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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).

 

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Entries in B737-800 (13)

Friday
Aug042017

OEM B737 CDU Conversion - Using SimStacks To Convert The CDU

This article follows on from an earlier post that introduced the concept of converting an OEM CDU to use in flight simulator.  The conversion has now been completed and the CDU operates seamlessly with ProSim-AR.   

LEFT:  OEM CDU fully converted and operational.  The CDU is from a classic 500 series aircraft.  Prior to my ownership, the CDU was used by United Airlines (click to enlarge)

Historical Conversion Techniques

To date, various OEM parts have been converted using Phidget cards, and to a lesser extent Leo Bodnar cards, Flight Deck Solutions system cards, and PoKeys interface cards.  Phidgets provide a stable platform, despite the disadvantage that they, at time of writing, only connect via USB to the server computer.  The primary advantage of using Phidgets is that they have been used in a wide variety of applications, are inherently stable (for the most part), and their configuration is well documented.

The conversion of the CDU was slightly different to the norm, in that a different interface system was used. 

SimStacks by Simulator Solutions

The conversion of the CDU was done in collaboration with Sydney-based company Simulator Solutions Pty Ltd.  Simulator Solutions utilise their propriety interface boards called SimStacks to convert OEM parts for use in commercial-grade simulators

SimStacks is a modular, stackable, and scalable hardware interface that is designed to integrate OEM parts into your simulator with little or no modification.    One of the many advantages in using a SimStack Foundation Board (SFB) is that the interface can connect with either the server or client computer via Ethernet (as opposed to Phidgets). 

To date, Simulator Solution’s experience has been predominately with the conversion of B747 parts and Rodney and John (owners) were excited to have the opportunity to evaluate their software on the 737 platform, with the 737 CDU being the ‘first cab off the rank’.

This article will not delve deeply into the SimStack architecture, nor will it document the wire pin-outs used with the interface card; a future post will tackle this topic in more detail. 

CDU Conversion - Choose Your Poison

There are two main camps when discussing how to convert an OEM part.  The first is to utilise as much of the original wiring and parts as possible.  The second is to completely ‘gut’ the part and convert it cleanly using an interface that connects seamlessly with the avionics software in use (ProSim-AR).  A third option, although expensive and in many respects ‘experimental’, is to use ARINC 429.

With regard to the CDU, the easiest route was option two; everything in the CDU was removed with the exception of the internal shelf divider and keypad.  In hindsight, the pin-outs of the Canon plugs could have been used, but to do so a female Canon plug would have been required, and for the use of a couple of pins, this seemed to be overkill.

Keypad and Screen

The keypad and screen are the two most important parts of the CDU, and it's vital that the connection between the keypad, screen, and the SimStacks Foundation Board is not compromised.  The actual functionality of the CDU is controlled by the avionics suite.

Keypad

The keypad forms part of the lightplate in which 5 Volt incandescent bulbs are strategically located to ensure even backlighting of the keys.  Disassembling and removing the keypad from the main body of the CDU is straightforward; several small Philips head screws hold the keypad in place.  Once the keypad has been removed, any ‘blown’ bulbs can be replaced. 

Table 1: Overview of bulb location, part number and quantity.

The keypad has several wires that connect to a terminus inside the main body of the CDU.  Care must be taken when cutting the strands of wire to ensure the connection between the terminus and the keypad is not damaged.  Depending upon your skill, the terminus can be removed and a longer wire soldered to the keypad connector, or the wire can be lengthened (by splicing).  The wires from the terminus connect with the SimStack Foundation Board.

CRT and LCD Screen

The Classic CDU is fitted with a solid glass cathode ray tube (CRT) screen.  The CRT screen is approximately 2 cm thick and fits snugly within the display frame of the CDU. 

LEFT:  The CRT screen forms part of the CDU casing.  The silver coloured foil indicates the thickness of the replacement glass that needed to be ground (click to enlarge).

It’s possible to make the CRT screen operational, however,  the display would be monochromatic (green) and the screen resolution poor.  Therefore, the CRT was replaced with a custom-sized high resolution colour LCD screen.

To retrofit a replacement screen is not without its challenges.  The LCD screen is not as thick as the CRT screen, and is also not the same shape.  Therefore, the screen will not fit snugly within the display recess.  To rectify this shortfall, a piece of clear glass was ground to correctly fit within the display frame of the CDU.  This piece of glass replaces the 2 cm thick CRT glass.  The thin LCD screen was then mounted behind the clear glass in a central position.

During the design phase, it was thought that the thick piece of glass would cause a refraction problem.  However, although the theory suggests refraction will occur, the practical application has been such that any refraction is not readily noticeable.

Mounting the LCD Screen

Mounting the LCD screen can be done a number of ways.  Commercial grade double-sided sticky tape is the easiest method, but it is rudimentary.

LEFT:  LCD screen is fitted and temporarily held in position by commercial tape and a foam spacer.  Prior to revamping the CDU, this area was used to house the very large square shaped CRT screen.  Note the ribbon cable linking the screen to the screen interface card and the two white cables that connect to the screen controller card and SFB (click to enlarge).

To secure the LCD so that the screen sat firmly against the glass, thin metal plate was used to replace the open space that was left after removal of the CRT screen.  The sides of the metal plate were fabricated to push against the rear edge of the LCD.  This firmly secured the LCD screen against the rear of the clear glass.

LEFT:  The photograph shows the metal plate that was fabricated to replace the original CRT unit.  The edge of the plate pushes against the rear of the LCD screen holding the screen in place.  To remove the plate cover, 2 screws need to be removed.  It's amazing that the CRT screen required the amount of space that it did  - about 5 inches square! (click to enlarge).

Although the use of metal plate appears slightly unattractive, the plate only serves to enclose the CDU.  Once the CDU is slid into the CDU bay, the the casing of the CDU is not visible.

An alterative to using metal plate is to use ABS plastic painted the correct Boeing grey colour.

SimStack Foundation Board, External Wires and Screen Controller Card

To ensure that the CDU is standalone and will function without external inputs other than power supplies, four items need to be mounted inside the CDU.

(i)    The generic Interface card that controls the LCD screen;
(ii)    The LCD screen controller (buttons that control brightness, contrast, etc);
(iii)   The SimStack Foundation Board; and,
(iv)   The wiring to connect the keyboard to the Foundation Board.

Fortunately, there is ample room in the cavernous interior of the CDU to fit these items.

LEFT:  SimStack Foundation Board (SFB) mounted into the lower section of the CDU casing.  The SFB is responsible  for registering the key presses made on the keypad which are then deciphered and communicated to the avionics suite (ProSim-AR).  Click to enlarge.

The SimStack Foundation Board is mounted on an angular metal bracket that is attached directly to the bottom of the CDU, while the LCD interface card has been installed on the upper shelf along with the screen controller.  A ribbon cable connects the LCD screen to the interface card while a standard VGA cable connects the LCD screen to the client computer. 

The SimStack Foundation Board is Ethernet ready and requires a standard Ethernet cable (CAT 6) to connect from the card to an Ethernet switch (located behind the MIP). 

In addition to the Ethernet  and VGA cable, six power wires leave the CDU via the rear of the casing; four from the SimStack Foundation Board (5 and 12 volts +-) and two from the keypad (5 volts +-) to control the backlighting.

Toggle Switch

A standard two-way toggle switch is mounted to the rear of the CDU casing.  This switch is used to control whether the LCD screen, used in the CDU, is always on, or is only turned on when ProSim-AR is activated.  The switch is set and forget, however, access to the switch can be made from the front of the MIP or by sliding the CDU our of the CDU bay.

LEFT:  Toggle switch and wire harness leaving the base of the CDU casing.  The switch position and harness use the existing holes in the casing that were previously used by the Canon plugs.  5 and 12 volt wires are connected to appropriate busbars behind the MIP, while the VGA cable connects with the client computer.  The Ethernet cable connects into the Ethernet switch, also mounted at the front of the MIP (click to enlarge).

Power Supply

To operate the CDU requires a 5 and 12 volt power supply.  The backlighting of the keypad is powered by 5 volts while the SimStack Foundation Board and CDU operation require 12 volts.

Backlight Dimming

On my set-up, to enable the CDU keyboard to be dimmed, the 5 volt wires that leave the lower section of the CDU, are connected to a dedicated 5 volt Busbar located in the center pedestal.  This Busbar is used to connect the backlighting from all OEM panels.  The Busbar is then connected to the panel knob on the center pedestal.  The ability to turn the backlighting on and off is controlled by opening or closing a 12 volt relay (attached in line between the panel knob and Busbar).  Dimming is controlled by a dimmer circuit.

Mounting the CDU to Flight Deck Solutions MIP

The MIP skeleton and CDU bay is manufactured by Flight Deck Solutions (FDS), and is designed to fit FDS’s propriety CDU unit (MX Pro) and not an OEM unit.

The casing for the OEM CDU is much longer than the FDS CDU and measures 24 cm in length.

The FDS MIP incorporates an aluminum shelf (used by FDS to mount various interface cards) that protrudes slightly into the CDU bay.  This protrusion stops the OEM casing from sliding all the way into the bay.  To enable the CDU casing to slide fully into the bay, a small section of the shelf must be cut away.

A small metal saw is used to trim the metal away from the shelf, and although an easy task, care must be taken not to ‘saw away’ too much metal.  Once the piece of offending aluminum is removed, the casing of the CDU slides perfectly into the bay, to be secured by the DZUS fasteners to the DZUS rail.

LEFT:  Using a small metal saw, s small section of the shelf is removed.  This enables the CDU to slide into the CDU bay.  Left image is the shelf projecting into the CDU bay while the right image shows the shelf removed and covered in protective tape (to minimise abrasion).  A small notch was made at the corner to facilitate the safe routing of the wires used to enable the Lights Test (click to enlarge).

Functionality and Operation

The CDU is not intelligent; it’s basically a glorified keyboard that requires interfacing with software for functionality.  The functionality, fonts, colour, etc are provided by the avionics suite (in this case ProSim-AR, but arguably it could also be Sim Avionics or Project Magenta). 

To enable communication between the avionics suite and the SimStack Foundation Board (in the CDU casing), SimStack proprietary software must be installed.

SimStack Software - SimSwitch

SimSwitch is installed on the client computer and when configured interfaces with ProSim-AR on the server computer and the network.  Configuring SimSwitch is straightforward and involves inputting the correct static IP address and port numbers.

LEFT:  Screen grab showing SimSwitch software interface.  This is located on the client computer.  The interface, once configured, is standalone.  The software can easily be opened in minimized mode via a batch file (click to enlarge).

SimSwitch can also be used to monitor all connected OEM panels and provide debugging information if needed.

SimSwitch is a JAR archive executable file.  The file must be in operation to eanable the CDU to communicate with the avionics suite. 

The JAR file and the ProSim CDU .exe file must both be open for the CDU to function correctly.  To expedite a simulator session, the JAR file can very easily be added to a batch file for automatic loading of software prior to a simulator session.  A timer command can be added to the batch file line ensuring the JAR file opens before the ProSim CDU.exe file. 

First Officer CDU

The First Officer CDU will be converted using a similar technique, with the exception that this unit will be converted more ‘cleanly’.  A dedicated plate (rather than an angular bracket) will be fitted to the inside of the CDU casing.  This will facilitate the mounting of the SimStacks Foundation Board and LCD screen controller card.

Additional Photographs and Video

Additional photographs can be viewed in the image gallery.

BELOW: A short video demonstrating the operation of the OEM CDU using ProSim-AR. 

Main points to note in the video are:

(i)    Heavy duty tactile keys;
(ii)   The definite click that is heard when depressing a key;
(iii)  The solid keypad (the keys do not wobble about in their sockets); and,
(iv) Although subjective, the appearance of the OEM CDU looks more aesthetically pleasing that a reproduction unit.

Final Call

This conversion, by using a SimStack Foundation Board (SFB), has enabled full functionality of the OEM CDU using ProSim-AR.  The SFB can also be used to connect with other avionics suites, such as Sim Avionics and Project Magenta.  However, although the wiring of the SFB would be identical, the way in which the card interfaces and communicates with the avionics suite will differ.

Glossary

ARINC429 –  A standard used to  address data communications between avionics components.  The most widely used  standard is an avionics data bus.  ARINC 429 enables a single transmitter to communicate data to up to 20 receivers over a single bus.

SFB - SimStacks Foundation Board.

Standalone – Two meanings.  (i)   Operation does not require an interface card to be mounted outside of the panel/part; and, (ii)  In relation to software, the executable file (.exe) does not need to be installed to C Drive, but can be executed from any folder or the desktop.

Friday
Dec192014

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.

Monday
Dec012014

Cost Index (CI) Explained

The Cost Index (CI) function of the Flight Management Computer (FMC) is an important and often misunderstood feature of a modern airliner.  Apart from real-world cost savings in fuel, differing CI values alter airspeeds used during the climb, cruise and descent phase of a flight.  Certainly, the CI value is not a pressing issue for a virtual pilot flying a simulator, but to an operating airline in a fuel-expensive environment, differing CI values can equate to thousands of dollars saved.

LEFT:  Screengrab from CDU screen showing  the Cost Index page in 'PERF INIT'.

Simply explained, the CI alters the airspeed used for economy (ECON) climb, cruise and descent; it is the ratio of the time-related operating costs of the aircraft verses the cost of fuel.  If the CI is 0 the FMC calculates the airspeed for the maximum range and minimum trip fuel (lower airspeed).  Conversely, if the CI is set to the highest number, the FMC will calculate higher airspeeds (Vmo/Mmo) and disregard any cost savings.

In practice, neither of the extreme CI values is used; instead, many operators use values based on their specific cost structure, modified if necessary to the requirements of individual flight routes.  Therefore, the CI values will typically vary between airline operators, airframes, and individual routes.

LEFT:  CDU showing Cost Index.  A CI of 11 will generate significant savings as opposed to a value of 300.  FMC is produced by Flight Deck Solutions (FDS) click to enlarge.  A review of the FDS CDU can be read here.

Access to the CI is on page 1 of 2 in the ‘ACT PERF INIT’ page of the Control Display Unit (CDU) of the Flight Management Computer (FMC).  It is on the left hand side lower screen and displayed ‘COST INDEX’.  The range of the CI is 0-200 units in the Boeing 737 Classics and 0-500 units in the Next Generation (NG) airframes.

Fuel Verses Time and Money

There is a definite benefit to an airline’s fuel cost when the CI is used correctly.  Bill Roberson in his excellent article ‘Fuel Conservation Strategies: Cost Index Explained’ states the difference between a CI value of 45 verses a CI value of 12 for a B737-700 can be in the order of $1790 - $1971 USD depending upon the price of fuel; the time gained by selecting the higher CI value (CI-12) is in the area of +3 minutes.  Although these time savings appear minimal, bear in mind that airlines are charged by the minute that they remain at the gate.

Granted fuel savings are important, but so is an airline’s ability to consistently deliver on time, its passengers and cargo. It is a fine line between cost savings and time management, and often the CI will be changed before a flight to cater towards unscheduled delays, a change in routing, short or long haul flights, cost of fuel, aircraft weight, or favourable in-flight weather conditions (i.e. tailwind).

A higher CI value may be used by airlines that are more interested in expediency than fuel cost savings; the extra revenue and savings generated by an airline that consistently meets its schedule with less time spent at the gate may be equal to, or greater than any potential fuel savings.  Boeing realizes that as fuel costs increase, airlines are reticent to only expend what is absolutely necessary; therefore, Boeing works with its clients (airlines) to determine, based upon their operating style, the most appropriate CI value to use.

Changing CI on The Fly'

Although not standard practice, the CI value can be changed during the flight.  Any change in the CI will reflect on climb, descent and cruise speeds, which will be updated in the CDU and can be monitored via the 'progress' page of the CDU. 

Figure 1 below compares the cost index values against climb, cruise, descent and recommended altitudes for the Boeing 757 air frame.  Although these figures do not relate to the Boeing 737-800 NG, they do provide an insight into the difference in calculated CI values for climb, cruise, descent and recommended altitude.

Is the Cost Index Modelled in all Avionics Suites

The CI is modelled by the avionics suite, and whether it is functional depends on the suite used.  ProSim737 and Sim Avionics have the CI modelled and functional, as does Project Magenta (PM), Precision Manuals Development Group (PMDG) and I-Fly.  

Airline Cost Index Values

As stated above, the inputted CI value is variable and is rarely used at either of the extreme ranges.  The following airline list of B737-800 carriers is incomplete, but provides guidance to CI values typically used.  Note that the CI is variable and the values below may alter dependent upon airlines operations.  A more detailed list can be found on the AVSIM website (Thanks Dirk (ProSim737 forum) for the link).

  • Air Baltic CI – 28
  • Air Berlin CI – 30
  • Air France CI – 35
  • Air Malta CI – 25
  • Air New Zealand CI – 45
  • Austrian CI – 35
  • Fly GlobesSpan CI – 13-14
  • Fly Niki CI – 35
  • Hamburg International CI – 30
  • KLM CI – 15/30
  • Nord Star CI – 30
  • Norwegian CI – 15
  • QANTAS CI – 40
  • Ryanair CI – 30
  • SAS CI – 45-50
  • South African CI – 50
  • South West CI – 36
  • Thomson Airways CI – 9
  • Ukraine International Airlines CI – 28
  • WestJet CI – 20-25

The CI is an important feature of the avionics suite that should not be dismissed.  Whilst real-world fuel savings are not important during simulator flying, the altered airspeeds that a different CI value generates can have consequences for the distance able to be flown, climb, descent and cruise speeds.

Acronyms

CDU – Control Display Unit
CI – Cost Index
FMC – Flight Management Computer
Mmo – Maximum operating speed
Vmo – Maximum operating limit speed

Sunday
Oct122014

Boeing Chart (Map) Lights - B737NG and Classic B737 Types

Chart lights (also called map lights) are attached adjacent to the overhead panel and are used to illuminate, in particular, the chart holders attached to the yoke during night time operations. There are two lights, one on the Captain-side and the other on the First Officer-side.

LEFT:  Chart lights removed from a Boeing 737-800 NG airframe.  Colour, appearance and design is different to the the older style lights used in the classic airframes (click to enlarge).

The light from the unit can be focused from a wide angle to a narrow beam by twisting the focus ring at the front of the light.  Each light can also be swivelled and moved vertically to position the light beam in a particular place on the flight deck (for example, chart plates).

The switches (knobs) that turn the light on and off are located on the siewalls of the Captain and First Officer side of the flight deck.  The light can be dimmed if necessary by rotating the knob.

The chart lights are mounted near each the eyebrow windows.

Two Styles (Classic and NG)

To my knowledge, there are two styles of chart light that have been used in the Boeing 737. The fatter style used in the classic series airframes and the more slender style used in the in the Next Generation airframes.  I have little doubt that there may also be small differences between light manufacturers.

LEFT:  Chart light removed from a Boeing 737-400 airframe.  The light has a differing focus ring, appearance and colour to the NG style (click to enlarge).  I believe this style of chart light is also used on the B747 aircraft.

The main aesthetic difference between the older 737 classic airframe chart lights and the newer NG style is that the older lights are squatter and a little fatter in shape; the NG style is longer, more slender-looking and has a smaller footprint.

Other differences are internal and relate to how the light is focussed on the lens and the physical shape of the focus rung used to alter the angle of light coverage.

Ingenious Design

Both style lights have an ingenious design to allow the light to be focussed.   Removing the rear plate of from the older style light reveals the inner side to be a circular reflector dish (see image) which evenly distributes the throw of light when the unit is set to wide angle. 

LEFT:  Chart light showing reflector dish on inner side of end cap.  This style is the older light type used in the 737 classic airframes (Click image for larger view).

The newer Next Generation style lights use an aperture blade which either enlarges or contracts as the focus ring is turned.  This design is identical to how a camera aperture works.

Both styles can use either a 12 or 28 Volt bulb; the later will generate a brighter light.  Connection is direct to the power supply (12 or 28 Volt).  An interface card is not required.

 

Original Equipment Manufacturer (OEM)

Put bluntly, you cannot achieve a more realistic end product than when using a real aviation part.  Genuine parts, although at times difficult to find, are built to last; if they can withstand the continue abuse of pilots in a flight deck then they are more than adequate for home simulation use. 

LEFT:  The NG style chart light.  A blade aperture controls the amount of light that is reflected onto the thick lens glass (click image to enlarge).

It's true that while some parts appear "used" with faded and missing paint, they can easily be cleaned up with a fresh coat of paint.  Personally, I prefer the worn-appearance.

Thursday
Sep182014

B737-800 NG Flight Mode Annunciator (FMA)

Automatic Flight System - Background

The Boeing 737-800 NG has a relatively sophisticated Automatic Flight System (AFS) consisting of the Autopilot Flight Director System (AFDS) and the Autothrottle (A/T).   The system can be explained as follows:

LEFT:  B737-800 NG FMA.  This is photograph has been take in a real aircraft and provides a good idea to the size, font and position of the FMA.

The Boeing 737-800 NG has a relatively sophisticated Automatic Flight System (AFS) consisting of the Autopilot Flight Director System (AFDS) and the Autothrottle (A/T).   The system is as follows:

  • The N1 target speeds and limits are defined by the Flight Management Computer (FMC) which commands airspeeds used by the A/T and AFDS;
  • The A/T and AFDS are operated from the AFDS Mode Control Panel (MCP), and the FMC from the Control Display Unit (CDU); 
  • The MCP provides coordinated control of the Autopilot (A/P), Flight Director (F/D), A/T and altitude alert functions; and,
  • The Flight Mode Annunciator (FMA), located on the Captain and First Officer side of the Primary Flight Display (PFD),  displays the mode status for the AFS.

If you read through the above slowly and carefully it actually does make sense; however, during in-flight operations it can be quite confusing to determine which system is engaged and controlling the aircraft at any particular time.

Reliance on MCP Annunciations

Without appropriate training, there can be a reliance on the various annunciations displayed on the MCP.  While some annunciations are straightforward and only illuminate when a function is on or off, others can be confusing, for example VNAV.

Flight Mode Annunciator (FMA)

All Boeing aircraft are fitted with a Flight Mode Annunciator (FMA) of some type and style.  The B737-800 NG FMA is located on the Captain and First Officer side PFD and is continuously displayed.  The FMA indicates what system is controlling the aircraft and what mode is operational.  All flight crews should observe the FMA to determine operational status of the aircraft and not rely on the annunciators on the MCP that may or may not indicate an operational function.

The FMA is divided into three columns and two rows. The left column relates to the A/T while the center and right hand column display roll and pitch modes respectively.  The upper row indicates modes that are operational while the lower row indicates modes that are armed.  Operational modes are always coloured green while armed modes are coloured white.  Below the two rows are the A/P Status alerts which are in larger font coloured green, and the Control Wheel Steering (CWS) displays which are coloured yellow.

When a change to a mode occurs (either by by a flight crew or by the AFS), a mode change highlight symbol (rectangle) is displayed around each mode annunciation for a period of 10 seconds after each engagement.  Depending upon which flight avionics suite is being used, the time that the rectangle is displayed may vary between 2 and 10 seconds.  According to the Boeing manual the default time should be 10 seconds.

The below table and image (ProSim737 avionics suite) indicates the various mode annunciations that the FMA can display.  The the pitch mode column and CWS display are not populated.  Furthermore, the FMA annunciations may differ between airframes depending upon the software installed to the aircraft.