Jaeger-LeCoultre Mark XI Australian Air Force (RAAF-issued), G6B/346, Steel

 The Royal Australian Air Force (RAAF) made three separate purchases of the Mk XI Navigators’ watch with Store Reference Number G6B/346; the first two coming from Jaeger-LeCoultre in 1950 and 1953 respectively. The separate purchases had distinct case-back markings; the later examples from 1953 are marked "G6B/346", “RA AF” (with center broad arrow), and a sequential serial number (362) with the extension "/53" for the year.  Of the 1,020 of these pieces purchased by the Royal Australian Air Force (indicated by the ‘RAAF’ designation), 600, of which this is one, come the second series from 1953.

The Jaeger-LeCoultre Mark XI, alongside its relatively more common sibling, the IWC Mark XI, is perhaps the finest military mechanical timepiece ever produced. It can certainly lay claim to being the original Pilot’s watch, and one of the most expensive commissions by a military, anywhere. Originally issued by the British Ministry of Defence (MoD), and later the Royal Australian Air Force (RAAF), these watches were made to the very strict 6B/346 specifications, and as such, are of an incredibly high quality. Typically issued to military pilots, the “RAAF” Mark XI’s were first introduced to navigators in the Royal Australian Air Force (RAAF) in 1950. As of September 1955, G6B/346 navigation watches were to be exclusively issued to Aircraft Captains, First Pilots, and Navigators. The RAAF downgraded the Mark XI’s status as ‘navigational wristwatch ’to ‘general service’ in 1971, finally decommissioning the reference ten years later.

The 35mm stainless steel case features long lugs, spring bars, screw-down case back and a domed plexiglass. One of the key differentiating factors of the RAAF Mark XI is the use of spring bars instead of traditional fixed bars of RAF watches, offering a degree of versatility and setting it apart from most other military watches of its kind. There were also variances in the hands Jaeger-LeCoultre used, with this example coming with syringe hands. The case-back features all of the correct engravings as designated when issued.

This is from 1953 as shown by the case-back designation ‘/53’. The dial is in exceptional unrestored condition, with its original radium material aged to a nice orange patina. The text remains crisp and white. There are some minor scratches to the case-back and plexiglass, as expected, given the age and function of the watch.

One of the important characteristics of the Mark XI was its need to be highly antimagnetic, achieved through the iron dial and iron dust-cap, which creates a Faraday cage, protecting the movement from magnetic fields.

Inside the watch, is perhaps its most impressive aspect, the JLC Calibre 488/SBr - a chronometer grade movement with a hacking device and center seconds. It is rhodium brass finished with Geneva stripes. It was the precursor to the famously accurate Geophysic movement, released in 1958. 

The Jaeger-LeCoultre Mark XIs were renowned for their timekeeping accuracy, as this was a fundamental specification required by the British Armed Forces, and later the Royal Australian Air Force. As a result, these watches were regulated in five positions and tested in temperatures ranging from -5 degrees to 46 degrees over a 44-day testing period. This was conducted in the chronometer workshop of the Royal Greenwich Observatory in Herstmonceux. 

With pilot watches very much in demand today, due to their casual and utilitarian feel, this particular piece certainly fits the bill, especially with its wearable 35mm case and with both dial and case in exceptional unrestored condition. It is also, exceptionally rare.

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