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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.


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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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Digital Chronograph Running ProSim737 Software

The Main Instrument Panel (MIP), unless a special order is made, usually will not include a chronograph.  Depending upon the MIP manufacturer, the MIP may have a cut out for the chronograph, a facsimile of a chronograph or just a bezel. 

The Next Generation aircraft use digital and mechanical chronographs.  However, for the most part all late model Next Generation airframes use digital chronographs.  The classic series airframes usually use (unless retrofitted) mechanical chronographs.

After Market Chronographs

There are several after-market chronographs that can be purchased.  SISMO Solicones produce a mechanical type that replicates the real world counterpart quite well, despite the awful orange-coloured backlighting.  Flight Illusion produces a quality instrument as does Flight Deck Solutions (FDS).  FDS replicate the digital chronograph. 

No matter which type you decide, be prepared to shell out 250 plus Euro per chronograph; for an item rarely used it's quite a financial outlay.

Whilst converting a genuine B737 mechanical chronometer is a valid option, finding one is difficult, as airlines frequently keep chronographs in service for as long as possible.  Converting a digital chronograph is an option, however, the initial price of the item and then conversion make this an expensive excercise.

Another option is to use a virtual chronometer (as included with Sim Avionics and ProSim737).

ProSim737 Virtual Chronograph

ProSim737 as part of their avionics suite have available a virtual chronometer.

LEFT:  Screen capture of ProSim737 chronograph.  ProSim737 have a Chronograph that can be used for the Captain and First Officer side of the MIP.

The display is very crisp, the size is accurate (1:1 ratio), and the software allows complete functionality of the chronograph. 

To use the virtual version a small computer screen is needed on which is displayed the virtual chronograph.


A friend of mine indicated that he wanted to make a chronograph for the simulator and use the virtual ProSim737 display.  He also wanted to incorporate the four setting buttons and have them fully functional. 

The components needed to complete the project are:

(i)    A small TFT LCD screen (purchased from e-bay);

(ii)    A standard Pokey interface card;

(iii)   Several LEDS; and,

(iv)   Four minature tactile switches and electrical wire. 

The screen used was 5.0" TFT LCD Module with a Dual AV / VGA Board 800x480 with a 40 Pin LED Backlight. 

The screen was small enough that it just covered the circular hole of the cut out in the FDS MIP.  The TFT LCD screen uses a standard VGA connector cable, 12 Volt power supply and a USB cable to connect the POKEY card to the computer.  

Two-part Fabrication

FDS supply with their MIP a bezel with four solid plastic and non-functional buttons.  The bezel does not support direct backlighting, nor does it have enough space for tactile switches or wiring. 

LEFT: The holes in the box provide ventilation for the Pokeys card.  The only portion of the box that is visible from the front of the MIP is the bezel and four buttons.

Therefore, the bezel must be modified to accommodate the wiring for the switches and LED illuminated backlighting. The easiest way to approach this modification is to use a Dremel rotary tool with a 9902 Tungsten Carbide Cutter.

Place the bezel on a hard surface using a towel to avoid scratching and damaging the bezel.  Then, with 'surgical' accuracy and steady hands carve out several channels (groves) at the rear of the bezel.  The channels enable placement of the miniature tactile switches, small LEDS and wiring. 

Space is at a premium, and to gain addition real estate, the LEDS were shaved to remove excess material.  This enabled the LEDS to fit into the excavated groove on the bezel.  Be very careful when using the carbide cutter to not punch out onto the other side of the bezel. 

The four solid plastic front buttons on the bezel were carefully removed.  each button was attached to the front of a miniature tactile switch, and using common ground leads, connected with the Pokey card.  26/28 AWG wire was used to connect the switches to the interface card.

Box Fabrication

A small box needs to be fabricated to house the Pokey card.  The size of the box is controlled by the size of interface card used and the length and width of the LCD screen. 

LEFT:  The box is not seen as it's attached to the rear of the MIP.  My friend's humour - several warning signs suggesting that I not tamper with his creation :)

The material used to fabricate the box is plastic signage card (corflex); real estate agencies often use this type of sign.  The main advantage of this material is that it’s not difficult to find and it's easy to cut, bend, and glue together with a glue gun.    

After the Pokey card is installed to the inside of the box, and the LCD screen attached to the front edge, the bezel needs to be secured to the front of the LCD screen.  The best method to attach the screen and bezel is to use either glue or tape. 

A hole will need to be made in the rear of the box to enable the fitment of the USB and VGA connectors.    Small holes punched into the side of the container ensure the LCD screen and Pokey card do not overheat.  To conform to standard colours, the box is painted in Boeing grey.

LED Backlighting

Careful examination of the backlighting will show that the light coverage is not quite 100%.  There are two reasons as for this.

(i)    There is limited space behind the bezel to accommodate the wiring and the LEDS; and,

(ii)   The material that FDS has used to construct the bezel is opaque.  The only way to alleviate this is to replace the stock bezel with another made from a transparent material.

Potential Problem

An issue can be the limited space to mount a a small LCD screen behind the MIP.  If you're forced to use a smaller screen, the outcome will be that you may see the screen edges within the bezel.  For the most part this is not an issue, if you ensure the desktop display is set to black.  Remember, you are looking at the chronograph from a set distance (from the pilot seat) and not close up.

ProSim737 Virtual Chronograph (position and set-up)

This task is straightforward and follows the same method used to install and position the PFD, ND and EICAS displays.  

Open ProSim737’s avionics suite and select the virtual chronograph from the static gauges:  resize and position the display to ensure the chronograph conforms to the size of the bezel.  To configure the buttons on the bezel, so that ProSim737 recognizes them with the correct function, open the ProSim737 configuration screen and configure the appropriate buttons from the switches menu (config/switches).

The four functions the buttons are responsible for are:

(i)    Chronograph start;

(ii)    Set time and date;

(iii)   Expired Time (ET) and Reset; and,

(iv)   +-

NOTE:  The above functions differ slightly between the panel and the virtual chronograph in use.

Chronograph Operation and Additional Configuration

The chronograph can be initiated (started) by either depressing the CHR button on the top left of the clock, or by depressing the CLOCK button located on the glarewing of the MIP. 

LEFT:  Captain-side CLOCK start button (FDS MIP).


Connecting the CLOCK button to the chronograph start (CHR) function is straightforward.

Connect the two wires from the Captain-side clock button to the appropriate interface card and configure in the switches tab of ProSim737 (config/switches/CAPT CHR).

The same should be done with the First Officer side CLOCK button and chronograph, however, ensure you select the FO CHR function in switches to be done for the First Officer side chronometer if fitted.

If configured correctly, one press of the CLOCK button will start the chronograph, a second press will stop the chronograph, and a third press will reset the chronometer to zero.


Here is a short video (filmed at night) showing the new chronograph running the virtual ProSim737 software.


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Reader Comments (6)

wow, this is a great solution! What size LCD TFT screens did your friend use? When I look for these on ebay most of the smaller screens seem to be from backup screens used in autos. Is this what your friend used? I"m not sure which screen to use for this.

Any help would be appreciated.

December 3, 2012 | Unregistered Commenteradineen

Hi Adineen

The screen used is a 5.0" TFT LCD Module+ Dual AV / VGA Board 800x480 40Pin LED Back-light.

I checked E-Bay and one is currently for sale at this vendor in China (which is the vendor I bought from)


Hope this helps. Good luck, F2A

December 3, 2012 | Registered CommenterFLAPS 2 APPROACH

F2A - Thanks for this information. i'm going to give it a go! I'll send an update on results!
Thanks again for posting this solution. The other clock options were not financially viable for me at this time.

December 3, 2012 | Unregistered Commenteradineen

Hi Adineen

Your more than welcome. I look forward to hearing how it turns out. I agree that many of the other options are just financially not on the same page, especially for an item which is not essential and not used very often. Enjoy the build, Regards, F2A

December 3, 2012 | Unregistered CommenterFlaps 2 Approach

Clive makes them for a pretty competitive price -- http://www.mycockpit.org/mcpclass/showproduct.php?product=1363

December 3, 2012 | Unregistered CommenterBen

Thanks for the note Ben. There are many ways to skin a cat and I appreciate your input. Cheers, F2A

December 3, 2012 | Registered CommenterFLAPS 2 APPROACH

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