Garmin 430 Approach Activation question

chemgeek said:
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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Nitpick: It is within 30 miles of the airport reference point. Lots of RNAV criteria are predicated on this 30 mile point from the ARP.
 
And RAIM (Receiver Autonomous Integrity Monitoring) can be calculated for a specific airport at a specific time based on a minimum of 5 GPS satellites being received with appropriate geometry.
 
This is slightly different — the diagram shows where the GTN 650 will autoswitch the CDI to VLOC on an ILS approach — but the boundaries may be similar for activating an approach. For this case, you have to be within 1.2 nm on either side of the approach course, and between 2 nm and 15 nm before the FAF for the switch to happen.
upload_2020-10-16_15-21-6.png
 
When you load an approach into the GNS, it inserts it as a flight plan section after the enroute section. You can edit the approach section or leave it as is. If you subsequently activate the approach, the effect is identical (except in the case of VTF) to selecting the first fix in the flight plan section and providing navigation via a direct-to the first fix. If you don't edit the approach section, it will always be direct to the original first fix in the approach section. If you edit the approach section, the first fix in the resulting approach sequence will be where the GNS will proceed direct-to. You can manually select any fix before the FAF in the approach section and use direct-to and the GNS will proceed direct and fully activate the approach sequence from that point. You can't go direct to the FAF as that will generate an error message to the affect that the approach has been cancelled. You can activate the leg ending at the FAF or you can activate the leg beginning at the FAF to the MAP. Either of those actions will end up providing you with vertical guidance for a GNS/W. Now on the GTN series, we have a visual approach option. You can get the equivalent on a GNS/W if you activate the leg between the FAF and the MAP (usually the runway) and I find this useful to obtain vertical guidance on a visual approach when you intercept the final approach course inside the FAF.
 
I both love and hate the fact that the GNS boxes have eleventy-seven ways to do the same task. It is sometimes the most challenging part of flying IFR!
 
chemgeek said:
I both love and hate the fact that the GNS boxes have eleventy-seven ways to do the same task. It is sometimes the most challenging part of flying IFR!
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Same as most computer programs.
 
Extra data point -- today I tested going direct to the FAF (more specifically, the FAWP) in an RNAV approach several times in the Garmin GTN trainer, and every time, the GPS switched into LNAV mode (even when I was further out than the IAF/IAWP and fairly far off track). That doesn't mean the same would happen with the GNC 430, of course, since it's much-older software.
 
David Megginson said:
Extra data point -- today I tested going direct to the FAF (more specifically, the FAWP) in an RNAV approach several times in the Garmin GTN trainer, and every time, the GPS switched into LNAV mode (even when I was further out than the IAF/IAWP and fairly far off track). That doesn't mean the same would happen with the GNC 430, of course, since it's much-older software.
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It is similar for a GNS530W. You can't use direct-to the FAWP, even if you are dead center on the final approach course. The approach indication won't be there and at 2 NM to the FAF you get the error message Approach Not Active, but at the FAF, the LPV annunciation comes on and vertical guidance is available. You can activate the leg of the approach that ends at the FAF or at the RWT and LPV plus vertical guidance will be available.

Direct to FAF approach not active GNS530W.jpg At FAF approach goes active and LPV annunciated.jpg
 
John Collins said:
It is similar for a GNS530W. You can't use direct-to the FAWP, even if you are dead center on the final approach course. The approach indication won't be there and at 2 NM to the FAF you get the error message Approach Not Active, but at the FAF, the LPV annunciation comes on and vertical guidance is available. You can activate the leg of the approach that ends at the FAF or at the RWT and LPV plus vertical guidance will be available.

View attachment 91271 View attachment 91272
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Interesting. I don't get the "Approach is not active" warning with the GTN trainer, just the switch to LNAV/LPV.
 
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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A good work-a-round for the "VTF" deletion of waypoints outside the FAF is to load the full approach, then highlight and activate only the leg to the FAF. That's the segment you'll be vectored onto by ATC and you'll still be able to see all the fixes.
 
If you just want to activate the vertical and lateral guidance for a pseudo visual approach or when you are cleared for a visual but inside the FAF, move the cursor to the RWY and hit direct-to, direct-to, and enter. That will turn on the vertical and lateral guidance. It can be useful for night time operations.
 
John Collins said:
If you just want to activate the vertical and lateral guidance for a pseudo visual approach or when you are cleared for a visual but inside the FAF, move the cursor to the RWY and hit direct-to, direct-to, and enter. That will turn on the vertical and lateral guidance. It can be useful for night time operations.
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Unless you have a G-1000Nxi, which has database visual approaches to all runway ends. I suppose this feature is also in some of Garmin's other more recent offerings.
 
Yes, but this is a GNS430 thread. I have that feature on my GTN750 and it is well publicised. What I wrote is not well known, and it preceded the later introduction of visual approaches on some of the GX000 and GTN systems and provides essentially the same capability with the GNS430W/530W. Just a note regarding the visual approaches, it is to most runway ends, but not all.
 
John Collins said:
Yes, but this is a GNS430 thread. I have that feature on my GTN750 and it is well publicised. What I wrote is not well known, and it preceded the later introduction of visual approaches on some of the GX000 and GTN systems and provides essentially the same capability with the GNS430W/530W. Just a note regarding the visual approaches, it is to most runway ends, but not all.
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I checked KUKI Runway 33. It has a database visual, which I find incredible.
 
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