LP approach question

benyflyguy

benyflyguy

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benyflyguy
During training I got my first crack at an LP approach last week in to RNAV08 at KDXR. I have a 430 with WAAS. As expected I didn’t get any vertical guidance.
So today I and flying an approach into KSEG on the RNAV 35, it too also has an LP approach. But this time a glide slope popped up?!? I didn’t expect it and was not sure what to think about it.
I was under impression that I should not get any vertical guidance on a LP approach. While I appreciated it I wasn’t sure I would be able to trust it.
Thoughts?
 
So I just looked at the plate again. The plot thickens. So if I’m getting vertical guidance the minimum is 600’ higher! As it appears if I’m getting vertical guidance then I have to use the LNAV minimums. I was planning on flying to the LP miminums. I need to go back to the gps and see if I can choose between the LP vs the LNAV. In this case I would prefer the LP as the miminums are much lower.
So if the 430 WAAS gives me vertical guidance on a LP approach my minimums might go up?? That doesn’t make a lot of sense.
 

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Yep be careful an advisory glideslope has gotchas like stepdown fixes etc


Sent from my iPhone using Tapatalk
 
Your charts are NACO. Your data subscription is Jeppesen. LNAV+V is a Jeppesen product to provide some guidance to the MDA.
 
benyflyguy said:
During training I got my first crack at an LP approach last week in to RNAV08 at KDXR. I have a 430 with WAAS. As expected I didn’t get any vertical guidance.
So today I and flying an approach into KSEG on the RNAV 35, it too also has an LP approach. But this time a glide slope popped up?!? I didn’t expect it and was not sure what to think about it.
I was under impression that I should not get any vertical guidance on a LP approach. While I appreciated it I wasn’t sure I would be able to trust it.
Thoughts?
Click to expand...
Pretty sure I read somewhere that just like LNAV+V, WAAS GPSs can add an advisory glideslope to a LP approach to make it LP+V - I think this is a Jepp innovation so it would also depend on the database. Your GPS should have a field that displays the approach type, and should say LP+V if that's what is going on.

I have never flown a LP approach with my 480, but I have flown LNAV-only approaches with advisory glideslopes, and it does annunciate LNAV+V for those.
 
benyflyguy said:
So I just looked at the plate again. The plot thickens. So if I’m getting vertical guidance the minimum is 600’ higher! As it appears if I’m getting vertical guidance then I have to use the LNAV minimums. I was planning on flying to the LP miminums. I need to go back to the gps and see if I can choose between the LP vs the LNAV. In this case I would prefer the LP as the miminums are much lower.
So if the 430 WAAS gives me vertical guidance on a LP approach my minimums might go up?? That doesn’t make a lot of sense.
Click to expand...
That is not correct. With a WAAS box where there are LP and LNAV minimums, so long as WAAS is functioning the avionics default to LP. And, the hint that you should get LP+V is indicated in the profile view. This must be confirm by seeing LP+V when you review or select the approach in your 430.
 

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gsengle said:
Yep be careful an advisory glideslope has gotchas like stepdown fixes etc
Click to expand...
Jeppesen won't include an advisory GS in the database if it doesn't clear stepdown fixes. The greater concern is using the advisory GS from MDA to the threshold.
 
aterpster said:
Jeppesen won't include an advisory GS in the database if it doesn't clear stepdown fixes. The greater concern is using the advisory GS from MDA to the threshold.
Click to expand...

Thanks for the help. Will look for the confirmation next time I fly that approach. An in future look for that with all LP approaches. The king 430 course doesn’t review that I think.
I would never use glide slope to threshold. That’s below miminums!!! If I don’t see at mda and at map then it’s go to the missed!
 
benyflyguy said:
I would never use glide slope to threshold. That’s below miminums!!! If I don’t see at mda and at map then it’s go to the missed!
Click to expand...
I don't think Wally's talking about using the glide path to bust minimums...but once you break out, there could be obstructions that penetrate that glide path as you descend visually from MDA to the runway.
 
As I am on the final approach course for an RNAV approach, one of my checklist callouts is the annunciation my WAAS GPS is showing me. This way I verify what I was expecting (and briefed) or recognize I got something else and I need to update the minima I'm using to the guidance I'm being provided.
 
benyflyguy said:
During training I got my first crack at an LP approach last week in to RNAV08 at KDXR. I have a 430 with WAAS. As expected I didn’t get any vertical guidance.
So today I and flying an approach into KSEG on the RNAV 35, it too also has an LP approach. But this time a glide slope popped up?!? I didn’t expect it and was not sure what to think about it.
I was under impression that I should not get any vertical guidance on a LP approach. While I appreciated it I wasn’t sure I would be able to trust it.
Thoughts?
Click to expand...

What did the flight mode annunciation say?
 
gsengle said:
Yep be careful an advisory glideslope has gotchas like stepdown fixes etc
Sent from my iPhone using Tapatalk
Click to expand...

Yep ESPECIALLY at a place like KDXR. That +V is advisory only on an LNAV approach. You still have to be above your step down mins.
 
labbadabba said:
Yep ESPECIALLY at a place like KDXR. That +V is advisory only on an LNAV approach. You still have to be above your step down mins.
Click to expand...
At KDXR was the first time I encountered a LP approach. So I wasn’t expecting glideslope and didn’t get one at all which makes sense. In fact the terrain is a good example of when a glideslope could get you in trouble.
Then less then a week later I do another LP and expected no glideslope. Thinking back I remember the the Left Lower corner area did have LP+V. I will have to shoot the approach and pay attention. Will make it part of my routine checklist to announce it as well when setting up my approach
 
benyflyguy said:
At KDXR was the first time I encountered a LP approach. So I wasn’t expecting glideslope and didn’t get one at all which makes sense. In fact the terrain is a good example of when a glideslope could get you in trouble.
Then less then a week later I do another LP and expected no glideslope. Thinking back I remember the the Left Lower corner area did have LP+V. I will have to shoot the approach and pay attention. Will make it part of my routine checklist to announce it as well when setting up my approach
Click to expand...

Yep, a LPV is protected precision guidance (like an ILS) but a LNAV+V is suggested vertical guidance and is not published; these are the ones that a really helpful but also can get you into trouble. The newer GPS boxes will even give you a 3-degree advisory glidepath for visual approaches but again, maintaining your situational awareness is incumbent upon you as PIC.

I know before my checkride, I wrote out the different types of GPS approaches and what they mean. Here's a solid article on it:

http://www.boldmethod.com/learn-to-...ference-between-lpv-and-lnav-vnav-approaches/
 
labbadabba said:
Yep, a LPV is protected precision guidance (like an ILS) but a LNAV+V is suggested vertical guidance and is not published; these are the ones that a really helpful but also can get you into trouble. The newer GPS boxes will even give you a 3-degree advisory glidepath for visual approaches but again, maintaining your situational awareness is incumbent upon you as PIC.

I know before my checkride, I wrote out the different types of GPS approaches and what they mean. Here's a solid article on it:

http://www.boldmethod.com/learn-to-...ference-between-lpv-and-lnav-vnav-approaches/
Click to expand...
Just to be clear, it looks like @benyflyguy wrote LP+V not LPV. Two different things. LPV is for all intents and purposes a precision approach as you said, LP+V is LP with an advisory glideslope.
 
benyflyguy said:
At KDXR was the first time I encountered a LP approach. So I wasn’t expecting glideslope and didn’t get one at all which makes sense. In fact the terrain is a good example of when a glideslope could get you in trouble.
Then less then a week later I do another LP and expected no glideslope. Thinking back I remember the the Left Lower corner area did have LP+V. I will have to shoot the approach and pay attention. Will make it part of my routine checklist to announce it as well when setting up my approach
Click to expand...

Good idea. The flight mode annunciation is pretty important.
 
luvflyin said:
Good idea. The flight mode annunciation is pretty important.
Click to expand...

Extremely. The joke on the GNS gear is that the most common way to bust a checkride is not to flip it to “VLOC” (so called “green needles”) when established on an ILS.

On the GTN ... *if* the unit is set to automatically capture and cycle it’ll flip it for you, but you’d better a) check the setting in the menu before takeoff and b) monitor it anyway and be ready to flip it yourself if it doesn’t switch.
 
On the 430W, if you're getting a "glideslope" the your unit will annunciate LP+V. The "glideslope" will take you down a slope at or above the published "step-down" altitudes. However +V also means that the piloy is still responsible for ensuring that safe altitudes during descent on the "Glideslope."
 
denverpilot said:
Extremely. The joke on the GNS gear is that the most common way to bust a checkride is not to flip it to “VLOC” (so called “green needles”) when established on an ILS.

On the GTN ... *if* the unit is set to automatically capture and cycle it’ll flip it for you, but you’d better a) check the setting in the menu before takeoff and b) monitor it anyway and be ready to flip it yourself if it doesn’t switch.
Click to expand...

Yup. It’s been called the $400 button. That’s what it’s gonna cost you for another checkride
 
From the 430 manual, page 6-26.

"The GNS 430 can be set to automatically switch the external CDI output from GPS to VLOC as the pilot intercepts the final approach course. When the ILS
approach is activated, the GNS 430 automatically switches within 1.2 nm left or right of the final approach course. This switch can take place anywhere from 2.0 to 15.0 nm from the FAF."

Please send your $400 to @Ted DuPuis to support Cloud Nine.
 
Ravioli said:
From the 430 manual, page 6-26.

"The GNS 430 can be set to automatically switch the external CDI output from GPS to VLOC as the pilot intercepts the final approach course. When the ILS
approach is activated, the GNS 430 automatically switches within 1.2 nm left or right of the final approach course. This switch can take place anywhere from 2.0 to 15.0 nm from the FAF."

Please send your $400 to @Ted DuPuis to support Cloud Nine.
Click to expand...

Thanks. Very helpful. Will plan on going into menu and updating this. I can’t think of a reason not to have this do it automatically??!!
 
Ravioli said:
From the 430 manual, page 6-26.

"The GNS 430 can be set to automatically switch the external CDI output from GPS to VLOC as the pilot intercepts the final approach course. When the ILS
approach is activated, the GNS 430 automatically switches within 1.2 nm left or right of the final approach course. This switch can take place anywhere from 2.0 to 15.0 nm from the FAF."

Please send your $400 to @Ted DuPuis to support Cloud Nine.
Click to expand...

Ted DuPuis said:
That would be much appreciated. Just dropped the MU-2 off for its first 100/200 hour (annual) inspection. :eek:
Click to expand...

Extra note for those interested: We have a crowdfunding effort going on for the inspection here:

https://poundwishes.com/donate/2869826/mitsubishi
 
benyflyguy said:
My buddy has an mu2. Sweet ride. But those bills I think are only ever in the 5 fig range:eek::eek::eek:
Click to expand...

It depends on the shop and the squawks on the plane, as with anything. The shop we are using is giving us a generous discount on the base inspection as well as labor, but we're also going in with a few known items to look at.
 
benyflyguy said:
During training I got my first crack at an LP approach last week in to RNAV08 at KDXR. I have a 430 with WAAS. As expected I didn’t get any vertical guidance.
So today I and flying an approach into KSEG on the RNAV 35, it too also has an LP approach. But this time a glide slope popped up?!? I didn’t expect it and was not sure what to think about it.
I was under impression that I should not get any vertical guidance on a LP approach. While I appreciated it I wasn’t sure I would be able to trust it.
Thoughts?
Click to expand...

Be very careful. Only the LPV or LNAV/VNAV approach provides vertical guidance inside the FAF that guarantees separation from terrain. The former has more precision. LP approaches are the GPS analog of localizer approaches, with precision lateral guidance, but no vertical guidance. Some LNAV approaches, e.g. LNAV+V in your GNS430, will provide advisory vertical guidance, but this does NOT necessarily provide for separation from terrain and may take you below stepdown fixes. Following that advisory vertical guidance when IMC could at some airports put you close to terrain. I'd be happy if Garmin disabled the +V in these approaches.
 
benyflyguy said:
Thanks. Very helpful. Will plan on going into menu and updating this. I can’t think of a reason not to have this do it automatically??!!
Click to expand...

Be mindful that the switch happens at between 2 and 15 nm from the FAF. I recall reading a post a few years ago by a pilot who on vectors to final intercepted the approach course inside of 2 miles from the FAF. The CDI didn't switch automatically. He caught it and switched it manually. Moral being that if you change to automatic switching, make sure you continue with a manual check.
 
After thinking and reviewing. I think I’m going to plan on making part of my “establishing on the approach” checklist. I have a habit of checking the approach chart MDA three separate times in short period of time. Checking the gps for type of approach/vloc can be something I do in between the altitude check. Why three? My CFII got me into that habit. You can look at something once and mix it up, even twice, but thrice, there’s little chance for a mistake three times in a row.
 
bkspero said:
Be mindful that the switch happens at between 2 and 15 nm from the FAF. I recall reading a post a few years ago by a pilot who on vectors to final intercepted the approach course inside of 2 miles from the FAF. The CDI didn't switch automatically. He caught it and switched it manually. Moral being that if you change to automatic switching, make sure you continue with a manual check.
Click to expand...

You have to. Automation must be managed. It lowers workload but it also goes wrong.

benyflyguy said:
After thinking and reviewing. I think I’m going to plan on making part of my “establishing on the approach” checklist. I have a habit of checking the approach chart MDA three separate times in short period of time. Checking the gps for type of approach/vloc can be something I do in between the altitude check. Why three? My CFII got me into that habit. You can look at something once and mix it up, even twice, but thrice, there’s little chance for a mistake three times in a row.
Click to expand...

If you’re inside the FAF and haven’t confirmed “the boxes” are set, sooner or later you’re toast. Checklists are great, but it also just has to become an internalized habit. The checklists help with that at first and confirm it later after it’s ingrained.
 
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