction Commenced - New Platform to Install OEM Control Columns

I thought it time to post what’s happening with regard to the construction of the simulator.  Additions and improvements are in the pipeline and it’s hoped that OEM control columns and a new platform will be installed very shortly.

Currently the simulator is mounted on a fiber-board and wood platform, which I constructed when I received my Main Instrument Panel (MIP) just before Christmas 2010. (picture here).  The platform has served me very well and was perfect for the installation of the ACE yoke and Precision Flight Controls (PFC) rudder pedals.  

Soon after constructing the platform and purchasing the ACE yoke, I was able to secure two OEM B737-500 control columns. I was surprised to find these units so quickly and I was fortunate that my timing coincided with the dismantling of a late model B737-500.

Fitting the OEM control coumns to the wooden platform appeared to be problematic, as the platform was a tad low in height and it was awkward to retrofit the linking rod that connects the control columns for duel operation.  Therefore, I decided that a new platform was required; custom designed  to fit the control columns.

Aluminium Modular Design

Rather than use wood and fiber-board, I selected aluminium tubing cut appropriately and TIG welded together.  To facilitate future transport, the platform has been constructed in modular form.  The forward portion comprises three modules bolted together in strategic places, while the rear part of the platform (not shown), where the seats and center pedestal reside, abuts snugly to the forward section.  It’s intended to use high density ¼ inch plastic/vinyl as the upper cover on the platform  as this material is easier to work than aluminium sheeting, is light in weight, very strong and comes from the factory in Boeing grey.

In the photographs (click to enlarge) you can see the control columns (striped completely) fitted to the forward modular section of the platform.  The control columns are connected to each other by a ¾ inch heavy duty shaft and heavy-duty double bearings.  Forward and aft movement of the control column is controlled by a heavy duty spring and left and right roll movement is controlled by another spring. 

Control Column Pull Pressures

The pull pressure on the control column is set to 24 pound which is slightly less that the standard pull in the B737 which is 34 pound.  The pull can be easily altered by moving the spring forward or backward on the spring retainer.  The pressure on the roll component is presently 12 pounds.  I've been told the roll pressure as per the Boeing maintenance manual is +_15 pound; therefore, I'm well within the ball park.

This link will take you to another article that addresses the installation of the floor to the platform.