Confused about ADF

[Fuji Abound]

I have it on good authority that Switzerland and Germany do not require the carriage of an ADF receiver for IFR alread.

I have seen a number of suggestions that the CAA are "poised" to change the position of the UK.

I dont understand how it is that different national authorities have different legislation (if this is so) and / or are seeking to change their own legislation given the intended European harmonisation. Presumably we are very close to having one single European rule, or is there a danger that we will see more national authorities filing exceptions?

If one were about to order a new aircraft the additional cost of fitting a decent ADF and DME is over £10K. I cant imagine one would be thrilled if the legislation were changed in six months or so?

[S-Works]

It is Enroute navigation that they refer specifically. That requirement goes in the UK next year as well.

But if the IAP requires an ADF then you will need one. You can open a whole can of worms on that subject.

But as I understand it from the CAA the reason you have to get an ADF in the Cirrus etc at the moment for IFR is that we require an ADF for enroute navigation even though we never use the damn things!

Don't confuse the issue with DME. You will STILL have to have a DME for the foreseeable future.

[IO540]

Fuji, every country has a different matrix of required equipment carriage versus airspace category versus flight rules.

The equipment list for each country is in the country's AIP GEN 1.5.

If you like opening cans of worms, try this one :)

Sweden needs an ELT. There's a good one :)

Almost nobody reads this stuff, and I bet there is a huge amount of "illegal" public transport, and I am talking about big jets especially 3rd world cargo ops. The big passenger carrying ops will have the whole lot I am sure; probably carrying two ADFs to do the Russian dual-NDB approaches.

Bose-x, do you have a reference for the ADF going away for enroute IFR in the UK in 2008? IHMO, when it goes it goes but it doesn't go until it goes. It was "about to go" 5 years ago. If the CAA really wanted it to go they could do that tomorrow, with an AIC.

[A and C]

I think that ADF is likely to stay, Jamming of GPS is quite easy to do with a low powerd signal over a wide area.

Jamming ADF & VOR over a wide area would be almost imposable, as VOR's are very costly it would seem that ADF/DME would be the best back up in the event of an "attack" on the GPS system. This also has the advantage that the DME is used as the second choice for navigation by most airliner flight management systems.

And also how on earth am I going to get the cricket results half way down Africa with out the ADF?

[S-Works]

Tell you what IO, you go and search for the reference, just like I did...... :p

There is an amendment to the ANO drafted and waiting for inclusion that removes the requirement for ADF ENROUTE from I seem to recall around March time next year. We actually did this discussion to death a couple of months ago either here or on flyer.

I am with A & C on the value of keeping the ADF...... :p

[mm_flynn]

I think that ADF is likely to stay, Jamming of GPS is quite easy to do with a low powered signal over a wide area.

This is not a good reason for holding onto ADFs. Airliners will have DME/DME and INS to backup GPS, there will be a basic VOR infrastructure for a long time - so the high profile traffic is sorted and the spam cans flying around just aren't a credible terrorist target. (radar vectors to the nearest small airport and that's us grounded if there is an attack on the navigation infrastructure. ) Cricket scores on the other hand seems like a good reason (or just slap an old AM/FM cassette deck in )

[A and C]

MM I beg to differ, the VOR is quite expensive to install and maintain and a lot of them are coming to the end of there lives.

So as the system is just a back up the most cost effective replacement for a VOR is an NDB it will do more or less the same job for en-roure navigation and if you put it on an airfied with a DME you do two jobs, an approach aid for GA and the DME and also helps the airline guys with FMS.

[IO540]

It would be wrong to think the NDB could replace the VOR for either enroute nav or for approaches.

Even ignoring for the moment the huge NDB accuracy problems in many locations, there is no autopilot AFAIK which can track an ADF but all hanf decent ones can track a VOR which wcan be used for both enroute and approaches.

[A and C]

IO540 I agree with you on the technical issues but this is about the Money, at long last we have GPS aproaches in the UK and now that we have the foot in the door with the CAA WAAS can't be far away, this will give us CAT 1 GPS approaches.

With all this hi-tech kit that is unlikely to fail the chances of using an NDB or VOR are very low. If this is the case the NDB will be the clear winner on a cost per occasions used basis.

[Fuji Abound]

Thank you for all your replies.

Whilst it is an interesting debate, I am not so much concerned with the merits of ADFs but whether the aircraft will need to have one installed.

As usual this business is so full of rumour and counter rumour.

I have written to the CAA and will be interested in what they have to say.

I have always found them very good in the past when clarrification is needed.

Bose-x - yes, you are of course correct so far as the DME is concerned which presumably will be around as long as VORs - which I guess is for a very long time!

[tmmorris]

I'm intrigued- how does a dual-NDB approach work? Have you got a plate?

Tim

[bookworm]

I dont understand how it is that different national authorities have different legislation (if this is so) and / or are seeking to change their own legislation given the intended European harmonisation. Presumably we are very close to having one single European rule, or is there a danger that we will see more national authorities filing exceptions?

They can "file exceptions" all they like but I would imagine they'll go straight into Claude Probst's trashcan. ;) Equipment requirements will come under EASA when they take over Ops, and I can't see them doing it other than "as appropriate to the route to be flown".

Here's what the Essential Requirements say, and I can't see that getting more than the lightest implementing rules for private flights:

An aircraft must be equipped with all navigation, communication and other equipment
necessary for the intended flight, taking account of air traffic regulations and rules of
the air applicable during any phase of the flight.

[A and C]

Tim

It's just an NDB approach that reqires two ADF recevers to fly.

I suspect that this could now be done with one of the more modern recevers with the standby FRQ and a very quick change over but it would not be leagal.

I think Ostend has one of these......... I will go check the Jepp's

[bookworm]

I'm intrigued- how does a dual-NDB approach work? Have you got a plate?


It works badly if you try it high and fast with just one ADF. The infamous one is Dubrovnik.

Here's the link I get to the EAD version (http://www.ead.eurocontrol.int/eadbasic/pamslight-6E2C7F70F1B92B85F8633E585F0A5C31/E4WR6Q7FVRAAU/EN/Charts/AD/NON_AIRAC/LD_AD_2_LDDU_2-33-1_en_2006-03-22.pdf). I don't know if it will work if you're not logged in to the EAD.

The USAF, with the US secretary of trade Ron Brown on board, managed to fly a 737-equivalent into the 2300 hill NE of CV.

[tmmorris]

Yes, that link worked fine. Thanks. Are the multiple NDBs at Dubrovnik needed simply because of all that unhelpful terrain? Here we would just put one half-way down the approach, as at Cranfield, surely?

Tim

[IO540]

I agree A&C re GPS taking over, but the earlier suggestion was that a backup for some sort of total loss of GPS will be needed.

I thought the Americans were going for Loran for that purpose.

With no VORs, one would need an awful lot of NDBs to navigate around the place, at the low levels where GA is generally forced to fly in Europe! Can you imagine dead reckoning in IMC from one DME arc to the next?

I can't see VORs disappearing. But I can see non-approach NDBs (e.g. WCO) disappearing - what purpose do they serve?

TMM - I think the idea of dual NDBs on approaches is that when you are between them the two needles point towards each other when you are lined up with the runway - whereas with a single NDB you are working on the relative bearing which is harder.

[DFC]

Yes IO540, with both pointers overlapping with one pointing ahead and one pointing behind you must be on the centrline between the beacons. If you drift right , both arrows point left (the way you need to go) If you drift left, they point right.

Makes it almost very easy to complete the approach. The problem is when in typical ADF fassion, one points left and the other right and then when you bank, you get dip added to the problem :)

Regards,

DFC

[A and C]

I would be delighted if LORAN became the GPS back up but for cost reasons I can'y see it happening this side of the atlantic.
What I can see is DME out lasting VOR & ADF simply because it backs up the GPS in most flight management systems, INS being the navigation of last resort!.

I have been trying to understand why GA has not got a multi-sensor navigation recever after all it cant be to much of a problem to use the GPS data base to auto tune three DME units to triangulate a fix. the (already fitted) altitude input would take the slant error out of the fix.

Something like that would no doubt meet P-RNAV by using both GPS and DME/DME.

What I fail to understand is why the only mulit-sensor navigation unit offerd on the GA market (Narco ND9000 Starnav) has vanished from the market without a trace? with GPS, VOR/DME used inside the box for area nav and an input for LORAN. The NS900 also had ILS and as far as I can see is still way ahead of the Garmin GNS430 in navigation terms (it has no communications radio) perhaps it was just too far ahead of its time!

Comments from the floor please!

[IO540]

I have been trying to understand why GA has not got a multi-sensor navigation recever after all it cant be to much of a problem to use the GPS data base to auto tune thee DME units to triangulate a fix. the (already fitted) altitude input would take the slant error out of the fix.
Something like that would no doubt meet P-RNAV by using both GPS and DME/DME.

I guess the problem is that DME/DME does not give you the continuous position reference which is needed for any kind of moving map application; one needs something else to fill in the gaps between the times you are banging the DMEs. And one can't just dead reckon for ages. GPS solves this by continuously computing the solution. Airliners use IRS (occassionally corrected by DME/DME triangulation) but inertial reference is expensive. The cheapest 3D fibre optic gyros come to about $10k in volume, and moreover are tightly export controlled.

One could fill in the gaps using solid state gyros and they are improving all the time, and would probably be good for a few minutes. This isn't really good enough though... imagine doing a descent from 5000ft to 1000ft and using the device to help find some grass field which looks just the same as the countryside around it, and 10 mins out you lose all DMEs...

In terms or marketing, "everybody" really knows since nothing short of WW3 or something close is going to switch off GPS, "nobody" is going to spend money on backing up their existing IFR GPS which works just fine. And one can always deal with total equipment failure by reverting to VOR nav or even vectors, or of course pulling out the backup GPS. There isn't really a market for something that "would be a super idea" but is not actually needed.

Google turns up nothing on Narco ND9000 - what is it??

Years ago, before GPS took over the world, somebody (Collins?) produced a moving map product which used VOR/VOR triangulation. Then, GPS killed the market and they dropped it. It would have been near-useless for European GA anyway due to poor reception distances and general VOR errors of a few degrees much of the time.

[DFC]

IO540,

DME-DME systems are in regular use and coupled to FMS and EFIS provide full RNAV and Moving Map.

The principle is very simplar to GPS i.e. if you have 3 distances from known DME positions then in general terms there is only one place on the earth you can be.

I don't know about your DME but my DMEs give constantly updated indications when tuned to stations within range. If you have 3 of those feeding into a computer, you can get RNAV and Moving map no problem.

------

A and C,

There are two problems. Firstly the cost of 3 DMEs and the associated equipment to do all the computer stuff.

The second one however, is probably the most limiting because even if you have the deep pockets to purchase the system, as you know a DME is very power hungry and try putting 3 of them into a system plus the extra stuff and your average light aircraft will be overloaded in bot electrical and empty weight limits.

Regards,

DFC

[IO540]

One would be hard pushed to get multiple DMEs at GA OCAS altitudes.

[bookworm]

try putting 3 of them into a system

Surely you wouldn't use 3 independent DMEs but rather scan the 3 frequencies in turn with a single DME transceiver? Aircraft move fast, but not that fast.

[DFC]

Bookworm,

Yes you are right, that is one way. However, think back to your DME theory and things like squitter and time taken to lock-on etc etc. Such factors can make the beast less reliable and more power hungry.

--------
IO540,

If you are remaining outside controlled airspace why do you need precision R-Nav equipment? Just point the aircraft where you want to go the RNP is up to you. ;)

Regards,

DFC

[A and C]

I don't see the DME power requiements of a modern DME unit such as the King KN64 as a problem the fact that it requires no cooling and if my memory is working a 3 Amp C/B sugests to me that unlike the previose generation of DME's that required "whistleing suitcase" to be fitted in the back of the aircraft these4 modern units don't use a lot of power.

Most IFR aircraft have at least one DME that can be remotly tuned so a system that uses two or three DME's should not cost two much and not as much as fitting a second Garmin GNS430.

As to IO540's issue of DME range, I think that not enough consideration has been given to the number of DME stations avalable, remember that most ILS now has a DME and the TACAN DME is also avalable, I doubt if there are a lot of places in Europe that at 5000ft en-route DME/DME is not avalable.

As for the Narco NS9000 if you take a look in the manuals & pinouts section of www.narco-avionics.com you will find all you could want to know about the box.

I still don't know why the NS9000 vanished without trace after all GPS,ILS/VOR in one box with DME and LORAN inputs thats three RNAV options in one box, sounds too good to be true!

[mm_flynn]

I suspect the main reason a GA DME/DME box doesn't exist is that GPS does such a good job.
The only real reason anyone would fit one is to cover for a general GPS outage (which isn't going to happen with GA able to fly) or a local outage/jamming - which (for a proper IFR installation) is a low probability event that most GA operators wouldn't backup.

The US is arguing for ELoran because in a pure ADS-B traffic environment it is critical everyone has continuos position data to transmit and they seem to have a clear plan to have moved away from ground based infrastructure in the foreseeable future.