With its Big Crown collection, Oris demonstrates its expertise in the field of watches that pay tribute to historical aircraft. Inspired by the Bell X-1, the first plane to break the sound barrier, the Big Crown X1 Calculator refers to the era when flight plans were still made using slide rules, and accentuates this unique mechanism. Its rotating bezel serves to adjust the slide rule and to calculate fuel consumption for a given flight time, while the caseback displays a m/ft conversion table for international use. The chronograph push-pieces bear the X and 1, like a last nod to the date of that historical feat accomplished at 10:18 on October 14th 1947.