What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

If VORs are going away...

Aviator

Well Known Member
So what will be the next big tech to take its place.
Already a LOT of em in our area are remarked inoperative, so perhaps its a prelude to them being gone. ( I have read from FAA and here about how they will keep most or some of them active for now, but I guess the writing is on the wall)
So if I have a GTN navigator without the Xi and have the itch to go Xi, I am thinking I should just wait a while.
Any thoughts on this.
 
GPS navigation to VORs and for VOR approaches make the nav receiver seem unnecessary.

HOWEVER...

I absolutely love the fact that that same nav receiver enables me to fly LOC and ILS approaches, which are my preferred instrument procedure. The RNAV LPV is a very close second, assuming the RAIM is available.

My 2 cents.
 
The FAA is all in on WAAS GPS for the foreseeable future so your investment in an Xi won't be wasted. WAAS GPS and VOR will be what we have for enroute navaids until INSs become much smaller, much more accurate and much less expensive - and that probably won't happen anytime soon.

HTH

Dave
 
Somebody please translate. What is Xi? I assume it is something we all have and have had for years, but this is a new acronym for me that I haven’t seen before. (I don’t do Facebook, tweeter, iMe, or any of those other ‘things’ so I guess I’m in the dark). Forgive me, but please ‘splain’ what you are talking about.
 
Somebody please translate. What is Xi? I assume it is something we all have and have had for years, but this is a new acronym for me that I haven’t seen before. (I don’t do Facebook, tweeter, iMe, or any of those other ‘things’ so I guess I’m in the dark). Forgive me, but please ‘splain’ what you are talking about.

It is Garmin's GTN Xi Series. Google is your friend. The term Xi means means eleven (roman numeral) or 14th letter in Greek alphabet.

https://www.garmin.com/en-US/blog/aviation/gtn-xi-series-fourth-generation-gps-nav-comm-solutions/
https://www.youtube.com/watch?v=ZdzUyxpv_fs
 
Last edited:
If I've got my facts straight, LPV requires WAAS which does not require RAIM.

You are correct. TSO-C129a GPSes use RAIM, TSO-146 use a different algorithm to calculate HPL and VPL (Horizontal and Vertical protection limits) and can use the WAAS signal to recognize an eliminate "bad" satellites.

RAIM calculations are included in WAAS GPSes, I believe, but are only used when WAAS signal is not being received (e.g. outside WAAS service areas, or during outages).
 
RAIM

If I've got my facts straight, LPV requires WAAS which does not require RAIM.

Actually, WAAS does require RAIM but most modern receivers perform the calculation on their own without requiring you to initiate the process. This is why you do not actually know the minimums line you will use on the approach until the unit annunciates it. Check your manual but usually within a cone (mine is 30 degrees of final approach course) the unit will display LNAV, LNAV+V or LPV. Even though you may have a WAAS IFR navigator and therefore think you need only brief and use the LPV minimums, the unit tells you based on the RAIM calculation it performs automatically. If LNAV is all that is annunciated, those are your minimums and procedures for this approach.
 
VOR cheap

GPS is great, but I am reluctant to rely on one source for navigation anymore. With VOR receivers Being cheap enough, it seems prudent to have it as a backup. It integrates well with modern glass cockpits to where is seamless.
 
About a year ago, I crossed the initial approach fix on an LPV and watched the GPS integrity drop to a combination on "none" and "entoute". My options after that were ILS with a 10kt tailwind, straight in NDB approach or divert.
 
Who needs VORs? Maybe you do.

GPS is great, but I am reluctant to rely on one source for navigation anymore. With VOR receivers Being cheap enough, it seems prudent to have it as a backup. It integrates well with modern glass cockpits to where is seamless.

+1

I use GPS 95+% of the time, and prefer it when available. That includes LPV approaches v ILSs. That said, as other threads have pointed out, the GPS signal isn't always available. At least in the SW, GPS outage NOTAMs are relatively common--White Sands Missile Range, Yuma Proving Grounds, and others. Just because there's a NOTAM doesn't necessarily mean the signal will be unavailable when you need it, but sometimes it is. Happened to me last summer--no GPS signal between El Paso and Tucson. On top of a solid layer (rare here), so pilotage wasn't a viable option. Mountains along the route range up to roughly 9K feet. Having access to the San Simon and Tucson VORs on the 430W made that last leg home a lot easier.
 
While I understand and accept the importance of VORs and ILS at the present time, but what will the future hold?
We always took VORs and ILS for granted until now, when Next Gen is pushed and VORs are downsized and most marked inop.
We have ADSB with weather, big changes.
 
I dont have a VOR in my plane. I tried using it when I was training in a 172 but now I am finishing up my license, I just have the G3X, my phone and Ipad with Garmin Pilot. For the flying I will be doing, I am satisfied with no VOR.

The problem for me is Im taking my written in the next couple weeks and will have to guess an answer on the test! I passed with 93% 3 years ago missing a couple VOR questions so I hope I can do it this time! The science behind the VOR is really interesting and the execution appeals to me but with no use for it in my future, Im concentrating on how to get into and out of a towered airport and request flight following!!
 
While I understand and accept the importance of VORs and ILS at the present time, but what will the future hold?
We always took VORs and ILS for granted until now, when Next Gen is pushed and VORs are downsized and most marked inop.
We have ADSB with weather, big changes.

I think the VOR MON program is gonna be around for awhile yet. Phase II will be complete by some time in 2030, according to current program guidelines.

That means that, in 2030 there will still be 509 VORs with large enough service volumes that you should be able to pick up crossing radials at 5,000' and above anywhere in CONUS. And, you should be within 100 miles of an MON airport as well.

That's the plan. I haven't heard anything different. Has anyone else?

https://www.ifr-magazine.com/avionics/backing-up-gps/
 
Last edited:
Good news

I think the VOR MON program is gonna be around for awhile yet. Phase II will be complete by some time in 2030, according to current program guidelines.

That means that, in 2030 there will still be 509 VORs with large enough service volumes that you should be able to pick up crossing radials at 5,000' and above anywhere in CONUS. And, you should be within 100 miles of an MON airport as well.

That's the plan. I haven't heard anything different. Has anyone else?

https://www.ifr-magazine.com/avionics/backing-up-gps/

This is good news on VORs being avialable for en route nav. I havent heard this but is nice to know. Glad I installed a VOR/ILS capability
 
This is good news on VORs being avialable for en route nav. I havent heard this but is nice to know. Glad I installed a VOR/ILS capability

There will always be some VOR DME's and ILS for our lifetime and beyond. GPS has outages from time to time (planned and unplanned) and in theory be taken out by our enemies. There is no way in the near term all NAV eggs will be in the GPS based basket.

I am NOT saying GPS is not now and will be in the future the prime NAV method. To operate effectively in the system you need GPS. You do. Just that VOR/DME/LOC/ILS are still a thing for some time in parallel. If you operate at secondary airports GPS approaches are the only choice.

ILS Cat I is still a very elegant simple accurate 200 and 1/4 (1800RVR) get er on the ground and beats most LPV's, waas or not. ILS does not rely on satellites... REAL PILOTS FLY ILS... Ha ha. Also you don't need a data base subscription just a current chart which is free on line your tablet/iPad software.
 
Last edited:
In aviation, we strive for redundancy as much as possible. Two ignition systems on each engine for example.

GPS is and will be primary source of navigation.
VOR/DME/ILS was the primary, but is now the backup source of navigation. Us Canucks are stuck with NDBs as backup in a large (but sparsely populated) chunk of the country as well.
 
I think the VOR MON program is gonna be around for awhile yet. Phase II will be complete by some time in 2030, according to current program guidelines.

That means that, in 2030 there will still be 509 VORs with large enough service volumes that you should be able to pick up crossing radials at 5,000' and above anywhere in CONUS. And, you should be within 100 miles of an MON airport as well.

That's the plan. I haven't heard anything different. Has anyone else?

https://www.ifr-magazine.com/avionics/backing-up-gps/

There is a YouTube video out there about future VORs and service volumes.
I don’t have the link handy but it was a nice and quick view that shared info on what is being said here by N894RV.
 
There is a YouTube video out there about future VORs and service volumes.
I don’t have the link handy but it was a nice and quick view that shared info on what is being said here by N894RV.

There is a good video on youtube. Simple google search. I was not aware until our friend brought it up. Great info on this forum. I feel better about my decision.
 
There is a YouTube video out there about future VORs and service volumes.
I don’t have the link handy but it was a nice and quick view that shared info on what is being said here by N894RV.

So that everyone can watch the video, here is the link.
 
So much reliance on GPS. A sensitive, interconnected system...... Seems overly ripe for hacking or other disruption. But clearly the "smart" people think otherwise.
 
In aviation, we strive for redundancy as much as possible. Two ignition systems on each engine for example.

GPS is and will be primary source of navigation.
VOR/DME/ILS was the primary, but is now the backup source of navigation. Us Canucks are stuck with NDBs as backup in a large (but sparsely populated) chunk of the country as well.

Here is a hood Vid on new VOR service volumes
https://youtu.be/gf2g_ddMO4o

Airlines are still dialing in the LOC and flying CAT I, II, III... the main deal primary NAV, not back up. Sorry. GPS signals are weak. Heavy wearher can play havoc on GPS signals. GPS is still 1/2 mile min. That will not hack it. ILS especially Cat III is still king and may be for a long time.
 
Last edited:
INS isn't good enough for approach level accuracy. Not sure about the new stuff, but the older mechanical INS systems could be off by several miles after an oceanic crossing. Poaition only updated by VORs and DMEs as they came back into range of the coast.

Interestingly even more recent airliner nav computers will have GPS as one of several inputs. My work plane for example, uses VORs and DMEs to triangulate it's position. Loose GPS, and it still knows where it is, where it's going and how to get there. Just needs sufficient number of VORs and DMEs. Won't fly an RNAV like that, but good enough for enroute navigation. The nav sources available are GPS primary (actually 2 GPS units) then VOR/DME and INS are secondary. My work plane doesn't have INS installed.
 
Been wondering about I-Nav too.

Do they still have inertial guidance systems?

Yes and with MEMS prices are not super high, $3-4K. But not integrated and only a single unit, not redundant. I thought the over-the-pond commercial used 3 I-navs and two had to match.

The experimental world is perfect for first applications at a reasonable price. Mike Vacarro uses these in his on-speed experiments.

Also, if all the orbital GPS were destroyed, ground based pseudolites can provide approaches like ILS and navigation, but limited to line of sight. They are required for autonomous mining trucks with high-wall shadowing. Like VOR's they would be would be a more robust system for attack.
 
Do they still have inertial guidance systems?

Yes all the airliners and heavy buz jets have IRU internal reference unit. INS went away in the 80s., especially mechanical gyros. INS was just for navigation. IRS that came in the 80s with honeywell's laser ring gyro and solid state accelerometers not only provides navigation but all the flight instrument attitude information and flight data recorder data.

I know of no civil airplane that routinely does inertial reference system Landings only unless it's military. This is not to be confused with FMC (flt mgmt computer) position our flight management system position shows on airliners PFD. The FMC uses the IRU mixed with terrestrial base Nav data like dme and localizer, along with GPS. In 2021 GPS is the prime Nav that the FMC prioritizes.

When you fly out over the Atlantic you have no ground base Nav. Think pre or early GPS. Your INS or your IRU position would start to drift. Once you got within the coastline and started picking up ground-based references you could see your (FMC) position actually jumping or moving. You could be up to a mile or two off laterally. Now with GPS the FMC kind of ignores (lower priority) the IRU position. GPS is of course a modern miracle.

IRU can be accurate but over hours errors build. Unless the technology changes drastically and there is error checking no IRU only approach will happen. GPS is the Tech that will likely be here for the foreseeable future.

IRU is still a thing but low cost units. I recall a Boeing IRU (and there are 3 of them per plane) cost almost $1M each I. The $80's. I found a used one for $200k. Honeywell is taking QST and 2bd Gen IRU's in trade for Gen 4 units at discount. No doubt the old designs are no longer repairable.

In our RV Skyscooter we have solid state gyros for Flt Inst. This did not exist 10 yrs ago. Just like smart phones did not exist 12 yrs ago, hand held computers with wireless internet connectivity. Now Internet (dial up AOL 14.4k baud in 90's) is 100's of Gigabytes/ Sec. First wide area NAV for Aviation LORAN mid 1980's. By 1990's GPS for planes was a thing. Non percussion approaches converted w/ GPS overlay fooled. Now... LPV with WAAS and NSB and for the most part VOR approaches are as rare as a dodo bird ( except in Alaska).
 
Last edited:
I wonder how the issues around 5G will impact the move towards GPS based approaches? The doomsday scenario (and the one the FAA is getting ready for) is no more CAT II/III approaches. Current LPV approaches are more or less equal to Cat I, but could those be improved upon with existing WAAS? Time will tell.

With the MON program I think VORs will still be around when the last RV built in 2021 is retired to the scrap heap- in other words several decades out. If I were building today I'd definitely put a VOR in if building an IFR airplane.
 
Last edited:
I wonder how the issues around 5G will impact the move towards GPS based approaches? The doomsday scenario (and the one the FAA is getting ready for) is no more CAT II/III approaches. Current LPV approaches are more or less equal to Cat I, but could those be improved upon with existing WAAS? Time will tell.

With the MON program I think VORs will still be around when the last RV built in 2021 is retired to the scrap head- in other words several decades out. If I were building today I'd definitely put a VOR in if building an IFR airplane.

I wonder how long it'll be before the Telecoms abandon the lower frequency 5G technology in favor of all millimeter-wave. Especially in light of the FAA's actions.

I'd heard that 5G operating below 6ghz was only a stop-gap measure until more mmWave infrastructure was online.
 
So what will be the next big tech to take its place.
Already a LOT of em in our area are remarked inoperative, so perhaps its a prelude to them being gone. ( I have read from FAA and here about how they will keep most or some of them active for now, but I guess the writing is on the wall)
So if I have a GTN navigator without the Xi and have the itch to go Xi, I am thinking I should just wait a while.
Any thoughts on this.

There's a lot of posts but nobody seems to have addressed your question.

Practically speaking, there is no difference between a 750 and 750Xi.

The Xi supports the smart glide feature, and has updated 'computer' hardware...maybe a nicer screen. This translates into faster boot times and means it will continue to get new software as Garmin brings new capabilities to market.

What doesn't change is that the 750, or 750 Xi radio, has a COM, NAV, and GPS transceiver.

So the only thing you gain switching from a 750 to a 750 Xi is the faster boot time; new screen resolution; maybe reassurance with product life; and smart glide feature.

What you lose is about $5k to upgrade.

Both radios have a NAV radio regardless.
 
Back
Top