How not to play nice with a GPS

I think the moral of the story here is that the computer is not good at
ad-libbing procedures.

I concur, but I think that's only part of the problem. A computer
won't ever get good at ad-libbing anything - that's a peculiarly human
trait. However, GOOD software allows the pilot to take control and
ad-lib easily and intuitively. I have yet to see any good software on
an IFR GPS.

The instruction you were given was clearly improper, but that happens.
Good software would be set up to allow you to easily deal with it,
rather than pretending it doesn't happen.

There used to be a similar quirk on the 430/530 when flying GPS
approaches with a hold in lieu (KEYQ is an example) rather than a
standard T. If you were approaching the IAF from some reasonable
angle, the controller would ask you to proceed straight in (no hold at
the IAF) but the software had no provisions for this, since it wasn't a
legal clearance. Thus it would not autosequence.

Garmin has solved the problem, and the solution is in itself an
admission that real life does not match the book. When you select the
approach, you are now asked if you want to hold at the IAF.

So it goes.

Michael

I was on the POU GPS-24 (http://204.108.4.16/d-tpp/0508/00286VDG24.PDF),
full procedure, Kingston IAF. We were IFR, in and out of IMC. We had been
cleared for the appoach, which was loaded and executed in the GPS. We were
on a heading of roughly 180 to IGN, and about a mile from the VOR, when the
controller said something like, "I need to you to stay at 4000 and keep
tracking outbound for a while for traffic below you". I agreed to do so
and turned to a 060 heading.

At this point, things started going downhill. I suppose, technically the
controller committed an error. He had already cleared me for the approach,
but then gave me instructions contrary to the procedure. I was in a sort
of half-way place between flying the full procedure pilot nav and being on
vectors. Better to have just canceled my approach clearance and given me
vectors to avoid the traffic then back around for a fresh start.

During my instrument training, I had a final checkout with the chief
flight instructor before my checkride, and one of the approaches we did
was this exact approach. And funnily enough, I remember getting a very
similar "cleared for the approach", followed by "stay at 4000 for
traffic". Unluckily for me, the controller forgot about us, and when we
were eventually cleared down to 2900, it took _forever_ for us to get
back to the airport because of some really strong winds that day (which
nearly caused me to be sick once the checkout was over!) So whenever I
fly out that way these days, I always try to stay on top of the
controller... the days where'd I'd be patient and wait for them to get
back to me are long since past.

--
Guy