RG1979

I have a DME question regarding the Garmin 1000 (G1000H).
The NAV1 and NAV2 needles on the PFD will give you a distance to the selected NAV source (Airport, VOR, ILS, etc). To my understanding this is a GPS distance.
The G1000 in the aircraft does not have the separate DME softkey, so that tells me I don't have the DME equipment on board.

When giving a 61.57(d) as a CFII, do I have to make the pilot do a DME/ARC (IFR PTS)?
The note in the PTS says that if the aircraft is not equipped with DME I don't have to do the approach.

In other words, does the distance I see on the PFD substitute DME?
Can I legally use it that way?

Anyone have any sources?

Thanks!

JohnBurke

AIM 5-3-13 https://www.faa.gov/air_traffic/publ.../media/AIM.pdf

You're not required to have the applicant demonstrate an approach with a DME arc. If you use GPS in lieu of DME, the waypoints used must be retrievable from the current database of an IFR-aproved GPS installation.

RG1979

Thanks for the source John!

It might be nitpicking, but it says "when holding". So does this apply to a hold only, or also an approach?

RG1979

I think I found the answer on page 1-1-29 of the AIM. This table applies to approaches.

JohnBurke

You're not nitpicking. That reference was to holding. It applies to all other phases of operation too. If operating under IFR, the GPS installation must be approved for that phase, and the fix must be retrievable from the database. The salient observation in the link was that the DME slant range difference is considered negligible.

GPS may also be used in lieu of NDB fixes.

You're still not required to have the applicant demonstrate every possible type of approach, during an instrument proficiency check.

Can you use the GPS distance to the primary facility fix for the arc? Yes, so long as the approach and the fix are in the database and the GPS installation is approved for the operation.

You indicated that you don't know if DME is installed (did you look in the equipment list, or check for the antenna?). You should know if the aircraft has that equipment, or not. DME as a sensor input, especially if autotuned by the system, may not have an independent control, but may still be installed. It should be found in your equipment list.

JamesNoBrakes

There are also some advisory circulars and other guidance that go into detail explaining what GPS can substitute for and how you can use it up to the FAF on an approach and then again for the missed segment.

Except for many legacy FMS boxes, where you don't really see the stand-alone equipment anyway, traditional DME receivers are becoming very rare, once you have a double GPS setup you can dump some weight by getting rid of the DME, and as explained, as long as it's in your GPS database and current, it's generally no problem to use.

RG1979

It's actually a level D sim I'm talking about ;)

PerfInit

Check the “T001-A” form for the FSTD. Usually located in a binder near the sim (often on a podium prior to the “gangway”. This form, in addition to the Statement of Qualification (SOQ) will help you determine the capability of the sim in question. Does the IOS panel have the capability to simulate a failure of the DME? Perhaps ask the “sim tech” as they can “dig” deeper and give you a reliable answer.

JohnBurke

With a multi-sensor system and display, you're not so much concerned about the source of the data as what you're given. Many units combine VOR information, DME, DME-DME, GPS, IRS/INS, etc; it only outputs nav data. You can delve into the system to explore sensors and sensor availability, but unless the system advises you that the input isn't available or is questionable, all you really care about is whether you have nav guidance.

You may be on an approach with a marker or NDB or DME inoperative, yet your system provides GPS data which replaces the missing elements and gives you what you need to fly the approach. So long as the required navigation performance is available, the particular source of the data becomes ancillary so long as it's valid data.