Above is a Longines reference 3775. I was informed about this piece just prior to visiting the museum in Saint-Imier. Amidst a number of truly special watches, this one stood out. The case style resembles that of the much more common 'Majetek' however it is significantly smaller. The sub-dial is unusually minuscule in order to accommodate the rotatable, outer portion of the dial. The sparing use of numerals on the inner dial, contrasting fonts, and combination of radial and upright numerals all help to create a clear and legible design. (From: http://www.ceasuripentruromania.ro/ceasuri.php?id_article=21&language=english) The intended purpose of the ref. 3775 was to track flight duration. At the start of a flight, the outer dial would be rotated, using the crown at 12 o'clock, in order to align the triangular index with the hour hand. The references 3772 and 3772 A. (seen above) functioned similarly but with the addition of a rotatable bezel. Attached to this bezel was a triangular pointer that could be used to mark the end of a flight for future reference. As is not always the case, detailed documentation, describing this watch, exists. Below is an excerpt from a letter to the Director of Aeronautics (Romania) from Longines. (From: http://www.ceasuripentruromania.ro/ceasuri.php?id_article=21&language=english) Thanks to Dan-Catalin Buzdugan of the invaluable site www.ceasuripentruromania.ro and Stéphanie Lachat for an unforgettable tour of the Longines museum.
Pretty cool, thanks for the information! Would love to see some of the other references that caught your fancy.
Thanks @Rumar89 and @Syrte. I wrote this partly in response to an article that was published today on A Collected Man: https://www.acollectedman.com/blogs/watch-life/four-longines-youve-never-heard-of I would not call this a 'GMT' watch.