Garmin 430 Approach Activation question

sarangan

sarangan

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Andrew, CFI-I
I am wondering if there is a difference between activating an approach via the PROC key, and manually highlight an approach waypoint in the active flight plan and hitting Direct. As far as I could tell there was no difference, but I wasn't sure if the former method also enables safety features such as RAIM etc...
 
For the past two generations of Garmin navigators (the GTN and GTN-xi), activating direct-to any waypoint in a loaded approach also activates the approach. It's probably the same for the old 430s, but best let someone who still has one pipe in.
 
On a GNS-430W you can activate sequencing of approach waypoints by either activating the approach (which will take you direct to the selected IAF when you loaded the approach), or you can select an IAF or IF on the loaded approach and enable direct to that waypoint. I would avoid VTF as it deletes all the intermediate waypoints, and if ATC changes their mind and clears you to an IAF or IF instead of vectors, you are in button-pushing hell.
 
chemgeek said:
On a GNS-430W you can activate sequencing of approach waypoints by either activating the approach (which will take you direct to the selected IAF when you loaded the approach), or you can select an IAF or IF on the loaded approach and enable direct to that waypoint. I would avoid VTF as it deletes all the intermediate waypoints, and if ATC changes their mind and clears you to an IAF or IF instead of vectors, you are in button-pushing hell.
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Agree. Stay away from vectors to final. It’s good to have all the waypoints available.

Another way to activate an approach is to highlight the next waypoint in the flight plan page and hit menu-> Activate leg


Sent from my iPhone using Tapatalk Pro
 
I looked this up because I have recently been on an approach and gotten a warning message from the GNS (430/530) that "approach has not been activated" even though I was navigating on a published segment of the approach course. All I can come up with is that I had inadvertently pressed "Direct-To" on one of the fixes and had failed to ever select Activate Approach.

That being said, I just looked it up in the manual and came up with this:

Take a second look at the ‘VOR 22’ approach into Billard Municipal. Instead of following the DME arc, ATC tells the pilot to expect vectors onto the final approach course. There are several ways to select ‘vectors to final’ with the GNS 430. The first two options below normally require the least workload to accomplish:

• When the approach is first selected, choose ‘VECTORS’ from the Transitions Window.
• Load a full approach (including the IAF from the Transitions Window) as described in Section 6.1. When cleared, press the PROC Key and select ‘Activate Vectors-To-Final?’.
• Load the full approach as described in Section 6.1. Use the Direct-to Key (by pressing it twice) from the Active Flight Plan Page to select the desired leg of the approach.

https://static.garmin.com/pumac/GNS430_PilotsGuide.pdf
Page6-17

So maybe I just found my way into some rabbit hole...... IDK. Anywhoo, my standard practice now, no matter what, is to switch the AP over to heading mode (to keep the airplane from immediately turning to the IAF), ACTIVATE the approach from the appropriate IAF, then select the desired leg from the FPL menu using "Menu" "Activate Leg".
 
KeepWatch said:
So maybe I just found my way into some rabbit hole...... IDK. Anywhoo, my standard practice now, no matter what, is to switch the AP over to heading mode (to keep the airplane from immediately turning to the IAF), ACTIVATE the approach from the appropriate IAF, then select the desired leg from the FPL menu using "Menu" "Activate Leg".
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Just so. If Warren Vanderburgh were still with us, he'd be nodding vigorously in agreement:
 
jimhorner said:
Another way to activate an approach is to highlight the next waypoint in the flight plan page and hit menu-> Activate leg
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I suppose that's useful for when instructed to "intercept the localizer". Direct-to gives a different outcome, right?
 
Garmin's use of the term "Activate" is unfortunate. When you select an approach, all it means is load the approach waypoints into the flight plan and change the "active" waypoint to the IAF. Or make "active" the segment the navigator determines you haven't flown past if selecting VTF. If it's active to a waypoint, you will immediately be given guidance direct to the waypoint. If a segment is active, you will be given guidance as to your position with respect to the segment (like a radial in a VOR application).

The same thing is achieved if you choose to "LOAD" the waypoints then go to the Flight plan page and select a waypoint and press direct. Or activate a leg. This is what I almost always choose because I don't want the navigator to change my guidance until I have a chance to check the approach waypoints.

So, I would prefer Garmin use the question, "proceed to IAF?" or "Activate abc to xyz leg?" instead of just "Activate?" Just my thoughts... I've gotten past the confusion and know what it means.
 
sarangan said:
I am wondering if there is a difference between activating an approach via the PROC key, and manually highlight an approach waypoint in the active flight plan and hitting Direct. As far as I could tell there was no difference, but I wasn't sure if the former method also enables safety features such as RAIM etc...
Click to expand...

Maybe someone will come along and correct me, but I don't believe there is a difference. Otherwise, what are you supposed to do if you chose to just "LOAD" the approach. You have to do what you just said.
 
noahfong said:
Garmin's use of the term "Activate" is unfortunate. When you select an approach, all it means is load the approach waypoints into the flight plan and change the "active" waypoint to the IAF. Or make "active" the segment the navigator determines you haven't flown past if selecting VTF. If it's active to a waypoint, you will immediately be given guidance direct to the waypoint. If a segment is active, you will be given guidance as to your position with respect to the segment (like a radial in a VOR application).

The same thing is achieved if you choose to "LOAD" the waypoints then go to the Flight plan page and select a waypoint and press direct. Or activate a leg. This is what I almost always choose because I don't want the navigator to change my guidance until I have a chance to check the approach waypoints.

So, I would prefer Garmin use the question, "proceed to IAF?" or "Activate abc to xyz leg?" instead of just "Activate?" Just my thoughts... I've gotten past the confusion and know what it means.
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I hear what you're saying, but going back to my example.....

I was shooting a practice RNAV approach. Despite sequencing just fine throughout the approach segments, I received a warning message as I approached the FAF that the approach was not activated. As one might expect, vertical guidance was not received as I approached the GS.

Where I really made things worse was when I tried to activate the approach to fix the problem. I had always told myself "never select vectors to final". So when I activated the approach and out of habit selected the IAF, the AP did exactly what I told it to do and immediately initiated a 180deg turn back to the IAF.

So yeah, now I just make sure at some point I actually select activate approach instead of selecting a leg for a "loaded" approach. Will it work another way? Yeah maybe. But I'd prefer not to find out as I near the FAF that the 430/530 and I disagree as to whether we're just performing lateral navigation along an approach path or flying an approach all the way to the MAP.
 
KeepWatch said:
I was shooting a practice RNAV approach. Despite sequencing just fine throughout the approach segments, I received a warning message as I approached the FAF that the approach was not activated. As one might expect, vertical guidance was not received as I approached the GS.

Where I really made things worse was when I tried to activate the approach to fix the problem. I had always told myself "never select vectors to final". So when I activated the approach and out of habit selected the IAF, the AP did exactly what I told it to do and immediately initiated a 180deg turn back to the IAF.
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This was actually a question on my written. If past the IAF and the approach is not activated, the FAA wants you to discontinue the approach as I recall.

Also, I remember my CFII describing a crash where someone activated the approach too late and initiated the 180deg turn back to the IAF exactly as you did, except they smacked into a mountain and died.
 
KeepWatch said:
I hear what you're saying, but going back to my example.....

I was shooting a practice RNAV approach. Despite sequencing just fine throughout the approach segments, I received a warning message as I approached the FAF that the approach was not activated. As one might expect, vertical guidance was not received as I approached the GS.

Where I really made things worse was when I tried to activate the approach to fix the problem. I had always told myself "never select vectors to final". So when I activated the approach and out of habit selected the IAF, the AP did exactly what I told it to do and immediately initiated a 180deg turn back to the IAF.

So yeah, now I just make sure at some point I actually select activate approach instead of selecting a leg for a "loaded" approach. Will it work another way? Yeah maybe. But I'd prefer not to find out as I near the FAF that the 430/530 and I disagree as to whether we're just performing lateral navigation along an approach path or flying an approach all the way to the MAP.
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What did you do to "activate" the approach after you selected it? I've never had the problem you described. By your saying "sequencing just fine", how did you determine that? Nav systems are NOT immune from bugs and that's why close monitoring of the system's progress and knowing what it is doing at all times is critical. Weird things do happen. This may have been one of them.

If you are convinced to never select VTF (which I also am convinced and practice) how will you set up if you are being vectored onto final? (You said you will always select "activate", which with IAF selected will always guide you to the IAF).
 
noahfong said:
What did you do to "activate" the approach after you selected it?
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Not 100% sure but I believe I "Loaded" the approach then went direct to one of the approach waypoints. If that was the case, I never selected "activate approach."

noahfong said:
By your saying "sequencing just fine", how did you determine that?
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The 430 was automatically transitioning between intermediate fixes. The warning message was returned only as I neared the FAF.

noahfong said:
If you are convinced to never select VTF (which I also am convinced and practice) how will you set up if you are being vectored onto final? (You said you will always select "activate", which with IAF selected will always guide you to the IAF).
Click to expand...

Make sure the AP is in heading mode, then activate the approach using the appropriate IAF. Sure, the nav will output guidance to the IAP at that point but AP is in heading mode so I'm still going where I need to be. Then select the appropriate leg of the approach in the FPL menu. Arm the approach mode on the FD/AP and continue accepting vectors until capture.
 
asicer said:
This was actually a question on my written. If past the IAF and the approach is not activated, the FAA wants you to discontinue the approach as I recall.

Also, I remember my CFII describing a crash where someone activated the approach too late and initiated the 180deg turn back to the IAF exactly as you did, except they smacked into a mountain and died.
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That's no doubt the right way to go. Go missed, fix it later. I was in visual conditions at an uncontrolled airport with no traffic, so part of me just wanted to understand what was going on, hence I let it develop a little bit. Going forward I need to practice like it's low IFR and when that happens follow through appropriately.
 
jimhorner said:
Agree. Stay away from vectors to final. It’s good to have all the waypoints available.

Another way to activate an approach is to highlight the next waypoint in the flight plan page and hit menu-> Activate leg
Click to expand...
Yep. Four ways ways to activate an approach once loaded.
  • Activate approach brings you to the transition you selected when you loaded it.
  • Direct to a "proper" waypoint in the approach.
  • Activate an initial or intermediate leg of the approach
  • Activate VTF.
BTW, I don't buy into the "never activate VTF" philosophy. Yes, I never load VTF as a transition, even in the later navigators which do show the waypoints on the extended FAC. But once it becomes clear (and it does if you maintain situational awareness) there is not going to be an instruction to go to another waypoint somewhere behind you, there's no harm in activating VTF, although "activate leg" is a good preference to have.

There are actually a few situations where activating VTF can be a benefit. I hate to bring him up as an example of anything, but I watched the evolution of Jerry W's "activate VTF" entry in his approach checklist and the context made a lot of sense (of course he uses it when it's not needed, but that's another story).
 
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KeepWatch said:
Not 100% sure but I believe I "Loaded" the approach then went direct to one of the approach waypoints. If that was the case, I never selected "activate approach."
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Which one? It makes a difference. In your situation it could also be the confusion of first sending it behind you.
 
noahfong said:
if you are convinced to never select VTF (which I also am convinced and practice) how will you set up if you are being vectored onto final? (You said you will always select "activate", which with IAF selected will always guide you to the IAF).
Click to expand...
Activate leg works well for that.
 
KeepWatch said:
Not 100% sure but I believe I "Loaded" the approach then went direct to one of the approach waypoints. If that was the case, I never selected "activate approach."


The 430 was automatically transitioning between intermediate fixes. The warning message was returned only as I neared the FAF.



Make sure the AP is in heading mode, then activate the approach using the appropriate IAF. Sure, the nav will output guidance to the IAP at that point but AP is in heading mode so I'm still going where I need to be. Then select the appropriate leg of the approach in the FPL menu. Arm the approach mode on the FD/AP and continue accepting vectors until capture.
Click to expand...

Many people think "activating" the approach does something magical to make the approach waypoints work. That's not what it is at all. It just means it will make one of the waypoints of the approach active. Or the final approach segment, in cast of VTF. You can do this yourself by going to the flight plan page and selecting one and "direct" key, etc.

If you went directly to one of the approach waypoints, YOU "ACTIVATED" the approach. I assume you went to the Flight Plan page, highlighted the waypoint and pushed "direct". Then enter. This makes that waypoint "active". And that is exactly what is meant by activating. NOW, if that waypoint was already in your flight plan and you selected it INSTEAD of the portion loaded by PROC, then you will have a problem.

Another problem that can occur is selecting a waypoint or segment that is "behind" you (or the 430/530 thinks you've already past). It can cause it to suspend.

I think what happened to you is either one of the problems I mentioned or a fluke. It will help you to talk to someone knowledgeable about the Garmin units to understand what activating the approach means.
 
noahfong said:
Many people think "activating" the approach does something magical to make the approach waypoints work. That's not what it is at all. It just means it will make one of the waypoints of the approach active.
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Well AIM 1-1-17 does talk about approach mode being armed so that you get RAIM and CDI sensitivity ...
 
noahfong said:
Many people think "activating" the approach does something magical to make the approach waypoints work. That's not what it is at all. It just means it will make one of the waypoints of the approach active. Or the final approach segment, in cast of VTF. You can do this yourself by going to the flight plan page and selecting one and "direct" key, etc.

If you went directly to one of the approach waypoints, YOU "ACTIVATED" the approach. I assume you went to the Flight Plan page, highlighted the waypoint and pushed "direct". Then enter. This makes that waypoint "active". And that is exactly what is meant by activating. NOW, if that waypoint was already in your flight plan and you selected it INSTEAD of the portion loaded by PROC, then you will have a problem.

Another problem that can occur is selecting a waypoint or segment that is "behind" you (or the 430/530 thinks you've already past). It can cause it to suspend.

I think what happened to you is either one of the problems I mentioned or a fluke. It will help you to talk to someone knowledgeable about the Garmin units to understand what activating the approach means.
Click to expand...

Your explanation is clear and aligns with what the manual says on the 430. I can say definitively that I did not have an approach waypoint in the flightplan that was imported without the approach. As for the possibility of selecting a leg that was behind me, I don't think that was the case but who knows. I'm still fine-tuning my button pushing procedures........ I certainly appreciate the video linked above about trying to use too high of a level of automation appropriate for the stage of flight involved. It certainly helps to have a fundamental understanding of how things work with your avionics, maintain situational awareness, and employ the systems appropriately.
 
Would be REALLY nice to do the on the KLN94. But alas... it get's angry with me when I try to do that.
 
asicer said:
Well AIM 1-1-17 does talk about approach mode being armed so that you get RAIM and CDI sensitivity ...
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Yes indeed. That is separate from "activate." If the approach is at the end of your flight plan it will arm automatically when you are within 30 miles of the airport reference point. You see that by the CDI switching from enroute to terminal sensitivity.
 
Did Garmin every produce a GNC 430(W) trainer that you could use on your PC to practice different scenarios? I found the GTN 650 trainer invaluable for that—just run through dozens of different scenarios and see what happens.
 
KeepWatch said:
I looked this up because I have recently been on an approach and gotten a warning message from the GNS (430/530) that "approach has not been activated" even though I was navigating on a published segment of the approach course. All I can come up with is that I had inadvertently pressed "Direct-To" on one of the fixes and had failed to ever select Activate Approach.
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Is this what you got?
upload_2020-10-15_14-57-19.png
 
KeepWatch said:
Yes I believe it is. Tell me how I screwed up please :confused:
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If you tell us the approach and the scenario I can probably be more certain but here's my guess. You can probably set it up in the emulator yourself.

You have the approach loaded from a logical transition (not VTF) and are being vectored (or vectoring yourself for practice). You take that final vector to intercept the extended final approach course. The problem is that the approach won't activate unless you intercept the final approach course a certain distance outside the FAF. I don't recall the exact number right now (I'm sure someone here will supply it) but it's similar to the "approach gate" concept for ATC. Since you eschew VTF altogether, I'm guessing you did either one of two things:
  1. Instead of cursoring to the FAF and activating the leg to it by hitting the Direct key twice, you only hit it once and went direct to the FAF. Direct to the FAA is not before the FAF on the extended FAC, so the approach didn't activate (that's what I did to get that message). That's what I meant earlier by activating an approach y going direct to a "proper" waypoint on the approach. The FAF is not a "proper" waypoint.
  2. You did activate the proper leg, but did it when you were to close to the FAF. Same result for the same reason.
Sound about right?
 
midlifeflyer said:
If you tell us the approach and the scenario I can probably be more certain but here's my guess. You can probably set it up in the emulator yourself.

You have the approach loaded from a logical transition (not VTF) and are being vectored (or vectoring yourself for practice). You take that final vector to intercept the extended final approach course. The problem is that the approach won't activate unless you intercept the final approach course a certain distance outside the FAF. I don't recall the exact number right now (I'm sure someone here will supply it) but it's similar to the "approach gate" concept for ATC. Since you eschew VTF altogether, I'm guessing you did either one of two things:
  1. Instead of cursoring to the FAF and activating the leg to it by hitting the Direct key twice, you only hit it once and went direct to the FAF. Direct to the FAA is not before the FAF on the extended FAC, so the approach didn't activate (that's what I did to get that message). That's what I meant earlier by activating an approach y going direct to a "proper" waypoint on the approach. The FAF is not a "proper" waypoint.
  2. You did activate the proper leg, but did it when you were to close to the FAF. Same result for the same reason.
Sound about right?
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That makes a lot of sense. I can't find specific guidance for that case in the manual for the later GTN series, but the auto switch to VLOC on an ILS approach won't happen unless you intercept the FAC at least 2 nm before the FAF, so it's probably similar for activating an approach.
 
midlifeflyer said:
If you tell us the approach and the scenario I can probably be more certain but here's my guess. You can probably set it up in the emulator yourself.

You have the approach loaded from a logical transition (not VTF) and are being vectored (or vectoring yourself for practice). You take that final vector to intercept the extended final approach course. The problem is that the approach won't activate unless you intercept the final approach course a certain distance outside the FAF. I don't recall the exact number right now (I'm sure someone here will supply it) but it's similar to the "approach gate" concept for ATC. Since you eschew VTF altogether, I'm guessing you did either one of two things:
  1. Instead of cursoring to the FAF and activating the leg to it by hitting the Direct key twice, you only hit it once and went direct to the FAF. Direct to the FAA is not before the FAF on the extended FAC, so the approach didn't activate (that's what I did to get that message). That's what I meant earlier by activating an approach y going direct to a "proper" waypoint on the approach. The FAF is not a "proper" waypoint.
  2. You did activate the proper leg, but did it when you were to close to the FAF. Same result for the same reason.
Sound about right?
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Yes. All of that is completely plausible and likely what I did. I really appreciate your reply. Aside from the extra button pushing it takes, is there any difference in activating the leg preceding the FAF and activating the approach VTF? Specifically, is there a difference in the distance from the FAF where you must intercept the FAC for the Approach to become active?
 
KeepWatch said:
Yes. All of that is completely plausible and likely what I did. I really appreciate your reply. Aside from the extra button pushing it takes, is there any difference in activating the leg preceding the FAF and activating the approach VTF? Specifically, is there a difference in the distance from the FAF where you must intercept the FAC for the Approach to become active?
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Not AFAIK.
 
KeepWatch said:
Yes. All of that is completely plausible and likely what I did. I really appreciate your reply. Aside from the extra button pushing it takes, is there any difference in activating the leg preceding the FAF and activating the approach VTF? Specifically, is there a difference in the distance from the FAF where you must intercept the FAC for the Approach to become active?
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Give it a try in the PC trainer and let us know (I'm curious, too).
 
David Megginson said:
I suggest that the OP @sarangan download that and try replaying the scenario.
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My question was whether I was bypassing any monitoring features such as RAIM by going direct to the FAF. In other words, does "Activate Approach" do some other stuff in addition to activating that leg of the route?
 
sarangan said:
My question was whether I was bypassing any monitoring features such as RAIM by going direct to the FAF. In other words, does "Activate Approach" do some other stuff in addition to activating that leg of the route?
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Fair enough. I think you have the answer in the comments above: unless you're already more-or-less centred on the approach course, going direct to the FAF won't activate the approach at all, because you have to be on the approach course a certain distance before the FAF (possibly 2 nm, but TBD). If you went direct to an earlier waypoint in the approach, all would probably be OK, but the FAF is just too late to intercept.
 
David Megginson said:
Fair enough. I think you have the answer in the comments above: unless you're already more-or-less centred on the approach course, going direct to the FAF won't activate the approach at all, because you have to be on the approach course a certain distance before the FAF (possibly 2 nm, but TBD). If you went direct to an earlier waypoint in the approach, all would probably be OK, but the FAF is just too late to intercept.
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I'd have to play around on my next flight or on the simulator software, but IIRC you need to navigate to the IAF or IF or activate a leg prior to the FAF to get everything to work properly. At any rate, you will know if the correct integrity checks are satisfied by seeing TERM within 31 nm of the destination airport when prior to the FAF, and when within 2 nm of the FAF an annunciation of LNAV, LPV, etc. As far as I know, a WAAS unit will check integrity continuously for the flight mode selected (ENR, TERM, various approach modes).
 
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