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Frank Reed wrote:

> Regarding the three LOP fix, clearly if all altitudes are
> displaced by 3 minutes of arc, the vessel's most likely
> position would be the center of the triangle rather than
> one of the vertices.

This is true if the bodies observed differ in azimuth by
120 degrees.  But if the bodies' azimuths differ by 60
degrees, and you have the same systematic 3 minute error,
you'll get a very similar-looking figure, but your true
position would be outside the triangle.

And, as discussed ad nauseum here not too long ago, if your
observation has random errors (and no systematic errors),
then your true position is quite likely to be outside the
triangle, even though the "Most Probable Position" -- the
peak of the probability density surface -- is indeed inside.

        -- Bill

   

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