I have never had a corrupted GPS waypoint, even when the
battery was so exhausted the receiver wouldn't turn on. But I have
experienced some bad lock-ons. The receiver seemed to be working
normally, but its velocity and distance to go were obviously wrong.
(Turning the unit off for a moment cleared the problem.)

A lot of GPS troubles are detectable that way. Don't just follow the
receiver's steering bug. Crosscheck its readouts, same as you
crosscheck your instruments.


"Cub Driver" wrote in message
...

The other day I flew up to Alton Bay. While over the bay, but still
flying north, I went go-to my waypoint for Hampton airport. (Not the
airport waypoint in the database, but one I programmed in, and that
puts me over the start of the 45 from the west.)

When I got up to the mouth of the bay, I turned around and followed
the bug back south. After half an hour I realized that I was west of
my expected track. Indeed I was going almost precisely south instead
of SSE.

What's more, my destination was 5,900 miles distant, and the time to
get there was 84 hours. The day was milky, so I couldn't see
anything
on the horizon, so I turned SE until I came over US 4, then followed
that back to the seacoast.

When I got home, I scanned out and out on the map, to find that my
waypoint was now located in the Andes on the Argentinian side of the
Chile-Argentina border. Still, the coordinates looked very familar.
On
a hunch, I changed the S to an N, and behold! The waypoint moved
back
to the seacoast of New Hampshire.

What happened?

And could it happen to the waypoints in the database?

(Garmin 296)

--
Paul Hirose
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