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    Re: Coordinate precision
    From: Paul Hirose
    Date: 2019 Jul 3, 16:37 -0700

    On 2019-07-03 4:16, Brad Morris wrote:
    >
    > At 3 decimal digits (.001° vs .002°), we are discussing just over 100
    > meters.  That's really good enough for SAR, and plenty good enough for CN.
    
    I'll allow that .001° precision should be enough to take the "search"
    out of search and rescue. However, decimal degrees is not optimum. In 15
    years in the radio scanning hobby I have heard — OVER AND OVER — trouble
    with that format. In my experience, the coordinates invariably need to
    be converted to degrees and decimal minutes for input into helicopter
    navigation systems. The operation is *not* trivial for the average
    person. Typically there's a delay of several minutes while an expert is
    located to make the conversion.
    
    That's an issue with cell phone "pings", which always seem to be
    reported in decimal degrees with 5 or 6 decimal places.
    
    Therefore, if you ever have to state your lat/lon in a call for help, I
    recommend degrees and decimal minutes. In my area, 3 decimal places is
    standard, probably because that's what the GPS receiver says. A tenth
    minute should be sufficient, and reduces the number of digits to read on
    the air, copy, and key in. But I once heard a copter say, "That's the
    wrong format. There should be more digits."
    

       
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