"Paul Tomblin" wrote in message
...
In a previous article, "S Narayan"
said:
"Paul Tomblin" wrote in message
...
mysql select * from waypoint where type = 'AIRPORT' and state = 'AK'
and
longitude -150 order by longitude;


Adak is at long -176.6460306, is open to the public and has a very
nice,
modern airport.
http://www.alaska.net/~vwadak/airport.html

-173 is further west than -176.


How did you arrive at that conclusion? Assuming -180 (W) = +180 (E) =
International date line.

Actually Adak is at +176.6460306 and Casco Cove is at -173. But even if
Adak was at -176 and Casco Cove was at -173 in my coordinate system (W is
positive), Casco would still be further west than Adak.

However, no matter how you slice it, if you're at Adak and you want to get
to Casco Cove, you go west. Look at a globe.

By international convention -ve longitudes apply to west of Greenwich and
+ve longitudes east of Greenwich. OK, let's forget that for the time being.

Taking your example of Adak at -176 and Casco Cove is -173 ---- you consider
Casco WEST of Adak. Using this convention let's take a simple example and
not get confused with the date line.
San Francisco, CA is at -122.4 and Reno, NV is -119.8. Using above
convention, would you say Reno is west of San Francisco? How about if we
designate SF at 122.4 and Reno at 119.8 (in your +ve coordinate system). To
go to Reno would you go West? A drink in the Pacific ocean is what I see
happening.

Adak really being at +176 indicates it is further West of Casco Cove which
is at -173. Moving Adak to -176 puts it 8 deg east of the original location
(but now across the date line) but still west of Casco Cove.