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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 Chronometer Running ProSim737 Software

Main Instrument Panels (MIPS), unless a special order is made, usually do not include a chronometer.  Some MIPs have an empty bay whilst others have a picture of a chronometer or only a bezel.

After Market Chronometers

There are several after-market chronometers that can be purchased to install into the MIP.  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.  The later using a digital screen type which replicates the latest NG series airframes.  

No matter which type you decide, be prepared to shell out 250 plus Euro per chronometer; a reasonable sum for an item rarely used.

Whilst converting a genuine B737 mechanical chronometer is a valid option, finding one is difficult, as airlines frequently keep chronometers in service for as long as possible.

Another option is to use a virtual chronometer instead of a mechanical type.

Flight Deck Solutions and ProSim737

The MIP produced by Flight Deck Solutions (FDS) has accurate cut outs for the installation of a chronometer and includes a detailed bezel with buttons, but uses a picture card to give the illusion that the instrument is installed – not the best option.

ProSim737 as part of their avionics suite have available a virtual chronometer (image below).  This virtual manifestation can be displayed on a computer screen and manipulated via software.  The display is very crisp, the size is accurate (1:1 ratio), and the software allows complete functionality. 

LEFT:  Screen grab of the ProSim737 chronometer with included framework - which can be removed.  The pixel detail is excellent.


A good friend of mine wanted to make a chronometer for the simulator and configure it so it blended with the existing FDS bezel and four buttons (thank you CP).  The components needed were:  a small TFT LCD screen (purchased from e-bay), a standard POKEY interface card, several LEDS and electrical wire. 

The screen I used was 5.0" TFT LCD Module with a Dual AV / VGA Board 800x480 with a 40 Pin LED Backlight.  This size screen was the best fit for the space I had behind the FDS MIP, however, your MIP maybe different so ensure you measure it before ordering.

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 Construction

The bezel of the FDS Chronometer doesn’t support direct back lighting, nor does it accommodate room for the tactile switches or the wiring!  Therefore, the bezel must be modified to accommodate the wiring for the switches and back lighting (LEDS).  The easiest way to approach this modification is to use a dremel rotary tool with a 9902 Tungsten Carbide Cutter.  

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

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 at the rear of the bezel to allow room for the installation of miniature tactile switches, small LEDS and associated wiring.  To gain as much accommodation space as possible, the LEDS were shaved to remove excess material to enable them 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 ideal tool for this modification is a hobby CNC machine or dremel tool.  

The four front buttons of the chronometer (which came with the FDS MIP) need to be carefully removed from the bezel and attached to the miniature tactile switches using common ground leads, and then linked to the correct functionality on the POKEY card.  The wire used to connect the switches to the interface card is 26/28 AWG wire.

Constructing a Box

The second task is to construct a small box to house the screen, wiring and interface card.  The size of the box is controlled by the size of interface card and LCD screen.  The material used is plastic signage card; real estate agencies often use this type of sign.  The main advantage of this material being it’s not difficult to find, and is easy to cut, bend, and glue together with a glue gun.    

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 :)

After the signage card is cut to size, glued together to make a box, and the interface card and screen secured inside, the bezel is glued or taped to the front of the box, directly in front of the LCD screen.  A VGA and USB connector is mounted on the rear of the unit.    Small holes punched into the side of the container ensure the screen doesn’t overheat.  To conform to standard colours, the unit is painted in Boeing grey.

LED Back Lighting

If you look carefully at the back lighting you will notice the LED light coverage is not quite 100%.  There are two reasons as for this.

  1. There is only a limited amount of space available behind the FDS bezel to accommodate the LEDS - add wiring to each LED and space becomes a premium
  2. The material FDS use to construct the bezel is not transparent but slightly opaque.  This means that light from the LEDS cannot penetrate the opaque material as easily as if it was transparent – this translates to poor light transmission and coverage.  The only way to alleviate this is to replace the stock bezel with another made from a transparent material.  

Potential Problem

One potential issue you may have, is limited space to mount a a small LCD screen behind the MIP.  If your 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 your screen colour is set to black.  Remember you are looking at the chronometer from the flight seat and will not be viewing it close up.

Selecting and Positioning the Chronometer

This task is straightforward and follows the same method used to install and position the pilots flight displays and EICAS screens.  

Open ProSim737’s avionics suite and select the virtual chronometer from the static gauges:  resize and position the chronometer so that it sits behind and conforms to the size of the bezel.  To configure the buttons on the bezel so that ProSim737 recognizes them, you open the ProSim737 configuration screen and program the appropriate buttons from the switches menu.

Presto!  A chronometer that looks pleasing to the eye, has full functionality and is relatively inexpensive to produce.

Here is a short video (filmed at night) showing the new chronometer 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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