# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: The Nonsensical Running Fix
From: Andrés Ruiz
Date: 2010 Oct 27, 10:54 +0200

JohK Karl says:

The concept of relative uncertainty and most probable position is a completely different topic: It's treated rather naively by AFPAM 11-216 with an equation that's dimensionally incorrect; it's too complex to be of interest to Ocean Voyager; and to most NavList members, including me. …

-          It could be, more or less, mathematically complex, but the concept is very simple. Traditionally is performed by hand using the bisector of the azimuths in a cooked-hat, and analytically using least squares techniques. If the uncertainty and errors were zero, the LoPs are cut off at one point, but as it really does not happen, where is there most probable position for me to be?

-          If anyone is interested in exploring the topic, is available for free on my website information and software.

-

-          An example, LoPs, MMP and Confidence Ellipse on a nautical chart::

-          An example, MMP by bisector of the azimuths:

AFPAM 11-216 definitions for MMP:

Pg 113

4.3.10. Most Probable Position (MPP). A position determined with partial reference to a DR position and partial reference to a fixing aid.

Pg 384

Most Probable Position (MPP)—The most accurate estimate of position where an element of doubt exists as to the true position.

-          First definition is not true, because DR is not a variable for the statistical treatment of the MMP.

And Gary LaPook, do you know if the AFM 51-40 is available for download?, I am interested.

Regards,

--

Andrés Ruiz

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