Mark Hansen wrote:

On 05/09/06 12:55, Steve S wrote:


We didn't know what caused it, and after thinking about it for some
time we assumed that we didn't actually "activate" the approach (this
is a separate step in the 430, don't know about your unit).

However, we were sure that we had activated it, but there you go.

Also, I've only seen it the one time, but I haven't used the 430 that
much.


The 400/500 Garmins will go to approach mode 2 miles prior to the FAF
even if you fail to activate the approach. The only condition is to
have selected the approach so it's the active flight plan and you're
where you should be.

The real purpose of activating the approach in those units is to have
the unit clean up the active flight plan so the approach flight plan
overrides junk you might have not cleaned up.

Having said that, there are issues that will prevent the approach mode
from becoming active, which are independent of selecting approach
activation. Approach RAIM is sometimes the culprit, even though
prediction said it was okay. Another reason, like someone else
mentioned, it being too far offset from the final approach course.

And, high level data communications between the unit and some high-level
unit like the Sandel, can sometimes not pass muster.

I am sure there are more "stop signs" that only the Garmin engineers
understand.

The TSO C-129 model is wrapped around the final approach segment.
Garmin was very careful to impliment it conservatively.

None of this is a worry with a handheld, though. ;-)