excerpts  from IWC catalogue. "....in 1948, another celebrity was launched : the by now legendary Mark XI from IWC. The simple, classic appearance of the latest addition to the range guaranteed it a special place in the history of pilot's watches from the beginning. Its cachet has never waned and, to this day, IWC lovers all over the world leave no stone unturned in their search for one of watchmaking's greatest prizes, aware of its immense value as a collector's item."

Press notes : 

"The first-ever watch auction on the Internet was scheduled to start Dec. 1. It is being conducted by upscale Swiss watchmaker IWC, which is auctioning one of its vintage Mark XI pilot's watches, a timepiece coveted by collectors........IWC chief executive officer Michael P. Sarp called the Internet auction "a breakthrough for the watchmaking industry" and one from which he expected "a lot of feedback."

"The timepiece being auctioned was the 107th Mark XI to be made in 1957. Its movement, dial and case are original but have been cleaned and refurbished by IWC. The strap and clasp are replacements."

"The auction will be held on IWC's homepage and last from Dec. 1 to Dec. 11. Bidder can select either English or German to use at the website."

Auctioned on the IWC website. The watch fetched a whopping US$12,500 on December 11 1998.

Extracts from the British MOD Specification above

1. Waterproof to 20 feet.

2. When winding the watch, wind the crown backwards at least half-turn after fully winding the watch. Reason being that the waterproofing gland in the crown is such a tight fit that it might not allow the stem to turn and release excess tension on the main spring, which could cause a banking problem.

3. The watch came as standard issue, a bonklip bracelet, nylon issue strap is optional.

 

1. The Mark XI in general

excerpts from Michael Friedberg's post. 

The Mark XI was produced from 1948 until at least 1979 and probably the very early 1980s. It used an IWC Cal.89 movement at all times. I have never seen production numbers, but it had to be considerably more than the shorter-lived and widespread Mark X.

There are numerous subtle differences among the Mark XI models. It was issued to the British Ministry of Defense, and used by English and Commonwealth forces, including South Africa, New Zealand and Australia. It was also issued by Quantas Air to its crews, and also was sold later on commercially. Variations include some early cases are chrome-plated brass and others are stainless steel. Early cases were 36 mm in width but most are 35mm. I have been told , but cannot verify, that some Cal.89 movements used were "hacking models" but others did not hack. Later civilian cases also seem  to have more of a brushed finish.

Dials also differ in several subtle ways, including size of tritium markers. Military markings vary, depending on the date of production and country. All military issued ones have a broad arrow on the dial; some also have an encircled T (Ministry of Defense specification for tritium). Numbers on the back can differ depending on service and , if issued, there is a broad arrow engraved on the case back.

2. On the encircled T emblem

excerpts from Ziggy Wesolowski in England, author of the Concise Guide to Military Timepieces posted by Michael Friedberg.  

"The Mark XI's were indeed first produced and issued in 1948. The T emblem was not used for sometime, perhaps not until well into the 1960's... I know that earlier watches do bear this emblem, but they would be ones that were bought up to the most modern spec, probably by having the dial refinished (often by the military), with the addition of the T."

"It should be noted that radiation wasn't fully appreciated yet in the 50's - Hence all the A-bomb tests etc., using human guinea pigs to monitor long term results... Then when problems began to evolve and a greater understanding of radiation exposure was grasped, the military began to worry about stockpiles of "radioactive" watches... Consequently many were destroyed - Quite a few were actually (and literally) blown up!"

"Of course Tritium has a shorter life than other radioactive sources, so watches were so marked to indicate that they were safe... Both for the wearer and the store man."

3. The testing done to the Mark XI

excerpts from Brain and OCD's dicussions on the IWC discussion forum. 

Q. I was flipping through "Wristwatches History of a Century's Development" 4th ed. and I came across a caption by the Mark XI that says, "...before delivery, every Mk XI is tested by IWC for 648 hours under extreme conditions." Does anyone have an idea what this "extreme" testing might include?

A. The Mk XIs that were headed to the RAF first underwent testing at Kew, I believe at the NPL (National Physics Laboratory). The NPL had taken over chronometer testing from the Observatory. Essentially the tests were the traditional chronometer tests involving different positions and temperatures. They lasted fifteen days. As a watch passed its tests, it was released for service.

Note that these tests were performed in England for the RAF, not by IWC in Schaffhausen. As these were military issue watches, no chronometer certificates were issued - either the watch passed and entered service, or it didn't. I do not believe that the civilian market pieces underwent analogous testing by IWC. On the other hand, I'm sure that IWC adjusted and regulated all of these watches to the same standard.

4. The many versions of the IWC Mark XI 

 

 

 

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