Fortis B-47 Calculator GMT 3 Time Zones Limited Edition
Comfortable and highly exact Swiss micro-mechanics in symbiosis with the classical slide rule function. 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.

Fortis B-47 Calculator
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.
The bezel is intended for the count down function and the setting of a third time zone. The B-47 CALCULATOR can assist as a professional navigating instrument if the electronic systems on board an aircraft should fail.
The Fortis B-47 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 count down function and the setting of a third time zone. The B-47 Calculator can assist as a professional navigating instrument if the electronic systems on board an aircraft should fail.
Diameter 47 mm. Developed following the pilots’ specifications to fulfil the requests of all typical flight parameters.
Case back with temperature scale Celsius and Fahrenheit and number of limitation.
Fortis B-47 Calculator Specifications
| Movement | Automatic Swiss Movement ETA 2893-2, 11 1/2 ''', 21 jewels
28,800 semi-vibrations per hour Fine timing device and Incabloc shock absorber |
|---|---|
| Function | Hour, minute, centre-stop-second, date, GMT 3 Time Zones
24 h display, calculator slide-rule, 60 minute countdown function |
| Case | Steel brushed, three-parts, 47 mm case diameter
Bidirectional turning bezel with 60-minute scale (120 divisions) For countdown function and with 24 hour GMT display Luminous capsule green afterglow at pos. 12 h Sapphire crystal anti-reflective coating 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 (xxxx/2012) Water-resistant 200 m / 20 bar |
| Dial/Hands | Matt black, flange with Calculator slide-rule scale hands
Arabic numerals and indices with Superluminova white Green afterglow in the darkness Second-hand white, GMT hand orange |
| Attachment | Leather strap brown padded with contrast stitching fitted to the case |
| Packaging | Leather box, pouch with FORTIS logo
Instruction manual with certificate of limitation International warranty card |
| Special Features | Limited Edition 2012 pieces
3 time zones, date at 4 h Slide-rule function with flange adjustable by crown At pos. 2 h, 20 simple calculations possible E.g. division, multiplication, multiple conversions Speed per hour, fuel consumption, height calculations Distance during ascent / descent Conversion table C° (Celsius) into F° (Fahrenheit) Engraved on the case back |
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