In aviation, watches are essential tools for navigation. From its earliest days, watch manufacturers endeavored to develop a timepiece that would allow a pilot to calculate his position at a glance. In 1929 Longines produced a "seconds-setting" watch designed by Philip Weems, a professor from the U.S. Naval Academy, and in 1932 produced the Hour Angle with insight from one of the most renowned aviators to ever take to the skies, Charles Lindbergh.
IWC established itself as a manufacturer of aviation watches, starting with the first watch ever developed solely for aviation, the Spezialuhr für Flieger or Special Pilot's Watch, in 1936. But as aviation became militarized, the importance of watches as navigational tools increased, and the British Ministry of Defense called upon manufacturers to design watches that could meet the rigorous standards required for military use.
We've mentioned the 'Dirty Dozen' before: military-issued watches manufactured by twelve companies that have now become the stuff of horological legend. These companies were: Buren, Cyma, Eterna, Grana, JLC, Lemania, IWC, Omega, Record, Timor, Vertex, and Longines. Watches issued as part of the Dirty Dozen carried the Caliber 83 movement and sported black dials distinguished by a broad arrow (indicating that the watch was property of the British crown); Arabic numerals; luminous radium hands; 15 jewel movement; and the case backs were stamped W.W.W., for "Watch Wristlet Waterproof."
But while these watches were approved for military use, and were indeed used by pilots, they did not prove ideal for aviation because they were produced with a lower level of accuracy than was required for dead-reckoning. Therefore, in the late 1940s the Ministry of Defense initiated a project to develop a watch designed exclusively for aviation. The new standard issued, which the MOD coded 6B/346, required chronometer-grade and anti-magnetic movements. The MoD gave the contract to two manufacturers: Jaeger-LeCoultre and, of course, IWC. Thus, the Mark XI was born.
IWC met the antimagnetic properties by covering the movement with a soft iron cage. Rather than the caliber 83 movement, the Mark XI was fitted with the Caliber 89, regarded as perhaps the most robust three-hand movements of all time. The Caliber 89 runs at 18,000 bph and features a double barrel, a Breguet hairspring, and a drive for the sweeping seconds hand that IWC patented.
The Ministry of Defense spared no expense in guaranteeing that the watches maintained their accuracy. Each watch was subjected to a 44-day testing period at the Royal Greenwich Observatory, which included 14 days in which the watches were tested in five different positions and at two different temperatures. Once the watches passed these rigorous tests, they had to be returned to the Royal Observatory for testing within a year.
The Mark XI entered military service in 1949 and was decommissioned in 1981. Its size (slightly small by today's standards) belies the sturdiness and dependability of this robust navigating machine. Reliable to the last, it exemplifies the truest notions of a tool watch.
This particular watch is in excellent condition, with only slight signs of wear that speak to the conflicts it's seen. The case back is stamped with the model number, case number, and year of manufacture, 1951. Its lovely condition makes this watch very desirable, both for its versatility and as an important horological artifact.
