Commencing a GPS approach from a fix other than the FAF

Roy Smith wrote:

In article ,
Sam Spade wrote:


Roy Smith wrote:

"Chris Quaintance" wrote:



Hi Folks-

Please forgive what is probably a simple question regarding GPS
approaches. I am new the the /G world. I was out flying my 182P today
to do some practice approaches. The airplane is equipped with a GNS480
and I have a Garmin 296 on the yolk. I was buzzing around NW of the
Salinas airport on vectors and was told to expect the GPS13 approach as
I requested. So far, so good. Fight plan entered into the 480 and the
296, approach loaded on both.

Here's the approach:
http://www.naco.faa.gov/d-tpp/0701/00363G13.PDF

NorCal cleared me direct EWTOF at 3200, cleared for the approach. When
looking at the approach on both the 480 and the 296, it seemed to
commence at UBBEP rather than EWTOF.


Yeah, right, you got a bum clearance. I had a similar experience not long
ago and wrote about it here (http://tinyurl.com/yt8vkn). It's pretty
common.

The problem is that while from the point of view of somebody sitting in a
dark room watching blips move around a screen, it's a perfectly reasonable
thing to have you do, the software in the GPS wants you to either start the
approach from an IAF, or get vectors to final. It would be nice if
controllers gave clearances that were flyable, but the often don't, and
then you're struggling to figure out how to tell the GPS to do something it
doesn't want to do.

Roy,

This handling is now approved and is no problem whatsoever with a Garmin
400 or 500.

Is it with the 480?


At least with the software rev we've got, it is. When you select an
approach, the only things that come up in the menu are Vectors and all the
IAFs. I believe you can fake it out by looking on the approach plate,
figuring out which IAF you can select that gives you a route including the
specified IF, load that up, then go into FPL mode, scroll down to the IF,
and do -D- to that. That's a lot of fumbling, looking, and button-pushing
to do at a busy time of the flight.

Yes, but once you select one of the IAFs and it loads the approach into
the active flight plan, aren't all of the waypoints then available for a
direct-to operation?


Matt

In article ,
Matt Whiting wrote:

Yes, but once you select one of the IAFs and it loads the approach into
the active flight plan, aren't all of the waypoints then available for a
direct-to operation?

Yes, but it would still be a lot simplier if the IF just showed up in the
initial menu.

I think this is the problem. I'd expect MOVER to be the first fix once
the approach is loaded and I expand the approach in the flight plan
view. I could then go Direct-to EWTOF quite easily and still be in
proper sequence. However, the first fix is UBBEP. I replicated this
behavior on the 480 sim, as well.

How do I load the approach such that at least all of the fixes from the
IAF (in this case MOVER) are there and ready to go? I can't seem to
find a way to make this happen. I'd like it to either magically be
there when the approach is loaded or at least allow me to select the
applicable transition. No dice.

Thanks,
--Chris


Mike Adams wrote:
Sam Spade wrote:
This handling is now approved and is no problem whatsoever with a Garmin
400 or 500.
Is it with the 480?

It works much the same on the 480. You have to put in the approach transition from the applicable IAF,
MOVER in this case, Execute it, and then do a Direct-to EWTOF as a separate action. The only
problem, mentally, is that you have to look on the chart to find the applicable transition that contains the
waypoint you're looking for, rather than being able to select it directly on the approach menu.

Mike

Dave Butler wrote:
When you selected the procedure from the database, it looks like the
only IAF is MOVER, so you must have selected the approach starting from
MOVER. So EWTOF should have been added to the flight plan (no?) and you
should be able to select DIRECT EWTOF from the flight plan(?), rather
from the NRST list. Then I think the 480 would have auto-sequenced you
through the rest of the approach.
snip

EWTOF was nowhere to be found.

You shouldn't have to "insert" it. It should have been added to the
flight plan when you selected the approach starting from MOVER. Did you
remember to EXECUTE the flight plan change? Did you EXPAND the flight
plan to see all the waypoints? I think EWTOF/ECYON should have been there.

Yes, I did execute the flight plan change and expand the plan to see
the waypoints. Again, UBBEP was the first waypoint of the approach. I
verified this behavior with the 480 sim.

In the 480, they all commence with an IAF (not FAF). In the 296, I think
only the FAF is shown on approaches. The 296 is only for
situational-awareness, after all. You can have an output from the 480
that automatically copies the flight plan from the 480 to the 296. I do
that with my 396. Then the 296/396 knows about all the same waypoints
as the 480.

Well, in my experience, the two approaches I referenced in my initial
post commence with the FAF on the 480. We'll leave the 296 on the yoke
out of it (even if there's yolk on my face!).

So, either I'm doing something incorrectly whilst loading the approach,
or there is some inconsistency or problem with these approaches and my
setup.

Interestingly enough, I was able to spend a very brief time behind a
530 today and it seemed to have "better" behavior in this regard. I
easily was able to commence the approach (to a different airport) from
a variety of fixes that were available on the plate.


You might want to join the GNS480 users group at
http://groups.yahoo.com/group/gns480-users/

I have already done so. Thanks for the lead.

Appreciate your time!
--Chris

Chris Quaintance wrote:
I think this is the problem. I'd expect MOVER to be the first fix once
the approach is loaded and I expand the approach in the flight plan
view. I could then go Direct-to EWTOF quite easily and still be in
proper sequence. However, the first fix is UBBEP. I replicated this
behavior on the 480 sim, as well.

How do I load the approach such that at least all of the fixes from the
IAF (in this case MOVER) are there and ready to go? I can't seem to
find a way to make this happen. I'd like it to either magically be
there when the approach is loaded or at least allow me to select the
applicable transition. No dice.

Huh, I get the choice of Vectors, MOVER, ISIFU, and SHOEY. Picking
any other than VECTORS gives me the the EWTOF waypoint. Are you
sure you selected something OTHER than vectors (and you did remember
to EXEC it!)

Mike Adams wrote:
Sam Spade wrote:

This handling is now approved and is no problem whatsoever with a Garmin
400 or 500.

Is it with the 480?


It works much the same on the 480. You have to put in the approach transition from the applicable IAF,
MOVER in this case, Execute it, and then do a Direct-to EWTOF as a separate action. The only
problem, mentally, is that you have to look on the chart to find the applicable transition that contains the
waypoint you're looking for, rather than being able to select it directly on the approach menu.

Well in this case, they all have it except for Vectors. There is only
one IAF (which there are two additional transitions leading to).

On Jan 17, 6:08 am, Ron Natalie wrote:
Huh, I get the choice of Vectors, MOVER, ISIFU, and SHOEY. Picking
any other than VECTORS gives me the the EWTOF waypoint. Are you
sure you selected something OTHER than vectors (and you did remember
to EXEC it!)

Aha! I spent some more time with the 480 simulator and seemed to have
figured it out. I see now when you load the approach, the "Vectors"
(top right) field can be changed at that point to (in this case) MOVER,
ISIFU, and SHOEY. Just as you said! I thought that the VTF mode was
selected after the approach was loaded. I didn't realize you can
change that before it's loaded. Thanks for the clues, Ron!

Now, a follow on question has surfaced. My flight plan in the 480 was
merely KRHV to KSNS with no other waypoints. This was actually my
clearance (radar vectors, direct). Now, in the sim, when I properly
load the approach with MOVER as a starting point, I get a
discontinuity. The flight plan, in it's XPND form, is KRHV,
discontinuity, (MOVER), and then the GPS13 approach commencing with
EWTOF. So, as a solution, I can select the discontinuity and clear it.
Then, EXEC the flight plan and things magically work and I am headed
Direct MOVER. Select Direct EWTOF and I am in business. It seems a
little ugly to me, though. Is there a more elegant solution?
Especially bearing in mind that I am briefly headed Direct MOVER even
though that's not my clearance.

Thanks for the help!

--Chris

Chris Quaintance wrote:

Now, a follow on question has surfaced. My flight plan in the 480 was
merely KRHV to KSNS with no other waypoints. This was actually my
clearance (radar vectors, direct).

I'm confused if you weren't cleared to EWTOF I'd just start out
going direct KSNS and not load an approach until I was cleared
for it (how do you know what you are going to get?).

Chris Quaintance wrote:

Now, a follow on question has surfaced. My flight plan in the 480 was
merely KRHV to KSNS with no other waypoints. This was actually my
clearance (radar vectors, direct). Now, in the sim, when I properly
load the approach with MOVER as a starting point, I get a
discontinuity. The flight plan, in it's XPND form, is KRHV,
discontinuity, (MOVER), and then the GPS13 approach commencing with
EWTOF. So, as a solution, I can select the discontinuity and clear it.

There's no need to clear the discontinuity. Just select EWTOF from the
flight plan and go direct.

Then, EXEC the flight plan and things magically work and I am headed
Direct MOVER. Select Direct EWTOF and I am in business. It seems a
little ugly to me, though. Is there a more elegant solution?
Especially bearing in mind that I am briefly headed Direct MOVER even
though that's not my clearance.

There's no need to ever be direct MOVER.

rant mode
Having earned my instrument rating and done all my flying behind panels
that do NOT include an IFR GPS, I frequently find myself a little
queasy when I read these posts about GPS approaches.

I'm a young man (33) and am a professional in the computer industry (or
was, until I decided to go back to grad school) and yet, I find the
complexity of operating a GPS just plain outrageous. I've rented
aircraft with panel GPS and fiddled with the simulators on my PC and I
always come away with this feeling of "argggh!" this is way too hard.

I think the people who invented these panel units (or set up the IFR
certification for them) seriously screwed up by not fully appreciating
what was good about the old nav radios. To me, the nice thing is that
using a nav radio is NOT A NEGOTIATION. You set it and that's that. You
can do it ahead of time. You can change it at any time, without
updating a plan, etc. You can put a frequency in there long before what
appears on the nav head will make sense -- and that's okay. You as the
pilot get to decide when to look at the needle. With these GPS systems
it seems like you are constantly dealing with the after-effects of some
engineer/programmer who is not in the air with you.

Oh, and here's another nice thing about nav radios. They look and work
the same in a 737 and a 152. But god forbid you jump into an aircraft
with a different GPS unit than the one you're familiar with. You're
gonna be in trouble!

I dunno. I get what's great about GPS. I have a handheld (196) and like
it. (And it's flightplan logic is substantially easier than a 430/530,
btw).

Aviation used to represent the cutting edge in human factors research.
What happened?

/rant mode

-- dave j