I was flying this weekend to maintain my instrument currency and came
across a GPS approach unlike any I'd seen thus far. Then again, I'm
pretty new to GPS approaches so I'm still finding new stuff fairly often.

I was flying approaches into Wellsvill, NY (ELZ) and was setting up for
the GPS RWY 28. I hadn't studied the approaches in advance, which is my
norm for instrument practice as I like to simulate having to divert to
an unplanned destination and thus find and brief the approach while also
flying the airplane.

I saw the two "waypoints" as I scanned the plan view and then selected
the GPS 28 approach on the King KLN 89B. I don't remember the details
exactly now, but the GPS didn't act as I expected in leg mode. It
wouldn't sequence the approach so I put it in OBS mode and flew the
approach in that manner. Looking at the plate later on the ground, I'm
pretty sure I understand what was wrong.

I mistakenly thought that RW28 was the MAP waypoint, but it appears that
this isn't the case. I don't have the GPS handy at home so I can't pull
up the approach again to see what waypoints it lists, but there is no
MAP WP symbol beside RW28. It looks like the MAP is simply the point
2.9 NM from HALOS and isn't a GPS waypoint at all. I'm also thus
assuming that this type of overlay approach can only be flown in OBS
mode with no automatic sequencing. Is this correct?

I also flew the VOR-A approach, but not its overlaid GPS-A approach. I
see that the chart shows what appears to be a MAP wapoint, MAGNV. This
is listed in parens at the location of the runway. I don't find this in
the terminal procedures legend, so can someone confirm that (MAGNV)
really is intended to indicate a GPS waypoint? However, again it has no
MAP WP symbol beside it, but if it isn't the MAP waypoint I can't figure
out what it is.

I also checked the GPS approaches into ELM and they do have the same
waypoint names RW06, RW28, etc., but they DO have the symbol for the MAP
WP as shown in the legend. I'd only flown GPS approaches into ELM
previously and thus I guess that is why when I saw RW28 at ELZ I assumed
it was the MAP waypoint.

It seems odd that there would be such subtle variations in the symbology
of various GPS approaches. Can anyone explain this briefly or refer me
to a good reference for GPS approaches? It is clear that reading the
King manual and my last ICC didn't yet cover all of the bases. I've not
yet flown a GPS approach in actual as I still don't feel comfortable
that I understand both the approaches and the 89B sufficiently to be
safe. However, I would like to get to that point before warm weather
returns to the northeast. :-)


Matt

Matt Whiting > wrote:
> I also flew the VOR-A approach, but not its overlaid GPS-A approach. I
> see that the chart shows what appears to be a MAP wapoint, MAGNV. This
> is listed in parens at the location of the runway. I don't find this in
> the terminal procedures legend, so can someone confirm that (MAGNV)
> really is intended to indicate a GPS waypoint? However, again it has no
> MAP WP symbol beside it, but if it isn't the MAP waypoint I can't figure
> out what it is.

Waypoints in parens, like (MAGNV) are Computer Navigation Fixes (CNFs).
They're waypoints which only exist in your GPS database (and on the SIAP
charts). They are not marked on the controller's radar display. If you
told the controller that you were "2 miles east of MAGNV", he wouldn't
know where that was. That's the explanation of what they are; as for
*why* they exist, I have no idea. See the AIM 1-1-19-k-2 for more
details.

MAGNV sure looks like the MAP to me. Although I can't find the
reference now, I vaguely remember reading that CNFs used as MAPs all
have names starting in MA.

Matt,

There are *no* GPS approaches that are authorized to be flown in the
OBS mode. In order for you to fly a GPS approach, it is required that
you approach the final approach fix in the LEG mode, and the TERM or
ARM annunciator light lit on your external control panel. As you hit
2nm outside the FAF, the annunciators should change from ARM to ACTV
(known as the approach mode on some other mfgs boxes). IT IS ILLEGAL
TO CONTINUE (DESCEND) inside the FAF if you do not get the ACTV
light--and you will never get it in the OBS mode.

The common problem with getting a GPS approach to work is that you miss
one of the nine or so conditions that are required to be true at the
FAF-2nm point to allow the box to switch into ACTV. Look in the manual
on your KLN89B, and you will see a list of those required by your box,
but they are all pretty similar since they are written into the TSO
under which all of the approach-certified boxes are approved.

Typically, to get it to go into the ACTV mode, these things must be
true:
1. In LEG mode (not OBS)
2. In ARM mode (this comes up when you have a valid approach loaded,
and you are within 30nm)
3. Valid RAIM now, and predicted at FAF and MAP
4. Outside FAF (110 degree arc each side of FAF)
5. Distance to FAF decreasing
6. Within 2nm of FAF, but not past (inside) FAF
7. NAV/GPS switch must be in the GPS position
8. No localizer frequency may be loaded into NAV 1 (some boxes)

You probably had one of these conditions not met.

The approach plate shows a procedure turn type approach. Assuming you
did this approach without ATC vectors to final, it should run something
like this:

Clear the flight plan

Check Nav 1, and make sure no valid localizer freq is in that radio.

Set the GPS/NAV switch to GPS

Load the approach (APT 8 page); select the version of the approach that
uses the LOM as the IAF. On this approach it is also the FAF, and in
the 89B they are the same waypoint, which can be a point of confusion.

Activate the approach, or put the cursor on the FAF waypoint in the
flight plan and hit direct-enter-enter (proceed direct to the IAF/FAF)

Now, heres the trick: push the OBS button on the external control
panel; this puts your system into the OBS mode and DISABLES AUTOMATIC
WAYPOINT SEQUENCING. We have to do this (temporarily), because we are
going to cross the waypoint twice (once outbound to the PT, and then
again inbound established on final) and we do NOT want the box to
sequence down the flight plan to the next waypoint (in this case the
MAP) at the first crossing; we need the box to keep the FAF as the
active waypoint until we are established inbound from the PT.

At 30 nm out, check that you get an ARM light on your external display.

Cross the FAF, and turn outbound towards the PT; set the obs on your #1
vor indicator to the outbound course (098). Intercept it and track
outbound until you are ready to do the PT (1 min, 2min or so)

Once you start the PT (left turn to 053) reset the obs on #1 indicator
to the inbound intermediate course (from the PT to the FAF), in this
case 278.

Turn inbound in the PT and then intercept and track the 278 course
towards the FAF.

DANGER!!! DO NOT MISS THIS NEXT STEP OR ALL IS LOST!!!
<<<<<Once established inbound, but prior to 2nm from FAF, push the OBS
button again on the external GPS display and VERIFY THAT THE OBS LIGHT
GOES OUT!!!>>>>>

The box will now go back into the LEG mode (you should see LEG
displayed in the left portion of the GPS display), which is necessary
to get to ACTV mode.

Watch the distance tick down; at 2nm from the FAF, the ARM light should
go out, and the ACTV light should come on. If this does not happen,
you have about 1:20 (2 nm at 90 kts) to figure out which of the nine
items in the list you missed and correct it prior to crossing the FAF.
If you do not get an ACTV light and pass the FAF, nothing you can do
will get it from there on. You have to abandon the approach, go back
out and start over.

At the FAF the box should sequence to the MAP, and then automatically
go into the suspend mode (waypoint sequencing disabled). At 0 dist to
MAP, you must either have the runway in sight and land visuallly, or
execute the missed.

If you go missed, hit the OBS button again; the box will go back into
the LEG mode just long enough for it to sequence to the MAHP, and then
it will go back into suspend mode again. This is so you can do
multiple turns in the hold at the MAHP without the box autosequencing
to some other fix.

If you want to go back and do another approach, you have to hit the OBS
button again (get it out of suspend mode and back into leg mode), and
set it up to proceed direct to the IAF and start the procedure over as
before.

Somewhere in there I think you will find a piece you missed.

When you get back in front of the GPS again, try loading the approach
and then scrolling down through the waypoints. There should be 3 for
this approach: the first one should be XXXXXf (database name of the
LOM, with a small f after it), the second one should be YYYYYm
(database name of the MAP, probably RW28 or some such, with a little m
after it), and then ZZZZZh (database name of the MAHP, with a little h
after it.)

If you dont have at least those three waypoints in the approach, time
to contact your database provider and ask some questions.

If at first you do not get an ACTV light, try, try again.
Gene
CFII, ASC

"CFII_ASC" > wrote:

> Typically, to get it to go into the ACTV mode, these things must be
> true:
> 1. In LEG mode (not OBS)
> 2. In ARM mode (this comes up when you have a valid approach loaded,
> and you are within 30nm)

Within 30 nm of what? The IAF? The destination?

> 3. Valid RAIM now, and predicted at FAF and MAP
> 4. Outside FAF (110 degree arc each side of FAF)
> 5. Distance to FAF decreasing
> 6. Within 2nm of FAF, but not past (inside) FAF
> 7. NAV/GPS switch must be in the GPS position
> 8. No localizer frequency may be loaded into NAV 1 (some boxes)

Wow, that last one is pretty strange. I often have an ILS frequency
loaded up, even if I'm not using it. The most frequent use I make of
the NAV part of the GPS/NAV/COM is to fly an ILS, so the last ILS flown
is usually what's left there. What is the logic behind requiring me to
change it to something else?

[GPS approach procedure snipped]

Wow... and people say GPS makes life =simple=? I'll take an ILS over
that any day!

Jose
--
Freedom. It seemed like a good idea at the time.
for Email, make the obvious change in the address.

Jose > wrote in news:Mm3Cd.4721$LH7.87
@newssvr31.news.prodigy.com:

> [GPS approach procedure snipped]
>
> Wow... and people say GPS makes life =simple=? I'll take an ILS over
> that any day!

Well, so would I, but most of the places I have to fly an approach to
don't have an ILS, or any other navaid. GPS is what there is, so GPS is
what we use.

--
Regards,

Stan

I don't have the book here, but I *believe* the 30nm is referenced to
the Airport Reference Point, which is the physical location from which
they began the survey of the land to lay out the airport. Mostly this
is somewhere near the center of the airport, but not always. sometimes
it is not even *on* the airport.

The last issue, #8, is implemented on some boxes and not others. I do
not remember if the 89B had that feature or not. But on some machines
it was wired to automatically switch the NAV/GPS switch back to NAV if
you had a valid Localizer freq in Nav 1. The theory was that if you
were trying to fly an ILS and fogot your NAV/GPS switch was left in the
GPS position, it would automatically default back to the NAV position
so that the data displayed on the needle you were tracking was from the
ILS and not the GPS (that you were presumably not using.)

Of course, this created the opposite problem; if you are trying to do a
GPS approach, and forget to get the ILS freq out of Nav 1, it would not
allow you to *load* the approach, let alone fly it. Infuriating.

I have not seen this feature implemented on any of the more recent
boxes.

Bottom line, you have to know what your box does and doesn't do
automatically, and when it does it, and why. An put a check of that
NAV/GPS switch in your set-up procedure for *all* your approaches, not
just the GPS ones.

Regards,

Gene

Roy Smith wrote:

> Matt Whiting > wrote:
>
>>I also flew the VOR-A approach, but not its overlaid GPS-A approach. I
>>see that the chart shows what appears to be a MAP wapoint, MAGNV. This
>>is listed in parens at the location of the runway. I don't find this in
>>the terminal procedures legend, so can someone confirm that (MAGNV)
>>really is intended to indicate a GPS waypoint? However, again it has no
>>MAP WP symbol beside it, but if it isn't the MAP waypoint I can't figure
>>out what it is.
>
>
> Waypoints in parens, like (MAGNV) are Computer Navigation Fixes (CNFs).
> They're waypoints which only exist in your GPS database (and on the SIAP
> charts). They are not marked on the controller's radar display. If you
> told the controller that you were "2 miles east of MAGNV", he wouldn't
> know where that was. That's the explanation of what they are; as for
> *why* they exist, I have no idea. See the AIM 1-1-19-k-2 for more
> details.

Thanks, the AIM was the next stop on my journey. I read the GPS section
back in the spring, but obviously didn't remember all of the requisite
details!


> MAGNV sure looks like the MAP to me. Although I can't find the
> reference now, I vaguely remember reading that CNFs used as MAPs all
> have names starting in MA.

Yes, it appears to be the MAP, but it doesn't have the map symbol beside
it so I'm not sure.


Matt

"CFII_ASC" > wrote:
> Bottom line, you have to know what your box does and doesn't do
> automatically, and when it does it, and why. An put a check of that
> NAV/GPS switch in your set-up procedure for *all* your approaches, not
> just the GPS ones.

Yeah, I've been burned by that one, and it's one of the most common
mistakes I see students make.

The other common one (at least on the CNX-80) is to forget to hit the
EXEC button after modifying a flight plan or selecting an approach.

"Roy Smith" > wrote in message
...
> Wow, that last one is pretty strange. I often have an ILS frequency
> loaded up, even if I'm not using it. The most frequent use I make of
> the NAV part of the GPS/NAV/COM is to fly an ILS, so the last ILS flown
> is usually what's left there. What is the logic behind requiring me to
> change it to something else?

Many, if not all, IFR GPS units and or switching relay/annunicators have an
option (often wiring) to force the switching relay to NAV if there is a LOC
frequency selected. In the newer integrated units, this "relay" is inside
the box.

Mike
MU-2

CFII_ASC wrote:

> Matt,
>
> There are *no* GPS approaches that are authorized to be flown in the
> OBS mode. In order for you to fly a GPS approach, it is required that
> you approach the final approach fix in the LEG mode, and the TERM or
> ARM annunciator light lit on your external control panel. As you hit
> 2nm outside the FAF, the annunciators should change from ARM to ACTV
> (known as the approach mode on some other mfgs boxes). IT IS ILLEGAL
> TO CONTINUE (DESCEND) inside the FAF if you do not get the ACTV
> light--and you will never get it in the OBS mode.

That is what I thought, but I couldn't figure out why it wouldn't sequence.


> The common problem with getting a GPS approach to work is that you miss
> one of the nine or so conditions that are required to be true at the
> FAF-2nm point to allow the box to switch into ACTV. Look in the manual
> on your KLN89B, and you will see a list of those required by your box,
> but they are all pretty similar since they are written into the TSO
> under which all of the approach-certified boxes are approved.
>
> Typically, to get it to go into the ACTV mode, these things must be
> true:
> 1. In LEG mode (not OBS)
> 2. In ARM mode (this comes up when you have a valid approach loaded,
> and you are within 30nm)
> 3. Valid RAIM now, and predicted at FAF and MAP
> 4. Outside FAF (110 degree arc each side of FAF)
> 5. Distance to FAF decreasing
> 6. Within 2nm of FAF, but not past (inside) FAF
> 7. NAV/GPS switch must be in the GPS position
> 8. No localizer frequency may be loaded into NAV 1 (some boxes)
>
> You probably had one of these conditions not met.

Yes, obviously, I'm just not sure which one. I know that 1, 3, 4, 5, 6
and 7 were satisfied. I don't remember if I checked the ARM
annunciator. I had flown the LOC 28 prior to the GPS 28 and still had
that frequency tuned, however, it was in the #2 NAV as the #1 NAV is
removed for repairs. I didn't realize that the GPS interfaced to the
NAVs, so that may be it. I'll check the King manual shortly to see if
that might be the problem. I later flew a GPS at N38 with no problem,
but by then I'd tuned the NAV to a non-localizer frequency.


> The approach plate shows a procedure turn type approach. Assuming you
> did this approach without ATC vectors to final, it should run something
> like this:
>
> Clear the flight plan

I didn't clear the flight plan, so that may have been the problem. I
flew a flight plan from ELM to N38, but simply did a DIRECT to ELZ and
therefore FP 0 would have still had ELM to N38. That may have been my
error.


> Check Nav 1, and make sure no valid localizer freq is in that radio.

Didn't have a NAV 1 that day!


> Set the GPS/NAV switch to GPS

I don't recall our club plan having such a switch. Is this required for
all IFR installations? This wasn't mentioned during my ICC either.


> Load the approach (APT 8 page); select the version of the approach that
> uses the LOM as the IAF. On this approach it is also the FAF, and in
> the 89B they are the same waypoint, which can be a point of confusion.
>
> Activate the approach, or put the cursor on the FAF waypoint in the
> flight plan and hit direct-enter-enter (proceed direct to the IAF/FAF)

I believe I did the normal approach activation such that it asks you if
you want to insert the approach waypoints into the flight plan. I said
yes thinking that my "flight plan" was the direct to ELZ, however, I'll
bet it added the approach to my FP 0 which was ELM to N38. That very
well would confused the GPS royally, and me in rapid succession. :-)


> Now, heres the trick: push the OBS button on the external control
> panel; this puts your system into the OBS mode and DISABLES AUTOMATIC
> WAYPOINT SEQUENCING. We have to do this (temporarily), because we are
> going to cross the waypoint twice (once outbound to the PT, and then
> again inbound established on final) and we do NOT want the box to
> sequence down the flight plan to the next waypoint (in this case the
> MAP) at the first crossing; we need the box to keep the FAF as the
> active waypoint until we are established inbound from the PT.

Yes, I did learn this during the ICC for both course reversals and holds
after a missed.


> At 30 nm out, check that you get an ARM light on your external display.
>
> Cross the FAF, and turn outbound towards the PT; set the obs on your #1
> vor indicator to the outbound course (098). Intercept it and track
> outbound until you are ready to do the PT (1 min, 2min or so)
>
> Once you start the PT (left turn to 053) reset the obs on #1 indicator
> to the inbound intermediate course (from the PT to the FAF), in this
> case 278.
>
> Turn inbound in the PT and then intercept and track the 278 course
> towards the FAF.
>
> DANGER!!! DO NOT MISS THIS NEXT STEP OR ALL IS LOST!!!
> <<<<<Once established inbound, but prior to 2nm from FAF, push the OBS
> button again on the external GPS display and VERIFY THAT THE OBS LIGHT
> GOES OUT!!!>>>>>

I did this and that is when things went nuts. However, it sounds from
what you wrote above that I entered the approach into a flight plan to a
different airport. I didn't realize that entering a direct to fix
wouldn't replace flight plan 0.


> The box will now go back into the LEG mode (you should see LEG
> displayed in the left portion of the GPS display), which is necessary
> to get to ACTV mode.
>
> Watch the distance tick down; at 2nm from the FAF, the ARM light should
> go out, and the ACTV light should come on. If this does not happen,
> you have about 1:20 (2 nm at 90 kts) to figure out which of the nine
> items in the list you missed and correct it prior to crossing the FAF.
> If you do not get an ACTV light and pass the FAF, nothing you can do
> will get it from there on. You have to abandon the approach, go back
> out and start over.
>
> At the FAF the box should sequence to the MAP, and then automatically
> go into the suspend mode (waypoint sequencing disabled). At 0 dist to
> MAP, you must either have the runway in sight and land visuallly, or
> execute the missed.
>
> If you go missed, hit the OBS button again; the box will go back into
> the LEG mode just long enough for it to sequence to the MAHP, and then
> it will go back into suspend mode again. This is so you can do
> multiple turns in the hold at the MAHP without the box autosequencing
> to some other fix.

I was taught to hit direct to at the MAP and then fly in leg more
towards the holding fix and then switch to OBS mode to fly the hold.


> If you want to go back and do another approach, you have to hit the OBS
> button again (get it out of suspend mode and back into leg mode), and
> set it up to proceed direct to the IAF and start the procedure over as
> before.

I've not heard of suspended mode before. I'll look this up. I only
read about LEG and OBS mode, and missed suspend.


> Somewhere in there I think you will find a piece you missed.
>
> When you get back in front of the GPS again, try loading the approach
> and then scrolling down through the waypoints. There should be 3 for
> this approach: the first one should be XXXXXf (database name of the
> LOM, with a small f after it), the second one should be YYYYYm
> (database name of the MAP, probably RW28 or some such, with a little m
> after it), and then ZZZZZh (database name of the MAHP, with a little h
> after it.)
>
> If you dont have at least those three waypoints in the approach, time
> to contact your database provider and ask some questions.
>
> If at first you do not get an ACTV light, try, try again.
> Gene
> CFII, ASC

Thanks, Gene, I appreciate the time you took to make this very detailed
approach. A few more flights and I'll get a handle on GPS approaches.
I still find them far more complicated than other approaches, even NDBs,
however, that is just my newness to GPS.


Matt

Jose wrote:

> [GPS approach procedure snipped]
>
> Wow... and people say GPS makes life =simple=? I'll take an ILS over
> that any day!
>
> Jose

Yes, I still feel that way, but I'm determined to learn GPS approaches
for two reasons:

1. I'm a computer science graduate and no computer is going to get the
best of me!
2. A lot of places that don't have an ILS do have a GPS.

I'm sure once learned, the GPS seem trivial, it is just taking me a
little while to get the hang of it. Then again, I've only flow about 6
GPS approaches so far, so I'm not too worried about my current ineptness.

Matt

> 2. A lot of places that don't have an ILS do have a GPS.

Agreed. Got to know GPS approaches.

> 1. I'm a computer science graduate and no computer is going to
> get the best of me!

Don't bet on it. A computer is a personal servant, to whom you give
the keys to your house, your car, and your bank, who only speaks
Swahili, who takes his orders from a high school student in Pakistan,
and who invites its friends over for parties when you are out of the
house.

The only way around this is to program the raw chip yourself.

(and yes, I also do programming)

> I'm sure once learned, the GPS seem trivial, it is just taking
> me a little while to get the hang of it.

With steam gauges, you depend on the laws of physics. With GPS, you
depend on the twisted logic of whoever had too much coffee the day the
design was burned in ROM.

The laws of physics have never failed me. I've yet to encounter a
computer that didn't go belly up just for jollies.

Jose
--
Freedom. It seemed like a good idea at the time.
for Email, make the obvious change in the address.

Jose wrote:
>> 2. A lot of places that don't have an ILS do have a GPS.
>
>
> Agreed. Got to know GPS approaches.
>
>> 1. I'm a computer science graduate and no computer is going to
>> get the best of me!
>
>
> Don't bet on it. A computer is a personal servant, to whom you give the
> keys to your house, your car, and your bank, who only speaks Swahili,
> who takes his orders from a high school student in Pakistan, and who
> invites its friends over for parties when you are out of the house.
>
> The only way around this is to program the raw chip yourself.

No, you can always turn off the power! :-)


> (and yes, I also do programming)

I did programming, but I grew out of that phase. :-)


>> I'm sure once learned, the GPS seem trivial, it is just taking
>> me a little while to get the hang of it.
>
>
> With steam gauges, you depend on the laws of physics. With GPS, you
> depend on the twisted logic of whoever had too much coffee the day the
> design was burned in ROM.

Yes, there is some truth to that.


> The laws of physics have never failed me. I've yet to encounter a
> computer that didn't go belly up just for jollies.

Well, the first computer I worked on was a PDP-11/34 running RSX-llM and
that sucker never crashed once in the five years we used it as a
development host. The only downtime it saw was when we applied patches
or did a sysgen to change its configuration.


Matt

In article >,
Matt Whiting > wrote:

> Jose wrote:
> >> 2. A lot of places that don't have an ILS do have a GPS.
> >
> >
> > Agreed. Got to know GPS approaches.
> >
> >> 1. I'm a computer science graduate and no computer is going to
> >> get the best of me!
> >
> >
> > Don't bet on it. A computer is a personal servant, to whom you give the
> > keys to your house, your car, and your bank, who only speaks Swahili,
> > who takes his orders from a high school student in Pakistan, and who
> > invites its friends over for parties when you are out of the house.
> >
> > The only way around this is to program the raw chip yourself.
>
> No, you can always turn off the power! :-)

Actually, with a lot of devices these days, turning off the power is
harder than it appears. It may have an on/off switch, but that usually
just shuts down the display and leaves the processor running. Pulling
the plug out may not even help, if it's got backup batteries.

Roy Smith wrote:
> In article >,
> Matt Whiting > wrote:
>
>
>>Jose wrote:
>>
>>>>2. A lot of places that don't have an ILS do have a GPS.
>>>
>>>
>>>Agreed. Got to know GPS approaches.
>>>
>>>
>>>>1. I'm a computer science graduate and no computer is going to
>>>>get the best of me!
>>>
>>>
>>>Don't bet on it. A computer is a personal servant, to whom you give the
>>>keys to your house, your car, and your bank, who only speaks Swahili,
>>>who takes his orders from a high school student in Pakistan, and who
>>>invites its friends over for parties when you are out of the house.
>>>
>>>The only way around this is to program the raw chip yourself.
>>
>>No, you can always turn off the power! :-)
>
>
> Actually, with a lot of devices these days, turning off the power is
> harder than it appears. It may have an on/off switch, but that usually
> just shuts down the display and leaves the processor running. Pulling
> the plug out may not even help, if it's got backup batteries.

They only keep track of the date and a few other key settings,
typically. Can't do much real processing for long on the backup battery.


Matt

> [battery backup only keeps track of] a few other key settings

Those may be the settings that prevent you from doing something you
thought was reasonable under the circumstances, but the programmer
didn't think of. You are always depending on the programmer to have
thought of whatever situation you are in, =and= come up with the right
answer.

Jose
--
Money: What you need when you run out of brains.
for Email, make the obvious change in the address.

Roy Smith wrote:
> "CFII_ASC" > wrote:
>
>
>>Typically, to get it to go into the ACTV mode, these things must be
>>true:
>>1. In LEG mode (not OBS)
>>2. In ARM mode (this comes up when you have a valid approach loaded,
>>and you are within 30nm)
>
>
> Within 30 nm of what? The IAF? The destination?

The FAF, I think, but someone else will give a more authoritative answer.

>
>
>>3. Valid RAIM now, and predicted at FAF and MAP
>>4. Outside FAF (110 degree arc each side of FAF)
>>5. Distance to FAF decreasing
>>6. Within 2nm of FAF, but not past (inside) FAF
>>7. NAV/GPS switch must be in the GPS position
>>8. No localizer frequency may be loaded into NAV 1 (some boxes)
>
>
> Wow, that last one is pretty strange. I often have an ILS frequency
> loaded up, even if I'm not using it. The most frequent use I make of
> the NAV part of the GPS/NAV/COM is to fly an ILS, so the last ILS flown
> is usually what's left there. What is the logic behind requiring me to
> change it to something else?

The GX50 I had installed in my old Archer worked that way. I've also seen a GX50
that didn't work that way. It must be an installation option.

In the plane that wasn't installed that way, I've been safety pilot and seen a
confused pilot when he tuned the localizer without switching the GPS/NAV switch
to NAV, and couldn't figure out why the OBS wasn't behaving the way he thought
it should. OTOH, I can imagine the inverse kind of confusion occurring if the
OBS switched to NAV mode on its own when a localizer is tuned. You have to know
your installation.

What is the logic? Dunno.

On Tue, 04 Jan 2005 12:01:19 -0500, Dave Butler > wrote:

>> Within 30 nm of what? The IAF? The destination?
>
>The FAF, I think, but someone else will give a more authoritative answer.
>
>>

the airport, if I am not mistaken.

Hah!

I looked it up. It is the ARP.

Gene

The GX50 is something of an oddity in some ways. I actually make a
fair amount of money just showing people how to set the OBS in that
box. It doesnt work like the others--wont read it from the external
display, you have to set it on the keyboard, and they hid it real good,
both on the box and in the manual.

For any GPS to be IFR approach approved, it has to drive an external
CDI indicator. In most installations, it shares the NAV1 indicator
with the #1 VOR receiver, and there is a switching unit on the panel
(somewhere), external to either the GPS or the indicator that controls
which box gets to talk to the display.

Some of the GX50 boxes came with their own, third display which is
dedicated to the GPS, so in these installations there is no NAV/GPS
switch.

The Garmin 430/530 boxes incorporate the #1 VOR rx and the GPS into the
same chassis, so on these boxes the NAV/GPS switch is a pushbutton on
the front of the box, rather than on an external panel. They also
renamed it: the button is labelled CDI, and the annunciator it controls
toggles between VLOC and GPS.

It helps to sit down with your avionics tech and make a block diagram
for your installation so you know how all this is hooked up--in *your*
airplane.

Think you got problems, consider the installation in a high-performance
single or twin, typically equipped with GPS, autopilot and DME:

NAV/GPS switch determines which box (VOR#1 or GPS) drives #1 CDI.
NAV1/NAV2 switch determines which CDI the autopilot follows.
Another NAV1/NAV2 switch determines which VOR rx is used by the DME for
remote automatic channeling.

These three switches are similar enough in appearance and function that
a lot of pilots get really screwed up. Add to this some faded out
labelling and you have a real opportunity to make a complete mess of
things. (Why is that guy in the F15 flying so close to me and waving?)
Gene

wrote in news:1104913014.473596.136650
@c13g2000cwb.googlegroups.com:

> (Why is that guy in the F15 flying so close to me and waving?)

Minor nit. They don't use F15s, it's F16s. And they don't wave. DAMHIKT.

--
Regards,

Stan

Stan,

The point was not about the model airplane that would conduct the
intercept--but why. It is a little known 'stat' about GPS that since
we got them in little airplane cockpits the frequency of airspace
violations have *increased.* People seem to be getting 'head down and
locked' trying to wade through the many options and pages and modes on
the black box while not noticing what is happening outside, i.e.
penetrating airspace they do not have permission for.

In general you must be correct; ie all of the intercepts I have been
made aware of in recent years involved F16s--including one during Pres.
Regan's funeral that had the F16 driver doing wingovers around our
aircraft as we tooled down the ILS--he was intercepting some poor
gentleman off to our left in a little Ercoupe that had apparently 'not
gotten the word' as the saying goes.

I do know of one gentleman (who, due to his incident became my customer
under the remedial instruction program) who penetrated the restricted
area over Groom Lake, NV and was intercepted by an F15. I suppose it
has something to do with which types are based where.

In either case, it is not something you like to see--military jets
pulling up alongside your flight. I understand it is especially
unnerving if they happen to have other than US markings.

Regards,

Gene

wrote in news:1105228604.387662.151640
@c13g2000cwb.googlegroups.com:

> In either case, it is not something you like to see--military jets
> pulling up alongside your flight. I understand it is especially
> unnerving if they happen to have other than US markings.

I haven't seen other than US markings, but it's not unknown for other
countries to fly aircraft close to the coast, just to reinforce their
right, just as it's not unknown for foreign warships to steam a few miles
out. I have seen US aircraft intercept me, once because my transponder
had slipped a cog internally, and once because a P3 (!) decided to come
take a look, even though I hadn't penetrated the ADIZ, just playing
around as far as I could tell. It's not that frightening, really, it's
more amusing to see a jet fighter try to slow down enough to do an
intercept of a helicopter.

Almost all the fighters doing intercepts of ADIZ inbounds are F16s,
because that's the standard type, but entering restricted or prohibited
areas inland may result in whatever type is based there.

--
Regards,

Stan

Stan,

I was only kidding about the frightening part... little exaggeration.

My closest encounter with a military type was when I came around the
west end of Catalina island at low level, and as I rounded the corner
there was an F16 coming the other way doing the same thing in the other
direction.

It wasn't *that* close (nobody had to maneuver)... and he *did* wave.
Regards,

Gene

wrote in news:1105262338.845935.121730
@c13g2000cwb.googlegroups.com:

> My closest encounter with a military type was when I came around the
> west end of Catalina island at low level, and as I rounded the corner
> there was an F16 coming the other way doing the same thing in the other
> direction.
>
> It wasn't *that* close (nobody had to maneuver)... and he *did* wave.
> Regards,

We used to see jets low-level in Germany all the time. F4s were no
problem, because you could see the smoke trailing from them for miles.
The bad ones were the F101s, just a small fuselage and about 3 feet of
wing on the sides, flying at 500' or less at better than 500 knots. You
didn't see them until they passed just off to the side, waving and
grinning. I still hate to see an F101.

--
Regards,

Stan

"Stan Gosnell" > wrote in message
...
> wrote in news:1105262338.845935.121730
> @c13g2000cwb.googlegroups.com:
>
snip

> The bad ones were the F101s, just a small fuselage and about 3 feet of
> wing on the sides, flying at 500' or less at better than 500 knots. You
> didn't see them until they passed just off to the side, waving and
> grinning. I still hate to see an F101.
>
> --
> Regards,
>
> Stan

Not the F-101 I'm thinking about. Wingspan is 39 feet 8 inches.
http://www.wpafb.af.mil/museum/research/fighter/f101b.htm

Maybe you were thinking the F-104 which has a wingspan just under 22 feet.
http://www.wpafb.af.mil/museum/research/fighter/f104g.htm

J. Severyn
KLVK

"J. Severyn" > wrote in news:1105314602.934461
@news-1.nethere.net:

> http://www.wpafb.af.mil/museum/research/fighter/f104g.htm

Yes, you're right, I meant F104. The numbers sometimes blur after 25+
years. ;-)

--
Regards,

Stan

"Stan Gosnell" > wrote in message
...
> wrote in news:1105262338.845935.121730
> @c13g2000cwb.googlegroups.com:
>
> > My closest encounter with a military type was when I came around the
> > west end of Catalina island at low level, and as I rounded the corner
> > there was an F16 coming the other way doing the same thing in the other
> > direction.
> >
> > It wasn't *that* close (nobody had to maneuver)... and he *did* wave.
> > Regards,
>
> We used to see jets low-level in Germany all the time. F4s were no
> problem, because you could see the smoke trailing from them for miles.
> The bad ones were the F101s, just a small fuselage and about 3 feet of
> wing on the sides, flying at 500' or less at better than 500 knots. You
> didn't see them until they passed just off to the side, waving and
> grinning. I still hate to see an F101.
>
Are you thinking of an F-104 with the stubby wings?

"Stan Gosnell" > wrote in message
...
> "J. Severyn" > wrote in news:1105314602.934461
> @news-1.nethere.net:
>
> > http://www.wpafb.af.mil/museum/research/fighter/f104g.htm
>
> Yes, you're right, I meant F104. The numbers sometimes blur after 25+
> years. ;-)
>
For some of us they blur after 25 _minutes_.


--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

**** ***** ******* ******** ****** ***** **** ****






I mistakenly thought that RW28 was the MAP waypoint, but it appears that
this isn't the case. I don't have the GPS handy at home so I can't pull
up the approach again to see what waypoints it lists, but there is no
MAP WP symbol beside RW28. It looks like the MAP is simply the point
2.9 NM from HALOS and isn't a GPS waypoint at all. I'm also thus
assuming that this type of overlay approach can only be flown in OBS
mode with no automatic sequencing. Is this correct?

The Fly Over WP is in the PLANVIEW, (circled WP and it is the RWY THLD). Don't let the chart folks fool you...it may not look that way when you look at the profile, but it's the THLD.


It seems odd that there would be such subtle variations in the symbology
of various GPS approaches. Can anyone explain this briefly or refer me
to a good reference for GPS approaches?

Keep in mind that the evolution of these approaches happened over a very short time and as a consequence lots of things have been changed. Also these approaches may not get rebuilt for over 5 years and you'll see lot's of gradation in charting style...it all doesn't happen overnight.

Matt