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GPS-only IFR?

airguy

Unrepentant fanboy
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There have been many discussions on here about how to implement a GPS-only IFR panel in our airplanes, going the wrong direction in my opinion. If you intend to equip, and actually operate, your aircraft for true IFR operations you should have both GPS and VHF capability.

Yesterday morning is a perfect example (again, my opinion) as to why. I launched out of my home base out here in west Texas with a passenger needing to get to a sick kid in San Antonio. Plan A was to have her picked up at 5C1 airport (Boerne-Stage) on the northwest corner of San Antonio, forecast was marginal for the RNAV 17 there with a minimum of 500'. I arrived and shot the approach, and sure enough no joy and went missed. I went to my filed alternate of KSAT and shot the ILS 13R all the way down to 260' before I broke out, with about a mile of visibility. We parked at Signature and put her in an Uber and I launched back for home, life is good.

Now it's true that there are some RNAV approaches that will take you as low as 200 feet, but they are certainly not common and in the heat of the IMC battle you don't want to be going through your plates while in a holding pattern trying to find one. The ILS is a known quantity and a solid standby. There was a time before WAAS that with low weather forecasts, either the primary or alternate airport must have VHF capability, but that requirement has now been waived with WAAS equipment. Don't get me wrong, I love the GPS stuff, it's very accurate and normally does the job, but we also know that sometimes it's not available - either from jamming (more frequent these days) or the minimums are not low enough.

I suppose some will say "If the weather is that bad, I'm not going" - and fair enough, but then why even pretend to have an IFR airplane if you're not going to utilize it as such?

I'll keep my VHF capability, YMMV. My opinion only, and worth what you paid for it.
 
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IFR GPS

I was under the impression that GPS without SOME alternate means of an approach is not legal? Is that so
Ed
 
I'm with Greg on this one, been preaching for years that VOR/LOC/ILS capability is REALLY nice to have in your IFR back pocket.
 
I don't disagree with Greg's opinion on this and have similar capabilities. However, from my limited experience, I have found that many runways with ILS capability typically have the matching RNAV with 200 or 250' LPV DA's. So looking for ILS runways could likely help to find an RNAV will better options.

For example, at KSAT, the RNAVs on top of ILS's are 200, 300 and 400 DA's for the three ILS equipped runways.

Larry
 
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Can't speak to the area outside of the SF Bay Area and valley. I can say that in this area the ILS and LPV approaches go down to the same DA. In many smaller airports (read coastal and mountains) we don't even have radio nave options left with only RNAV for approaches. I won't argue that a nav radio is a great back up, but the truth is many IFR pilots (in this area) would choose a RNAV over radio nav approach, unless it's training or currency they are working on.

My 2 cents, not worth much, but it's my opinion. YMMV
 
Another consideration is looking at the GPS planned outage charts. People would be amazed at the areas scheduled to be out daily, plus additional outages happen that aren't even charted.
 
I suppose some will say "If the weather is that bad, I'm not going" - and fair enough, but then why even pretend to have an IFR airplane if you're not going to utilize it as such?

While I agree with your basic premise of this post Greg (and we have VHF Nav capability in all of our IFR-Equipped airplanes), I want to pick on this statement just a little - not for you, but for the less-experienced folks who might be reading. There are "IFR airplanes", and there are IFR AIRPLANES. We shouldn't ever forget that not all aircraft with IFR capabilities are created equal. I am happy flying single engine IFR to places with questionable ceilings and visibility so long as I have iron-clad ability to retreat to a place where I don't have to shoot an approach to minimums to survive - AND I don't HAVE to get to my planned destination. That frequently means holding a lot of gas in reserve to make sure I can get to a real (not just legal, filed) alternate. But I am not going to launch an RV into forecast or known icing, or a line of embedded thunderstorms just because it is IFR legal. And I don't think you would either, having read your many posts here over the years.

I used to fly from the clear blue sky in Houston to the overcast, ILS-minimums hill country on an IFR flight plan, knowing that if I couldn't get in to New Braunfels or San Marcos, I could turn around and fly back to Houston and land. The hill country has lousy weather in the winter. And I'm pretty sure that you had the gas in this case to retreat all the way back to home base if you needed.

The purpose of having an IFR-equipped RV and a current pilot is not so that you can go "anywhere, anytime" - it is so that you can increase the probability of going and having a look.

Paul
 
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The purpose of having an IFR-equipped RV and a current pilot is not so that you can go "anywhere, anytime" - it is so that you can increase the probability of going and having a look.

Very well stated! Totally agree, we are not commercial airliners, and need to have that understanding on our minds.
 
I enjoy having the options that come with a dual mode (GPS + NAV Radio) IFR. It minimizes the chance of a common mode failure taking out the entire navigation capability of the airplane. If something happens that renders the GPS useless, then what's your alternative? If you want to use your iPad as backup, but its a GPS jamming situation, now you're relying on cell tower position information (if your iPad is a cellular version) to keep you safe in IFR conditions. The other alternative is relying on vectors from ATC in the event of a failure. I've got mountains around me and if GPS systems fail, ATC is going to be extremely busy, so that doesn't seem like a good back-up plan either. If there's no backup to the GPS, you don't just lose the ability to shoot an approach, you lose all ability to navigate except for pilotage (which is hard to do if there's clouds between you and ground).

Every system has the ability to fail. If you use the risk matrix assessment, I would put the probability of a GPS system failure as remote/improbable, but the consequences as catastrophic if you're in IFR conditions. That puts you in a medium/high risk category for the failure. If your backup has a common mode failure, then you don't really have a backup. My personal risk tolerance doesn't allow a design to have a single failure that results in a catastrophic outcome, so putting in a NAV radio, even if I never have to use it, allows me to satisfy my personal risk tolerances.
 
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VHF Nav vs. GPS

I suspect this same topic came up with respect to still needing ADFs when VORs originally came out. And maybe the pro-ADF folks were right! :)

I have VHF nav, train with it, and consider it a useful backup. But as a practical matter, with my kind of IFR flying and the places I do it, the odds of me REALLY needing it are certainly very remote.

So if I had to go buy a new RV to replace my current one (heaven forbid!), the fact that a candidate plane had only GPS IFR wouldn't cause me much concern. Others' mileage obviously varies.

Also, although I suspect a lot of big airports will maintain ILSs for quite some time, in general I think VORs and ILSs are on the way out. Those suckers are super expensive to maintain.

There have been many discussions on here about how to implement a GPS-only IFR panel in our airplanes, going the wrong direction in my opinion. If you intend to equip, and actually operate, your aircraft for true IFR operations you should have both GPS and VHF capability.

Yesterday morning is a perfect example (again, my opinion) as to why. I launched out of my home base out here in west Texas with a passenger needing to get to a sick kid in San Antonio. Plan A was to have her picked up at 5C1 airport (Boerne-Stage) on the northwest corner of San Antonio, forecast was marginal for the RNAV 17 there with a minimum of 500'. I arrived and shot the approach, and sure enough no joy and went missed. I went to my filed alternate of KSAT and shot the ILS 13R all the way down to 260' before I broke out, with about a mile of visibility. We parked at Signature and put her in an Uber and I launched back for home, life is good.

Now it's true that there are some RNAV approaches that will take you as low as 200 feet, but they are certainly not common and in the heat of the IMC battle you don't want to be going through your plates while in a holding pattern trying to find one. The ILS is a known quantity and a solid standby. There was a time before WAAS that with low weather forecasts, either the primary or alternate airport must have VHF capability, but that requirement has now been waived with WAAS equipment. Don't get me wrong, I love the GPS stuff, it's very accurate and normally does the job, but we also know that sometimes it's not available - either from jamming (more frequent these days) or the minimums are not low enough.

I suppose some will say "If the weather is that bad, I'm not going" - and fair enough, but then why even pretend to have an IFR airplane if you're not going to utilize it as such?

I'll keep my VHF capability, YMMV. My opinion only, and worth what you paid for it.
 
Weather

I have had Atlantic City and Groton CT go from good VFR to zero zero while I was VFR on one mile final. Good close alternate with good VFR. But what happens when the weather goes below forecast for a large area. In the case of Atlantic City on another occasion plan B was to head for a new alternate with marginal weather and marginal fuel. Fuel could be further compromised by delays. So the decision was to land at Atlantic City. Approach lights at 200 feet, runway at 50 feet. Night with all the lights, centerline, touchdown zone etc. No fog in the forecast for destination or alternate.
If you are going to mess with "light IFR" and you do it enough you may find yourself in the same situation.
I have found it very rare that an airline crew will voluntarily provide information to a small airplane. XYZ Air: tell the guy in the MU2 that if he turns the panel lights down low and leaves the landing lights off he MIGHT see the runway.
 
Handheld Nav-com

I have an RV9 with GTN625, after four years flying I have never missed not having a NAV.

Just to be safe, I purchased a handheld NAV-COM as a backup with a wingtip NAV antenna, the handheld's antenna range was insufficient, but is over 70miles using the full antenna.

I flew a few ILS's with the handheld, and it worked fine, requires a bit of practice for a good approach, but sure beats the olds days of ADF.

With the MON NAV network for guidance to an ILS airport, the risk of GPS loss is not even a consideration for me. Although, I think the GPS network is so embedded in our airspace I don't think the handheld was even necessary, as GPS will always be there for the flying I do.
 
Part of my job at Gulfstream was comparing ILS and LPV approaches, and I regularly downloaded the FAA databases of each. (The ILS database is no longer public...)

As I recall, when there was a difference in minimums, it was because of the missed approach procedures and required terrain clearance. As GPS approaches matured, there were proportionately more and more approaches with low minimums and fewer with high minimums.

I remember giving a presentation to the FAA lady in charge of GPS approaches and showing her bar graphs of GPS minimums vs ILS minimums. Let's just say that she did not keep a straight face.

There were some interesting approaches... On one approach, if a restricted area was hot on the far side of the airport, minimums were higher so that the missed approach could be flown without intrusion.

And there was at least one airport with parallel runways where two adjacent runway ends each had two different ILSes. One pair of ILS was aligned with the runways, the other pair came in to the runways at an angle to provide more separation on final approach.

I should have written an article on it when I still had the data...
 
+1 on Paul’s reply.
1. Hopefully folks understand that many non-ILS airports don’t get 200-1/2 minimums on their LPV approaches because they lack approach lights.
2. Never say never. I was sitting safety pilot for an instrument rated pilot under the hood (VMC) shooting the LPV approach into KLVK. One advantage of the right seat is that I have to look past the 650 to see the flight instruments, so I immediately saw the green ‘LPV’ change to a yellow ‘LNAV’. Pilot flying continued for about 30 seconds, then said, “I don’t think the glide slope is working”. I tapped the CDI and said that’s probably why that red flag is showing, and why the 650 has degraded to LNAV. Pilot was slightly freaked, asked what we should do. I said that since we about to descend below the LNAV minimums, we should probably stop the descent. Just about then, a big red x went across the gps screen, all data lost. I suggested he remove the hood and land. Later we discussed the value of having the ILS set up and ready to go - he could have switched over with one button push. Also discussed real world options (LVK sits in a valley, below radar coverage. Never did find out the issue, most likely a truck with a jammer going past on the interstate. But I’m comfortable with my decision to carry around a VOR-ILS receiver, just in case.
 
Yeah, but what I *really* miss are the 4-course ranges! (And the Lighted Airway system). :)

Show of hands - who has flown an A-N range approach? I got to do it in an old Link Trainer a few times …. Made me appreciate ADF’s, to be honest! ;)
 
So, what do you make of this from the GTN manual?
 

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So...I remain curious. VHF navigation does appear to be going away, and appears to be doing so in favor of GPS. I see it in the substantial decrease in VORs over the years, and multiple articles detailing the decrease in ILS systems as noted in the IFR article I mentioned. This is all happening in the face of seemingly increasing unreliability of GPS. Obviously...demise of ILS is years away, but.....what's going to take its place? Anything? How is this "end of NAV" going to unfold, if it does? Will we be a couple of "satellite killers" away from pilotage?

Not alarmed, just curious.
 
If an airport has an ILS, I choose it. If not, then a GPS approach. Sometimes the winds determine which I use if the ILS is only for one runway.

It’s amazing that the dollars that are spent on backup batteries and alternators but don’t have a backup precision instrument approach or route guidance.

GPS only, not for me.
 
Show of hands - who has flown an A-N range approach? I got to do it in an old Link Trainer a few times …. Made me appreciate ADF’s, to be honest! ;)

My hand is down, as in, ‘no, never’. But I loved NDB approaches. Not to fly in actual, of course - they were the very definition of ‘non-precision approach’ - but when an instrument student could do a reasonable NDB approach in a cross wind, I knew he had his act together.
 
So, who has DME for those ILS approaches that require DME?

Not me, and few others, I’d guess. Options:
1. Go somewhere else. For me, locally, that would be KSCK, which has an ILS approach with a VOR, not DME, cross fix. I like to show people how my single SL30, feeding a GRT Hx, can simultaneously show ILS and VOR cross fix data.
2. Quite often ATC will call a dme fix for you, if you’re within radar coverage.
3. Also, sometimes, the dme fix is only needed for the miss. Do you feel lucky? Or, see #2.
 
My hand is down, as in, ‘no, never’. But I loved NDB approaches. Not to fly in actual, of course - they were the very definition of ‘non-precision approach’ - but when an instrument student could do a reasonable NDB approach in a cross wind, I knew he had his act together.

I liked them too. There's beauty in the simplicity. Seems to me that NDB's would make a great en route back-up system and still works as a non precision approach too... but that's based on my assumption it would theoretically at least be cheap and easy to maintain the network...and I'd imagine a modern variant of the receivers and indicators could be simple, lightweight, and relatively cheap.

My biggest struggle with them was maintaining situational awareness in training..shooting multiple complex approaches with failures, etc... just a lot of mental gymnastics that I don't think are as necessary when just shooting a simple approach.
 
Used the ADF many times when the icing level was too low, staying under what was a reliable VOR coverage altitude. I had a great Narco ADF that could pick up an NDB 100 miles away, the controllers in the 80's seemed to be OK with filing and using it for IFR. Outer markers with a co-located NDB are a thing of the past, as are most NDB's on rural airports.

We had an excellent back up with LORAN, but with the advent of GPS the Loran stations were shut down and the in panel equipment was removed to become door stops. I think the same will happen with traditional ILS and VOR.
 
I wanted to put the 430 in my airplane, it has the antenna and coax pre-run. I couldn't justify the $4000 cost difference at the time between the 400 and the 430.
Previously my alternate had to be VFR, with the fuel range and speed of the RV this never limited me on my XC flights as I could always find a suitable alternate within range. Sometimes it included an extra fuel stop but no big deal, never couldn't do a flight because I didn't have a V-Loc. New rules WAAS only the Alt has to be non-precision mins is even better/easier.
There will be days that I will not fly because the low IFR is so widespread, but rarely do those couple days match up with the days I was flying anyway/icing etc.
Almost 10 years of flying IFR not once did I not go because I didn't have V-LOC. A large percentage of the airports I fly into only have GPS approaches. A large percentage of my IFR flying is 500 OVC or greater. ILS equipped airports are usually more involved and have higher fuel prices etc and the GPS approach has the same if not very similar minimums. In Greg's scenario the ILS gets him 98' lower than the comparable GPS at KSAT. I'll bet there's more airports within his IFR reserves with a GPS approach with comparable mins than ILS's.
I wouldn't mind the ILS capability but it hasn't got me anywhere WAAS GPS hasn't........yet. Someday there might be the exception like in Greg's case, but I haven't found it worth the $4000 yet.
 
I have an RV9 with GTN625, after four years flying I have never missed not having a NAV.

Just to be safe, I purchased a handheld NAV-COM as a backup with a wingtip NAV antenna, the handheld's antenna range was insufficient, but is over 70miles using the full antenna.

I flew a few ILS's with the handheld, and it worked fine, requires a bit of practice for a good approach, but sure beats the olds days of ADF.

With the MON NAV network for guidance to an ILS airport, the risk of GPS loss is not even a consideration for me. Although, I think the GPS network is so embedded in our airspace I don't think the handheld was even necessary, as GPS will always be there for the flying I do.

This is my set-up. The only time I had to divert, the ILS wouldn't have got me in either. Most places I go have no ILS or the LPV mins are the same. Handheld is for emergency backup...I practice using it...hopefully never need it.
 
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GPS vs VHF

This seems like a sensible and cost-effective approach.

This is my set-up. The only time I had to divert, the ILS wouldn't have got me in either. Most places I go have no ILS or the LPV mins are the same. Handheld is for emergency backup...I practice using it...hopefully never need it.
 
One of the reasons I'm an advocate of haivng a a VHF Nav capability is I like having options. The whole reason I got my IR asn fly IFR is to increase the utlity of aircraft. I get I'm not an air carrier, but neither am I a day VFR local flyer. IFR isn't a perfect solution and there have been times when despite the best of intentions, weather dictated a change of plans (usually due to T-storms or icing). There are other times (NOTAM'd GPS outage along the route) that by having more than one Nav source I was able to comfortably and legally launch and safely completely the flight. YMMV......

I'm kind of the mind at this point that there's not much in the way of fence sitters on this topic and most folks have their minds made up one way or the other as the way to go. No right or wrong answer, I suppose.
 
So...I remain curious. VHF navigation does appear to be going away, and appears to be doing so in favor of GPS. I see it in the substantial decrease in VORs over the years, and multiple articles detailing the decrease in ILS systems as noted in the IFR article I mentioned. This is all happening in the face of seemingly increasing unreliability of GPS. Obviously...demise of ILS is years away, but.....what's going to take its place? Anything? How is this "end of NAV" going to unfold, if it does? Will we be a couple of "satellite killers" away from pilotage?

Not alarmed, just curious.

I will give my guess. First, there is no way IMHO that ILS will ever go away at any B or C airport due to the commercial traffic and the fear of the media circus that would ensue after an airliner crash due to the FAA having reliance on just GPS, with known outages. Not to mention that Class III approaches allow lower wx entry. Further, many airports, like ORD and ATL, rely heavilly on localizer signals to separate parallel landing traffic during the final 30 miles. I would not be surprised if ILS starts going away some day at smaller airports. Someday we will have a few fatal crashes due to a GPS outage and the FAA will rush to institute surveillance approaches (current coverage is very small) at a level to create a backup network. We have pretty wide radar coverage these days (just don't know how much covers down to 500' AGL) and then it is just training cost along with writing the procedures.

VORs add little value IMHO and expect them to keep going away. They are unnecessary for enroute these days (very broad radar coverage) and are not cost effective for approach coverage.

Larry
 
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So, who has DME for those ILS approaches that require DME?

I believe that GPS can be used in lieu of DME, just like it can be used for outer markers and VORs. Obviously that doesn't apply in an outage, but didn't think that was the intent of the question.
 
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While I agree with your basic premise of this post Greg (and we have VHF Nav capability in all of our IFR-Equipped airplanes), I want to pick on this statement just a little - not for you, but for the less-experienced folks who might be reading. There are "IFR airplanes", and there are IFR AIRPLANES. We shouldn't ever forget that not all aircraft with IFR capabilities are created equal. I am happy flying single engine IFR to places with questionable ceilings and visibility so long as I have iron-clad ability to retreat to a place where I don't have to shoot an approach to minimums to survive - AND I don't HAVE to get to my planned destination. That frequently means holding a lot of gas in reserve to make sure I can get to a real (not just legal, filed) alternate. But I am not going to launch an RV into forecast or known icing, or a line of embedded thunderstorms just because it is IFR legal. And I don't think you would either, having read your many posts here over the years.

I used to fly from the clear blue sky in Houston to the overcast, ILS-minimums hill country on an IFR flight plan, knowing that if I couldn't get in to New Braunfels or San Marcos, I could turn around and fly back to Houston and land. The hill country has lousy weather in the winter. And I'm pretty sure that you had the gas in this case to retreat all the way back to home base if you needed.

The purpose of having an IFR-equipped RV and a current pilot is not so that you can go "anywhere, anytime" - it is so that you can increase the probability of going and having a look.

Paul

Paul - you're correct on all points, of course. As I write this I'm sitting in Williston, North Dakota (18 below zero this morning) for work for a couple days, and I took United Airlines up here because they are much better equipped for December in North Dakota than I am. I've had my RV up here several times - but December is off the list. We (both people and airplanes) do have limits, and the smart ones among us recognize them and live longer for it.

I'll admit that my typical use of my airplane is more of a corner case with regard to IFR ops and dispatch reliability, and many/most folks are just equipping for "light IFR" in their airplanes. My contention is that there is no such thing as "light IFR".
 
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My hand is down, as in, ‘no, never’. But I loved NDB approaches. Not to fly in actual, of course - they were the very definition of ‘non-precision approach’ - but when an instrument student could do a reasonable NDB approach in a cross wind, I knew he had his act together.
Anther reason I believe I was born 20, 30 years too late. I could nail those NDB approaches in the worst of conditions...
 
Anther reason I believe I was born 20, 30 years too late. I could nail those NDB approaches in the worst of conditions...

The issue wasn’t, or at least shouldn’t be, the pilot. It was the fundamental limitations of the equipment. I always remember my ifr check ride: Examiner loved NDB approaches. He has me tracking inbound from some distance out. I can tell he’s fidgeting a bit. Finally, he leans over, turns off the alternator field switch. The ADF needle jumps about 10 degrees. He turns the alternator back on, needle jumps back. I peeked out sideways from under the hood and looked at him. He says, ‘You know, in the old days, that was all they had.’ End of discussion.
 
And if you still have an ADF receiver, you can listen to AM radio while traveling.
Oh my, does the newer generation know what AM radio is?
 
And if you still have an ADF receiver, you can listen to AM radio while traveling.
Oh my, does the newer generation know what AM radio is?

You’ve jogged my memory. Pre GPS, when east Bay pilots wanted to duck under the SFO class B airspace, we proceeded to south of the San Mateo bridge, set our ADF to 560 KHz (KNBR), turned west at 1400’, made sure to pass just south of KNBR, then up and over the ridge to the ocean.
 
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