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Zevering's article is comically absurd. He tries to solve the combined
altitude problem for a running fix by advancing the first circle of
equal altitude. His method for doing so is seriously flawed, leading to
wrong results. Noting the discrepancy with a solution obtained by the
well founded intercept method, Zevering concludes that the latter is
unreliable!

Actually, there is no rigorous method of advancing the circle of equal
altitude, but an approximate solution can still be had. How this is to
be done properly was shown by A'Hearn and Rossano in Navigation, Journal
of the Institute of Navigation, Spring 1977, Vol. 24. For the simple
case where both altitudes are taken simultaneously, see S. Howell,
Practical Celestial Navigation. Other variants of solutions to the
combined altitude problem (by Kotlaric, Dozier, etc.) are described in
editions of Bowditch of the late 60s to 80s.

Herbert Prinz



George Huxtable wrote:

>The method has also been described in
>"The K-Z position solution for the double sight", in European Journal
>of Navigation, vol.1 no, 3, December 2003, pages 43-49, but that
>article was bedevilled by printing errors that render it more-or-less
>unintelligible, which were corrected in a later issue. Not to mention
>several serious errors and misunderstandings by the author, which have
>never been acknowldged or corrected in that journal.
>
>
>

   

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