Value of DME

Salty

Salty

Touchdown! Greaser!
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Salty
I'm making some panel changes and debating whether I keep the DME or not. I probably will, but looking for thoughts.

I'll end up with

GNC-355 Comm/GPS
Dual G5 with HSI
SL-30
GI-106A VOR with glide slope
*DME

Keep it or ditch it?
 
Salty said:
I'm making some panel changes and debating whether I keep the DME or not. I probably will, but looking for thoughts.

I'll end up with

GNC-355 Comm/GPS
Dual G5 with HSI
SL-30
GI-106A VOR with glide slope
*DME

Keep it or ditch it?
Click to expand...

Keep it until if/when you need the room for something else. You only have one other source of distance, the 355. It might come in handy
 
I'm in the "ditch it" crowd as well. A dedicated DME is useless with a proper GPS. Just takes up panel room and weight for nothing. Why do you need two things to measure distance? No reason to have a backup of everything.

If your GPS fails the DME ain't going to help you shoot an RNAV approach, if your DME fails...who cares?

@Salty I had almost the same panel in my Cherokee. Cept I had a GTN 650 for a GPS. Worked very well.
 
luvflyin said:
Why?
Click to expand...

The only time you will use it is when you panel GPS fails or the GPS system is down. The unit you have is probably 20+ years old. Take the opportunity to remove now rather than having it fail later and paying again to remove or repair.
 
Clip4 said:
The only time you will use it is when you panel GPS fails or the GPS system is down. The unit you have is probably 20+ years old. Take the opportunity to remove now rather than having it fail later and paying again to remove or repair.
Click to expand...
By that logic I should remove the GI-106A also.

Seems like having the backup to GPS would be a good thing.
 
I would at least argue that in the event of a GPS failure, DME would allow you to fly a LOC approach (provided you still have a nav/com wired to a CDI). The class D that I fly out of has a LOC that will get you down to 360'. Not a bad option really.
 
I’m not an expert about these things, but why put in the GI106A if you’re going to have the G5 HSI?
 
Caramon13 said:
Dunno, maybe the SL30 feeds the G106A and the GNC feeds the G5's?
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But the point of the GI106A is to be an indicator head for a GPS, which he/she gets with the G5 HSI (and it’s better). If you wanted an analog VOR head with glide slope for that second VOR, you could save some money and just buy a normal VOR head with GS.
 
How much does it weight? Our home airport requires dme for most of the loc and vor IAPs. Keep it if it doesn’t weigh much and its still useful.
 
I have one along with an IFD 440. I frequently use the e for a quick distance check. If it’s not doing any harm, and it still works, keep it.
 
The plane already has the sl30 feeding the 106A. I’d leave that alone.

Adding the gnc355 to feed the g5 hsi
 
I'm keeping mine. Finding it very useful, and yes I have a GPS. GPS can do one thing, DME can do another.
 
I took my DME and ADF out 2 years ago with a 430W/GTX-345 upgrade. I still wish I had the DME as as a back up to GPS, but I sold it for a few hundred bucks to subsidize the panel. I was torn between having it as a back up or leveraging the cash for the new stuff. In the end I’m glad I did sell it for $440. If the unit was worthless, then it would still be in the panel.

Even though I wish I had it for “just in case”, the money was better invested in the new.
 
I would say that if it works, keep it until it dies. But I would not replace it after it dies.
If you need panel space, get rid of it. I don't really see any need for DME anymore.

Sent from my Pixel 2 XL using Tapatalk
 
steingar said:
I'm keeping mine. Finding it very useful, and yes I have a GPS. GPS can do one thing, DME can do another.
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Just curious, what does the DME do that the GPS doesn't? (I have neither GPS, nor DME, for what ever that's worth.)
 
PPC1052 said:
Just curious, what does the DME do that the GPS doesn't? (I have neither GPS, nor DME, for what ever that's worth.)
Click to expand...

Nothing, the two are interchangeable for all purposes in instrument approaches.

DME measures how far away you are from a DME ground station by using pulses. GPS shows you where you are right now and calculates distance to where you want to go. There's virtually no reason to use DME today unless you are nostalgic or just paranoid.

From a technical perspective (via google):

GPS only knows the position of the receiver and the position of the fix in the database, and just calculates the distance between. That means that GPS is using trigonometry and math to calculate the distance between two points on an idealized sphere, while DME is also accounting for slant-distance.

There's also an old thread about the pros and cons here on POA.
 
I’d ditch it. GPS in the panel, probably have an iPad with ForeFlight or similar, and then backup ForeFlight on the iPhone. And for us, also an old 496 on the yoke.
 
Clip4 said:
The only time you will use it is when you panel GPS fails or the GPS system is down. The unit you have is probably 20+ years old. Take the opportunity to remove now rather than having it fail later and paying again to remove or repair.
Click to expand...

Hey now, what if likes listening to Braves Games?
 
If you have room for it leave it. Having backups is something you may never need, but if you were to lose the GPS it might save your bacon some time. Keep as many backups as you can.
 
Caramon13 said:
I'm in the "ditch it" crowd as well. A dedicated DME is useless with a proper GPS. Just takes up panel room and weight for nothing. Why do you need two things to measure distance? No reason to have a backup of everything.

If your GPS fails the DME ain't going to help you shoot an RNAV approach, if your DME fails...who cares?

@Salty I had almost the same panel in my Cherokee. Cept I had a GTN 650 for a GPS. Worked very well.
Click to expand...

^ that.

If you have a IFR GPS yank the DME and eBay it, loose the weight, wiring and stuff in the panel.
 
PPC1052 said:
Just curious, what does the DME do that the GPS doesn't? (I have neither GPS, nor DME, for what ever that's worth.)
Click to expand...
I can give one solid example. On a VOR approach the other day, I was easily able to read distance off on the DME for step-down fixes. I haven't a second VOR to read radials. Yes, I could have done it with the GPS, but he buttonology to get there is far more complicated than just tuning the DME to station. If I didn't have the DME I'd not go out and buy one. But I'm not getting grid of mine, and will probably fix it if it breaks.
 
steingar said:
I can give one solid example. On a VOR approach the other day, I was easily able to read distance off on the DME for step-down fixes. I haven't a second VOR to read radials. Yes, I could have done it with the GPS, but he buttonology to get there is far more complicated than just tuning the DME to station. If I didn't have the DME I'd not go out and buy one. But I'm not getting grid of mine, and will probably fix it if it breaks.
Click to expand...
That's because you went cheap on your GPS. With a good one, you load up the VOR approach into the GPS and the buttonology is minimal.
 
I'd vote to keep it, if you don't need the panel space, and assuming the DME unit still works. Good for backup in case of failure, or if you happen to be flying in one of those huge areas where they routinely test GPS jamming. I also like having an immediate direct distance readout to VORs that are maybe not on my direct route line, or, somtimes, flying a GPS approach, a VOR may be nearby that, while not a waypoint in the approach lineup, may still be useful to see the distance at a glance for increased situational awareness.
 
I retained the DME ten years ago because it was relatively new, when I put the WAAS GPS but frankly, I've only turned it on for amusement purposes
 
I'd vote to keep it unless one of the following applies:
  • Need the space
  • Need the weight
  • Need the cash
  • It gets in the way
  • It's ugly
  • It brings back bad memories
It's one of those things that I wouldn't feel bad about keeping and wouldn't feel bad about dumping.
 
asicer said:
That's because you went cheap on your GPS. With a good one, you load up the VOR approach into the GPS and the buttonology is minimal.
Click to expand...
What GPS is "going cheap"? Just curious.
 
asicer said:
That's because you went cheap on your GPS. With a good one, you load up the VOR approach into the GPS and the buttonology is minimal.
Click to expand...
The idea was to use the VOR for the approach. I doubt I would ever do this in the real, but I am in the middle of IFR training. I'll have to demonstrate two non precision approaches, and I think the DME will help mightily with the VOR approach. That said, I can see myself using the VOR if I'm on victor airways, and once again the DME gives added situational awareness.
 
steingar said:
The idea was to use the VOR for the approach. I doubt I would ever do this in the real, but I am in the middle of IFR training. I'll have to demonstrate two non precision approaches, and I think the DME will help mightily with the VOR approach. That said, I can see myself using the VOR if I'm on victor airways, and once again the DME gives added situational awareness.
Click to expand...

Yes, and you need it to be able to file alternates as your GPS is not WAAS. But I still find them quite useful. (And, by the way I rather liked the KLN-94 I was training with until they upgraded to GNS-430W.)
 
jsstevens said:
Yes, and you need it to be able to file alternates as your GPS is not WAAS. But I still find them quite useful. (And, by the way I rather liked the KLN-94 I was training with until they upgraded to GNS-430W.)
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I have a KLN94 in my panel. My plan is to use alternates that have ILS.
 
Caramon13 said:
Nothing, the two are interchangeable for all purposes in instrument approaches.
Click to expand...

Not entirely true. GPS cannot replace ADF or DME when the latter is used for lateral course guidance on the final approach segment.

This is super rare, but it does exist. The one example I know of is Martin State KMTN where the VOR/DME or TACAN Z RWY 15 has a DME arc as the final approach. That approach cannot be legally flown with just an IFR GPS and no DME - You've gotta have a "real" DME.

I think there are one or two other examples of a DME arc final, but I do not remember where they are. And, of course, you'd do better with the RNAV(GPS) 15 anyway there.

They sure do like their weird approaches, though... There's also an LDA/GS.
 
steingar said:
I can give one solid example. On a VOR approach the other day, I was easily able to read distance off on the DME for step-down fixes. I haven't a second VOR to read radials. Yes, I could have done it with the GPS, but he buttonology to get there is far more complicated than just tuning the DME to station. If I didn't have the DME I'd not go out and buy one. But I'm not getting grid of mine, and will probably fix it if it breaks.
Click to expand...

Newer gps solves this issue, buttonolgy, plus you can still easily fly the approach even if the DME is out.
 
PaulS said:
Newer gps solves this issue, buttonolgy, plus you can still easily fly the approach even if the DME is out.
Click to expand...
You really aren't getting this. I can fly the approach with the GPS. The DME gives me extra functionality. Now I can easily do VOR approaches with a single VOR by using the DME to get the step down fixes. If the GPS takes a dump I have recourse. Without the DME and with a single VOR my recourse is limited. Given that the military is ceaselessly experimenting with GPS jamming technology this does give me some piece of mind.
 
The vor approaches are disappearing quickly around here.
 
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