xyzzy wrote:
When I fly with my GPS396, I usually don't put in a flight plan or any
direct-tos; I use the panel mounted KLN94 for that. I use the 396 just
for weather, terrain, and additional situational awareness. I had
never heard the spurious terrain warnings near airports that Dave
Butler reported in another thread. Btw last week I updated the
software in the 396, but I never heard the warnings before that either.

good stuff snipped

After reporting my complaints about the terrain warnings here, I got a surprise
phone call from a Garmin Engineer. They do read these newsgroups! He offered a
beta-version of what I assume is the fix that eventually went into version 2.80
of the software, in return for which I was to provide some testing, which I
happily did.

My observations:
- before the fix, I got the terrain warnings on every landing, whether the
airport was in the flight plan as the destination or not.

- with the beta version of the fix, no terrain warnings when landing except
during one circling approach at TTA. I haven't had a chance to try this again
with the 2.80 software, but I assume it's the same code.

- with the 2.80 software, no terrain warnings except one time last week when
approaching runway 32 at RDU. I was following the GNS480 glideslope to the
runway, so no high descent rates were involved.

In my discussion with the Garmin engineer about the beta code, he attempted to
explain the algorithm on the phone... a difficult task without a picture phone.
What I did get out of that explanation was that the protected area around an
airport is shaped differently in the direction of that airport's longest runway.
Since runway 32 is perpendicular to the main runways at RDU, that could be part
of the explanation for receiving that warning.

Dave