IMHO: GPS stinks (today) for airspace mapping/boundaries.

About a year ago I was flying a 172 with a B&W Garmin (Panel mounted -
I'm not sure the model) and the database was somehow incorrect -
placing Santa Rosa STS about 8-10 miles North of it's actual position.
There was a VOR on field - why use GPS there?

A month ago, I was flying a club 172 with a panel mounted Garmin 430
(I think IFR certified too). As I skirted San Jose's (SJC) class C,
the 430 showed me about 1mi *inside* the outer shelf. I stayed low
around 2000'-2500' (I forget at the moment, but was being a 'good
citizen') and as I saw the mountains ahead (flying South towards
Monterey) asked Norcal Appch/Dep if I was clear of SJC's C. They were
nice, friendly, and said something like: "Yeah - you were clear miles
ago". Looking out the window, I would roughly estimate my distance to
SJC to be in the 10-15mi range, but I was waiting for the magical
gizmo to *show* me that I was clear of the shelf.

Moral of the story: I purchased a simple handheld Magellan that I can
use as (a) a backup, and (b) a simple course/groundspeed calculator.
I'd rather not have the distractions of potentially inaccurate
colorful inside maps when my eyeballs should be outside the plane at
as much as possible.

Just my 2c.
Noah



It appears that a lot of pilots are violating airspace even with GPS on
board.

Actually, from what I've read, *more* violations occur with GPS on board than
without. The reason is that pilots with GPS tend to cut pretty close to the
limits because the *think* they know exactly where those airspace limits are.
Pilots without GPS receivers tend to give protected airspace a little more
leeway because they aren't exactly sure where they are.

George Patterson
You can dress a hog in a tuxedo, but he still wants to roll in the mud.