Wrist Watch Mk 11, G6B/346 in the Royal Australian Air Force

The Royal Australian Air Force (RAAF) made three separate purchases of the Mk 11 Navigator’s watch with the Store Reference Number G6B/346. The first two purchases in 1950 and 1953 were from Jaeger-LeCoultre (JLC) and the last, in 1957 was from the International Watch Company (IWC). The separate purchases had distinctive case back markings; the JLC from 1950 were marked with the broad arrow “”, "G.6B/346" and a sequential serial number without a year. The 1953 purchase retained the “G6B/346” (without the dot), replaced the broad arrow, with "RAAF" and had a serial number with the extension "/53" for the year. The IWC watches were only marked "G6B/346" with a serial number and "/57" for the year.

The RAAF used the Store Reference Number G6B/346 rather than 6B/346 as used by the Royal Air Force (RAF). The RAAF Vocabulary of Stores (as described in AAP 281, 2nd edition September 1943, "Standard Notes for Equipment Personnel") classified the various equipment into Groups, Sections and Parts. The "G" group is Electrical Stores, Instruments and Aircraft Personnel Equipment and to this was added the Section, “6B” for Navigational Equipment and the part "346". An explanation of the RAAF Vocabulary of Stores can be found on the RAAF section of Craig Pearce's  Aircraft Clocks of the World.


The numbers purchased can be determined from the “Air Board Order” recalling each watch for servicing. The highest numbers known are 420 from the first JLC series, 599/53 from the second JLC series and 600/57 from the IWC series. The numbering of each series began at one indicating that the likely numbers purchased were 420, 600 and 600 for a total of 1620 Mk 11 wristwatches.

The following is an example of a recall for periodic servicing:


The recall dated 1st September 1958 includes Mk 11 from both of the JLC series and IWC.

Using the records that I have been able to get so far (sixteen years of data) it has been possible to identify the individual watches recalled: 303 of 420 from the first JLC series, 595/600 from the second JLC series and 598 of 600 from the IWC series. As I get further records (assuming all the records exist) the identified watches will increase and the recall for service of each watch may eventually be known. Early records would also add significantly to the number of the first series JLC Mk 11 watches. There are also six (possibly seven) watches recalled for service bearing RAF numbers. These could represent watches held by Navigators/Pilots from the RAF on temporary transfer to the RAAF with the RAAF having those watches serviced, or watches that permanently came into the possession of the RAAF. One of these watches has markings that are consistent with JLC numbering and the remainder are consistent with IWC numbering.

The Mk 11 watches were initially required to be returned for service at an interval of twelve months, with the interval extended to eighteen months in 1957. In practice the recall intervals varied from what was required, but some watches were not returned for servicing despite being recalled as can be seen from the following statement in 1959:

"It is obvious that the provisions of ABO E 8/5 are not being complied with, as is evidenced by the appendix to this order which lists by serial number those watches being recalled for servicing over a period of five years and which have NOT yet been received at No. 1 Stores Depot."

Reminders were also issued at later dates as some watches were still not being returned.

Introduction into the RAAF

The first series of JLC watches (without year markings) were introduced into the RAAF in August 1950. The following table shows their initial allocation:

It clearly shows the allocation of the watches was first and foremost to Navigators, not to Pilots, and 12 of the 71 went to the School of Air Navigation (S.A.N.).

As supplies of the Mk 11 increased, the Mark VII, Stores Reference G6B/159, was recalled and by June 1954 the total stock of Mk 11 had risen to 905. In the following month the number of G6B/159 in the Consolidated Equipment Establishment table was reduced by 372 and the number of Mk 11 increased by 380. The Consolidated Equipment Establishment table shows the allocation of watches to Squadrons, but does not include the numbers held at the Stores Depot. The number held at the Stores Depot was required to be at least 25% greater than in the Consolidated Equipment Establishment table to allow for replacement watches while those due for service were recalled, as well as a providing a reserve.

Given the total number of Mk 11 held as at June 1954 and the increased allocation to squadrons I believe this represents the arrival of the second series of JLC Mk 11 wristwatches.

As of September 1955 the policy for the issue of navigation watches was as follows;

1. Item G6B/346 Watch Wrist Mk 11 LeCoultre is to be issued to, Aircraft Captains, First Pilots and Navigators
2. Item G6B/159 Watch Navigation Omega is to be issued to all other aircrew.

There is no indication that this policy was changed when the IWC Mk 11 was introduced in 1957.

The Air Board Order shown above is dated September 1958 and is the first recall of the IWC Mk 11. Given that the service interval was extended to eighteen months in 1957, the introduction of the IWC Mk 11 into the RAAF probably occurred in the first half of 1957, i.e. eighteen months earlier than the above recall.


Australia is a long way from Switzerland to return the RAAF Mk 11 watches for service so this was undertaken locally. Two firms, Prouds Pty Ltd in Sydney and W.M. Drummond in Melbourne had previous experience servicing other RAAF watches and were selected to service the Mk 11. I have been unable to establish whether this arrangement continued throughout the life of the Mk 11.

Most mechanical devices are subject to modification during their life and the Mk 11 was no exception.

Two modifications have come to light:

The first relates solely to the JLC Mk 11, "Technical Order Instrument Modification No. 2. 60/1 Watch Wrist Navigators Mark 11 – Improved Glass and Sweep Second Hand". A new acrylic crystal with a square step was introduced to replace the existing crystal and the sweep second hand was luminized. The technical order is dated February, 1957 and both series of JLC watches would have been modified.

 The following diagram shows the square step on the new crystal:

The second modification was to both the JLC and IWC Mk 11 in October 1959, "Technical Order Instrument Modification No. 2. 60/2 Watch Navigators Mark 11 – Improved Pendant Sealing". The winding button and pendant was replaced on the JLC and IWC with the IWC case drilled to 1.7mm to accommodate the new stem.

The service contractors undertook the modifications when the watches were returned for routine periodic maintenance.

The other item that was modified was the band of the Mk 11. Originally the watches were supplied with the stainless steel “Bonklip” adjustable band, most likely Stores Reference G6B/2763. In July 1951 nylon watch bands meeting US "Military Specification, Strap, Wrist Watch, Nylon. MIL-S-3035" (dated 8 September 1949) were imported and tested for use on the Mk 11 and the re-cased G6B/159 watches (with minor modification of loops). At least 250 (black in colour) were sent by airfreight for use on the G6B/159 in February 1952. Another 1750 appear to be ordered, but this may also cover Navy (Air) and Army requirements. A local plastics firm was also approached to manufacture the bands to the above specification. In a 1959 – 1960 Provisioning Review file there is an undated page with the following note:


Stores Reference G6B/2617 is the correct number for the nylon watch band for the Mk 11. The cryptic note may not indicate that the RAAF used the nylon band, it may refer to the nylon band as used by the RAF. Research has not discovered any details of the Welsh firm M. Furst & Co.

The RAAF may have used any, or all of the above sources for their nylon watch bands. Unfortunately the relevant RAAF files are listed as destroyed making it difficult to determine what was definitely used.

To date I have found little about the Mk 11 during the 1960’s but remain hopeful that more information will emerge.


The recall for periodic servicing in the Air Board Orders of October 1971 classify the Mk 11 as "Watches Navigational MKXI 6645-041-7754", but the following month they are reclassified as "Watch, Wrist, General Service" with the same 6645-041-7754 stock number.

A little more than twenty-one years after its introduction, it is November 1971, that signifies the end of the Mk 11 as a navigational watch for the Royal Australian Air Force.

Watch, Wrist, General Service, 6645-66-041-7754 continued to be recalled for periodic servicing before being sold at auction as surplus equipment, at what are today bargain basement prices.

Any corrections are most welcome.

I’d like to thank the National Archives of Australia and the Royal Australian Air Force Museum for access to their records and Craig Pearce for AAP 281, 2nd edition September 1943, "Standard Notes for Equipment Personnel".

Greg Steer, June 2004

My ex RAAF IWC Mk 11


Cheers from the cellar


A link to: Royal Australian Air Force Watches