Diameter 47 mm. Developed following the pilots’ specifications to fulfil the requests of all typical flight parameters. Comfortable and highly exact Swiss micro mechanics in symbiosis with the classical slide rule function. An uncomplicated service of this modern classic permits the exemplarily good legibility. 3 time zones, countdown function, country specific conversion scales. Case back with temperature scale C° and Fahrenheit and watch-identity number.

The FORTIS CALCULATOR is not just a watch but also an instrument for simple calculations used in the same manner as slide rules were before electronic calculators became popular. A second, separate time-zone is available which can also be used as a 24 hour indicator. The bezel is intended for the countdown function and the setting of a third timezone. The CALCULATOR can assist as a professional navigating instrument if the electronic systems on board an aircraft should fail.

A Swiss watchmaker was the first to find out by thought about the relation of numbers and the way to control them in the system of the logarithms. Jost Bürgi, born in 1552 in the Swiss canton St. Gallen, conceived the base of the arithmetic system which was a must and the basic tool for every engineer or architect and many other technical occupations until 1969: The slide rule, squeezed out by the battery-operated pocket calculator of the 70s, at the same time, when the quartz watch took over from the mechanical watches.
Technical details

Reference 666.10.11,Case Nr. 666.10.148

Automatic ETA 2893-2, 11 1/2 ”’, 21 jewels, 28,800 semi-vibrations per hour, fine timing device and Incabloc shock absorber

hour, minute, centre-stop-second, date, GMT, 3 time zones, 24 h display, calculator slide rule, 60-minute countdown function.

Steel, three-parts, brushed, 47 mm case diameter,unidirectional turning bezel with 60-minute scale (120 divisions) for countdown function and with 24 hour GMT display
Superluminova capsule at Pos. 12h, flange with Calculator slide rule scales, sapphire crystal anti-reflective on both sides
Screw-down steel case back with engraving of temperature
Conversion table from C° (Celsius) into F° (Fahrenheit)
Two crowns with FORTIS logo, individually numbered
Water-resistant 200 m / 20 bar.

Black matt, oversized Arabic numerals, indices and hands with Superluminova white, blue afterglow in the darkness, second hand in white, GMT hand in orange.

Padded calf leather with contrast stitching,24 mm to 20 mm tapered to the buckle

Special Features
Slide-rule function with flange adjustable by second crown at pos. 2 h, GMT, 3 time zones, date at 4 h,conversion table engraved on the case back C° (Celsius) into F° (Fahrenheit)

Leather box, pouch, instruction manual, international warranty card.

666.10.11 L.16 : leather strap dark brown with contrast stitching
666.10.11 M : brushed steel bracelet with security folding clasp
666.10.11 K 01 : rubber strap black with folding clasp
666.10.11 Si 02: silicone strap white with folding clasp
666.10.11 Si 20: silicone strap orange with folding clasp
Option : steel brushed folding clasp for leather strap

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