Re: Learning curve on Garmin 430 and GPS approaches

A Lieberman <lieberma@xxxxxxxxxx> wrote:

> I see in the book, that it changes from TERM (Terminal) to APR (Approach)
> automatically and the CDI changes to .3 NM 2 miles prior to the final
> approach fix. Has this ever not happened automatically?

In theory, yes, this can happen (vectored inside the IAF, a RAIM error, or
failing to activate the approach). Has it ever happened to me? No.

> This brings up another question. What is the benefit of "loading an
> approach"?

When loading the approach, the waypoints of the approach do not become
active. Thus, you can load the approach well before checking in with the
approach facility that controls the approaches for your destination
airport, as if the approach is in your flight plan on "standby" mode.

What does this mean? It means that the GPS won't auto-sequence to the IAF
of the approach while you might still be cleared and flying to your filed
waypoint (for example, a VOR, which is farther out than the IAF).

In other words, you haven't been cleared to the IAF yet so you do not
necessarily want the GPS auto-sequencing to the IAF waypoint so don't
activate the approach in the GPS until you are cleared to the IAF or
cleared for the approach.

> Why not just activate it from jump start and answer the question Activate
> VTF or Activate Approach like 15 miles from the airport?

Based on my experience with the GNS430, activating the approach early on
will cause the GPS to skip all intermediate waypoints and make the IAF the
current active waypoint. Not good.

Additionally, unless your destination airport only has one approach, you
probably are not going to know with any certainty what approach you will
end up flying. Any number of circumstances could arise that require you to
choose a different approach.

While I am certainly thinking about the approach early on, it is not until
I can get a good idea of the weather at my destination (flight
watch/service) and/or listen to the airport's ATIS/ASOS/AWOS will I
consider loading an approach in the GPS.

Which brings up two other learning tasks for you to practice with the
trainer: Learn how to use the GPS to go missed (simply hit the OBS button
*after* crossing the MAP will make the GPS sequence to the first waypoint
along the missed - of course, understand the approach plate's missed
instructions exactly, don't simply fly direct to the missed waypoint unless
directed to do so by the approach plate).

Also, learn how to delete an approach and load another. (On the Flight
plan 0 page, hit the cursor, scroll to and highlight the name of the
approach in the flight plan, hit the clear button will delete it, then hit
the PROC button to find and load another).

--
Peter
.