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Is it time to forgo VHF navigation?

Ahhh..but when (if) NextGen kicks in for real, it (ADS-B) will be the ONLY way of separating traffic because radar goes away. That is, if you believe the plan....

Very little radar going away IMO. center cant get rid of any - no univeral adsb requirement . Approach can only get rid of secondary radar. Atc simply cant get rid of primary radar, especially in approach areas. How else do they avoid collisions when aircraft equipment fails or gps is shut down. The entire at. System is designed to deal with aircraft equipment failure. Why would this be an exception.

I would hate to be the guy that approved radar removal after the first near miss occurs.
 
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Ummm

Not sure what you are referencing but vor/dme is used to update the iru system. The airplane can navigate just fine using the irus even without the vor/dme updates. Think about it. There are NO vor/dme stations 2000 miles out over the ocean...
 
GPS helps align, update and provides containainment. Required Nav Performance vs. Actual Nav Performance.

We can do VOR/DME/ILS with just Land based signal updating- but it would slow the flow into and out the hubs using the RNP SIDS and STARs to even vanilla ILS and visuals.

Bad actors will need to be seen- RADAR really can't go away. I smell sales over sanity.
 
Airline navigation

This is really interesting.

The more I fly little planes, the more I realize how little I actually know about bigger planes. And I used to be an expert. :)

You are correct but would not say no effect.

It depends... a typical Boeing or Airbus has three IRU (internal reference unit). They are totally independent of any outside navigation using laser rings and accelerometers. However that position (voted on by three IRU's) is mixed with GPS and terrestrial navigation (DME, LOC, VOR's) to get a FMS (Flt Management Sys) position. FMS position ranks the navigation sources and presents on the PFD (primary flight display). I can tell you the FMS ranks GPS very high except maybe on an ILS approach when the FMS will update on LOC and DME.

With that said for domestic navigation, more than IRU position is needed. If no GPS the FMS auto-tunes in all available terrestrial navigation units. Some of the regional jets need GPS I believe. So they would be grounded unless they can revert back to full steam (ground based Nav).

Would it affect operations? If the airplane has a destination or required alternate that requires GPS, yes it would effect operations. A GPS based approach has no IRU/FMS or ground based NAV alternate.
 
Airlines don’t use GPS for enroute navigation. Shutting down the system would have little to no effect on airline travel.


Huh. Well, I can tell you that almost all the enroute legs as well as RNAV SIDs and STARs I've flown for a U.S. airline over the last year have used GPS navigation.

Not sure where you get your information from, but it's wrong.
 
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Most airliners use GPS for nav now. They can use LNAV which is based off VOR DME?s as a backup and will downgrade to IRS/INS as a last resort. Loss of GPS would however cause many system wide problems including GPS approaches and arrivals and RVSM airspace. Shutting down GPS has far greater implications beyond aviation. It would be a national disaster.
G

The GPS leap second issue a few months ago played havoc with lots of airlines whose aircraft were equipped with certain versions of Collins FMS software. They were unable to use their GPS sensors as a result, and the remaining RNAV capability (based off VOR/VOR/DME/etc) while good enough for enroute was not sufficient to navigate on RNAV SID/STARs used at most major airports. This was minor in comparison to a full GPS outage.

I not only agree with you, but think that "national disaster" might even be understating the problem a bit.
 
If the GPS constellation was shut down, not only would the airlines have issues but so would over the road truckers, amazon, first responders, etc.

The worst part would be that my wife wouldn't know how to get home! 😆
 
Huh. Well, I can tell you that almost all the enroute legs as well as RNAV SIDs and STARs I've flown for a U.S. airline over the last year have used GPS navigation.

Not sure where you get your information from, but it's wrong.

I think we have an issue of semantics, and I should have been more clear I guess. Of course transport category airliners use GPS, but NOT AS THE PRIMARY SOURCE OF ENROUTE NAVIGATION. The primary source is Inertial navigation. GPS serves, along with old school NAV, as a cross checker, verifier, position tweaker to the primary INS/IRS/IRU?s. Both GPS systems in the B737 can be MEL?d, even for class II operations, with GPS approaches being the only navigational consideration.

Losing Inertial NAV in a Boeing is a big deal. Losing GPS is a nuisance light and a yawn.
 
I think we have an issue of semantics, and I should have been more clear I guess. Of course transport category airliners use GPS, but NOT AS THE PRIMARY SOURCE OF ENROUTE NAVIGATION. The primary source is Inertial navigation. GPS serves, along with old school NAV, as a cross checker, verifier, position tweaker to the primary INS/IRS/IRU?s. Both GPS systems in the B737 can be MEL?d, even for class II operations, with GPS approaches being the only navigational consideration.

Losing Inertial NAV in a Boeing is a big deal. Losing GPS is a nuisance light and a yawn.

FWIW, transport category airliners are using GPS as the primary source of enroute navigation. IRS/INS is the last backup source, after VOR and DME..

You're right about MEL'ing the GPS not being a major issue, but the fact is that GPS is the primary source of enroute navigation when you're flying around in your Boeing...
 
I think we have an issue of semantics, and I should have been more clear I guess. Of course transport category airliners use GPS, but NOT AS THE PRIMARY SOURCE OF ENROUTE NAVIGATION. The primary source is Inertial navigation. GPS serves, along with old school NAV, as a cross checker, verifier, position tweaker to the primary INS/IRS/IRU’s. Both GPS systems in the B737 can be MEL’d, even for class II operations, with GPS approaches being the only navigational consideration.

Losing Inertial NAV in a Boeing is a big deal. Losing GPS is a nuisance light and a yawn.

I understand. But that's fleet specific, of course. For example, there are hundreds and hundreds of regional jets don't have any form of INS and use GPS directly. For those aircraft, losing GPS means they can't utilize RNAV-based navigation except when enroute as VOR/VOR or VOR/DME don't meet RNP requirements. Losing GPS in a CRJ, for example, is no big deal unless you want to go into a big airport such as DFW/ATL/ORD/etc. then it's a pretty big headache since ATC wants nothing to do with non-RNAV procedures for the most part.

So that's why I say, there are absolutely airlines that would be impacted by loss of GPS. The delays throughout several major airline systems that occurred with the GPS leap second issue in Collins equipment bears this out - that hiccup caused lots of delays, cancellations, etc.
 
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hmmm...

"... IRS/INS is the last backup source, after VOR and DME..."

Might want to tell Boeing that, because that is NOT what they are training...

Also, in my previous aircraft (757/767), there were no GPS receivers...and the VOR/DME was used to update the IRS...

Again, when you are 2000 miles out over the ocean, there are NO VOR/DME stations...
 
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Might want to tell Boeing that, because that is NOT what they are training...

I have sent a PM to rocketman1988 to get further information on this. I have committed to work with Boeing training to get the issue worked out.
 
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Bob,
Originally (before GPS) the Boeing birds (757,767) had triple IRS units that were updated by Vor/Dme signals, over water they went into IRS nav only mode, once back over land they updated. Most of these have been upgraded to the Pegasus flat panel displays utilizing dual GPS receivers.
 
VHF Nav communication

I like the idea of having the VHF Nav receiver in the airplane even if I do not use it for much navigation.

There have been a number of airports that have the AWOS, ASOS, or ATIS transmitting over a VOR frequency. There also is the possibility of communication with Flight Service by receiving over the VOR frequency.

The communication signals that I can receive over the VHF / VOR Nav receiver makes the added cost, weight, and panel space worth it to me.

Being able to use if for an ILS is just a plus.

I have been using ADS-B in for about 6-years. Yes I have ADS-B out as of May 2019 but have not used the ADS-B IN Wx enough to feel safe without hearing it on VHF.

Unfortunately my certified GPS approach receiver requires a VHF nav receiver. Yes it is an older unit dating back over 15-years. I have a VHF nav receiver in my RV-6 and would like to have one in the RV-8 project but when it becomes time to part with money, I may end up not having one.
 
The primary source is Inertial navigation. GPS serves, along with old school NAV, as a cross checker, verifier, position tweaker to the primary INS/IRS/IRU?s.

Losing Inertial NAV in a Boeing is a big deal. Losing GPS is a nuisance light and a yawn.

There will be a difference between fly by wire aircraft and the older ones. I think the 787 was the first. IRS is extremely important to the "inner loop" control laws. I can't speak for the "outer loop" navigation/autopilot laws though.

We are well along in the process to have the 777X fly by wire certified. Wish that bird would fly already!
 
"...Might want to tell Boeing that, because that is NOT what they are training...

Also, in my previous aircraft (757/767), there were no GPS receivers...and the VOR/DME was used to update the IRS...

Again, when you are 2000 miles out over the ocean, there are NO VOR/DME stations...
Bob. The 757767 came out in the early 80s and there was no GPS. Most have been upgraded with dual GPS.

You're correct out over the ocean IRU was all you had and HF radio for voice position reports. (Use to be INS inertial nav system, but IRU's are not only nav they drive flight instruments.) However to fly North Atlatic today you are required to have "navigation precision", "surveillance and communication precision", part of Future Air Navigation System (FANS). You need GPS as well as digital satellite communication. Clearance comes direct to your CDU/FMS. You use the HF radio only to make initial contact with Gander or Shanwick as a backup, and that's it. The vertical and in trail separation across the Atlantic has been reduced which requires very high level of nav, surveillance and commuication. There may be no radar or ground base navigation over the water, but the game has completely changed in the last 10-15 years, much less since early 80's. GPS is part of FANS....

You might recall before GPS flying Atlantic seeing your 757/767 nav display jump as you got close to land again and FMS started updating on DME and VOR. IRU is accurate but after a few hours it will have error. GPS is more accurate indefinitely.
 
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"... IRS/INS is the last backup source, after VOR and DME..."

Might want to tell Boeing that, because that is NOT what they are training...

Also, in my previous aircraft (757/767), there were no GPS receivers...and the VOR/DME was used to update the IRS...

Again, when you are 2000 miles out over the ocean, there are NO VOR/DME stations...

To allow RVSM and reduced track separations there have been changes. In the original 757/767 configuration the aircraft never used VOR?s. It navigated off DME/DME and downgraded to IRS Nav if two valid DME signals could not be received. This caused the infamous 30 AOB wake up turns at two in the morning when the aircraft grabbed two DME?s at track exit and the magenta line moved 1 or two miles instantly. This could put the aircraft into buffet. They added a algorithm to smooth that out but the aircraft did not blend position sources. It was one or the other. With the retrofit of GPS they are 100% GPS for actual position however the GPS position is used to update the IRS?s. If you have a GPS loss the IRS?s should be right on. Different airlines and boxes may have different solutions.
 
Wow...

Soooo many experts!

Yes, different airlines have different configurations.

I flew the original 757/767 with no gps up through the pegasus update.

I flew the tracks during this time. (16+ years)

I know the systems...as they were taught then.

I'm still new on the 737...

Did I miss anything?

Yes, I did. I will dig out my 757 manuals for then (yes, I still have them) because now I am curious about the updating and what was taught. Not that it matters, but I am curious...
 
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With the world rapidly moving to a GPS/RNAV enroute and approach environment I'm struggling with whether to even install VHF nav capability into the airplane.

Anyone else been pondering this?

Interesting thread..... Back to OP's original question of installing VHF nav into his airplane. There are as many opinions and reasons for those opinions as there are people. I currently fly a Mooney with both capabilities (GPS and VHF). Been flying IFR for 10 years. I have NEVER done a VOR or ILS approach in all that time. I prefer GPS and have always been able to get GPS approaches. For that reason, I'm building my 10 with GPS only (no VHF). I know many will have reasons why that may not be the best decision. Not trying to debate the merits of it, as much as I'm simply sharing one aviators personal decision with OP for his consideration.
 
I fly day VFR, not very much anymore, and am building an RV-3B, which has a tiny panel. I'm not installing VOR.

But if I flew more often, or had a larger panel, or flew more than occasional day VFR, I certainly would install it. It's very useful backup, and I'm one of the people who have had GPS outages in flight. Yes, even flying day VFR, it can happen and it's annoying. When it happens, I revert to pilotage with VOR as an aid - my non-RV has a VOR.

Note that even with GPS unavailable, an iPad can still display maps, making pilotage possible. It's even easier with paper maps.

Dave
 
I?ve been flying gps approaches since before WAAS, and never had an outage - until about 6 months ago. Instrument student under the hood, LPV approach into LVK. He says, ?The glide slope isn?t working.? I tapped the 650 with my pencil, where ?LPV? had been replaced by ?LNAV?. A minute later, a big red X appeared, along with ?no gps?, and the cdi totally flagged. Now, if we had been in IMC, and had not had an ils/vor, we would have had some interesting choices: 4000? peak to the north, high terrain to the south. SFO class B to the west, incoming LVK ifr traffic to the east. LVK is below radar coverage. So I?m still carrying around an SL30.
 
When there's a GPS outage, does GLONASS go down too? If your receiver receives both, you at least have system redundancy.
 
I just watched the latest AOPA live article and didn't truly appreciate how tough you guys had it over there with respect to this GPS jamming issue.

https://www.youtube.com/watch?v=80wTkOG3Yy0

My aircraft in Aus is set up IFR with GPS only, mainly because of the fact that the majority of the ground based nav-aids are being decommissioned, and there are only two ILS approaches anyway in the entire state where I live. They are still partially dependant on GPS as they got rid of the NDB approach points and replaced them with some GPS coordinates.
Best bet here is a compass, map and stopwatch as your backup or radar vectoring, but in the US I can understand why you may want the backup if you were flying IFR given the reported regularity of GPS jamming exercises.

Tom.
RV-7
 
When there's a GPS outage, does GLONASS go down too? If your receiver receives both, you at least have system redundancy.


This brings up a good point that it would be awesome if the gps units received and compared multiple GNSS systems at the same time and went with the most accurate at the time. The US has GPS, the Russians have GLONASS, the EU has Galieo, the Chinese have BDS etc.
 
Forgive if this was posted already: They talk about FAA reducing VOR's and more GPS outages from military activity.

https://aopalive.aopa.org/detail/vi...ive-this-week---august-29-2019?autoStart=true

The GPS commentary starts at 0:43. Wiki:


"Developed in the United States beginning in 1937 and deployed by 1946, VOR is the standard air navigational system in the world,[2][3] used by both commercial and general aviation. In the year 2000 there were about 3,000 VOR stations operating around the world including 1,033 in the US, reduced to 967 by 2013 (stations are being decommissioned with widespread adoption of GPS)."

RIP VOR From 1937 to 20??
 
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I was flying on an IFR flight plan monday to Las Cruces NM when the airplane symbol on the G1000 MFD changed into a DR (dead reckoning mode). The data for time and distance changed from magenta to yellow. We started navigating via VOR. That lasted about 10 minutes then all data was lost. We used ground based navigation for the rest of our flight. There was a NOTAM out for GPS jamming originating from the White Sands Missile Range. GPS jamming is occurring more regularly with no end in sight.
With that caveat, I flew my RV6 for 10 years with 1 GPS and no other nav capability other than a sectional!
 
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This brings up a good point that it would be awesome if the gps units received and compared multiple GNSS systems at the same time and went with the most accurate at the time. The US has GPS, the Russians have GLONASS, the EU has Galieo, the Chinese have BDS etc.

The short answer is that individual positioning systems should be independent of each other.

The longer answer is that somebody with some smarts, enough to jam GPS, could likewise wipe out the relatively small signals of other space-based positioning systems.

When faced with the option of upgrading my GRT AHARS to their new Adaptive AHARS I looked at its optional built-in multi-constellation GNSS receiver and that's what pushed me over the edge to do the upgrade. Now at least I should be able to retain the moving map / synthetic vision presentation on the EFIS in the presence of a GPS-specific outage.

In the example above of an approach with terrain, airspace and other traffic nearby, being able to retain the situational awareness afforded by retention of the moving map / synthetic vision would be a big safety enhancement. While I have an SL30 in the panel it might take me a few moments to get it set up and working if I had been flying a GPS-based approach when GPS went Tango Uniform. I'd like to think that while I'm configuring the EFIS to NAV2 and tuning NAV2 that the synthetic vision and moving map might help keep me out of the cumulo-granite! :eek::D
 
This has been a pretty amusing thread full of "experts" about GPS. Anyone who believes in the rock-solid infallibility of ground-based navaids compared to GPS... well, I have a nice bridge in NY to sell you. Try flying the ILS into KMRY or into KSBP. I'll take the GPS approach any day. If I have to rely on a VOR approach it might as well be into VFR conditions for how accurate they are.

As for the ability to get you in low, it is one thing to strap on the foggles and go bouncing around to simulate an approach to ILS mins. When you can't cheat by cross-checking the compass above your glareshield, it is a different experience altogether, more so if you are hand-flying a touch-sensitive RV. If you're only doing occasional IFR approaches, then you should keep your personal minimums quite a bit higher than 200' and 1/2 mile.
 
This has been a pretty amusing thread full of "experts" about GPS. Anyone who believes in the rock-solid infallibility of ground-based navaids compared to GPS... well, I have a nice bridge in NY to sell you. Try flying the ILS into KMRY or into KSBP. I'll take the GPS approach any day.

I don't think anyone is saying they are infallible, just that they are a solid backup to GPS nav. The FAA seems to agree, which is why the MON network exists.
 
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They need to bring back the ADF. They still work well here in Canada and besides you can listen to the hockey or ball games on them when flying at night.
 
Well slap my arse and call me Bridget, look what the locals just sent me. How appropriate:

https://www.faasafety.gov/files/notices/2019/Aug/PAXRVR_19-03_GPS_Flight_Advisory.pdf

bCpjRB1l.jpg
 
This has been a pretty amusing thread full of "experts" about GPS. Anyone who believes in the rock-solid infallibility of ground-based navaids compared to GPS... well, I have a nice bridge in NY to sell you. Try flying the ILS into KMRY or into KSBP. I'll take the GPS approach any day. If I have to rely on a VOR approach it might as well be into VFR conditions for how accurate they are.

As for the ability to get you in low, it is one thing to strap on the foggles and go bouncing around to simulate an approach to ILS mins. When you can't cheat by cross-checking the compass above your glareshield, it is a different experience altogether, more so if you are hand-flying a touch-sensitive RV. If you're only doing occasional IFR approaches, then you should keep your personal minimums quite a bit higher than 200' and 1/2 mile.

Interesting since I have been flying into KMRY for decades. Monterey reports Low IFR regularly. They are reporting 100 feet as I am typing. I have kept my VHF because of the reliability and ease of use. I have lost GPS several times but never lost ILS unless the NOTAMS reports that it is out. My son is a Captain for SkyWest. He told me that they always fly the ILS because of lower minimums. Take MRY for instance, LPV is 520 feet and ILS is 200 feet. Good luck regularly getting into MRY since 500 feet is the norm. VOR approaches are never a problem because I back them up with a non WAAS GPS. However, I am making room for a Garmin 175 because VOR approaches are most likely going away??
 
This has been a pretty amusing thread full of "experts" about GPS. Anyone who believes in the rock-solid infallibility of ground-based navaids compared to GPS... well, I have a nice bridge in NY to sell you. Try flying the ILS into KMRY or into KSBP. I'll take the GPS approach any day. If I have to rely on a VOR approach it might as well be into VFR conditions for how accurate they are.

At no point in this discussion has there been made a mention of VHF navigational aids as being better than GPS. In fact this entire discussion has been about using GPS as primary, but being prepared in the event GPS fails.

That's the same discussion that used to be had around failure of ILS, with VOR- and ADF-based non-precision approaches as the backup in case the ILS failed.

Yes, we would all prefer that GPS works reliably all the time. The reality is that it doesn't. The reality is that a number of contributors have the potential to remove GPS from the "get home safely" equation. The other reality is that, if and when GPS fails, those who have not prepared a fallback plan will experience some severe pucker factor as they try to figure out how to get down out of the clouds. Several of us here have laid out our plans with respect to how to decrease that pucker factor, including having VHF navigation as a backup plan.

Aviation is all about mitigating risk to the best and most practical extent possible. Not having a backup nav system for IFR flight would seem to leave that risk unmitigated thus perhaps not the most wise plan. Thanks, I've figured out a way to have two backups. If anybody doesn't want to have a backup, that decision is on them. Please do try to keep your name out of the NTSB reports.
 
Interesting since I have been flying into KMRY for decades. Monterey reports Low IFR regularly. They are reporting 100 feet as I am typing. I have kept my VHF because of the reliability and ease of use. I have lost GPS several times but never lost ILS unless the NOTAMS reports that it is out. My son is a Captain for SkyWest. He told me that they always fly the ILS because of lower minimums. Take MRY for instance, LPV is 520 feet and ILS is 200 feet. Good luck regularly getting into MRY since 500 feet is the norm. VOR approaches are never a problem because I back them up with a non WAAS GPS. However, I am making room for a Garmin 175 because VOR approaches are most likely going away??

I realize there can be different minimums for various companies. Currently I show Monterey with 300 foot ILS minimums to RWY 10 if the aircraft can make a minimum climb gradient on the missed. If not the ILS minimums are 700’. There are no ILS approaches to 28 because of terrain but there are 2 GPS options with minimums down to 300’.
Skywest May have a special aircrew certified approach down to lower mins but it would not be available to GA.
 
The FAA has gradually been shutting down VOR's since 2016. Their plan by 2025 is to decomission 311 VOR's (35%) leaving 585 still in service. The plan called Minimum Operational Network (MON) is designed to allow an aircraft flying at 5000' to be within 100 miles of an airport not dependant on a GPS approach. The majority of the VOR shutdowns will be in the East and Midwest.
 
This has been a pretty amusing thread full of "experts" about GPS. Anyone who believes in the rock-solid infallibility of ground-based navaids compared to GPS...
Yes this expert says ILS is more accurate than GPS even with WAAS... ILS it's called a "Precision Approach" for a reason. Do you have some data that shows ILS is inaccurate? Rhetorical. The answer is no. Also there all kinds of fail safe monitoring and backups and flags built into an ILS.

GPS based approaches generally are not a Precision approach and have much higher minimums including KMRY 520-1 1/2....... ILS at KMRY is 200- 1/2, lower mins by 320 and 1 mile. Why ILS is more accurate. Want to get in? ILS everytime. The higher min to 10R for ILS is only of you cant miss and climb 265 ft/min per NM to 1360 feet. An RV can exceed that x4 at least. Even the # mins are lower than the GPS approach.

Bottom line thousands of airliners world wide are flying ILS to every runway with an ILS (even in VFR condtions). Most major airports served by airlines have an ILS approach. The lowest mins still belong to Cat 1 ILS not GPS. ILS Cat 2 and 3 of course is even lower.

LPV approaches with WAAS/GPS are similar to an ILS, but even though LPV approaches have vertical guidance, they're not considered precision approaches at this time. Forget GPS autoland anytime soon if ever. GPS is awsome and GPS only IFR is a resonable choice. My argument with you is that the ILS is highly accurate and reliable, still rules at this time and likely for decades to come, before commercial aircraft stop using the ILS.

You other argument is you should not fly an ILS to.mins and double mins if you are not current (for discussion purposes not current = legal but not proficient). I agree, but then by that logic you should not fly GPS RNAV approaches to mins if not current. Even if you double the ILS min it is still lower than the RNAV approach at KMRY! Ha ha.
 
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Yes this expert says ILS is more accurate than GPS even with WAAS... ILS it's called a "Precision Approach" for a reason. Do you have some data that shows ILS is inaccurate? Rhetorical. The answer is no. Also there all kinds of fail safe monitoring and backups and flags built into an ILS.

GPS based approaches generally are not a Precision approach and have much higher minimums including KMRY 520-1 1/2....... ILS at KMRY is 200- 1/2, lower mins by 320 and 1 mile. Why ILS is more accurate. Want to get in? ILS everytime. The higher min to 10R for ILS is only of you cant miss and climb 265 ft/min per NM to 1360 feet. An RV can exceed that x4 at least. Even the # mins are lower than the GPS approach.

Bottom line thousands of airliners world wide are flying ILS to every runway with an ILS (even in VFR condtions). Most major airports served by airlines have an ILS approach. The lowest mins still belong to Cat 1 ILS not GPS. ILS Cat 2 and 3 of course is even lower.

LPV approaches*with WAAS/GPS are similar to an ILS, but even though LPV approaches*have vertical guidance, they're not considered*precision approaches at this time. Forget GPS autoland anytime soon. GPS is awsome and GPS only IFR is a resonable choice. ILS still rules at this time and likely for decades to come, before commercial aircraft stop using the ILS.

You other argument is you should not fly an ILS to.mins and double mins if you are not current (for discussion purposes not current = legal but not proficient). I agree, but then by that logic you should not fly GPS RNAV approaches to mins if not current. Even if you double the ILS min it is still lower than the RNAV approach at KMRY! Ha ha.

My point, for those who have experience with those particular ILS approaches, is that following them with the autopilot on is akin to a Six Flags roller coaster. Very unreliable/sensitive below a certain altitude. We fly them by hand to reduce the significant aircraft oscillations as the autopilot chases the signal (in fact, I believe that is a charted requirement on KMRY). Never had a GPS approach do that. My observation was simply that not all ground based navaids are rock-solid guarantees, and knowing what I know about those approaches I would not be gung-ho hand flying an RV down to minimums there.

Can you lose GPS? Certainly. Particularly as one pointed out, in the vicinity of military test areas. Once got jammed in the vicinity of White Sands at FL370. Ended up getting radar vectors from center, rather than instructions to join a V- or J- route. But my jab at those broadly proclaiming that Commercial Passenger craft do not rely on GPS so you shouldn't either are frankly wrong on both counts. Leaving aside the fact that 121 requirements are significantly more stringent on redundancies for obvious reasons, not everything out there is a 767 that rolled off the line in the 70's. I've flown 80 hours a month on average for work over the last 15 years, and can count on one hand the number of times I lost a GPS signal. The handful of times I've gone to mins on an approach in the last year, it has been to CAT II mins and/or in icing conditions or high crosswinds, so I wouldn't be flying recreationally then anyway. So I feel pretty confident that I don't need the weight or expense of a NAV radio in my RV to supplement my WAAS GPS.

End statement: Put in a VHF radio if it makes you feel good, but don't tell me that it is certain that you'll be dead in the water if you don't have one, just because one time you had loss of RAIM.
 
Good Thread.

I like the capabilities that GPS has brought us. The ability to shoot near-ILS-minnimum approaches to podunk airports that didnt have any approaches in the past is a wonder. In 20 years of professional flying I have only seen GPS fail me once or twice where I wouldn't have been able to shoot an approach without it. (RAIM conked out) That being said, if I were building a cross-country bird I would still install some sort of terrestrial based navigation system. The satelite constellation is only one good solar storm away from being knocked out.
 
My point, for those who have experience with those particular ILS approaches, is that following them with the autopilot on is akin to a Six Flags roller coaster. Very unreliable/sensitive below a certain altitude. We fly them by hand to reduce the significant aircraft oscillations as the autopilot chases the signal (in fact, I believe that is a charted requirement on KMRY). Never had a GPS approach do that. My observation was simply that not all ground based navaids are rock-solid guarantees, and knowing what I know about those approaches I would not be gung-ho hand flying an RV down to minimums there.

Can you lose GPS? Certainly. Particularly as one pointed out, in the vicinity of military test areas. Once got jammed in the vicinity of White Sands at FL370. Ended up getting radar vectors from center, rather than instructions to join a V- or J- route. But my jab at those broadly proclaiming that Commercial Passenger craft do not rely on GPS so you shouldn't either are frankly wrong on both counts. Leaving aside the fact that 121 requirements are significantly more stringent on redundancies for obvious reasons, not everything out there is a 767 that rolled off the line in the 70's. I've flown 80 hours a month on average for work over the last 15 years, and can count on one hand the number of times I lost a GPS signal. The handful of times I've gone to mins on an approach in the last year, it has been to CAT II mins and/or in icing conditions or high crosswinds, so I wouldn't be flying recreationally then anyway. So I feel pretty confident that I don't need the weight or expense of a NAV radio in my RV to supplement my WAAS GPS.

End statement: Put in a VHF radio if it makes you feel good, but don't tell me that it is certain that you'll be dead in the water if you don't have one, just because...
1) No ILS should be unstable. They are flight test by the FAA to high standards. There's something seriously wrong with the ILS if it's like a rollercoaster. it should be reported. If it doesn't meet strict standards then it would be decommissioned.

2) You're making straw man arguments and off the point. Nobody's saying anything bad about GPS approaches they're fantastic, and if your mission calls for it and you can afford it, get IFR GPS. Your needless bash of ILS approaches as inferior approach is just pointless. GPS rnav approaches provides very good IAP's to airports that didn't have any ILS. However the fact is as I stated I'll less is a higher Precision approach than just about any GPS approach to date. I mean it's just a fact.
 
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