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DME

jpowell13

Well Known Member
I have two NAV receivers in my IFR equipped 6A. They both have VOR/Glideslope capability, but my NAV 2 has never received VOR stations well enough to be useful in flight. For this reason, I can't easily detect intersections, based on VOR radials.

My thought is that it would make more sense to pull out the faulty NAV and replace it with a used DME receiver. I got my IFR in the days before GPS and remember how easy and useful DME is for IFR operations.

My questions are "will the ground based DME system continue to be maintained over the next few years?" And, "have those of you with DME noticed many outages?"

(I know I can use my 400W to detect intersections, but My NAV radios and my G5 PFD back up my 400W and my EFIS.)

John
 
I have a Garmin 430 and a King DME in my Cherokee panel. I fly it IFR. I never look at the DME anymore. Reception is weak. Ipads also give distance. I would not waste the money and weight on a DME system. My RV is all GPS.
 
Phase 1 VOR shutdowns 2016-2020 74 VOR,s. Phase 2 2021-2025 234 additional shutdowns as the FAA moves to Performance based Navigation. However the remaining facility's are scheduled to remain for the foreseeable future.
 
Radios

Bob, I have VAL radios. One is a NAV2000 and the other is a INS429 with built in CDI, VDI and marker lights. I have them attached to separate Bob Archer antennae. The INS429 works great, but the NAV2000 seems blind to VOR's. I've tried swapping antennae, but never was able to get the NAV2000 to work right.

My main reason for adding the DME would be to fly those ILS approaches that require DME (should my GPS go belly up or I run into a GPS blackout). Another factor is that I think it would be an easy and inexpensive swap-out to go from the low profile NAV2000 to an old King DME. I don't know how much a DME receiver weighs, but the net increase should be minimal since I would be swapping radios and a DME antenna and a little coax isn't much. John
 
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ILS/DME- you fly loc and GS from your Nav receiver and load same approach from current database on 400W, no?

Isn't the 400W now, same as DME based as long as the DME "Limitation", is met?

https://www.aopa.org/advocacy/advoc...-services-brief-use-of-gps-in-lieu-of-dme-adf

Quoted below:

Services Brief -- Use of GPS in lieu of DME/ADF
AIR TRAFFIC SERVICES BRIEF -- USE OF GPS IN LIEU OF DME/ADF
Air Traffic Services Brief
USE OF GPS IN LIEU OF DME/ADF
Background
Until recently, pilots operating with GPS receivers certified for instrument flight rules (IFR) were not permitted to use GPS for any approach operations where no GPS overlay or stand-alone approach existed. Furthermore, GPS was not approved for use in any capacity for localizer-type approaches; e.g., ILS, localizer, SDF, or LDA. This forced those equipped with IFR GPS receivers to maintain and replace DME and ADF receivers in order to utilize all approaches in the National Airspace System. GPS has proven itself a reliable and highly accurate navigation system over the past four years, which warranted a change in these policies.

AOPA, working together with the FAA Flight Standards Division, has reached agreement on FAA policy changes that permit IFR-certified GPS receivers to be used in lieu of DME and ADF for most IFR operations (see " Limitations"). This policy fundamentally permits DME and ADF avionics to be removed with little compromise in operational capability. AOPA will continue to work with the FAA to implement GPS approaches at airports served only by an NDB approach.

This fact sheet is intended to clarify and provide guidance on how to take advantage of this new policy.

The new policy
Effective July 16, 1998, pilots may substitute IFR-certified GPS receivers for DME and ADF avionics for all operations except NDB approaches without a GPS overlay. GPS can be used in lieu of DME and ADF on all localizer-type approaches as well as VOR/DME approaches, including when charted NDB or DME transmitters are temporarily out of service. It also clarifies that IFR GPS satisfies the requirement for DME at and above Flight Level 240 specified in FAR 91.205(e). This approval represents a major step toward removing the need to retain DME or ADF in our cockpits for any reason.

Note: Air carrier operators should consult their operations specifications and their principal operations inspector for approval.

Limitations
There are still three instances in which DME or ADF are still required.

NDB approaches that do not have an associated GPS overlay approach must still be flown using an ADF.
A non-GPS approach procedure must exist at the alternate airport when one is required to be filed by regulation. If the non-GPS approaches on which the pilot must rely require DME or ADF, the aircraft must be equipped with DME or ADF avionics as appropriate. GPS substitution for DME/ADF is not permitted in this case.
DME transmitters associated with a localizer may not be retrievable from your GPS until the manufacturer incorporates them in the database. Pilots are not authorized to manually enter coordinates.
AOPA is working with the FAA and the manufacturers to have these restrictions removed and will keep you informed.

Note: Pilots should exercise caution when selecting the appropriate DME and NDB/LOM locations to avoid erroneous distance information.

Requirements
As with most operational capabilities, there are minimum requirements that must be met in order to take advantage of their benefits in a safe manner. When using GPS in lieu of DME and ADF for the purposes stated above:

The receiver must be certified for IFR operations and be installed and approved in accordance with FAA guidelines.
When using GPS course guidance; i.e., navigating to/from an NDB or locator outer marker (LOM), the course deviation indicator (CDI) must be set to 1 nm or terminal sensitivity.
The required integrity for these operations must be provided by at least en-route receiver autonomous integrity monitoring (RAIM), or an equivalent method. Wide Area Augmentation System (WAAS) receivers are also eligible for the substitution.
Pilots must conduct GPS operations within the guidelines contained in the aircraft flight manual supplement or approved operations manual.
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.
Pilots should be careful to ensure that correct distance measurements are used when utilizing GPS in lieu of DME. It is recommended that pilots review distances for stepdown points during preflight preparation.

In this Elko procedure, a GPS receiver would be counting down the distance to each stepdown fix and/or to the missed approach point (ZABTU), where as a DME would be counting down to reach 0.8 at the same missed approach point. Pilots should use caution to ensure they are using the correct distance for stepdown fixes and the missed approach point. (Image courtesy of FAA)

DME arcs associated with instrument approaches may be flown using GPS distance provided the DME transmitter, on which the arc is based, is identified in the GPS database.
The aircraft must be equipped with a DME receiver if DME is required to fly the approach procedure(s) at the alternate airport.
Aircraft utilizing IFR GPS in lieu of DME operating at or above FL240 are not required to be equipped with DME.
GPS substitution for NDB
All LOMs and NDBs with three-letter identifiers should be available from the GPS database. Again, an NDB approach without a GPS overlay cannot be flown using GPS. It must be flown using an ADF.
Pilots flying the VVS approach can use GPS to satisfy the ADF requirement as the ADF is not used for final approach course guidance.
Most LOMs are assigned a two-letter identifier and a five-letter name. Some GPS manufacturers have designed their receivers to use the five-letter name, not the two-letter ID. Five-letter names are retrieved through the intersection waypoint page. Other manufacturers use the two-letter ID retrievable through the NDB waypoint page.
Pilots flying the EWK approach may need to identify HARVS LOM by its 5 letter or 2 letter identification.
Pilots must be equipped with an ADF receiver if ADF is required to fly the approach procedure(s) at the required alternate airport.
Installation considerations
Consider your instrument panel scan visibility of the GPS output information. (Neither IFR enroute or approach receivers require a separate CDI by the TSO 129A specifications. However, both probably do require a separate conventional CDI display, or connection to an existing VOR-CDI, to meet Advisory Circular 20-138 installation requirements for display within the pilot's field of vision/scan.)
Some GPS receivers can drive an ADF bearing pointer; this would make a handy GPS/RMI-like presentation for improved situational awareness. Note: Labeling or switching functions would be required.
Verify how any switching of GPS vs. ILS/VOR input to an external CDI is to work.
Caveat: The FAA offers the following GPS is a supplemental navigation system, in part due to signal availability. There will be times when your system will not receive enough satellites with proper geometry to provide accurate positioning or sufficient integrity. Procedures should be established by the pilot in the event that GPS outages occur. In these situations, the pilot should rely on other approved equipment, radar vectors, delayed departure, rerouting, or discontinuance of IFR operations.

Further guidance will be provided in updated editions of the Aeronautical Information Manual (AIM) and Advisory Circular AC 90-94 titled "Guidelines for using global positioning system equipment for IFR en route and terminal operations and for non-precision instrument approaches in the U.S. National Airspace System."

AOPA members may direct questions to the AOPA Aviation Services Department at 1-800-872-2672.
 
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That?s a long answer to a question that wasn?t asked. He asked about one ILS and one DME, as a backup to his gps, in case of gps failure.
 
Old tech

Jim, if I wasn't an old git with time on my hands, I'd probably agree. I'd never install an ADF in my plane, even though I learned to use one, because they are too big and heavy, but DME is so simple and on rare occasions my GPS looses signal for short periods. (Seems to be during rain.) We have two ILS approaches into BTR and one requires DME (or GPS). I just like the idea of knowing I can safely fly a ILS/DME approach into BTR or other airport.

I think I can do this for about $500 and a couple hours of work. I never even turn on my second NAV radio that I would be replacing so to me it is worth it.

As for old tech, I like to use an old brace and bit or an axe once in a while for the fun of it. And, you never have to update the data for a nav radio. On the other hand, It's awesome to program that GPS and EFIS to fly your holding pattern or approach and watch it perform perfectly. John
 
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That’s a long answer to a question that wasn’t asked. He asked about one ILS and one DME, as a backup to his gps, in case of gps failure.

Some don't click urls, so I added the wall of text;)

The OP confused me in the context of a 400W-

"(I know I can use my 400W to detect intersections, but My NAV radios and my G5 PFD back up my 400W and my EFIS.)"

He did not mention dropouts of GPS in the OP, hopefully 400W operators know its full function set.

Old skool belt and suspenders of DME wanted is not what I read, obviously. If I'd had enough ANP/RAIM issues or lived near DoD jamming ranges- I see the utility.
 
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It works.

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"The new (to me) DME works fine."


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"Now if I loose my EFIS or GPS I can get down with the G5, DME and VAL nav/glideslope/cdi/vdi."


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I don't think she's very impressed.
 
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