NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Coordinate precision
From: Paul Hirose
Date: 2019 Jul 3, 16:37 -0700
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."
