"Sam Spade" wrote in message
news:l8n3g.174223$bm6.98713@fed1read04...
I got an interesting lesson in GPS recently while traveling with a
handheld
GPS as the passenger in a plane. The GPS showed us landing about two
miles
east of the airport. I figured out only later that the position of the
antenna was such that many satellites were blocked, so the accuracy of
the
GPS signal was greatly diminished.

That large of an error was probably due to the substantial altitude
change of the airliner while your GPS was staggering along in 2-D mode.

I think the reason may have been that most satellites were blocked inside
the cockpit. But why would anyone object to this non-FAA software simply
self-reporting that its current accuracy was some huge number of horizontal
and vertical feet (i.e., that it was not currently very accurate)? I
cannot understand why anyone would feel that this is a bad thing to tell a
user of that device. If you don't want the information then ignore it.


airliner. Some owners, who are savvy on this still, install an external
antenna on their aircraft for their hand-held GPS. It will never have
the problems you experienced with an external antenna.

That's a great idea. Maybe more handheld GPS users would become aware of
the need for for an external antenna if their GPS software clearly
communicated when the signals they are getting are not very accurate? That
fact might inspire more users of these devices to understand that antenna
placement is quite critical for these devices.

--
Will