DME requirement

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DME requirement

Unread post by savas » Wed Jul 31, 2019 9:15 pm

Hi, I’m installing a GTN 650, will I need to keep my DME FOR IF rated panel?
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Re: DME requirement

Unread post by Mach Decimal 83 » Thu Aug 01, 2019 12:03 pm

savas wrote:
Wed Jul 31, 2019 9:15 pm
Hi, I’m installing a GTN 650, will I need to keep my DME FOR IF rated panel?
Depends on which approaches you will fly. If the approach title consists of a DME requirement i.e. ILS/DME, VOR/DME, then yes.
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Re: DME requirement

Unread post by Hop Harrigan » Sun Aug 04, 2019 10:16 pm

Hi Savas,
If I was you, I’d keep it in the panel for the present at least. That is at least until these illogical approaches are changed.
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Re: DME requirement

Unread post by tansg » Mon Aug 05, 2019 6:30 am

Hop Harrigan wrote:
Sun Aug 04, 2019 10:16 pm
Hi Savas,
If I was you, I’d keep it in the panel for the present at least. That is at least until these illogical approaches are changed.
Hop
Why illogical? Generally if DME is specified it is used to create Step-Down-Fixes to obtain a lower minima or in the case of ILS to replace Marker Beacons which were continually u/s or been stolen as they were off field and had lots of valuable copper, solar panels and A/Cs.
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Re: DME requirement

Unread post by Iceberg » Mon Aug 05, 2019 8:04 am

tansg wrote:
Mon Aug 05, 2019 6:30 am
Hop Harrigan wrote:
Sun Aug 04, 2019 10:16 pm
Hi Savas,
If I was you, I’d keep it in the panel for the present at least. That is at least until these illogical approaches are changed.
Hop
Why illogical? Generally if DME is specified it is used to create Step-Down-Fixes to obtain a lower minima or in the case of ILS to replace Marker Beacons which were continually u/s or been stolen as they were off field and had lots of valuable copper, solar panels and A/Cs.
Tansg, I am in a similar situation, and the question is, if you have equipent that can deliver RNP of 0.1, why the need for the DME, as long is the MAP is part of the approach sequence, which is loaded in the GPS. As things are developing, even if you fly the ILS and your system can deliver RNP 0f 0.1, why the need for the DME?
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Re: DME requirement

Unread post by Mach Decimal 83 » Mon Aug 05, 2019 7:05 pm

Iceberg wrote:
Mon Aug 05, 2019 8:04 am
tansg wrote:
Mon Aug 05, 2019 6:30 am
Hop Harrigan wrote:
Sun Aug 04, 2019 10:16 pm
Hi Savas,
If I was you, I’d keep it in the panel for the present at least. That is at least until these illogical approaches are changed.
Hop
Why illogical? Generally if DME is specified it is used to create Step-Down-Fixes to obtain a lower minima or in the case of ILS to replace Marker Beacons which were continually u/s or been stolen as they were off field and had lots of valuable copper, solar panels and A/Cs.
Tansg, I am in a similar situation, and the question is, if you have equipent that can deliver RNP of 0.1, why the need for the DME, as long is the MAP is part of the approach sequence, which is loaded in the GPS. As things are developing, even if you fly the ILS and your system can deliver RNP 0f 0.1, why the need for the DME?
Very simple answer to your question: If you fly a ILS or VOR approach without a co-located DME, how will you be able to do your distance/height check(s) on the approach, without a DME installed? Sometimes a DME can be up to 3 miles away from the runway threshold, or even worse, not even co-located with the VOR. Examples are the ILS 05 in HRE and the ILS W 28 in Rio.
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Re: DME requirement

Unread post by Iceberg » Tue Aug 06, 2019 9:16 am

Mach Decimal 83 wrote:
Mon Aug 05, 2019 7:05 pm
Iceberg wrote:
Mon Aug 05, 2019 8:04 am
tansg wrote:
Mon Aug 05, 2019 6:30 am

Why illogical? Generally if DME is specified it is used to create Step-Down-Fixes to obtain a lower minima or in the case of ILS to replace Marker Beacons which were continually u/s or been stolen as they were off field and had lots of valuable copper, solar panels and A/Cs.
Tansg, I am in a similar situation, and the question is, if you have equipent that can deliver RNP of 0.1, why the need for the DME, as long is the MAP is part of the approach sequence, which is loaded in the GPS. As things are developing, even if you fly the ILS and your system can deliver RNP 0f 0.1, why the need for the DME?
Very simple answer to your question: If you fly a ILS or VOR approach without a co-located DME, how will you be able to do your distance/height check(s) on the approach, without a DME installed? Sometimes a DME can be up to 3 miles away from the runway threshold, or even worse, not even co-located with the VOR. Examples are the ILS 05 in HRE and the ILS W 28 in Rio.
I understand and agree with your explanation. All I was wondering - if the GPS has the DME position in its database - one can use that to get a direct distance to the DME position which in most cases will be more accurate than the DME itself, whilst using the ILS. As I mentioned in another thread - the difference between the slant distance (DME) and the horizontal (GPS) distance on a typical ILS is a few meters - much larger than the accepted DME error. The procedure would have to be adapted to allow for that -sure - but why not? But this is something that is probably still developing.


Edit: This is in fact already allowed by the FAA in the states. See the attached advisory from the FAA dated 2011.
FAA AC90-108.pdf
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Re: DME requirement

Unread post by Hop Harrigan » Tue Aug 06, 2019 12:27 pm

Mach Decimal 83 wrote:
Mon Aug 05, 2019 7:05 pm
Iceberg wrote:
Mon Aug 05, 2019 8:04 am
tansg wrote:
Mon Aug 05, 2019 6:30 am

Why illogical? Generally if DME is specified it is used to create Step-Down-Fixes to obtain a lower minima or in the case of ILS to replace Marker Beacons which were continually u/s or been stolen as they were off field and had lots of valuable copper, solar panels and A/Cs.
Tansg, I am in a similar situation, and the question is, if you have equipent that can deliver RNP of 0.1, why the need for the DME, as long is the MAP is part of the approach sequence, which is loaded in the GPS. As things are developing, even if you fly the ILS and your system can deliver RNP 0f 0.1, why the need for the DME?
Very simple answer to your question: If you fly a ILS or VOR approach without a co-located DME, how will you be able to do your distance/height check(s) on the approach, without a DME installed? Sometimes a DME can be up to 3 miles away from the runway threshold, or even worse, not even co-located with the VOR. Examples are the ILS 05 in HRE and the ILS W 28 in Rio.
Gents,
For example in the case of the FALA Nav GNSS approach to Rwy 07 for instance...when the designers created the chart they could have easily used the distance to the LIV VOR (which is in the Rnav database) instead of the distance to the DME. This way the approach would have been a clean Rnav approach instead of a messy mixture of GPS and ground based instrumentation. I have just discussed this design with a couple of European (Germany) based instructors who agree that its "illogical".
While on the subject, I also don't understand why we don't have many, many more Rnav approaches published for SA. This would eliminate the need for maintenance on VOR/DME/NDB ground equipment which would save money as well as provide more instrument approaches generally.
Hop
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Re: DME requirement

Unread post by tansg » Wed Aug 07, 2019 6:39 am

Hop Harrigan wrote:
Tue Aug 06, 2019 12:27 pm
Gents,
For example in the case of the FALA Nav GNSS approach to Rwy 07 for instance...when the designers created the chart they could have easily used the distance to the LIV VOR (which is in the Rnav database) instead of the distance to the DME. This way the approach would have been a clean Rnav approach instead of a messy mixture of GPS and ground based instrumentation. I have just discussed this design with a couple of European (Germany) based instructors who agree that its "illogical".
While on the subject, I also don't understand why we don't have many, many more Rnav approaches published for SA. This would eliminate the need for maintenance on VOR/DME/NDB ground equipment which would save money as well as provide more instrument approaches generally.
Hop
I take it you talking about the Missed Approach Procedure for FALA RNAV RWY 07? Well yes we also told ATNS it is illogical, bad practice and creates more dependencies. We were told we were being obstructive, over critical and operating outside our legal mandate. As I have said before CAA has the responsibility to validate IAPs for safety and SARP/CAR compliance and can only recommend on best practice. So if you have an issue with this procedure take it up with the IAP owner Lanseria Airport and their ANSP (ATNS) they the ones that decided this is good idea.

As to the reason why aren't there anymore RNAV procedures, I can tell you that when I was at CAA I was the catalyst for the introduction of the RNAV IAPs and was pushing from 2006 already for the design and implementation of these procedures. However ATNS was of the opinion that it would be to expensive and not provide them with a revenue flow to recover the design costs as many of these procedures would replace NDB based procedures at unmanned airfields where no mechanism was in place to recover the user fees. They were backed by AOPA who saw it as another the way the CAA was bullying GA aircraft owners into fitting new equipment into their aircraft at great cost while according to them the then current NDBs were just fine. It was for the same reason that they kept running interference on the SBAS/WAAS/EGNOS project for Southern Africa which had the potential to provide the functionality to have IAPs at every runway end in the coverage area with ILS Cat I like minimas. They were supported in this opposition by the Airline industry who had the opinion that would ultimately have to pay for this system which they didn't need as all the airports they operated into were sufficiently equipped for their operations. All this despite the European Union offering to pay for the majority of the costs. RNAV IAPs in SA only really got off the ground when SA Airlink had the need for a better procedure into FAPM than the multi-NDB horror that was the legacy approach and which was not suit for purpose. SA Airlink, through their Chief Pilot Oupa Lindveldt, contracted Cathy Pak Poy from Strategic Airspace out of Sydney to design the procedures. Theses were the first RNAV IAPs published in SA. The incredible success of this project convinced then to have similar procedures designed, at their cost, for all the airfields that they operated into where only NDB or VOR based IAPS or no IAPS present. This forced the hand of ATNS and they started to design these approaches for all the major airports. This to me was illogical as these airports were already well served with multiple approaches including ILS when the pressing need was for these procedures the smaller less well equipped airfields but it all came back to that revenue thing. So you have to thank SA Airlink and Oupa Lindveldt for being the engine that created the momentum in the implementation of RNAV IAPs. Further along as the benefits of GNSS based IAPs became to be realised, SAA largely through Andrew Smit and Comair through Gerhard van Beek became the drivers and kept the momentum going. SAA was instrumental in the RNP AR procedure design and implementation which they paid for (designed by Airbus) and which can provide considerable economic benefits, despite ATNS's kicking and screaming. Some of the stuff that happened over this period was incredible, good and bad, better than in the movies. So that is the concise history of RNAV in SA. A story of visionaries and plonkers unfortunately.
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Re: DME requirement

Unread post by Hop Harrigan » Thu Aug 08, 2019 8:38 pm

Hi,
Interesting to know the background...thanks!
But this is the sorry story of South Africa under the current regime...govt departments not doing their job, being obstructionist, incompetent and only looking after their own interests.
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