Garmin GPSmap 496 False Terrain Alert

Garmin have pointed out how I can read the terrain data from the 496. On the
Terrain page use the cursor to point to a location. The elevation MSL is
shown on line two in the black band above the map.

The south end of runway 15 has a terrain elevation of 715 ft msl in the
database. In fact, it has an actual elevation of only 639 ft msl using the
Jeppesen chart for the airport.

In addition, the terrain just north of the airport is also shown as 715 ft
msl. Using the GPS I've gotten readings that this terrain is actually more
like 650 ft msl.

That may be part of this problem.

Thanks,
-Ron


"Ron Gordon" wrote in message
. net...
That's a very good suggestion. I will make the request on Monday. Since I
can carry the 496 to the elevation data points leading to and around the
approach path, these should be easy to confirm. And as you point out, the
terrain around KADS is very flat. It is likely that an erroneous data
point may be self evident. Thanks! -Ron Gordon

Ron, have you asked Garmin if they're willing to give you a copy of the
raw datapoints of the terrain elevation around ADS? I'm thinking the
erroneous datapoint(s) will be terrain data since an obstacle should be
easily displayed as such on the 496 map. Since you know the area, you
might be able to spot the errant datapoint and help them out.

Marco