Writing an Almanac for WP-34S - Use Bowditch?

[Santi]

The best book you can use on the matter is Astronomical Algorithms written by Jean Meeus.
For Great Circle and Rhumb Line runs, as well as Nautical Tables you can't go wrong with the Bowditch.
For the analytical solution of intercepts into a geographic position, read the following link:
http://astro.physics.uiowa.edu/~rlm/math...001418.pdf
Have fun!