In an era before GPS calculators and digital computers were created, pilots used analog computers or slide rule functions to do their navigational computations. Slide rules may seem a bit outdated now but they still perform mathematical calculations as efficiently as before. Here is a quick guide on how to use this function.

The slide rule bezel has two matching logarithmic scales - one stationary and one on a rotating outer ring. You perform multiplication and division by rotating the outer ring. You can use a slide rule bezel to handle airspeed, rate/time of climb or descent, flight time, distance, and fuel consumption, as well as distance unit conversions.

Calculations can be made by using one or more of the three reference points.

  • number 10 on the outer scale
  • 12 o'clock on the dial
  • text STAT on the outer scale


These reference points allow you to use the given data to perform the correct calculations. For more information and details, download the Chronofixe user manual.


 Download User Manual