Why buy new VHF Nav?

CRQFlier

CRQFlier

Pre-takeoff checklist
Joined
Jan 22, 2018
Messages
222
Display Name
Display name:
CRQFlier
I've been planning a panel upgrade for a few months. The goal is light IFR capability. The plan includes a new audio panel, GPS, and comm plus an indicator (G5, E5, 275, 106b - not sure which). I had planned on keeping my Narco 12D that includes GS and DME. But... the Narco has gotten squirly with intermittent lost comm. Not good.

So I "assumed" I should just get a GNC255 replacement and tie it to whatever indicator i buy - easy. But then I started thinking - when exactly do I use VHF nav only? I initially thought, well it's good backup if gps goes down, I can run an ILS or LOC. But reviewing dozens of approaches they all require DME (or GPS). So the backup idea doesn't hold water for IFR.

Is VHF nav really just a VFR dinosaur at this point? Keep it if you got it, but don't buy new?

Sent from my SM-G960U1 using Tapatalk
 
Fallowing! I’m in the same place. Backup GPS or GNC255
 
CRQFlier said:
I've been planning a panel upgrade for a few months. The goal is light IFR capability. The plan includes a new audio panel, GPS, and comm plus an indicator (G5, E5, 275, 106b - not sure which). I had planned on keeping my Narco 12D that includes GS and DME. But... the Narco has gotten squirly with intermittent lost comm. Not good.

So I "assumed" I should just get a GNC255 replacement and tie it to whatever indicator i buy - easy. But then I started thinking - when exactly do I use VHF nav only? I initially thought, well it's good backup if gps goes down, I can run an ILS or LOC. But reviewing dozens of approaches they all require DME (or GPS). So the backup idea doesn't hold water for IFR.

Is VHF nav really just a VFR dinosaur at this point? Keep it if you got it, but don't buy new?

Sent from my SM-G960U1 using Tapatalk
Click to expand...


Depends on the flying you do. Personally I still want to be able to do an ILS. But as a practical matter they all have LNAV/VNAV / LPV overlays in the USA these days, so I’d be tempted to go dual gps and be done. Not sure if there is a regulatory reason you can’t do that part 91..


Sent from my iPhone using Tapatalk
 
With all the military jamming "tests" of GPS it would be advisable to have a backup! But I err...they tend to do those "tests" only in the "fly-over" parts of the country.
 
I would be very reluctant to go with no VHF nav abilities at all. In addition to the times when GPS may be unavailable, there may be times when you are going to somewhere that is advertising the ILS, and for whatever reason won't let you shoot the RNAV.
 
gsengle said:
Depends on the flying you do. Personally I still want to be able to do an ILS. But as a practical matter they all have LNAV/VNAV / LPV overlays in the USA these days, so I’d be tempted to go dual gps and be done. Not sure if there is a regulatory reason you can’t do that part 91..


Sent from my iPhone using Tapatalk
Click to expand...

I was planning to keep that narco for exactly the ILS reason - it has DME. But the GNC255 does not, so you need GPS for every ILS/LOC i looked at. So if GPS is down - either the box or system - you need dme for the ILS, technically. That's why I'm rethinking even needing VHF nav.

Sent from my SM-G960U1 using Tapatalk
 
Groundpounder said:
I would be very reluctant to go with no VHF nav abilities at all. In addition to the times when GPS may be unavailable, there may be times when you are going to somewhere that is advertising the ILS, and for whatever reason won't let you shoot the RNAV.
Click to expand...
I haven't found an ILS (nearby) that doesn't require DME or GPS. Also haven't found an airport that has ILS but no VNAV/RNAV and usually LPV. Found a few LOC that don't require the DME/GPS.

Sent from my SM-G960U1 using Tapatalk
 
CRQFlier said:
I haven't found an ILS (nearby) that doesn't require DME or GPS. Also haven't found an airport that has ILS but no VNAV/RNAV and usually LPV. Found a few LOC that don't require the DME/GPS.

Sent from my SM-G960U1 using Tapatalk
Click to expand...

So get a GNC355, which will give you a GPS and a COM, and then get a GNC255, which will give you a VOR/ILS receiver and a com #2.
 
CRQFlier said:
I haven't found an ILS (nearby) that doesn't require DME or GPS. Also haven't found an airport that has ILS but no VNAV/RNAV and usually LPV. Found a few LOC that don't require the DME/GPS.
Click to expand...
What about VOR approaches that don't require DME?
 
Groundpounder said:
So get a GNC355, which will give you a GPS and a COM, and then get a GNC255, which will give you a VOR/ILS receiver and a com #2.
Click to expand...
That's what I originally thought. But then I wondered what I'm I really getting, when do I use VHF only nav - without dme or gps? Cost wise the 255 is maybe $3-4k more than a 225 when you include fresh install.

Sent from my SM-G960U1 using Tapatalk
 
asicer said:
What about VOR approaches that don't require DME?
Click to expand...
I suppose that's probably it if GPS is inop. Pretty rare bird.

Sent from my SM-G960U1 using Tapatalk
 
CRQFlier said:
I suppose that's probably it if GPS is inop. Pretty rare bird.
Click to expand...
Perhaps, but not rare enough for the FAA to stop worrying and discontinue their MON program.
 
asicer said:
What about VOR approaches that don't require DME for when the GPS is being jammed?
Click to expand...

If you’re that unlucky, divert.


Sent from my iPhone using Tapatalk
 
asicer said:
What about VOR approaches that don't require DME for when the GPS is being jammed?
Click to expand...

I have 3000 hours. I’ve flown one VOR approach that wasn’t part of a check ride ever. Not sure if it required DME or not.


Sent from my iPhone using Tapatalk
 
It seems that there is some condition that would allow an ILS approach to an airport but not allow an RNAV approach. The RNAV (GPS) 24R into Burke Lakefront (BKL) is NOTAMed unavailable, but the ILS 24R is available. If you don’t have an ILS, you can’t shoot an approach to that airport.
 
CRQFlier said:
I initially thought, well it's good backup if gps goes down, I can run an ILS or LOC. But reviewing dozens of approaches they all require DME (or GPS). So the backup idea doesn't hold water for IFR.
Click to expand...

As a kind of side note, If you can get radar vectors, no ILS procedure really requires DME or ADF, even if it says it does. All you really need to be able to do intercept the glideslope and ride it down. If your primary navigation radio fails, you have the ability to treat it as an emergency anyway, and do what you need to. Safely.
 
bluesky74656 said:
It seems that there is some condition that would allow an ILS approach to an airport but not allow an RNAV approach. The RNAV (GPS) 24R into Burke Lakefront (BKL) is NOTAMed unavailable, but the ILS 24R is available. If you don’t have an ILS, you can’t shoot an approach to that airport.
Click to expand...

It’s almost always the other way around...


Sent from my iPhone using Tapatalk
 
CRQFlier said:
That's what I originally thought. But then I wondered what I'm I really getting, when do I use VHF only nav - without dme or gps? Cost wise the 255 is maybe $3-4k more than a 225 when you include fresh install.

Sent from my SM-G960U1 using Tapatalk
Click to expand...

If you truly want to fly IFR, and reliably get to your destination each and every time, $3-4k is short money. If you're OK with there being times you can't get there from here, well.....
 
He can keep the narco 12D as-installed for cheap and retain VHF nav capes.Way cheaper than reinventing the wheel with a fresh high faluting garmo moneybag navcom box. Furthermore, the OPs concern for DME is moot in the first place, if he's committed to install a GPS in the plane. Post 19 already explained the real-world flying reasons why.
 
Groundpounder said:
If you truly want to fly IFR, and reliably get to your destination each and every time, $3-4k is short money. If you're OK with there being times you can't get there from here, well.....
Click to expand...
I agree 3-4k isn't much in the broader picture. But my use case is light IFR - meaning a marine layer or MVFR when I'd rather be IFR. I don't do single engine IMC over mountains any more - so I'm pretty limited anyway.

Sent from my SM-G960U1 using Tapatalk
 
hindsight2020 said:
He can keep the narco 12D as-installed for cheap and retain VHF nav capes.Way cheaper than reinventing the wheel with a fresh high faluting garmo moneybag navcom box. Furthermore, the OPs concern for DME is moot in the first place, if he's committed to install a GPS in the plane. Post 19 already explained the real-world flying reasons why.
Click to expand...
This might be the way to go.

Sent from my SM-G960U1 using Tapatalk
 
CRQFlier said:
This might be the way to go.
Click to expand...
I concur, but didn't you say in post #1 that it was giving you problems? I thought Narco's were pretty much un-repairable at this point in time?
 
asicer said:
I concur, but didn't you say in post #1 that it was giving you problems? I thought Narco's were pretty much un-repairable at this point in time?
Click to expand...
Yes, the comm in intermittent inop. The nav has been OK - as far as I know. But honestly, I gotta think the nav is next - might already have issues, but we haven't noticed since we rarely use it. Bevan will repair still, but that's likely good money after bad.

Sent from my SM-G960U1 using Tapatalk
 
The odds of both ground based and satellite based navigation going dark simultaneously are pretty low.

So... Dual GPS only protects against your equipment failing. Having GPS and NAV gives a backup for things outside your cockpit.

Seams like cheap insurance to me.
 
As RussR pointed out, if there is radar coverage, they will vector you to the ILS intercept, so lack of DME is not too important.

I have been vectored to the intercept several times, they did not want me flying the whole procedure. I have not flown a plane with DME, except when training for the IFR add on.
 
Arrow76R said:
With all the military jamming "tests" of GPS it would be advisable to have a backup! But I err...they tend to do those "tests" only in the "fly-over" parts of the country.
Click to expand...

Like California. :(
 
The 12D is a solid radio, and is certainly repairable. Bevan (among others) can certainly renew the Mark 12D.

That’s what I’d do.
 
You must log in or register to reply here.
Back
Top