A highly-collectible and sought-after vintage and original Aviator's watch - The GLYCINE Airman.Back in the 1950's it was observed by a pilot that there was a need for an aviation watch that did not exist at that time. It would be required to track two time zones on a 24 hour scale, giving a pilot access to both his local time as well as a GMT reference - important since GMT is the time standard referred to by Air Traffic Control no matter where a plane is in the world.The resulting watch - The Glycine Airman debuted in 1953 and has become a cult favourite for many watch collectors. It has also been a companion for many military pilots - particularly during the Vietnam War era.This particular watch is a rare early example with a dial and hands that have obviously aged, but are untouched and still in original condition. The case and caseback also appear to be unpolished. Having researched this watch, I have found that the Felsa 692 automatic movement was only used by Glycine until approximately 1960, when it was replaced by the A Schild 1700/1701. Therefore this particular watch dates to pre-1960, which is also consistent with the non-hatched crown. The screw-down case back was also only used until 1965 when it was replaced by a push-down back.The early Felsa movement watches have an interesting hack mechanism with a unique tiny hairspring that pops up at the 24 hour position, when the crown is pulled out, to physically stop the second hand for precise time-setting. Under magnification the tiny pin-hole is there at the 24hour position, but unfortunately the spring no longer pops up.    The stainless steel case measures 36mm, excl crown, and has 20mm lugs. It is attached to a vintage-looking waxed leather strap with military-style steel buckle that I think suits the watch very well.The Felsa 692 automatic movement is in full working order.