The Glycine Airman was released in 1953 as a pilot’s watch able to show two time zones at once. It combines a dial with a 24-hour scale, so the hour hand turns once a day, with an engraved rotating 24-hour bezel that is locked in place by a second crown at four o’clock, plus a date and automatic winding in a water-resistant case. A 1953 patent for a 24-hour watch was used for it. The original case measured 36 mm, the size later revived for the Airman No. 1 reissue, and early watches are reported to use Felsa automatic calibres. Some versions also had a hacking feature in which a small wire emerges at the 24-hour mark when the crown is pulled, stopping the seconds hand for precise setting. It arrived two years before the Rolex GMT-Master of 1955.

According to the story Glycine tells, sales director Samuel Glur met a pilot on a flight between Bangkok and Calcutta who described the watch he needed: automatic, waterproof, with a date, a 24-hour dial and a matching rotating bezel. Company head Charles Hertig had it designed to those specifications. The Airman was sold through US military exchange stores and became popular with American pilots in the Korean and Vietnam wars, which helped keep its design essentially unchanged; over the first years the handset settled into the arrow-shaped hour hand that defines it. Astronaut Pete Conrad wore an Airman on Gemini 5 in 1965 and Gemini 11 in 1966. Later models included the tonneau-cased Airman SST of 1967 and the four-time-zone Airman 7 of 2000.

Collectors and writers regard the Airman as one of the most important early pilot’s watches and a pioneer of the 24-hour, dual-time format, and its association with Vietnam-era aircrews gives vintage examples strong appeal. Gear Patrol includes it among the watches you should know and notes that the founding story is part legend. Wikipedia also describes the Airman worn by Conrad as the first automatic watch flown in and exposed to outer space. The original 1953 Airman is no longer produced, but Glycine, owned by the Invicta Watch Group since 2016, continues to make the Airman in many iterations, including reissues such as the 36 mm Airman No. 1.