
NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
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.
…
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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.
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http://fer3.com/arc/m2.aspx?i=112143&y=201003
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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
Navigational Algorithms
https://sites.google.com/site/navigationalalgorithms/