Swiss military navigation watch with power reserve Circa 1940

Metal open faced precision watch
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A military pilot’s watch, the Navigation Master Type A-13, with power reserve made for the U.S. Army by Longines Watch Co in Saint-Imier, Switzerland, circa 1940. Retailed by Wittnauer Watch Co Inc. in New York, U.S.A. The numbered case of this watch, crafted from metal, has a screwed back and a U.S. Army marking on the reverse. The original white enamel dial has an inner 24 hour track, outer minute divisions with Arabic five minute numerals, a power reserve indicator at 12 o’clock and blued steel hands. The numbered chronometer quality movement has Geneva striping decoration, 21 jewels, a lever escapement, screwed gold chatons, and is adjusted to temperature and five positions. Case and movement signed.
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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 GCT was manufactured in two versions. The widespread, relatively common version fitted with caliber 19.71, and pieces like the present one, equipped with the top chronometer caliber 21.29, which Longines also used for siderographs. At the time, it was considered one of the most accurate chronometer movements and Longines’ best chronometer caliber.
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This watch comes from one of the most important Longines collections, a large part of which is now in the Longines Museum.