The number “12” on the dial, marked with an arrow, enabled the pilot to get a fast orientation in each situation, and by means of the disproportional big crown the watch could be handled without having to remove the gloves. In order to ensure that the dial could be read during night the hands and the numbers on the dial were equipped with radium, a radioactive material with high luminosity. These observation watches were classified with “FL23883”, a description for navigation instruments. This number was engraved on the outside of the case, on the opposite side of the crown.
Due to the high standard concerning precision and reliability the production of the observation watches was a great challenge for the watch manufacturers. In the 1930s and 1940s, only five companies were authorized to produce such observation watches: IWC in Schaffhausen, Lange + Söhne in Glashütte, Wempe in Hamburg, and Stowa and Laco (Lacher & Co.) in Pforzheim. From these five companies only two (Lange + Söhne and Laco) used movements of their own production. The other three companies used Swiss movements.
LACO Black Pilot's Watch Limited Edition only 50 pcs. in the World based on original Observation Watch design
