GPS distance VS DME distance

[satpak77]

good info B350

good info nonethess b350...I also was wrong on this

FYI, FAA has hundreds of lawyers that do this sort of stuff (legal interpretions) every day, and you can't even get them to agree on anything half the time

another example of why flightinfo is a good resource

 

[DC8 Flyer]

Hey guys, I might be reading this the wrong way, but from that AOPA article

The DME, ADF, or intersection names or identifiers must be retrieved from the database, and pilots must ensure that data is current in accordance with the aircraft flight manual supplement or approved operations manual.

That seems to me, you can't use the GPS like a DME receiver, ie for raw distance readout, while doing an approach. The fixes would have to be in the database. The approach the OP posted is a timing approach but has lower minimums if you can ident the 5DME fix off of HAR.

Maybe this particular fix is in the database, if so no biggie, but if not, from the wording in the AIM and from the AOPA article it seems you can't just go direct to the HAR VOR and use the GPS to give you "DME" distance.

I could be reading it wrong though, and since HAR is in the database you can use it. Seems a little vague. Good article though.

 

[midlifeflyer]

That seems to me, you can't use the GPS like a DME receiver, ie for raw distance readout, while doing an approach. The fixes would have to be in the database. The approach the OP posted is a timing approach but has lower minimums if you can ident the 5DME fix off of HAR.

There's two pieces to the use of,say DME. In both cases =something= has to be in the database. Either the DME named intersection or waypoint that's, say at 6.2 DME or the facility that is producing the DME, like the XYZ VORTAC. Take a look at AIM 1-1-19.f.1.c (including the notes). It talks about the alternate ways to use DME. One is using the DME source as the active waypoint.

b350, this was a good conversation. This is still really so new that the way the FAA looks at this changes as we go along. What wasn't allowed yesterday is allowed today (and maybe vice versa). And, in some ways, the AIM language isn't as clear as it could be. So kicking it around is pretty worthwhile.

Besides, look at how many posts we made disagreeing with each other without even once coming close to calling each other an idiot

 

[b350capt]

i know! we should be proud....do we get gold stars or anything? And it is good to discuss these things, we all benifit. thanks for the kind words skip

 

[DC8 Flyer]

There's two pieces to the use of,say DME. In both cases =something= has to be in the database. Either the DME named intersection or waypoint that's, say at 6.2 DME or the facility that is producing the DME, like the XYZ VORTAC. Take a look at AIM 1-1-19.f.1.c (including the notes). It talks about the alternate ways to use DME. One is using the DME source as the active waypoint.

b350, this was a good conversation. This is still really so new that the way the FAA looks at this changes as we go along. What wasn't allowed yesterday is allowed today (and maybe vice versa). And, in some ways, the AIM language isn't as clear as it could be. So kicking it around is pretty worthwhile.

Besides, look at how many posts we made disagreeing with each other without even once coming close to calling each other an idiot

There it is, thanks midi, gotta read the fine print.

 

[Lead Sled]

Besides, look at how many posts we made disagreeing with each other without even once coming close to calling each other an idiot

Yeah, but were you thinking it?

'Sled

 

[mflyer]

I would use the DME and use the GPS as a cross reference. Even though there is probably not much difference between the two...I guess one thing to think about is the location of the actual GPS reference point on the field! I have seen them located in various places!

 

[midlifeflyer]

Yeah, but were you thinking it?

'Sled

LOL! No, I really wasn't. It probably doesn't come through in print, but I didn't have my usual ingratiating air of absolute certainty in my answers to this one. Considering their tone and quality, every time b350capt made another point, I had to go and recheck my sources.

 

[A Squared]

I would use the DME and use the GPS as a cross reference. Even though there is probably not much difference between the two...I guess one thing to think about is the location of the actual GPS reference point on the field! I have seen them located in various places!

I think that something needs to be clarified here. In order to use gps for a substitute for DME in any case, the actual location of the actual, physical navaid must be used. IE if you're looking for distances relative to the ILS DME at XYZ airport, you had better be sure that you have the coordinates of the XYZ ILD-DME antenna dialed up in your GPS, not the KXYZ ARP (airport reference point)

 

[DC8 Flyer]

I think that something needs to be clarified here. In order to use gps for a substitute for DME in any case, the actual location of the actual, physical navaid must be used. IE if you're looking for distances relative to the ILS DME at XYZ airport, you had better be sure that you have the coordinates of the XYZ ILD-DME antenna dialed up in your GPS, not the KXYZ ARP (airport reference point)

That location has to be pulled from the database, you cannot plug in the LAT/LON of a LOC/DME antenna and be "legal" to use the GPS for DME if so required on the approach.