Mandatory / minimal IFR equipment for Europe

Also DME/DME, but that’s out of the price range for light GA as well.

Is there a non-INS product which uses DME/DME?

All INS product use DME/DME for the corrections, and newer ones use multiple GPS sources.

Back in time, before GPS did to the navigation business what the CD did to the vinyl record business, there were a few products aimed for that space. The KNS80 of course became popular – that creates a virtual VOR/DME based on a real VOR/DME (the DME has to be co-located) but obviously is usable only within the coverage area of the real VOR/DME. I vaguely recall reading that Collins did an RNAV box in the 1990s which used multiple VORs or DMEs and had a moving map display, but I have never seen that on the GA market.

DME/DME is not hard because a DME is digitally tuned so you can get multiple fixes from all around you very rapidly even if you have just one DME, so it is “just software” and a box like a GNS430 could easily interface to a DME and use it when GPS is not available. You need a database of DMEs but a GNS already has that, and anyway you can freely download a worldwide database of DMEs from Eurocontrol.

Except that, I suspect, a lot of the time you would be out of range of any DME especially at low levels like a few k feet. That is why this is normally on INS systems which can run for hours. You can get your own INS for about €20k (non certified).

If you fly in airspace where RNAV is required, then you also must have a DME

True but not enforced – loads of Cirruses in Europe don’t have a DME. My view is that it depends on the wording. The UK wording is “distance measuring equipment” and a lawyer with more than 2 braincells would argue that a GPS does exactly that, and this is one of many things the CAA would never want to create case law on.

Airborne_Again wrote:

Under EASA regs, yes, not necessarily under national regs. Currently, SE-reg aircraft must have a VOR and an ADF to fly IFR, no matter the airspace requirements.

Hmm. Norway has the same thing, but I understand it as the triplet ADF, VOR and DME as the bare minimum for IFR. Thus a (redundant) GPS will effectively nullify the need for any of the “basics”. The 172SP I have been flying lately is fully IFR equipped, G1000, but there is no ADF or DME there as far as I know, only two GPS’es and two NAV (VOR/ILS?). But then I only fly VFR

Also. I have seen on the approach charts that GNSS and one additional chart called GLS is popping up. What is this GLS?

In the USA, a “W” GPS i.e.

GNS430W
GNS530W
GTN650
GTN750
IFD440
IFD540
G1000 (some versions only!)

avoids the requirement for VOR (etc) carriage for IFR, but I don’t thing there is such a reg in Europe. Is there one? I have never heard of any such concession. I researched this some years ago and found that Switzerland permitted an IFR (BRNAV) GPS to replace the ADF for enroute IFR.

Also, do the Avidyne boxes have an EASA STC anyway? (comment applicable to non-N-regs)

Peter wrote:

True but not enforced – loads of Cirruses in Europe don’t have a DME.

Is that true also in the UK?

My view is that it depends on the wording. The UK wording is “distance measuring equipment” and a lawyer with more than 2 braincells would argue that a GPS does exactly that, and this is one of many things the CAA would never want to create case law on.

Of course, today I would want a DME anyway since many approach procedures require it (and on final approach you can not substitute DME distance with distance measured by a GPS navigator), but the connection with RNAV doesn’t make sense.

Yes, and I agree

However, I can also see why somebody who doesn’t already have a DME doesn’t want to fit one. The good quality ones like the KN63 are awfully pricey. Imagine you have a homebuilt and you want to one day go for IFR approval. One day the UK LAA scheme will allow this for certain types, G-reg, UK airspace, and it may be possible already in some other countries. If it was me, I would really want ILS capability because that will save my life one day.

Peter wrote:

DME/DME is not hard because a DME is digitally tuned so you can get multiple fixes from all around you very rapidly

Don’t know what you mean by “digitally tuned”, most DMEs (read KN62 8-)) still have an analog PLL that needs to retune. But this is besides the point, you still need a bit of time to get confidence that the pulses you receive are actually your pulses.

The system’s not really built for fast channel switching. But if you know the distance to expect, you can of course reduce the search space…

DME/DME is not hard because a DME is digitally tuned so you can get multiple fixes from all around you very rapidly

DME/DME is virtually useless to GA as there are simply not enough stations to get a position fix at our standard altitudes. It’s designed as a backup system for airliners at airline altitudes.

DME/DME is virtually useless to GA as there are simply not enough stations to get a position fix at our standard altitudes.

Out of curiosity, I am regularly checking the precision of our FMSs, which use GPS and DME/DME. At 5000ft and above DME/DME gives almost 100% coverage in Europe (away from the mountains of course) with a precision that is in the same order of magnitude as GPS. In flat terrain, DME/DME gives good fixes almost down to the ground – I know that from a couple of flights where a GPS antenna connection was loose and we had to fly with conventional navaids only.

Assuming your airworthy, second hand, four seater tourer needs a minimalist IFR capability, what might be the required budget and paperwork? This discounts finding second hand kit on eBay etc.

A working assumption is that the aircraft comes with a legacy NAV/COM 760 VOR/ILS, and ideally a DME. The assumption is that it may even have an ADF for BBC Radio 4 listening purposes. It should also have a turn coordinator and a heated pitot, plus the usual AI, DG, vacuum indicator.

Would you therefore only need:

A second altimeter (€750)

.833khz and Mode S (€4,000)

IFR GPS with display (eg 400W €9,000)

The above would include fitting, although not sure what the paper work expenses might be, have estimated the avionics labour though.

eBay might be a source for a 155xl or KLN84 for a much lower investment (€5,000 less?)

On an aircraft with a Vref of 70 knots and capable of light IFR only why would you spend more?

I f u have an adf, DME, and a NAC com can’t you just put a Garmin 430 in?

This would also be future proved with the option of replacing the 430 with a IFD440