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    Re: Why Not To Teach Running Fixes
    From: Frank Reed
    Date: 2009 Dec 15, 19:12 -0800

    John K, you wrote:
    "Come on you guys, this has nothing to do with radar, loran, or any other navigation system. It has nothing to do with terminology, DR versus EP, etc, It has nothing to do with teaching. It concerns the validity of the traditional running fix concept."

    I'm not buyin' it, John. Your diagram is deceptive because you're "assuming" that both imaginary vessels are actually -at- the DR. But they're not.

    Calling "Up" in your diagram "North", the vessel on track 2 heading NNW was "actually" at a position well to the southeast of the DR at the time LOP1 was laid down. Meanwhile, the vessel on track 1 heading ENE was "actually" at a position somewhat to the northwest of the DR at the time LOP1 was laid down. This assumes that the shots are good and the course and speed estimates are good and that therefore the error ellipse is quite small relative to the distances in the diagram.

    I've modified your diagram to illustrate what I'm saying above.


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