Known as a "computergraph " these watches were very popular in the early 70's and the Chronosport is one of the rarer models.
This is a rarely seen vintage Swiss watch from British company called “Chronosport Special watches”. The advertisement from 1977 describes it as “Military air crew issue mathematical slide rule watch” A similar one, albeit an earlier version with Chronograph function, was covered by Hodinkee, and has been described as follows: “In the original user manual, this Chronosport is described as “a real calculating machine,” and boy, is that the truth. Much like the Breitling Navitimer, it associates a slide rule and a chronograph to calculate average speed, convert between speed units, and perform all critical calculations required while flying. The focus on this type of functionality explains the plane emblem of the Chronosport brand; the stealthy black look and bright orange hands further complete the aesthetic. As can be expected, this tool watch is shock resistant and antimagnetic. The user manual will show you all the technological feats this "genuine computer on the wrist" can accomplish”.
