ILS vs LPV

[jetdriven]

Just now, Jim Peace said:

if there was ever an approach that could be flown below a DH it is an ILS.....below DA or MDA is a different matter....

DH and DA are the same thing, just different reference points. WRT the pilot initiating a missed at the DA, a LPV or ILS is the same.

[Jim Peace]

Just now, jetdriven said:

DH and DA are the same thing, just different reference points. 

true I meant to write AH on an ILS,,,,,,how many space based approaches have an AH and are trusted to land in zero vis?

[jetdriven]

What is an AH?

[Jim Peace]

12 minutes ago, jetdriven said:

What is an AH?

Alert height....get to the alert height and if all components and legalities met and working land...usually 50 feet...if you cant see then still land....the taxi part is real fun....I know this is done with space based systems on drones but when its in the 121 world then I will get serious with GPS approaches...right now they are just an annoyance.  Must consider them non precision and do a special briefing etc.  ILS is just a normal day.....

I get the usefulness in the part 91 world where an airport does not have the budget for ILS equipment and GPS gives a lot more options....but in the 121 world give me an ILS everyday.

[PT20J]

43 minutes ago, jetdriven said:

A stands for "Don't add"... airline guys will get this"

(don't add 50' to the MDA for missed transition allowance)

MDA is a hard floor whereas you are expected to descend below DA while transitioning to the missed.

I like whatever has the easiest setup and most direct navigation. That said, I've suffered the galloping glideslope at KMRY in a 30 kt gusting crosswind, and I've had the tower switch runways 180 deg and forget to switch the localizer, and I've had to shoot the backcourse at KMFR  for real when iced up. All mildly unpleasant experiences that would not pertain to LPV approaches.

[M016576]

56 minutes ago, PT20J said:

MDA is a hard floor whereas you are expected to descend below DA while transitioning to the missed.

I like whatever has the easiest setup and most direct navigation. That said, I've suffered the galloping glideslope at KMRY in a 30 kt gusting crosswind, and I've had the tower switch runways 180 deg and forget to switch the localizer, and I've had to shoot the backcourse at KMFR  for real when iced up. All mildly unpleasant experiences that would not pertain to LPV approaches.

That backcourse at MFR sucks.  During the day, VMC it sucks.  Night or imc- geez... 

those mountains always seemed a lot closer in my mind than they are, when on that thing....

[mark21m20c]

ILS is a better approach because it allows aircraft with capability to auto land down to 300 rvr. Your going into to KSEA RVR is 1800 alternate is kpdx  . wx  AT kpdx IS 400 AND A 1/2 DROPING FAST . YOU HAVE LEGAL FUEL PLUS A LITTLE  HOLDING FUEL WHAT APPROACH WOULD YOU ASK FOR ?

[aviatoreb]

This is a good thread for sharpening ifr decision making concepts.

who remembers that jimmy Stuart movie where he lands a 1950s Bomber in Japan to minimums with only 3 min of fuel remaining and a numb arm and no chance to go around.

the new age of digital autopilots they should build in auto land at least for emergency use like a single panic button around land to nearest.  Even if it’s a rough metal bending landing I’m thinking of a non pilot passenger just in case it would be better than the alternative.

[Jerry 5TJ]

2 hours ago, m20c1967 said:

ILS is a better approach because it allows aircraft with capability to auto land down to 300 rvr.....

That’s not your garden-variety (category I)  ILS.  Category II and III ILS require special aircrew and aircraft certification.  The ground based equipment of a Category II and III ILS is special, too, and more carefully surveyed.

There are GBAS GPS approach equivalents that meet the Category II and III landing mínima including autoland in zero-zero conditions. 

Interesting aside: During a Category III missed approach the plane may briefly touchdown on the runway.   

 

[midlifeflyer]

16 hours ago, jaylw314 said:

Just for S&G's, here's a video of my approach yesterday.  Thanks to @gsxrpilot for suggesting neutral density filters, I think I might have gone too dim so I'm going to try the next darkness up next time...  Yes, I know, it's not my best landing ever 

 

NICE!

Thing about ND filters is they are essentially dimmers for our cameras. In the clouds things are already dimmer. So the number which looks great above the clouds in the sunshine might be too high when in the clouds.

[Bob - S50]

Having been following this thread, if there is anyone here who will launch when their destination is at or forecast to be at minimums or below has bigger gonads than I do.  So all this talk about which is better below 200' is moot to me.  And I wish the best of luck to anybody who does have those oversized gonads and doesn't have the fuel to reach an alternate with current and forecast weather ...well above... minimums.

[Oscar Avalle]

I paid so much money for the receiver and the data base that I prefer to use the LPV. 

[jaylw314]

5 hours ago, midlifeflyer said:

NICE!

Thing about ND filters is they are essentially dimmers for our cameras. In the clouds things are already dimmer. So the number which looks great above the clouds in the sunshine might be too high when in the clouds.

Thanks, I think the trick is finding the darkest filter that doesn't wash out the image at the dimmest lighting.  It wasn't hideously dim below the clouds that day, so I clearly guessed too dark.

[jaylw314]

15 hours ago, gsxrpilot said:

I'll just mention here (not to call out @chrisk and the GTN650) but my IFD540 loads the ILS or the LP/LPV approach exactly the same. All I have to do is select the ILS off the list of available procedures, it sets up the radios appropriately and flies the approach. So from a button pushing perspective, there is no difference for me between an ILS, VOR, or any GPS approach.

It was also mentioned that the LPV can be followed below minimums whereas the ILS can't? I shot the ILS into KOKC one day and only acquired the lights (barely) at 200 ft. I'm sure the autopilot continued to follow the ILS lower. I didn't punch the red button until I had the runway clear in my sights and was rounding out to land. 

FWIW, on the 530W, it will automatically change from GPS guidance to ILS when you are on final within a certain distance UNLESS you forget to flip the ILS to the active frequency.  Ask me how I know that

I thought our typical approach autopilots were only authorized for use down to 200' AGL?  I can't remember where I heard that...

[gsxrpilot]

9 minutes ago, jaylw314 said:

Thanks, I think the trick is finding the darkest filter that doesn't wash out the image at the dimmest lighting.  It wasn't hideously dim below the clouds that day, so I clearly guessed too dark.

I thought the dark gloomy view in the clouds was perfect and made the lights the focus as they started to come visible out of the dark.

[gsxrpilot]

1 hour ago, Bob - S50 said:

Having been following this thread, if there is anyone here who will launch when their destination is at or forecast to be at minimums or below has bigger gonads than I do.  So all this talk about which is better below 200' is moot to me.  And I wish the best of luck to anybody who does have those oversized gonads and doesn't have the fuel to reach an alternate with current and forecast weather ...well above... minimums.

The first time for me it was forecast at minimums all morning at KOKC. I launched with a full load of fuel out of Austin knowing it would be severe clear all day in Austin. I had enough gas to get to OKC, shoot the approach a few times, and fly all the way back to Austin with plenty in reserve. So I figured if there was ever a time to put the skills to the test, that was it. 

There was huge satisfaction in making the flight, shooting the ILS right to minimums, landing and getting to my destination.

I've done 3 or 4 since then, but always with plenty of fuel to go where it's easy VFR if it doesn't work out. It's one of the nice things about flying a Mooney with speed and 1000 miles of range.

[PaulM]

20 minutes ago, jaylw314 said:

I thought our typical approach autopilots were only authorized for use down to 200' AGL?  I can't remember where I heard that...

That is a standard caveat,  generally the design is "what happens if a runaway AP/trim event happens *now*."  

It wold be in the AFM suppliment, here is the S55X one:

https://cdn2.hubspot.net/hubfs/4147179/technical_documents/AFM Supplements/SUPP0014A.pdf

6. Autopilot use prohibited below 240’ AGL during coupled approach operations.

Some ILS approaches are not authorized to be AP coupled that low: 

KMMU ILS LOG RWY 23: Autopilot coupled approach NA below 732

https://aeronav.faa.gov/d-tpp/1813/00931IL23.PDF

No Limitation on the RNAV Z RWY 23. 

https://aeronav.faa.gov/d-tpp/1813/00931RZ23.PDF

All approaches and approach types have error margins. Fly each one and see which gives you, in your current equipment the best performance.   I have found that the LPV approaches are rock solid, where coupled ILS approaches can wander a bit inside of the OM, you will still get to 200 & 1/2... but it doesn't feel as stabilized. 

Here is an ILS siting guide, and in image A2-4 there is an example of charted error with reflective obstacles. As long as the parameters are within tolerances the approach will be approved.    Not all antenna installations are the same, and you can't compare a CATIII site with a CAT I site... not all ILSs are built to the same specifications.    The ILS signals are that stable, at KEWR, KJFK, KBOS, for the CATIII runways only. They are not required to be that stable at other airports. 

https://www.faa.gov/documentLibrary/media/Order/FINAL_SIGNED_Order_6750_16E_ILS_Siting_Criteria_06-09-2014_for_Web_posting[1].pdf

[Marauder]

How about we end this debate and be happy to say that in today’s environment we can fly both and not have to do an NDB approach?

 

Here is an example of both of my HSIs flying a practice approach. The PFD showing the LPV and the MFD HSI showing the ILS.

 

 

What I love about this new technology is the ability to do something like flying a VOR approach and having the GPS overlay available for cross reference. Or you could go crazy and have all available Nav sources to look at!

 

 

 

 

Sent from my iPad using Tapatalk Pro

 

[Jim Peace]

3 hours ago, Marauder said:

Here is an example of both of my HSIs flying a practice approach.

Yeah but can they core an apple?

 

[co2bruce]

38 minutes ago, Jim Peace said:

Yeah but can they core an apple?

 

One of the funniest things I remember from my youth. Thank you.

[mark21m20c]

The point I was trying to make is if weather is deteriorating(not forcasted). Your getting low on fuel the ILS is best approach because of lower mins. do not trust wx reports when picking your approach, take approach with lowest mins . wx changes fast . I have gone into airports reporting 6 miles and 5000 broken and had to go around due wx below mins on ils.  The only time I would take gps over ils is if I didn't trust ground based equipment . Your going into bogota Colombia the wx report is 9000 overcast 3000m , would you ask for rnav 13L with mins of 8736 / 1700m or ILS 13L with mins of 8576 and 550m ???? 

[mark21m20c]

wx 900 overcast not 9000 

sorry

[jaylw314]

1 hour ago, m20c1967 said:

The point I was trying to make is if weather is deteriorating(not forcasted). Your getting low on fuel the ILS is best approach because of lower mins. do not trust wx reports when picking your approach, take approach with lowest mins . wx changes fast . I have gone into airports reporting 6 miles and 5000 broken and had to go around due wx below mins on ils.  The only time I would take gps over ils is if I didn't trust ground based equipment . Your going into bogota Colombia the wx report is 9000 overcast 3000m , would you ask for rnav 13L with mins of 8736 / 1700m or ILS 13L with mins of 8576 and 550m ???? 

I think the OP was considering airpots where the (LPV) RNAV and ILS have identical or near identical DA's.  I have at least one in my local area where they are identical, and another with only a 50' difference

[mark21m20c]

what airport has same mins for ils and rnav ?

 

[mark21m20c]

I stand corrected I see kewr rnav z 22l is down to 211 /1800rvr. what I fly cant do rnp and only do gps .

sorry!!!