More KAP 140 questions

"Peter R." wrote:

With my KLN94 I use the OBS mode for VOR approaches. Direct to the VOR
used in the approach, then OBS mode. This allows the GPS to provide more
relevant distance information. The VOR approach in the GPS database many
times does not provide published approach distance information, since often
these distances are measured to the MAP, rather than to the VOR.

This is not an approved use of the GPS equipment. VOR approaches are
supposed to be flown using actual VOR course guidance, or as a GPS overlay
approach. The latter must be loaded from the database because there are
operational consequences when you do it that way. Substitution of GPS for
ground-based navaids in the approach phase is limited to DME and ADF.


Additionally, I use the OBS mode to provide situational awareness when
intercepting an airway. If I just departed an airport and am given a
heading and a request to intercept an airway, I switch the GPS to OBS mode,
hit direct-to the VOR (or intersection) defining that leg of the airway,
dial in the airway radial on the VOR OBS, and momentarily flip the GPS/NAV
switch to NAV.

Why just use GPS for situational awareness, when you can use it to navigate?
What you're describing is just the normal GPS technique for radar vectors to
an airway, except that you've added the byzantine step of bring your VOR
back into the equation. You don't need the VOR. If you don't trust the
GPS, you can always back it up with the VOR; turn on the digital readout so
you can see what radial you're on, but leave the NAV/GPS selector set to GPS
and let your GPS navigate for you.


This draws the airway on the moving map (both the KLN94's map and the
multi-function display map), which gives me a good idea where the airway is
relative to my position. Once I intercept the airway, I place the GPS back
in LEG mode and again hit direct-to VOR.

It's not necessary or desirable to hit direct-to VOR in this case. Now this
gets into one of the more esoteric operational characteristics of your GPS,
but whenever you take the GPS out of OBS mode and back to leg mode, if the
TO/FROM flag is presently indicating TO the station (the VOR station is
still in front of you), the GPS will automatically set DTK to the correct
value for your selected OBS course which is ostensibly the airway. In other
words, it automatically does the right thing.

If, on the other hand, you do not roll out precisely on your airway, then
you insist on doing a Direct operation after returning to Leg mode, you have
now decided that it's OK to proceed to the VOR Direct from wherever you
happened to roll out rather than along the charted airway.

Greg Esres ) wrote:

This allows the GPS to provide more relevant distance information.

I don't understand what you're saying. I don't see how OBS mode has
any relation to this. The distance information should always be to
the active waypoint, either in leg mode or OBS mode.

Of course, you are correct.

My previous post's intent was not to strictly compare the distance
abilities of leg mode to OBS mode. I was comparing using the VOR approach
in the database (in leg mode) to "rolling my own" approach with OBS mode,
so to speak.

Many VOR approaches in the KLN94 GPS database (at least here in the NE US)
count down distance to the MAP. However, as you know, VOR approaches are
often published with distance to/from the VOR. For me, using the GPS to
monitor the VOR approach is situationally more beneficial using OBS mode
because the distance reported by the GPS now matches the published approach
plate.

Additionally, by using OBS mode I am able to set up the GPS ahead of time
so that the VOR final approach course is accurately depicted on the moving
map. If I leave the GPS in leg mode and hit direct-to the VOR, the course
is drawn from my current position direct to the VOR, rather along the final
approach course.

--
Peter












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Craig Prouse ) wrote:

This is not an approved use of the GPS equipment. VOR approaches are
supposed to be flown using actual VOR course guidance, or as a GPS overlay
approach. The latter must be loaded from the database because there are
operational consequences when you do it that way. Substitution of GPS for
ground-based navaids in the approach phase is limited to DME and ADF.

sigh I am not *substituting* the VOR with GPS during a VOR approach.
Sorry if my post reads that way. I fly the VOR approach primarily with VOR
and use the GPS for distance and situational awareness (by having the
course drawn on the moving map) only. Properly setting up the GPS for
this type of SA monitoring is what I was describing.

Why just use GPS for situational awareness, when you can use it to navigate?
What you're describing is just the normal GPS technique for radar vectors to
an airway, except that you've added the byzantine step of bring your VOR
back into the equation. You don't need the VOR.

I respectfully disagree. The VOR becomes the waypoint that defines that
leg of the airway. Unlike other GPS's (notably the UPSAT CNX80), setting
up the KLN94 GPS to navigate along airways is a bit cumbersome in that it
involves programming all waypoints, intersections and VORS, where the
airway changes direction. To have the airway drawn on a moving map
correctly, you need to direct the GPS to the closest fix (VOR or
intersection) of the desired airway, then OBS off that fix the proper
radial.

Let me ask you this: You depart an airport and are given a heading to
intercept an airway. The heading you are given is not direct to an
intersection or VOR of that airway. Instead, the heading you are given
will eventually cross some undefined point of the airway. How do you
program the GPS to fly to this point?

I don't. I fly the heading, but for SA I like to set up the GPS as
described to give me a picture of where the airway is in relation to my
current course. I also back that up that with both VORs. Perhaps you
might think this both redundant and overkill; I do not.


--
Peter












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For me, using the GPS to monitor the VOR approach is situationally
more beneficial using OBS mode because the distance reported by the
GPS now matches the published approach plate.

Gotcha. That makes sense. Quite often students want to go missed on
a GPS overlay when the GPS indicates something like 1.3 nm to the MAP,
because the underlying approach has a MAP 1.3 nm from some Navaid.
That's part of the problem having two approachs on one plate.

I also back that up that with both VORs. Perhaps you might think
this both redundant and overkill; I do not.

I think you're using all of your available resources, which is a good
thing. It also seems like you're very knowledgeable about the
limitations and advantages of your equipment, which is another good
thing--and not so common. ;-)

Greg Esres ) wrote:

For me, using the GPS to monitor the VOR approach is situationally
more beneficial using OBS mode because the distance reported by the
GPS now matches the published approach plate.

Gotcha. That makes sense. Quite often students want to go missed on
a GPS overlay when the GPS indicates something like 1.3 nm to the MAP,
because the underlying approach has a MAP 1.3 nm from some Navaid.
That's part of the problem having two approachs on one plate.

About three months after receiving my instrument rating I took a lesson
with a CFI who was also an active airline pilot. He surprised me by
directing me to fly a partial panel VOR approach when we were already
somewhere inside a VOR approach. Overload the pilot, then see how he flies
was his intention.

For distance and SA, I pulled up the VOR approach from the database, tuned
the VOR, pulled out the plate to brief it, and began trying to figure out
where I was. I used the GPS distance, which was counting down to the MAP,
not counting up from the the VOR (the VOR was was located early in the
approach, not beyond the airport) so I was unable to place myself on the
approach plate. Thus, I could not determine what my current altitude
should have been.

Needless to say, I failed his test miserably, but I learned several things,
which made the lesson a complete success. One of the lessons was how (for
me) to use the GPS to properly monitor a VOR approach. I spent the next
several practice approach sessions with a safety pilot practicing VOR
approaches.

--
Peter












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"Peter R." wrote:

sigh I am not *substituting* the VOR with GPS during a VOR approach.
Sorry if my post reads that way. I fly the VOR approach primarily with VOR
and use the GPS for distance and situational awareness (by having the
course drawn on the moving map) only. Properly setting up the GPS for
this type of SA monitoring is what I was describing.

OK, I misunderstood. But that raises the question, why fly the VOR approach
with a VOR when you can fly it as a GPS overlay? You've got this great
technology sitting there, ready to give you nice stable course guidance with
the approximate precision of a localizer...


Why just use GPS for situational awareness, when you can use it to navigate?
What you're describing is just the normal GPS technique for radar vectors to
an airway, except that you've added the byzantine step of bring your VOR
back into the equation. You don't need the VOR.

I respectfully disagree. The VOR becomes the waypoint that defines that
leg of the airway. Unlike other GPS's (notably the UPSAT CNX80), setting
up the KLN94 GPS to navigate along airways is a bit cumbersome in that it
involves programming all waypoints, intersections and VORS, where the
airway changes direction.

What did I say that is open to disagreement?

What you're describing is mostly the normal GPS technique for radar vectors
to an airway.

To clarify terminology, perhaps, you don't need a VHF NAV receiver to join
or fly an airway. So what I'm asking is in what sense is your GPS a
"situational awareness" tool vs. a navigation tool? Don't you just put your
IFR flight plan in your GPS and fly it?

You're also talking about changing back and forth between NAV/GPS modes
while doing something as mundane as joining an airway, and I don't
understand why. So I'm asking.


To have the airway drawn on a moving map
correctly, you need to direct the GPS to the closest fix (VOR or
intersection) of the desired airway, then OBS off that fix the proper
radial.

I don't think there's any disagreement here, although in some cases, a
"virtual" route can be contrived in the flight plan which will obviate the
need for OBS mode. You can, for example, add excess waypoints to make the
course line work out, even if you don't plan on flying via every single
waypoint in the plan. The GPS will sequence automatically while you're on
vectors and everything will work out nicely.


Let me ask you this: You depart an airport and are given a heading to
intercept an airway. The heading you are given is not direct to an
intersection or VOR of that airway. Instead, the heading you are given
will eventually cross some undefined point of the airway. How do you
program the GPS to fly to this point?

I don't. How could I even know what that point is going to be?

I do it the way you describe that you do it, because that's the normal way
one does it, except I never have to mess with the NAV/GPS annunciator. My
desired airway is already depicted because I have entered waypoints into my
GPS flight plan to cause it to be depicted. All I have to do is fly my
vectors until the needle centers and then resume own navigation (turn and
track).


I don't. I fly the heading, but for SA I like to set up the GPS as
described to give me a picture of where the airway is in relation to my
current course. I also back that up that with both VORs. Perhaps you
might think this both redundant and overkill; I do not.

You can fly the intercept using VHF NAV, with or without GPS backup for SA;
or you can fly the intercept using GPS, with or without VHF NAV backup.

The only way NOT to have the GPS for SA is to use VHF NAV and not back up
with the GPS, which seems like a waste of a perfectly good GPS. One could
fly using VHF NAV and back it up with the GPS, but that seems like extra
effort and wasted opportunity to set up the GPS and then not use it for
navigation. It also sounds like the GPS is not fully integrated and
utilized in the best interests IFR CRM.

It is still somewhat ambiguous to me how you do it, but I submit that you
make it sound more difficult than it needs to be, so I'm trying to
understand what it is that you're doing and perhaps cajole you to try
something a little different.

For the record, I usually navigate exclusively by GPS. I may or may not
back up my navigation by keeping the appropriate frequencies dialed in on
NAV1 and NAV2, keeping both OBS aligned with my airway. It depends on how
critical it is that I have an immediate backup ready to go. In good VMC
it's usually not that critical. It's very rare that I ever need to select
the NAV mode on the NAV/GPS switch except to fly an ILS. So it's not like I
think in terms that my GPS is set up especially for situational awareness of
the airway intercept. The GPS is set up because that's simply how I
navigate. How else would I get established on the airway? See where I'm
coming from?

"Craig Prouse" wrote in message
...

snip
For the record, I usually navigate exclusively by GPS. I may or may not
back up my navigation by keeping the appropriate frequencies dialed in on
NAV1 and NAV2, keeping both OBS aligned with my airway.

wouldn't it make sense to tune the radios as a source of "situational
awareness"?

It depends on how
critical it is that I have an immediate backup ready to go.

I think tuning those radios has a lot to do with knowing where you are
enroute, in the case of some GPS failure.

In good VMC
it's usually not that critical.

A knapping we will go ...

It's very rare that I ever need to select
the NAV mode on the NAV/GPS switch except to fly an ILS. So it's not like
I
think in terms that my GPS is set up especially for situational awareness
of
the airway intercept. The GPS is set up because that's simply how I
navigate. How else would I get established on the airway? See where I'm
coming from?

We need to get sole means caught up to you.

Greg Esres ) wrote:

It also seems like you're very knowledgeable about the
limitations and advantages of your equipment, which is another good
thing--and not so common. ;-)

Thanks, Greg. I imagine that many pilots who come from a computer
background really enjoy exploring and learning new computer equipment, so
learning the GPS is natural.

However, knowing the old reliable equipment cannot be ignored either. I
learned this last year when I and a copilot were flying to Boston in IMC.
I opened a soft-plastic bottle of water at 9,000 feet and the water sprayed
all over the GPS, causing a short in the Message button and rendering the
GPS temporarily useless. It certainly paid off that we had both VORs
already dialed in.

--
Peter












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Craig Prouse ) wrote:

snip
OK, I misunderstood. But that raises the question, why fly the VOR approach
with a VOR when you can fly it as a GPS overlay?

For practice of flying VOR approaches.

You've got this great
technology sitting there, ready to give you nice stable course guidance with
the approximate precision of a localizer...

Oh, I agree. If I had to choose between GPS and VOR approaches, it would
be GPS any day in actual IMC, assuming the approaches were nearly identical
(mda, descent rate, straight-in versus circle-to-land, etc).

snip
I respectfully disagree. The VOR becomes the waypoint that defines that
leg of the airway. Unlike other GPS's (notably the UPSAT CNX80), setting
up the KLN94 GPS to navigate along airways is a bit cumbersome in that it
involves programming all waypoints, intersections and VORS, where the
airway changes direction.

What did I say that is open to disagreement?

I was disagreeing to your comment about bringing the VOR back into the
equation. I thought you were wondering why I was navigating to a VOR in my
example.

I agree with you that it would be easier to simply program in excess
waypoints (perhaps one even at a point prior to my departing airport), if
those waypoints help to display the first airway.

To clarify terminology, perhaps, you don't need a VHF NAV receiver to join
or fly an airway. So what I'm asking is in what sense is your GPS a
"situational awareness" tool vs. a navigation tool? Don't you just put your
IFR flight plan in your GPS and fly it?

Mostly I do, but I also like to keep current from a FAR standpoint.
Sometimes I purposely will navigate with VORs to remain current as per the
instrument currency requirements, as wells as to maintain proficiency with
VOR navigation.


You're also talking about changing back and forth between NAV/GPS modes
while doing something as mundane as joining an airway, and I don't
understand why. So I'm asking.

See above.

I don't think there's any disagreement here, although in some cases, a
"virtual" route can be contrived in the flight plan which will obviate the
need for OBS mode. You can, for example, add excess waypoints to make the
course line work out, even if you don't plan on flying via every single
waypoint in the plan. The GPS will sequence automatically while you're on
vectors and everything will work out nicely.

Yes, excellent point. I sometimes fly with another pilot who programs the
GPS from the first airway (including those extra points that define the
first leg of the airway) rather than the departing airport. I always start
at the departing airport.

Although I don't agree with leaving out the departing airport (in the event
one needs to get back to it quickly in IMC), I now see the value of putting
in those extra waypoints that show the entire first airway, rather than
having the first waypoint my first (usually VOR) waypoint en route.

snip
The GPS is set up because that's simply how I
navigate. How else would I get established on the airway? See where I'm
coming from?

Yes. But don't forget those free opportunities to track a few VOR radials
for currency during those routine flights.

--
Peter












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