Value of 2 VORs

AA5Bman

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He who ironically no longer flies an AA5B
In contemplating panel upgrades and finally adding an IFR GPS to my plane, I stumbled upon the GNC 355 which is basically a GTN 650 without the VOR. Given that my plane already has two VORs and post-upgrade I’d still have at least 1 VOR (presumably with GS), is there value in having a second VOR that’s integrated with the GPS?

I keep reading about how VORs are “dead” and being decommissioned. In choosing a IFR GPS, is it important to have an integrated VOR, or does it make sense to just save the money and go to a single VOR?

Basically: GTN 650 vs. GNC 355?
 
In contemplating panel upgrades and finally adding an IFR GPS to my plane, I stumbled upon the GNC 355 which is basically a GTN 650 without the VOR. Given that my plane already has two VORs and post-upgrade I’d still have at least 1 VOR (presumably with GS), is there value in having a second VOR that’s integrated with the GPS?

I keep reading about how VORs are “dead” and being decommissioned. In choosing a IFR GPS, is it important to have an integrated VOR, or does it make sense to just save the money and go to a single VOR?

Basically: GTN 650 vs. GNC 355?

VOR is not dead. https://www.faa.gov/about/office_or...chops/navservices/transition_programs/vormon/
 
If you have GPS and a VOR/ILS, do you really need a 3rd navigation source? That seems to be the question. My answer another question: is triple redundancy worth the weight and expense?

As far as having a 2nd VOR, how often in the past have you used it to find crossing radials since you started using GPS?

In the panel I'm building, I'll have the Garmin GPS/NAV/Com feeding an EFIS, and an iPad for backup. I don't expect to fly hard IFR to minimums. I just want the ability to depart from those stable marine layers that seem to take most of the day to burn off around here.
 
I see I’ve touched a nerve. Is it more than backup? If you’re going to have an IFR GPS and at least one VOR, is there much benefit to having an IFR GPS and two VORs?
 
If you have GPS and a VOR/ILS, do you really need a 3rd navigation source? That seems to be the question. My answer another question: is triple redundancy worth the weight and expense?

As far as having a 2nd VOR, how often in the past have you used it to find crossing radials since you started using GPS?

In the panel I'm building, I'll have the Garmin GPS/NAV/Com feeding an EFIS, and an iPad. I don't expect to fly hard IFR to minimums. I just want the ability to depart from those stable marine layers that seem to take most of the day to burn off around here.

Ahh, Southern California, I see? My use would be similar. Very interested to hear that you are considering GPS + no standalone VORs, hadn’t really even considered that but it makes sense. I haven’t flown much IFR with a GPS, but the only real reason I can see to have a VOR in a GPS world is for cross radials (?) and ILS, but I’m open to other ideas!
 
No need to have two VOR's. I had a GTN-650 and it was fine with the GI-106A. Also had an SL-30 as a backup NAV2/COM2.
 
Ahh, Southern California, I see? My use would be similar. Very interested to hear that you are considering GPS + no standalone VORs, hadn’t really even considered that but it makes sense. I haven’t flown much IFR with a GPS, but the only real reason I can see to have a VOR in a GPS world is for cross radials (?) and ILS, but I’m open to other ideas!

I know there's a lot of folks out there that don't trust GPS. I'm sure they all have up-to-date paper chart subscriptions too. But, as long and RAIM is good, your position is known more accurately than with VOR crossing radials anyway. And, once the 2020 mandate becomes the law of the land, its gonna be really hard to get lost anywhere inside the lower 48.
 
I know there's a lot of folks out there that don't trust GPS. I'm sure they all have up-to-date paper chart subscriptions too. But, as long and RAIM is good, your position is known more accurately than with VOR crossing radials anyway. And, once the 2020 mandate becomes the law of the land, its gonna be really hard to get lost anywhere inside the lower 48.

I know my ancient GPS496 has been more accurate and reliable than any of the analog instruments in my plane have ever been. I mean, im considering this upgrade because one of my VORs has been dead for a while and now my AI is going too!
 
I'd rather have two VORs. If you really have to use it, you want two. That said, I've only one and will have to make do.
 
I think it wise to keep at least one VOR/ILS for ground based nav backup. Two is a luxury that is unlikely to be needed. The reality is that despite GPS interference testing, I have NEVER used VOR nav since installing a GNS-430W a decade or more ago. I have flown some ILS approaches, but could have easily requested LPV instead. The main activity for my two VOR receivers is doing dual VOR checks every 30 days in case I need them. Which I haven't yet.

The VOR system is not dead, but will be greatly curtailed over time, with more limited routings available, and no guaranteed reception below 5000 feet when the minimum operating system is complete. In my neck of the woods, area VOR stations are going out of service or are being decommissioned at quite a clip.
 
If you’re going to have an IFR GPS and at least one VOR, is there much benefit to having an IFR GPS and two VORs?
30 day VOR check. It's easier to tune one against the other than it is to fly to some waypoint and then log it in the air. But I suppose if you have a VOT in the run up area at your home airport, you've got that part made in the shade.
 
30 day VOR check. It's easier to tune one against the other than it is to fly to some waypoint and then log it in the air. But I suppose if you have a VOT in the run up area at your home airport, you've got that part made in the shade.

Yes 30 day VOR check and Flying a radial to a crossing radial. Not lots of these but enough. Also like the redundancy in case of losing GPS. Someone else’s minimums might be different.
 
I'm re-doing my whole panel, and I had the chance to get a 2nd VOR, and chose not to.

This!

I dumped the second VOR. I’m redoing my whole panel in a 310.

I went with
GTN 650
345 ADS B in/out
Aera 660 with Air Gizmo
Dual G5’s
Garmin 225 Backup Comm radio

My HSI and AI needed rebuilt. Going to the G5 was a no brainer.

My original thought was to just do the 375 and 2 Garmin 225’s. That gave me everything I needed and I would lose all VOR capability and be strictly GPS.

The 375 and 2 225’s are about the same price for just one GTN 650. I only gain a VOR/ILS with the 650 versus my configuration choice.

Some good points were made and I got talked out of what I wanted to go with and into what my current configuration is being installed now. It cost me about $5k more in avionics and who knows yet how much extra on the install. I haven’t got the final bill yet. I know it’s at least $2k extra.

The only thing I gained in my current configuration is a VOR. Not sure if it was worth the $7k price yet.

I fly my 310 just as a convenience and don’t plan to fly to mins. I use GPS for everything and would generally take an LPV over an ILS any day. I guess time will tell if it was worth the extra expense for the VOR/ILS.



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Ahh... recalling the days when GPS was non-existant, and DME was rare in GA airplanes.
Intersection holding was done with two radials. It actually could be done with a single VOR, but two was a complete luxury.

On a side note, I also remember holding with a VOR and an ADF to define an intersection.

Those were the days..!

Edit: typo
 
Last edited:
Pretty much same as the OP. Were gonna dump our non ILS kx155 and swap it with a GNC355a. Really looking forward to the map context easier to program frequencies vs the old dial in and swap (which you gotta admit has worked quite well). Just wondering if the 335 radio will sound like the kx155. I like the kx155 audio. I guess we can always use the remaining kx155 but I would think ease of use will make the new one the winner.
 
Now I just need to find/understand VOR check procedures for single-VOR installations.

I need checkpoints for the DVT and SDM area.

It’s all in FAR 91.171


(a) No person may operate a civil aircraft under IFR using the VOR system of radio navigation unless the VOR equipment of that aircraft—

(1) Is maintained, checked, and inspected under an approved procedure; or

(2) Has been operationally checked within the preceding 30 days, and was found to be within the limits of the permissible indicated bearing error set forth in paragraph (b) or (c) of this section.

(b) Except as provided in paragraph (c) of this section, each person conducting a VOR check under paragraph (a)(2) of this section shall—

(1) Use, at the airport of intended departure, an FAA-operated or approved test signal or a test signal radiated by a certificated and appropriately rated radio repair station or, outside the United States, a test signal operated or approved by an appropriate authority to check the VOR equipment (the maximum permissible indicated bearing error is plus or minus 4 degrees); or

(2) Use, at the airport of intended departure, a point on the airport surface designated as a VOR system checkpoint by the Administrator, or, outside the United States, by an appropriate authority (the maximum permissible bearing error is plus or minus 4 degrees);

(3) If neither a test signal nor a designated checkpoint on the surface is available, use an airborne checkpoint designated by the Administrator or, outside the United States, by an appropriate authority (the maximum permissible bearing error is plus or minus 6 degrees); or

(4) If no check signal or point is available, while in flight—

(i) Select a VOR radial that lies along the centerline of an established VOR airway;

(ii) Select a prominent ground point along the selected radial preferably more than 20 nautical miles from the VOR ground facility and maneuver the aircraft directly over the point at a reasonably low altitude; and

(iii) Note the VOR bearing indicated by the receiver when over the ground point (the maximum permissible variation between the published radial and the indicated bearing is 6 degrees).

(c) If dual system VOR (units independent of each other except for the antenna) is installed in the aircraft, the person checking the equipment may check one system against the other in place of the check procedures specified in paragraph (b) of this section. Both systems shall be tuned to the same VOR ground facility and note the indicated bearings to that station. The maximum permissible variation between the two indicated bearings is 4 degrees.

(d) Each person making the VOR operational check, as specified in paragraph (b) or (c) of this section, shall enter the date, place, bearing error, and sign the aircraft log or other record. In addition, if a test signal radiated by a repair station, as specified in paragraph (b)(1) of this section, is used, an entry must be made in the aircraft log or other record by the repair station certificate holder or the certificate holder's representative certifying to the bearing transmitted by the repair station for the check and the date of transmission.


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Ahh... recalling the days when GPS was non-existant, and DME was rare in GA airplanes.
Intersection holding was done with two radials. It actually could be done with a single VOR, but two was a complete luxury.

On a side note, I also remember holding with a VOT and an ADF to define an intersection.

Those were the days..!

I had a sadistic CFII. He had me hold at an intersection defined by bearings from two NDB’s (one was actually a broadcast radio station.) I stayed in the County, I think:(
 
Ahh... recalling the days when GPS was non-existant, and DME was rare in GA airplanes.
Intersection holding was done with two radials. It actually could be done with a single VOR, but two was a complete luxury.

On a side note, I also remember holding with a VOT and an ADF to define an intersection.

Those were the days..!

I remember those days, thinking to myself, damn, it would be cool to have DME.
 
In contemplating panel upgrades and finally adding an IFR GPS to my plane, I stumbled upon the GNC 355 which is basically a GTN 650 without the VOR. Given that my plane already has two VORs and post-upgrade I’d still have at least 1 VOR (presumably with GS), is there value in having a second VOR that’s integrated with the GPS?

I keep reading about how VORs are “dead” and being decommissioned. In choosing a IFR GPS, is it important to have an integrated VOR, or does it make sense to just save the money and go to a single VOR?

Basically: GTN 650 vs. GNC 355?

Flying an ILS with the 650 allows you to navigate via GPS up to the point of LOC intercept, then the 650 switches from GPS to VLOC mode automatically (and will have auto loaded the LOC frequency). Can’t do that if your GPS and NAV radio are in separate boxes.
 
Flying an ILS with the 650 allows you to navigate via GPS up to the point of LOC intercept, then the 650 switches from GPS to VLOC mode automatically (and will have auto loaded the LOC frequency). Can’t do that if your GPS and NAV radio are in separate boxes.

You’re correct. Instead you would just shoot the LPV which the airport most likely had if it had an ILS. Usually LPV mins are within 50 feet of ILS mins.


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Ahh... recalling the days when GPS was non-existant, and DME was rare in GA airplanes.
Intersection holding was done with two radials. It actually could be done with a single VOR, but two was a complete luxury.

On a side note, I also remember holding with a VOR and an ADF to define an intersection.

Those were the days..!

Back then two 5 1/4 floppy drives in your desktop PC was also a complete luxury. :D
I just wish it was as inexpensive to bring a 1980s panel current. :(
 
In the past the second VOR served as a backup to the first. Now the first VOR is a backup to GPS, so I don't see a need for a GPS and two VORs anymore than the need for 3 VORs before GPS.

I do think one VLOC is very important as there are still a few places w/ an ILS and no LPV approach. Also if you fly through a GPS outage one VOR receiver will get you where you need to go on the MON, or if you are VMC you can of course always fly IFR (I Fly Roads).

The Air Force will make sure the GPS system works when it's needed, despite the annoying test outages. I'd argue one GPS receiver is safer than two VOR receivers.
 
I've been ruminating about this lately, since I only have one VOR. The method I would have to use to check would be flying a Victor Airway and checking the signal over something super visible on the ground. Problem is there isn't anything unambiguous lying under any of the local VOR airways. I'd have to go a half hour out of my way just to do this. Not certain what I'm going to do about it.
 
I've been ruminating about this lately, since I only have one VOR. The method I would have to use to check would be flying a Victor Airway and checking the signal over something super visible on the ground. Problem is there isn't anything unambiguous lying under any of the local VOR airways. I'd have to go a half hour out of my way just to do this. Not certain what I'm going to do about it.

Have you looked for either VOR check points (defined in the green book formerly known as AFD) or VOT stations in your area? There happen to be two ground VOR check points at my home 'drome (KORL) but that's not everywhere...
 
there are still a few places w/ an ILS and no LPV approach.

Not debating the value of having a VOR receiver, but the only examples of this that I am aware of in the U.S. are military bases, or places like Hawaii and Guam, that are outside the WAAS coverage area. Do you know of some in the CONUS?
 
I've been ruminating about this lately, since I only have one VOR. The method I would have to use to check would be flying a Victor Airway and checking the signal over something super visible on the ground. Problem is there isn't anything unambiguous lying under any of the local VOR airways. I'd have to go a half hour out of my way just to do this. Not certain what I'm going to do about it.
Save the lat/long of the checkpoint as a user defined waypoint into your GPS and then every 30 days D-> enter enter.
 
I think someone who wants to fly instruments on a single VOR is a masochist.
 
And ex-military. An oldie but goodie:
https://www.pilotsofamerica.com/community/threads/airport-with-ils-no-rnav.109463/#post-2478879

Maybe @chartbundle can let us know if the list has changed.
Doesn't look like it, only one I see that's not all .mil is MCC:
KBAD | BARKSDALE AFB | BOSSIER CITY
KDMA | DAVIS MONTHAN AFB | TUCSON
KDYS | DYESS AFB | ABILENE
KHIF | HILL AFB | OGDEN
KLRF | LITTLE ROCK AFB | JACKSONVILLE
KLSV | NELLIS AFB | LAS VEGAS
KMCC | MC CLELLAN AIRFIELD | SACRAMENTO
KMMT | MC ENTIRE JNGB | EASTOVER
KMUO | MOUNTAIN HOME AFB | MOUNTAIN HOME
KMXF | MAXWELL AFB | MONTGOMERY
KNOG | ORANGE GROVE NALF | ORANGE GROVE
KNQI | KINGSVILLE NAS | KINGSVILLE
KRCA | ELLSWORTH AFB | RAPID CITY
KSSC | SHAW AFB | SUMTER
KVBG | VANDENBERG AFB | LOMPOC
PASY | EARECKSON AS | SHEMYA

Unfortunately I don't have an automated way to see if/how much higher the RNAV minimums are for all the airports with both an ILS and RNAV.
 
Doesn't look like it, only one I see that's not all .mil is MCC:
KBAD | BARKSDALE AFB | BOSSIER CITY
KDMA | DAVIS MONTHAN AFB | TUCSON
KDYS | DYESS AFB | ABILENE
KHIF | HILL AFB | OGDEN
KLRF | LITTLE ROCK AFB | JACKSONVILLE
KLSV | NELLIS AFB | LAS VEGAS
KMCC | MC CLELLAN AIRFIELD | SACRAMENTO
KMMT | MC ENTIRE JNGB | EASTOVER
KMUO | MOUNTAIN HOME AFB | MOUNTAIN HOME
KMXF | MAXWELL AFB | MONTGOMERY
KNOG | ORANGE GROVE NALF | ORANGE GROVE
KNQI | KINGSVILLE NAS | KINGSVILLE
KRCA | ELLSWORTH AFB | RAPID CITY
KSSC | SHAW AFB | SUMTER
KVBG | VANDENBERG AFB | LOMPOC
PASY | EARECKSON AS | SHEMYA

Unfortunately I don't have an automated way to see if/how much higher the RNAV minimums are for all the airports with both an ILS and RNAV.

KVNY (Van Nuys) does not have any GPS approach and does have two ILS approaches. There are several others, including some popular GA destinations, but I can't think of off the top of my head.
 
KVNY (Van Nuys) does not have any GPS approach and does have two ILS approaches. There are several others, including some popular GA destinations, but I can't think of off the top of my head.

Ahh, my script didn't properly filter RNAV departures out. Looks like KVNY was the only public field missed though.
 
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