VOR Test 30 days

[Marc_B]

Just wondering if seeing VOR error is just a throwback to the past?  I understand misalignment of compass card with radio signal, but with all glass does anyone ever get something other than zero deg error without something broken?  My n is 2 years checking every 30 days and it’s always been ZERO error/ZERO difference between Nav 1&2.  Have any of you with glass ever seen an error?
Of course vast majority of my flying is GPS, but I do use radios for ILS approaches.  If 14 CFR 91.171 was drafted for the glass cockpit, do you think 30 days** still needed?  What are the chances that Garmin could draft a self test utility that would check and log these? Ala RAiM for VORs?

**edit: by “needed” I mean would it still be 30 days vs annual? Or some other interval? Vs done autonomously by Garmin unit…

Edited July 13, 2023 by Marc_B
Clarification

[midlifeflyer]

At this point, everything about VOR is arguably a throwback to the past

The receivers have probably gotten better but there are plenty of older ones out there and I've definitely seen small errors within the testing tolerance. 

ILS doesn't count - localizers are not VORs and the check is not required for them.

I don't see any reason there wouldn't be a test for the accuracy of VOR even today. AFAIK, glass hasn't changed VOR technology. When you switch to VLOC on a G1000 or GTN or GNS, you are using VOR, not GPS. 

 

[N201MKTurbo]

The older radios used analog demodulators and mechanical resolvers. They could drift, and did. The modern receivers use DSP demodulators and the resolvers are replaced with digital displays. They are either going to work perfect or not at all.

It would be good to change the regs to reflect this reality, but I don’t think it is high on the FAAs priority list. 
 

You should contact AOPA and maybe they will take on the cause. 
 

I get good response from AOPA. I emailed them the other day to tell them an answer on Test Pilot was wrong. Barry Schiff replied from his personal email a couple of hours later.

[Marc_B]

@N201MKTurbo I just sent AOPA an email. Of course my comment was much less thought out than a specific request. More a curiosity if an all glass approved equipment 91.171 check could safely be extended to annual vs 24 month with pitot/static/altimeter/transponder check….

[N201MKTurbo]

13 minutes ago, Marc_B said:

@N201MKTurbo I just sent AOPA an email. Of course my comment was much less thought out than a specific request. More a curiosity if an all glass approved equipment 91.171 check could safely be extended to annual vs 24 month with pitot/static/altimeter/transponder check….

Good luck! I think it would be a worthwhile change.

[Pinecone]

There is no reason that a GPS/VOR unit manufacturer could not build in automatic testing.

Compare the VOR radial to the GPS location.  No difference than using an airborne checkpoint.   And the GPS could even tune a nearby VOR if the current frequency is out of range of any VOR.

I just set NAV 1 and 2 to the same VOR and check that the pointers are aligned.  I do it almost every flight.

 

[midlifeflyer]

5 hours ago, Marc_B said:

@N201MKTurbo I just sent AOPA an email. Of course my comment was much less thought out than a specific request. More a curiosity if an all glass approved equipment 91.171 check could safely be extended to annual vs 24 month with pitot/static/altimeter/transponder check….

I have a funny feeling creating a special VOR verification rule so glass pilots don't have to go through the awful burden of taking a minute to do a VOR check for something which at this point is necessary only in the event of a GPS failure isn't high on the FAA's list.  

If you prefer to pay an avionics shop instead, I'm sure it can be arranged,

[Andy95W]

1 hour ago, Pinecone said:

There is no reason that a GPS/VOR unit manufacturer could not build in automatic testing.

Compare the VOR radial to the GPS location.  No difference than using an airborne checkpoint.   And the GPS could even tune a nearby VOR if the current frequency is out of range of any VOR.

I just set NAV 1 and 2 to the same VOR and check that the pointers are aligned.  I do it almost every flight.

 

I just installed a Trig NAV/COM that has a continuous readout of the radial from the VOR, so it kind of has what Pinecone is talking about.

But from a “legal” standpoint, could I compare my VOR indicator to that digital readout and count that as my VOR check?  I don’t have an FAA sanctioned VOR checkpoint near me.

[EricJ]

56 minutes ago, Andy95W said:

I just installed a Trig NAV/COM that has a continuous readout of the radial from the VOR, so it kind of has what Pinecone is talking about.

But from a “legal” standpoint, could I compare my VOR indicator to that digital readout and count that as my VOR check?  I don’t have an FAA sanctioned VOR checkpoint near me.

The idea is to try to verify performance error tolerance by comparing two separate receivers.  If what you're describing is comparing two displays from the same receiver I wouldn't think that would be a very good test, since the receiver could be way off and just displaying the same error twice.

[N201MKTurbo]

I haven’t read the rules for a while, but you can use a VOT, VOR checkpoint, check two VORs against each other. Or check the VOR against a known landmark.

I think I read somewhere that a check between a GPS waypoint and a VOR radial counts as a landmark check. 
 

Just put a comment in your ForeFlight log that you did the test and you are good to go. If you record the error all the better. 
 

I don’t know about the rest of you, but on a cross country, it gets a bit boring sometimes, might as well do a VOR check to pass the time.

[Pinecone]

7 hours ago, N201MKTurbo said:

I don’t know about the rest of you, but on a cross country, it gets a bit boring sometimes, might as well do a VOR check to pass the time.

That is what I do.   I dial in the same VOR on both, and put them on the Aspen as the two pointers.  They I write the error on my flight log sheet on my knee board.

[FlyingDude]

15 hours ago, Andy95W said:

I don’t have an FAA sanctioned VOR checkpoint near me.

there is one at KYIP   108.85  On the chart supplement https://skyvector.com/files/tpp/2306/afdpdf/EC_173_15JUN2023.pdf

accessible by clicking on small icon on upper left side of the page: https://skyvector.com/airport/YIP/Willow-Run-Airport

 

[Marc_B]

I have a VOT on the field where I get maintenance. And it’s easy enough to get airborne VOR checks (<6deg error). But my question was has anyone seen anything other than zero error on TAA/glass cockpit and would there be safety issues to align this with IFR cert every 24 months with pitot-static/altimeter/transponder? 

[PT20J]

Given the number of NOTAMs I see for VORs out of service or unmonitored, I don't think it really matters that much.

[PeteMc]

 I've had an issue with the VOR check since I upgraded and now only have one VOR.  Not every Airport has a check point and it can be done in flight, but with GPS a lot of flying is Direct or not exactly where you need to be to have a known ground fix - or be exactly over it.

I'd love for the FAA to simply modify the Regs to allow for a comparison to a GPS with some know variable like is down with the VORs.  Either that, or just make it a ground check when the other equip. is tested for IFR.

[McMooney]

even my old units kx170b, gns480 have read zero diff for all of the last 5 years.  

no worth an FAA rule though,  not even 30 seconds to compare them.  To be honest, as much as VORs are out these days kinda like who cares.  

wish the FAA had just said we're taking out all VORs instead of this MON stuff

 

 

[hammdo]

I don’t mind the MON. In those cases I’d probably get radar vectors and have an ILS. I’d also look for airports with ASR/PAR approaches if the GPS is unreliable. I like having a backup to land. Navigating, I’d be busier than a one armed paper hanger trying to cross check radials on my single VOR - if IFR, just get me down. Flying VFR, vector if possible ( I should know where I’m at if I’m following my route VFR).

I like options. VOR check - I don’t mind doing the check when necessary. We have many airway checks around where I fly to do an airborne check.

-Don

[N201MKTurbo]

44 minutes ago, hammdo said:

 I’d also look for airports with ASR/PAR approaches if the GPS is unreliable.

VOR approaches are usually pretty easy. The -As are all circle to land, so the minimums are pretty high. I've only done PAR approaches to three (KDMA, KIWA, KNYL) airports and all had ILS to the same runways. So you are unlikely to find a PAR or ASR where there isn't an ILS nearby.

[N201MKTurbo]

Seeing that I have never flown IFR without ATC. Sure I have been out of radar contact and/or radio contact for a while at times. But, if I lost my GPS nav, I would just ask for vectors for the rest of the flight. They would probably be good with that, but would probably give you a few VOR waypoints at least near you destination just in case you lost comm.

[PeteMc]

1 hour ago, McMooney said:

who cares.  

wish the FAA had just said we're taking out all VORs instead of this MON stuff

Yea, let's see how much you like that when the miliary or some industry is testing something and you have no GPS coverage in the area you're flying.  

 

[McMooney]

Much more likely

33 minutes ago, PeteMc said:

Yea, let's see how much you like that when the miliary or some industry is testing something and you have no GPS coverage in the area you're flying.  

 

I'm just being honest, VORs are down a helluva lot more than GPS.

Currently 3 of 4 in my area are Notam'd out, one being a MON vor.

think i've had gps blip once or twice in 6 years

Edited July 14, 2023 by McMooney

[PeteMc]

22 minutes ago, McMooney said:

think i've had gps blip once or twice in 6 years

Granted they're rare, but I think they happen more to the West of you in some of the bigger testing areas.  I see the NOTAMs for possible outages when I'm looking at possible flight in the SW.

My beef is not with the MON system, I see the need for a second type of tech when we're poking holes in the clouds.  Just wish some of the Regs would catch up with the current technology.  And I also get how SOME Regs shouldn't be changed on a whim and need through review.  But saying it's okay to compare your VOR to a GPS isn't one of them.  If it's off it's going to be way off.  If it's off a little, so what, they allowed a pretty big error factor when you could compare to a second VOR where both could be off at the max error in the same direction and you think you're spot on.

 

[kortopates]

Much more likely
I'm just being honest, VORs are down a helluva lot more than GPS.
Currently 3 of 4 in my area are Notam'd out, one being a MON vor.
think i've had gps blip once or twice in 6 years

It depends on where you fly and frankly if i didn’t have any VOR’s still in service i’d be concerned flying IMC without a backup of VOR’s. GPS is extremely vulnerable to bad actors due to the weak signal. Military for example are always doing interference testing - which is still rare to cause an outage.
Personally i’ve never had an issue of lost GPS here in the US but have spoken to many pilots that have. But there are some areas in Mexico where i have been repeatedly jammed by a probably a $10 jammer. In VFR it’s not a big deal but i have experienced it in turbulent IMC and was very thankful to have VORs to fall back on to navigate till i got out of the area of being jammed.


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[McMooney]

43 minutes ago, PeteMc said:

Granted they're rare, but I think they happen more to the West of you in some of the bigger testing areas.  I see the NOTAMs for possible outages when I'm looking at possible flight in the SW.

My beef is not with the MON system, I see the need for a second type of tech when we're poking holes in the clouds.  Just wish some of the Regs would catch up with the current technology.  And I also get how SOME Regs shouldn't be changed on a whim and need through review.  But saying it's okay to compare your VOR to a GPS isn't one of them.  If it's off it's going to be way off.  If it's off a little, so what, they allowed a pretty big error factor when you could compare to a second VOR where both could be off at the max error in the same direction and you think you're spot on.

 

I believe they had dme/dme or Loran lined up but guessing that's not going to happen.