Rare Swiss metal military pilot’s navigation watch Circa 1940

Navigation Master G.C.T. by Longines
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A rare Swiss metal open faced military pilot’s navigation watch with power reserve and centre seconds, circa 1940. Longines G.C.T., Navigation Master Type A-13, calibre 21.29. Calibre in chronometer quality, Geneva striping decoration, special fine adjusting device, screwed gold chatons. White enamel 24-hour dial with Arabic numerals, power reserve indication and centre seconds, blued steel hands. Original case, the screwed back with complete military marking U.S. Army A.C. Navigation Master Watch MFR’S. Assy. D.W.G. No. 2129A Serial No. 41-784 Order No. W.535 AC-16030 Specification No. 27968 Longines – Wittnauer Watch Co. Inc. New York. Case signed, movement signed and numbered.
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Diameter: 54.5 mm
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Weight: 125 g
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Signed: Longines Watch Co. Swiss
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The Navigation Master G.C.T. was made in two versions. The most common and relatively frequent version was equipped with the calibre 19.71. This piece, however, is equipped with the top chronometer calibre 21.29, which Longines also used for its siderographs. It was considered one of the most accurate chronometer movements and Longines’ best chronometer calibre. The watch comes from one of the most important Longines collections, of which a large part is now in the Longines Museum’s ownership.