Waltham Aircraft Clocks

Brooke Clarke 2000 - 2018

Waltham 8-Day
Waltham Digital
Russian A4C-1
Longines Wittnauer

General Comments

The thing that's nice about the mechanical clocks is the second hand.  The problem is they need to be wound.  A Self Winding mechanism would be a big plus. The Waltham has a 24 hour dial that I like much better than the A4C-1 12 hour dial.  The A4C-1 has a stop feature allowing the time to be preset and then started at the set time.  The Waltham does not have a stop (hack) feature.

Waltham 8-Day

Waltham Watch Co.
Mfrs part no. CDIA
F.S.S.C. NO R-88-c-590-100
Contract No. NOA (S)-577
------------ ---------------

Waltham 8-Day
        Aircraft Clock

The case is just under 3.25" x 3.25".  The back has what appears to be 2 adjustments for rate?
Used on the Lockheed Ventura

1 Second Exposure, UV Flashight - you can see 5 movements in the 1 second
Click on photo to see a larger version and if the cursor is (+) click again
                8-Day Aircraft Clock 1 Second Exposure
I've seen some people comment that these clocks have "glow in the dark" marking.
That's to say the hands and numbers will glow in the dark after being exposed to white light.

They were not designed with "glow in the dark" capabilities, rather they were designed
to be used with UV cockpit lights.  That way the pilot can read the instruments at night
 without having his night vision diminished.
White Light Illuminating clock
Waltham 8-Day
                Aircraft Clock
UV Light Illuminating clock
Waltham 8-Day
              Aircraft Clock
To open:
1. remove plug behing wind/set knob.
2. While holding wind/set shaft from behind with flat blade screwdriver,
    unscrew knob using pliers or other way to grab it.
3. remove 8 screws behind bezel
4. remove 3 scrfews that hold mechanism into case.
Waltham 8-Day
                Aircraft Clock
Waltham Watch Co.
U.S.A.  8 Days
15 Jewels
Adj. Temp. & 1 Pos.
Waltham 8-Day
                Aircraft Clock

Waltham Digital

Waltham Clock co inc
Electronic Aircraft Clock
6648-01-874-83 (<- very illegible and sure to have many wrong numbers)

Astrotech LC-20 is the current Model

Astrotech LC-20
        Aircraft Clock
The case is 2.385" x 2.385" square.  The circular part in back would pass through a 2" diameter hole.
The SEL and CTRL appear to be push buttons.
A sticker on the cylindrical part says:
Functional Test, Accept (QA stamp), Bell Helicopter Textron.

In the correct lighting you can see on the front the LCD patterns:


There is a circle made up of many tick marks like would be used for hours, minutes and seconds hash marks (too many to count)

Inside there are what appears to be hundreds of fiber optic light pipes to back light the LCD.
If the fiberoptic bundle is unplugged from the lamp and light shined into it, the whole face of the clock is illuminated, so the fibers are not going to specific locations, they just provide even back lighting.
There are a few date codes that indicate this was made after 1992.

A 3.65 Volt Lithium 850 mAh, 1/2 AA size battery marked TL-1250 is connected to the 71701BG IC.  Radio Shack has an replacement RS 23-026 = TL5101

On one of the printed circuit boards there is a small transparent surface mount crystal marked "2.0000 M" and there is a seperate 2.097152 MHz crystal in a can,
the IC marked 71701BG, an 8-pin IC marked "34164, 2335" and the are a number of discrete components.

The 6-pin MIL connector on the back is marked:
92 26 SOURIAU FR MS27466 T 9B35 P
The connector has an Outside Diameter of 0.565" with 2 lugs higher and an I.D. of 0.445" with 5 groves going to a larger diameter.

There are 6 wires going to the connector:
        1 - +28 DC
        2 - 28V Return
        3 - See notes
        4 - 5V AC/DC Return
        5 - Safety Ground
       6 - Blue - spare - provision for second lamp - not used on this model

The Black, White & Green wires are for supplying power to the unit and are under investigation.
(In the process of working on the wiring, 2 broken solder joints were found - helicopter environment)

Aerospace Display Systems (ADS) Ph 215 8226090 , Fax 215 8227974 -   - Makes the LC-20 which is the same clock!
Astrotech - repairs aviation chronometers - Products - LC20

Liquid Crystal Display for excellent sunlight readability
24 hour clock
Sweep second hand
24 hour elapsed timer
Two-button operation
Back lighting for night operations
Front mounts into aircraft panel
Internal keep-alive battery - Radio Shack has an replacement RS 23-026 = TL5101
Fitted to a wide variety of military aircraft

Russian A4C-1 Aircraft Clock

Russian A4G-1
                  Aircraft Clock Russian
                  A4G-1Aircraft Clock

The eBay descriptions say this is a 25 jewel (two are on the verge that contacts the balance wheel) 4-day movement (another web page says it's a 2-day movement) and it's rated for all military applications including space.  It has rear terminals for a heater.  The glass is 72 mm (2.8") in diameter where you can see through it.  Based on Jaeger Le Coultre design.
The dial markings and hands are painted with phosphorescient panit so that when a UV cockpit light is shined on them they glow.



  1. Time of day in 12 hour, minute & seconds
    Turn (5) Counter Clock Wise to wind.
    Pull (5) and turn to set Time of Day clock.
  2. Note:  When in Flying Time run mode (red flag in window)
               This also sets the Flying Time clock,
               So the Flying Time clock can be set to another time zone.
  3. Flying time in 12 hour, minutes.
    Press (5) to start.  Window (6) shows Red for Running.
    Press (5) to stop.  Window (6) shows Red-White.
    Press (5) to Reset.  Window (6) Shows White.
  4. Stop Watch in 60 minutes & seconds.
    Press (4) to start.  Second hand advances.
    Press (4) to Stop.
    Press (4) to Reset.
  5. (Right) Knob Clock Stop & Stop Watch Button
    Turn Counter Clock Wise to stop time of day clock (1).
    See above (3) for using as button.
  6. (left) Knob Winding - Setting & Flying Time push Button.
    Turn Counter Clock Wise to wind.
    See above (1 & 2) to control Flight Time clock.
  7. Flying Time Status Window (red, Red-White or White)

                Russian Aircraft Clock Labels


  1. Large screw is access cover for rate regulating setting
  2. Two black binding posts for 24 V heater power
  3. Thumb nuts on "U" bracket for panel mounting.  
  4. Stainless steel screwshold heater to case
  5. Red screws hold movement
  6. Green dot covers scres that holds movement (QA seal).

                Russian Aircraft Clock Labels


  1. Brass screws to allow removing front bezel.
  2. Mounting "U" bracket
  3. Notch to remove dial glass snap ring

                Russian Aircraft Clock Labels


Russian A4C-1
                  Aircraft Clock Movement
Russian A4C-1 Aircraft Clock
Russian A4C-1 Aircraft Clock Case

This is an easier way to get the mechanism out where it can be seen, than removing the bezel from the mechanism as was done for the above photos.
Remove two red screws (11) on back.
Scrape the green potting from the screw (12) on back and remove.
Remove four bezel to case screws (13).  Lift the bezel and mechanism from the case.

Problem After Reassembly

The clock stops after running for some time.  Not yet sure if it's because of the three rear mounting screws or the four bezel mounting screws.
The problem is related to what the clock is doing.  For example it runs fine when just the main time of day clock is running (the flying time and stop watch functions are not running).

Video -
Russian or Soviet MiG cockpit clock model 123CS - main dial plus 60 minute timer, no aux clock
Soviet or Russian MiG cockpit clock model ACS-1M
Soviet / Russian MIG Aircraft Cockpit Clock

Longines Wittnauer

This was sold on eBay as an A11, but all of them I've seen have the set/wind stem sticking straight out.  The dial is stamped A.F. U.S. Army, Type A-11.  Maybe this was a prototype or a later version of the A-11?  This type of stem that sticks out at the 45 degree angle is what I remember as applicable to clocks used in time and distance rallies. If this was surface mounted on a wooden instrument panel the stem would be above the surface and could be wound/set.


Fig 1
                  WittnauerA.F. U.S. Army Type A-11 8-day clock
Fig 2
                  WittnauerA.F. U.S. Army Type A-11 8-day clock
Fig 3
                  WittnauerA.F. U.S. Army Type A-11 8-day clock
Fig 4 Note dial stamped:
A.F. U.S. Army, Type A-11
                  WittnauerA.F. U.S. Army Type A-11 8-day clock
Fig 5 With UV light (see Cockpit UV Lights)
The hands are not glowing, maybe they are old Radium dials (Wiki: Dials, Girls))? Radium dials up to 1960.
Note the second hand moved.
                  WittnauerA.F. U.S. Army Type A-11 8-day clock
Fig 6
Three brass screws on back of main body (left) hold movement to back. Four smaller black screws hold front-glass to body.
                  WittnauerA.F. U.S. Army Type A-11 8-day clock
Fig 7 There was no oil on a number of the pivots!  Maybe the clockwork was cleaned but not oiled?
                  WittnauerA.F. U.S. Army Type A-11 8-day clock
Fig 8 Body and Front-glass partially opened.
Has been running for half an hour so far.
31 Aug 2018 - it has been running for a couple of days and the time is correct.
4 Sep 2018 still running - 6 days total
5 Sep 2018 - 7 days
8 Sep 2018 stopped at 12:20 (just after midnight) 10 days actual run time.
Without taking my thumb and first finger off the winder, it takes about 20 back and forth movements to wind.
It takes some rocking back and forth to get the balance wheel going.
stopped 3:07 am 16 Sep 2018 - 8 days run time.
Started as soon as wound, not shaking needed.

                  WittnauerA.F. U.S. Army Type A-11 8-day clock


M800 series of digital aircraft clocks.

4486077 Digital meter with uniform illumination and less inadvertent setting, David N. Torresdal, DAVTRON Inc, 1984-12-04, - better illumination and prevent inadvertent resetting.


Craig Pearce - Aircraft Clocks of the World - Waltham Aircraft Clock Corp.-
Barnstormers - Instruments/Clocks - Aerospace Display Systems - LC20 -

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