"What is the minimum useful display size adequate for a portable GPS with
the features found in the Garmin 396?"

Well, I've got the two biggest portable color GPS screens around in my
plane, with the AvMap on one yoke, and the 2000c on the other.

The AvMap, with its huge screen (over twice the size of a 396) would make an
unbelievably marvelous platform for weather -- and AvMap knows it. I spoke
at length with their reps at OSH, and they were EXTREMELY frustrated that
Garmin had beaten them to the XM weather thing. They had been working on it
for a few years (according to Vern, their head cheese), but the
muckity-mucks upstairs had cut the program off to devote more $$$ to their
marine market -- a segment where they make vastly more $$$ than our puny
little aviation market can provide. (Now, of course, boaters need weather,
too -- but apparently aren't as willing to pay for it.)

The Lowrance unit would be second best, and is about the size that Dan is
advocating (an inch bigger than the current 396) -- but more square-ish. I
don't like the screen resolution of the 2000c as well as the AvMap (it's
about the same as the 396s) -- but it would be okay.

One crucial change that must be made is to put the units in portrait mode,
like the AvMap and (sorta) the 2000c. I want my track "up", which means my
route of flight is "up" -- which means the maximum distance out will be at
the TOP of the screen. On the 396, that's the "short direction" (due to
its landscape-only mode), and (as a result) the weather gets cut off --
nearly in half.

In this, size really matters. To be able to adequately depict your entire
route of flight, in a size that can easily be seen, in a resolution that
allows for great detail, will be the ultimate "Holy Grail" of in-flight
weather depiction As with all first-generation electronics, the Garmin 396
is a compromise, and we can all rest assured that the next generation will
be far better. (And bigger! And cheaper!)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"