GPS overlay removed from SBA VOR 25 approach... why?

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dougmcclean@reddit

Unpopular opinion: Now that paper is free, there shouldn't be any THIS OR THAT plates. Publish a THIS plate and a THAT plate, and avoid the chance for confusion and some of the notes, * LOC Only crossing restrictions, and arcane rules of interpretation. This is ultimately about safety not creating a mystical cult of elect clerics who can tell a Maltese cross from a squiggly arrow.

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kmac6821@reddit

So if you lose glideslope on your ILS or LOC procedure, are you automatically going to go missed? There isn’t anything mystical about identifying the precision and non-precision FAFs. It’s been this way for what, 50+ years? Have pilots in the age of tablets just not been as good as their paper-only forerunners? But aside from that… how would you make charts?

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dougmcclean@reddit

If you lose glideslope on your ILS during the approach am I going missed? Yes, I'm not rebriefing it and figuring out what's up when already past the FAF. I may already be below a crossing restriction. I might already be below the MDA, did I memorize it or am I still descending while I diagnose that the GS failed and look down at what the MDA was? Do you routinely brief MDA on your ILS approach briefings so that you'll be ready to fail over instantly? Are you confident that the instrumentation failure didn't also affect the localizer? Are you configured to identify the charted MAP? Have you passed it? Just go around and figure it out away from obstacles. There is something mystical about it, we are just initiate. It confuses every new student, and you can easily find one zillion posts of people asking questions about it and people giving various correct or subtly incorrect answers. I would start demultiplexing the charts. Make an ILS one and a LOC one. If you can fly the track of a VOR approach in GPS only mode make an RNAV approach that just so happens to have the same track, etc. (It would take much more work and is a different category of plan, but in the longer term it would be better to have the first several layers of chart interpretation be automated. Ask me 4 questions and then remove the 70% of stuff that became irrelevant (categories this aircraft isn't capable of, stuff for falling back to remote altimeter settings that almost never happens, winter stuff in summer, night stuff at 1 pm, the list goes on. I understand how to read past it and so does everyone else, but it's vulnerable to error and time consuming, neither of which is good. But again this goes much farther and makes the chart a living thing with a rigid datastructure, not a raster graphic. Therefore it's hard because it's significantly more complicated to review during publishing.)

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kmac6821@reddit

ILS or LOC is one procedure, so those shouldn’t be split. The same thing happens with any RNAV… whether you’re flying LNAV or LPV, it’s the same procedure. Why is anything on a chart mystical? Do students not read the legend pages? Or the Chart User’s Guide? Most of the posts I see here could have easily been answered by simply turning to the source. My hunch is that those folks only using tablets are simply not aware of the chart basics. With paper charts, both enroute and terminal, the legends are readily apparent.

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dougmcclean@reddit

I understand that it's charted as one. It's two procedures that are overlaid. This burdens the chart user to un-overlay them while moving at 200 kts with lives on the line, when they could be un-overlaid on the ground at 0 kts by experts with a chance for review. Same goes for LPV vs LNAV. The current state exists because flight bags used to be too heavy already. If it wasn't for that history, and ILS was invented today, ILS OR LOC charts would not be a thing. What's mystical about it? It's insanely complicated. Simple cases are only very bad, but then the complicated cases become insane and people can have headscratching 20 minute debates about which minima pertain to a given situation that can be easily missed in flight. (I'm looking at you, notes and INOP table.) The mere existence of a tome explaining the mystical symbols does not mean they are not mystical symbols. Show an approach plate to a non-pilot and see what you get. Worse, ask hard questions to students in instrument ground school. It's mystical. I get why it is how it is, these procedures have to capture a lot of nuance to provide operational flexibility and safety. We don't need to make that problem worse than it needs to be by continuing to conserve a resource that we no longer actually use in flight anyway.

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kmac6821@reddit

This is a common misunderstanding. An ILS or a LOC is a single procedure when it comes to both TERPs and charting. Many pilots treat these as two separate procedures, but they’re the same lateral guidance with separate minima. Hence, they’re one procedure. Previously, the title was just ILS. It still had localizer and circling minima. “ILS or LOC” charts exist so that controllers can clear you for the localizer instead of the old way, in which they would clear you for the ILS but say “glideslope inop.” That change occurred after the Korean Air 801 incident, when the crew didn’t seem to understand that the glideslope was inop on the ILS approach. This is different from a VOR or TACAN approach, which has separate lateral guidance for the final approach course. This also happens for ILS or RNAV (GPS) approaches. When the lateral guidance is not the same, it’s a separate procedure. Your point about a non-pilot reading a chart is a red herring. Being an instrument rated pilot requires a minimum standard of knowledge. Understanding the symbols on a chart is part of that requisite knowledge. As for the resource of paper… you won’t have a disagreement from me. I don’t like charting separate procedures on a single chart. However, this doesn’t change the fact that your clearance for an ILS approach is also clearance for the localizer minimums. Hence, it’s one approach. Finally, and totally out of order, I agree completely with you on both chart notes and the inop components table. I’m not sure the chart modernization effort will truly fix that. The plan for the FAA is to not show the visibility penalty for ALS INOP if it’s standard. I disagree with that, because the new chart will have space for whatever the visibility penalty is… there wouldn’t be a need to turn to a different table.

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fountainsofvarnoth@reddit

You’re a military guy, so you’ll be familiar with this one: brief the flight, fly the brief. If I’m in a single seat fighter and I have to degrade approaches, sure. I don’t have to brief shit, I really don’t have to change anything…but playing the game in a multi-piloted transport category aircraft, I’m just gonna discontinue the approach, set everything up properly, and take another crack at it. Not because we cant hack it…but because if something does go awry, you can bet your ass the company is going to be six feet up my ass for not discontinuing, resetting all the minima, briefing, blah blah blah. Unless I’m on fire or about to flame out, it’s not worth risking that ass pain.

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Direct_Cabinet_4564@reddit

Yes, I only brief 1 approach. If the GS fails I’m going missed.

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kmac6821@reddit

Interesting. It’s actually the same approach with different minima. You absolutely can continue the approach as a localizer only, assuming you can identify the MAP.

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IFlyAirplanes@reddit

Right, but if I briefed an ILS and am flying and ILS, I’m flying an ILS. I didn’t brief Localizer minimums and on the approach isn’t the time to be re-briefing and twisting the ‘minimums’ knob. Go missed, brief the NEW approach, and come back around.

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kmac6821@reddit

Yep, it’s just interesting. That’s just an overly conservative approach, but I get it. If you brief the ILS and your glideslope goes out, you’re just having to fly any step down and go to a different minima. Are you saying you can’t brief that on the fly? I’ll say it again… an ILS and a LOC are not separate approaches. Going missed approach in my view adds unnecessary risk. My background is military, so maybe we were just trained for that scenario. If that’s not part of civilian training, I can see going missed is the safer bet.

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IFlyAirplanes@reddit

The ILS and LOC are separate approaches, they’re just charted on the same chart. -One is a precision approach, the other is a non-precision approach. -One has a glide slope, the other does not. -One has a DA, the other has an MDA. -They have different approach minimums. Explain to me how approaches with obvious differences are the same approach.

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kmac6821@reddit

Because it’s the lateral guidance on final that constitutes what is an approach. It’s no different from an RNAV (GPS) approach. That has both precision and non-precision minima. When you’re cleared for the approach, you’re cleared for any of the minima. A VOR or TACAN is two procedures because the lateral guidance is separate. The same goes for an ILS or RNAV (GPS). When you are cleared for the “ILS RWY XX”, you are cleared for either set of minimums. Either way, the lateral guidance is obviously the same. These used to be titled ILS RWY XX. The title was changed to “ILS or LOC” to give the controller the option to clear you only for the localizer minimums (i.e., cleared localizer). Before this change in the title, the controller would have to clear you for the ILS but specify that the glideslope was inop.

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IFlyAirplanes@reddit

That’s inaccurate. If you’re cleared for the RNAV (GPS) yes, you can use any of the minimums. LPV, LNAV/VNAV, LNAV…. If you’re cleared for the LOC, you cannot use ILS minimums. They’re not interchangeable approaches. Thats why the plate says “ILS *or* LOC”. RNAV is just “RNAV”

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kmac6821@reddit

Go back and reread my response. If you are cleared for the ILS, you can use any minima. The reason “or LOC” was added was so that controllers had an option to limit you to just the localizer mins without having to say “cleared for the ILS, glideslope inop.” Nothing on the approach changed other than the title being renamed. It was purely for controllers.

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Khantahr@reddit

Going missed only adds unnecessary risk if you suck at going missed. If that's the case, practice going missed until you no longer suck. Switching from an ILS to a LOC mid approach adds unnecessary risk with different minimums and identifying the MAP. There is no way I'm going switch if the GS fails, I'm going missed, and then I'm picking a GPS approach. I hate everything about LOC approaches.

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kmac6821@reddit

No, it’s a fuel situation. And you’re welcome to go missed. I’m not saying that. If you prepare in advance, however, it’s not a big deal to continue the approach.

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dougmcclean@reddit

Does anyone, in actual practice, prepare in advance for this? Has it ever, in actual practice, paid off even once? Is a genie announcing these GS failures or might the failure have caused you to deviate low before you noticed it? Does preparing in advance for this, loading your mind with 4 numbers that have a 1e-6 chance of applying to what you are doing, actually increase safety or decrease it? If it's a fuel situation, above localizer minima, and you are concerned about GS failure, brief and fly the localizer minima and use the glideslope as advisory if there are no complex crossing restrictions.

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Khantahr@reddit

If you don't have enough fuel to go missed on your first approach, you screwed up somewhere earlier. Preparing in advance is pointless. The minimums are set for the ILS, and the procedure to fly an ILS vs a LOC is different. Different brief, different automation. The chances of the GS going out are so miniscule that you're wasting time briefing both, and even if you do, switching minimums and modes mid-approach is asking for trouble. Go around, pick another (non LOC) approach, and do it again. The previous airplane I flew, the procedure for flying a LOC started with "choose a different approach if available." LOCs suck, do something else.

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kmac6821@reddit

Your assumption about screwing up prior to the approach is unfounded. Military fuel planning (Navy example here) is from departure to the destination’s IAF to the alternate plus a small reserve. It does not take into account fuel burned shooting an approach at the destination. I’m guessing that you’ve never been low fuel on an approach with weather at mins. I’m also guessing that you’re having to dial in minimums as opposed to just flying the procedure. It’s a different type of flying when you’re relying upon the aircraft’s systems. I get it. If I was switching to an MDA rather than a DA, I wouldn’t be changing a thing, to include the RADALT. I’ve also never been in a situation where the brief for an ILS is that different from a LOC. Your experience and mine must be vastly different.

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Khantahr@reddit

20 years of airlines. ILS and LOC are distinctly different. Not planning fuel for a go around at your destination is insane. What if you shoot the approach and don't see anything at minimums? I've been low fuel with low weather, but only because things went sideways earlier. Never because we didn't plan fuel for a go around, that does not happen.

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kmac6821@reddit

Yep, different regs. “What if you… don’t see anything at minimums?” That’s a risk. At that point you really only have the option of trying again and again. The idea of going to an alternate is if you know you don’t have the mins to see the runway. That’s why you start heading to your alternate before you’re at the IAF, down low and burning more fuel. We also do blue water ops. There is no divert. Having low fuel there certainly increases the pucker factor.

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Khantahr@reddit

You guys have a strange attitude toward alternates and fuel planning, blue water aside, you're adding risk. I've done plenty of approaches where we had the minimums to shoot the approach but never saw anything and ended up diverting to the alternate. Sometimes after a single try, sometimes a couple. It's not common, but it happens, and that's exactly why we have an alternate and go around fuel. It's more rare to just divert without trying an approach. Planning on not doing a go around is asking for trouble.

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kmac6821@reddit

Not arguing with you… it’s just the way it’s been… forever.

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Direct_Cabinet_4564@reddit

Why would going missed add unnecessary risk? Trying to re-brief an approach when you are going 140 knots and 700 fpm into the ground at somewhere less than 1500’ agl doesn’t seem really smart. I’m also wondering what the odds are that a glide slope suddenly quits during an approach. I’ve been flying almost 25 years at this point and I’ve never had it happen.

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FlyingPetRock@reddit

A perfect example of "just because you can, doesn't mean you should." If you plan an approach, and something goes amiss? Go missed. Going missed should be routine and not anything exciting if you are IFR current and familiar with your aircraft. Diverting important brain resources while already on an approach to re-evaluate a new approach, even if it just so happens to be practically the same like here at SBA, is a great way to kill your SA and put you in the ground forever. The risk vs. reward is not even worth asking its so bad. Go around and re-plan the new approach. It will save your life.

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Weaponized_Puddle@reddit

But but but you’re timer you remembered to set /s

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BonaFidePirate@reddit

Yes, I would go missed 100% of the time if in IMC below the MSA.

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kmac6821@reddit

That’s not a correct answer in the US.

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Khantahr@reddit

The only times going missed is not a correct answer is if you're going to run out of fuel, you're filling up with smoke, or you're on fire. Even then, it's sometimes correct.

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Sunsplitcloud@reddit

You can still fly the approach with gps all the way to minimums as long as you are monitoring the VOR

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fly123123123@reddit (OP)

For sure - just a bummer if the VOR is U/S. Looks like they also made the procedure NA at night :/

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Sunsplitcloud@reddit

Yep, AIM 1-2-3. They still have an ILS that’s available at night. Don’t worry, you can practically always get into SBA unless it’s too foggy to get below minimums on the ILS.

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AlexJamesFitz@reddit

I can't find the source at the moment, but I vaguely remember reading that "VOR or GPS" approaches are being phased out, and some such approaches that don't meet RNAV criteria may be downgraded to VOR-only in the process. You can still use GPS to fly this as long as you're monitoring the raw VOR data, but obviously only if the VOR is working.

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chipc@reddit

>You can still use GPS to fly this as long as you're monitoring the raw VOR data, but obviously only if the VOR is working. You don't need to be monitoring the VOR and the VOR does not need to be working. In fact, it's common for VOR's to be NOTAM's out of service and FDC NOTAMs issued that make departures/arrivals/approaches unavailable **unless you can fly it** with **RNAV (GPS).**

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AlexJamesFitz@reddit

You sure about that? I'm open to being proven wrong, but AC 90-108 seems pretty clear about not using GPS to substitute for a navaid on a final approach segment. See 8b: https://www.faa.gov/documentLibrary/media/Advisory_Circular/90-108.pdf

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DuelingPushkin@reddit

GPS can be substituted as primary navigation for all but a Localizer even for the final approach segment BUT you have to be able to monitor the navaid. So you can't fly it with the navaid out of service.

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Rexrollo150@reddit

This is an easy AIM section to remember. As easy as 1-2-3 😁

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fly123123123@reddit (OP)

This is not correct. You must be monitoring the underlying navaid. This applies to all approaches that do not contain GPS in the title.

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Ezekiel24r@reddit

I've most often seen that NOTAM for RNAV required come up when the Missed Approach Procedure requires use of a VOR that is temporarily down. Happens all the time at KOXR ILS 25 when the CMA VOR is down.

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Ezekiel24r@reddit

Look in the document you linked at 8(b): **8.** **USES OF SUITABLE RNAV SYSTEMS NOT ALLOWED BY THIS AC**. An otherwise suitable RNAV system cannot be used for the following: * **b.** **Substitution on a Final Approach Segment.** Substitution for the NAVAID (for example, a VOR or NDB) providing lateral guidance for the final approach segment.

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cazzipropri@reddit

See AIM 1-2-3 c Note 5 >*The underlying NAVAID must be operational and the NAVAID monitored for final segment course alignment.*

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kmac6821@reddit

All “… or GPS” approaches were supposed to be removed whenever an RNAV procedure served the airport. These GPS overlays do not fall within the Performance Based Navigation construct… they were a stopgap until PBN became widespread. See this [ACM issue.](https://www.faa.gov/sites/faa.gov/files/about/office_org/headquarters_offices/avs/Hist%252002-01-244.pdf)

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fly123123123@reddit (OP)

Bummer. Still seems like a step backwards. Sure, there’s an RNAV to runway 7, but that doesn’t replace the GPS overlay for runway 25.

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Yossarian147@reddit

You can check out the details of why procedures change [here](https://www.faa.gov/air_traffic/flight_info/aeronav/procedures/), pick your airport, and click the "IFP documents" tab. Here's the procedure in question [SBA VOR 25](https://www.faa.gov/aero_docs/acifp/NDBR/2FC0F0ECD873490F9F8FCE5654B8E5A0-SBA-NDBR/CA_SANTA%20BARBARA_V25_SBA_CORRECTED.pdf) The first item is 1.CHANGED PROCEDURE TITLE FROM VOR OR GPS RWY 25 TO VOR RWY 25 - PER FPT REQUEST. Maybe there's more in there.

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fly123123123@reddit (OP)

Had no idea this existed. Thanks for sharing.

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Yossarian147@reddit

Happy to pass along a nugget I learned myself from this very sub some time ago.

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fly123123123@reddit (OP)

I see the procedure is NA at night now... huge bummer.

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chipc@reddit

You can fly the VOR approach with your IFR certified GPS. They're just normalizing the naming scheme.

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cazzipropri@reddit

Only if the VOR is active and monitored. AIM 1-2-3 c 5

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makgross@reddit

It also changed from the 099 radial to the 100 radial. Might be related. The navaid is not on the field (indeed, it’s pretty far at 20 miles), so perhaps it wasn’t possible to guarantee arriving close enough to the MAP within visibility. TERPS can get esoteric. It may be as simple as it wasn’t surveyed using GPS.

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rFlyingTower@reddit

This is a copy of the original post body for posterity: --- A friend of mine noticed that the VOR or GPS 25 into SBA is now just the VOR 25. Looks like the amendment was made last month. Does anyone know why they removed GPS support? \[VOR 25 (current plate)\](https://skyvector.com/files/tpp/2503/pdf/00378V25.PDF) \[VOR or GPS 25 (old plate)\](https://www.flightaware.com/resources/airport/KSBA/IAP/VOR+OR+GPS+RWY+25) Seems like a bit of a strange downgrade, and I'd expect the GPS to be a bit more precise than the VOR, especially at the IAF (which is 19 miles from GVO). What reasons would the FAA have for removing a GPS overlay? I would assume there is little to no cost to maintain it. There are now no other approaches available for runway 25, so if GVO goes out (which does happen), the only option is to fly an approach to runway 7. --- Please downvote this comment until it collapses. --- I am a bot, and this action was performed automatically. If you have any questions, please [contact the mods of this subreddit](https://www.reddit.com/message/compose?to=/r/flying).

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