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Greg R_ wrote:
> I've been getting up to speed on the UTM grid system, and have a question 
that I haven't been able to find an answer to: Since the northings are based 
relative to the equator, why do we need more than 2 northing zones (1 north 
and 1 south) for the non-polar regions?

We don't. For example, if northing is a big number, you're either in the
northern hemisphere and far north, or in the southern hemisphere and
near the equator. In practice that's not much ambiguity! Nevertheless,
on my scanner I hear search and rescue teams incluing a latitudinal zone
letter in their UTMs.

I suspect these people are using Garmin GPS receivers. None of my
Magellans displays the latitudinal zone letter with UTM coords. If you
enter a waypoint, they only need you to specify northern or southern
hemisphere.

Another silly Garmin-ism is to show easting and northing coordinates
with the same number of digits. But easting is always less than 500 000
meters, while northing can be millions. Thus there's always a useless
leading zero on easting. It's like displaying degrees of latitude with
three digits. The leading digit will always be zero.

I know someone who wrote Garmin to point out their illogical UTM format.
They never responded. To be fair, my info is several years old. I'm not
familiar with their current receivers.

Latitudinal zone letters *are* needed in MGRS coordinates, which are
based on the same grid as UTM but written in a much different format.

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