Fix Calculator V1.09 – Copyright © 1999-2017 Henning Umland

Assumed position: 1st LOP: 2nd LOP:
Longitude  °  E W           Azimuth  °  '           Azimuth  °  '
Latitude  °  ' N S Intercept  nm Intercept  nm

Change in position:
Course: °
Distance: nm

Calculated position (fix):

This program for celestial navigation calculates the point where two lines of position intersect (intercept method) and replaces a graphic plot. Enter longitude and latitude of an assumed position, azimuth and intercept of the first observation, and azimuth and intercept of the second observation. Hit the "Calculate" button, and the program does the rest. Blank dialog boxes are regarded as zero. Use the radio buttons to select N, S, E, or W.

A running fix is obtained by entering course and distance traveled between both observations. The program advances the first LOP accordingly.

The program uses the laws of plane geometry and is subject to the known restrictions. The angle between both LOP's should be in the range from 30° through 150°, and the calculated position should be less than approx. 50 nautical miles away from the assumed position. The method is not accurate in the vicinity of the poles.


This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the license or any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License ( for more details.

Henning Umland    N 53° 20' 34''   E 9° 52' 00''

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