The end of ADF at last? [Archive]

Droopystop

10th Aug 2007, 19:55

What on earth do have against the poor ADF? OK it has its limitations but its beauty lies in its simplicity. There is something very comforting about having a needle that points home.

Ducking from those who'll accuse me of living in the past and obstructing progress! But remember the ultimate goal of progress in aviation is total safety. And that means the end of the weakest link in the chain. You and me. I don't know about everyone else, but I enjoy hands on flying, get great satisfaction on the odd occasion I do it well. Taking the challenge away, takes away the fun!

glazer

10th Aug 2007, 20:02

What do I have against ADF? How about the time when I did a practice NDB approach (fortunately not under real IFR) into Gloucester some years ago to find the ADF needle pointing 180 degrees the wrong way. It was being interfered with I believe by a radio station in France.
:=

gcolyer

10th Aug 2007, 20:18

The ADF or NDB as it is better known is great! old but simple. With the inception of VOR's the NDB has been forced to take a back row seat. A bit like good ole map, compass and stop watch has been canned by anyone who owns a GPS!.

NDB with a DME is perfectly adequate and I will be sad to see it go.

Maybe you all think I am sad to want to see it stay.:}

IO540

10th Aug 2007, 21:10

The ADF system is quite good for the purpose for which it was developed around the time of WW2: providing crude but usable guidance for long distance flying. The NDB transmitter is a simple thing to make and to keep going, and the more kilowatts you pump into the bottom of it the longer its range will be. It works well over flat open country, the sea, and over long ranges (hundreds or even - with huge amounts of power - thousands of miles).

I routinely tune in an NDB when flying long VFR legs across e.g. France, for both backing up the primary nav (GPS) and to give me a well known clear waypoint for the flight plan. I do this a lot less now because I do long flights under IFR and IFR (airways) is all GPS - GPS (RNAV) is in fact mandatory.

Unfortunately NDBs have gone out of fashion for enroute nav a long time ago, due to VORs and more recently GPS, and tend to be used mostly for instrument approaches, and that is where they fall down badly. When you are close to the beacon, say tens of miles or less, you are entering the part of its radiation pattern which is affected by terrain/coast assymetry, electrical storms, god knows what else, and it's easy to find one's track 30 degrees off. The approach designers know this of course so NDB approaches are designed with loads of latitude for lateral errors, often using DME to ensure that if the radiation is disrupted so badly you end up way off track (but have followed the DME stepdowns) you will probably not hit any hills (but may not be able to land, which is "OK"), but the end result is an instrument approach with a decision height like 800ft which is basically useless for the average British Warm Front kind of weather...

Airliners use inertial navigation now, the new ones with GPS, and they totally ignore NDBs enroute. They also tend to ignore NDBs on approaches, flying the approach using the INS (FMS) and only checking the NDB at the start. However I think there are enough dual-NDB approaches in Russia to keep the ageing CAA ATPs happy :)

To top it, of all the avionics you can stuff into a GA plane, the ADF is probably the least reliable. The current KR87 is generally OK but most of the others were crap, and expensive to repair. It is common to find, on the average spamcan, that the ADF is duff and nobody wants to pay the £3000+ to get it fixed.

AFAIK the current proposal is to do away with the requirement for the ADF for IFR in CAS i.e. enroute. Most European countries never had such a requirement in the first place - it's a peculiarly British=Superior thing - and just looks plain silly.

I don't see the ADF going away on instrument approaches in Europe, where it is widely used as a locator.

I would keep my ADF working but won't be sorry to see enroute NDBs disappear.

Droopystop

10th Aug 2007, 22:15

What is it that will be done away with, the NDBs, the approaches or the ADF kit in the aircraft? Sounds to me that it simply means that there will be no requirement to have a (servicable) ADF fitted to fly IFR in controlled airspace. It would be a shame to loose the NDB network, if nothing else because it is such a great gross error check. I have to say that I have never had the inaccuracies or unserviceabilities experienced by others here and the MDHs I use seem to be about 450' which are still reasonably useful.

BackPacker

11th Aug 2007, 08:34

Would this have something to do with pressure from Cirrus/Garmin?

When the Cirrus first came out with the glass cockpit based on the G-1000, I believe they could not get the combination certified for IFR airways (in the UK only) because of the UK-only requirement to carry an ADF. So they had to put a 19th century ADF in an otherwise 21st century cockpit. And, obviously, none of the drivers actually used the ADF, possibly except for training, because it wasn't integrated with the G-1000 like the other NAV instruments (GPS, VOR, ILS, DME, marker). Very expensive ballast. I have no doubt that Cirrus and the other a/c manufacturers that use the G-1000 (or any of its competitors), plus the drivers of these machines, do not regret seeing the requirement disappear.

I would also imagine that the law says something like you can only plan and execute a flight for which you are suitably equipped. So if the planned flight ends in IMC, at an airport which only has an NDB approach, then, by law, for that flight you need an ADF anyway - or make a different plan. Nothing new there really.

As for using NDBs enroute: yes, it's a shame that they are disappearing, but we GA have to remember that we are making free use of an infrastructure which is mostly installed, maintained and used for/by the commercials. If they have no need anymore for it, then either we have to find a way to convince the authorities to keep them in place, or pay for them ourselves.

glazer

11th Aug 2007, 10:35

I assume that what the CAA intends is to remove the REQUIREMENT to have ADF while flying IFR in controlled airspace, and at this time no suggestion that NDB's will become unavailable (although I am pretty sure that eventually that will happen too).

By the way, the ADF is the thingy you have in the aircraft while the NDB is the thingy on the ground that transmits a radio signal: they are not the same thing.

With modern GPS systems and PDF's one can now have a bearing indciator pointing to wherever you want which looks to all intents just like an ADF RMI. The only difference from a true ADF is that it is not actually in receipt of the radio signal ( together with all its well known errors) and there is no dip error. This makes a vastly superior, simpler to use, and more precise effective ADF than a true ADF. It does seem to me that one should be allowed to substitute this for an ADF in order to perform an NDB approach where at present there are no official GPS approaches. In due course I would expect in any case NDB approaches to disappear and be replaced entirely by GPS approaches.

FullyFlapped

11th Aug 2007, 10:55

Nobody will be removing my ADF : not while BBC Five Live keeps broadcasting live football on medium wave !

FF :ok:

IO540

11th Aug 2007, 16:27

With modern GPS systems and PDF's one can now have a bearing indciator pointing to wherever you want which looks to all intents just like an ADF RMI

True, but TBH I doubt that if the GPS was invented in WW2 anybody would be using "needles" today. The CDI/RMI/HSI bar or needle representation dates back to the goode olde days when a map type representation was technologically all but infeasible, and clever people invented all kinds of ways to enable planes to navigate relative to beacons.

Today, if really using the GPS, you would dial the inbound on the OBS mode of the GPS and track the magenta line (inbound) or the white line (outbound).

S-Works

11th Aug 2007, 17:36

It is interesting to note that none of the brigade that will be sad to see ADF go are actually serious IR flyers.

Everyone of us with an IR flying proper IFR all the time cant wait to see the back of the NDB/ADF kit and that none of us actually fly pure NDB approaches and all use the GPS overlay.

As IO540 points out ADF was made for a day one nothing else was available, now the military would not even consider its use.

Croqueteer

11th Aug 2007, 18:52

No one seems to have mentioned the main use of the NDB (The ground station cost about half-a-crown a week to maintain) It is ideal for situational awareness during the initial approach phase, ie if the radar controller has forgotton about you, which I've experienced a few times, or just knowing where you are at a glance during prolonged radar vectoring, especially when adjacent to lumps of rock. It helps to keep the flight deck in contol. When STN ditched the SAN, it wasn't long before pilot pressure had an NDB reinstated.

Stampe

11th Aug 2007, 19:32

Spot on croqueteer and sadly the GE and GY have been withdrawn at LGW simultaneously.Mine seems to have been the lone voice raised in protest (sign of changing times and generations).No sign yet of a single airfield located replacement which is a happy compromise,there dores not seem to be a head of steam! in protest.So now total reliance on the radar controler to get you on the correct centreline and far less situational awareness.

IO540

11th Aug 2007, 20:16

total reliance on the radar controler

What about looking at the GPS moving map? That tells you exactly where you are.

The NDB or the ADF could fail and the fault may not be evident; the needle will always point somewhere on the 360 deg circle. The morse code ident only proves the frequency tuner is demodulating the AM portion with the ident on it; it says nothing about the rest of the instrument.

Cough

11th Aug 2007, 20:24

LGW's GE/Y are to be replaced with an on site NDB (Glasgow style) according for our fleet manager.

Serious IFR stuff - ADF's are invaluable in a steam driven cockpit. The simplicity of the system and the situational awareness that it gives you (particularly when tied to a DME) in a glance can not be understated. With a glass flight deck with map displays they largely become the third glance rather than the first. BUT, when the map displays go up the swanny, guess which needle you will be searching for first...I know, been there!

Croqueteer

11th Aug 2007, 20:42

IO, just for once give some credance to people like the last two posts that have spent their working lives on the flight-deck in all weathers and terrains.

Dysonsphere

11th Aug 2007, 20:53

And whats wrong with ADF for those of us without glass cockpits or GPS its still handy

IO540

11th Aug 2007, 21:41

Having recently watched a presumably overloaded commercial flight (ME piston) climb only about 500 feet some 5nm after departure, it should come as no suprise to me that there are commercial operations which rely on the ADF needle "especially when adjacent to lumps of rock", but I hope that I never end up sitting in the back of one of them, Croqueteer.

If you really rely on the ADF needle "especially when adjacent to lumps of rock" then presumably you don't carry an EGPWS either.

I agree that every bit of situational awareness helps (and I use the ADF needle on the RMI too) but IMHO you are just trying to justify some of the dinosaur hardware that is still flying "commercially". Of all the stuff one can screw into one's panel, the ADF is the last thing I would rely on for obstacle clearance.

Dyson - the proposal, AIUI, is to do away with the mandatory ADF for IFR in UK CAS, which is basically airways flight, and you can't fly airways without BRNAV capability, which in the GA context means a mandatory IFR GPS. In Class G, it won't worry you.

Droopystop

11th Aug 2007, 22:24

Bose,

I do hold an IR and do use it. I have been compelled to use NDBs alot, due to the type of flying that I do. Enroute, we rely on a (non moving map) GPS. It's ok. But its a long way outwith the standard scan, so we don't even look at it for approaches. NDBs allow us a level of capability that would not be improved upon if we were to use GPS for approaches. Yes a fancy moving map properly integrated into the instrument fit would make life easier but it would also mean that my IF and spatial awareness skills will degrade through lack of use.

It's horses for courses. Aviation is wonderfully diverse - we all fly different machines in different roles for different rewards. To generalise is inappropriate.

Progress will ultimately turn an airline pilot into a customer service role. The pilotless airliner is almost here. Private flying offers the opportunity to preserve proper flying skills - look how many airline pilots swap their nice big air con quiet cockpits for a smelly old string bag or cramped glider? Please don't demean others by assuming we all want progress in private flying.

Gipsy Queen

12th Aug 2007, 04:02

Is some of this resistance to the loss of ADF just nostalgia?

I have flown aircraft which were DF equipped - the "A" had not arrived then - and the advent of the automatic bit was just the most wonderful thing! I have no experience of ADF coupled with DME but we managed very well without the DME since nearly all aircraft had two ADFs on the panel and a circular computer in the flight bag. The system worked well although it did have its limitations. But nothing like as user-friendly as VOR/DME for example but we didn't know that at the time as we struggled to ascertain frequencies, obtain DF cuts and juggle the computer, pencil and paper, maintain the scan and verify a position in turbulent IMC.

This level of flight deck workload is stupidly high if there is an acceptable alternative -and there is. In fact, these days there are several choices so despite my sentimental attachment to the venerable NDB and its associated navigation, I can see no useful purpose in retaining it. Now if it's Console we are talking about . . . ;)

GQ.

Dan Winterland

12th Aug 2007, 05:15

With night error, coastal refraction, turn error and the tendancy to point at the nearest thunderstorm, it's amazing that the NDB is still in existance. It appeared in the 1920s - imagine introducing and trying to get it certified now!It may be of some comfort to the GA flyer, but most GPS sets will give bearing and distance to a waypoint - so why not use that!

In the USA, nearly all NDBs have gone - I can't think of any off hand. Where I fly now (China), there are quite a few still around. This is historic and they are gradually disappearing. However, when we use them as a navaid, we will always have GPS as our primary navaid, so we are just referring to the position and not the NDB itself. And if we have to fly an NDB approach, it is essentially a GPS approach.

As part of the IR I used to fly on a Classic 747 (only two years ago), we had to fly an NDB approach. If faced with that situaion for real with weather on minimums, I don't think many of us would have not first considered flying to the alternate. In fact, our chief pilot hinted that he didn't want anyone doing it for real.

Consol - now there's a system!

Semaphore Sam

12th Aug 2007, 06:49

Come on guys. Times, and technology change. When I first started flying, they had Adcock Range approaches (N/A), Loran C (and probably B), Consolan, navigators, star charts, sextants, and Ocean Stations. The ADF/NDB had its day...the only reason to keep them (mentioned only once in an earlier post) is to get the news and broadcasts of sports events. These are admittedly very important..if technology can provide these services without ADF/NDB, they should go the same as steam engines and semaphores (sad, but part of life). Sam

Fuji Abound

12th Aug 2007, 08:13

Is some of this resistance to the loss of ADF just nostalgia?

I think this is the correct question - in other words do we need the ADF.

Practically, so far as GA and en route navigation is concerned the answer has to be no, because GPS has replaced the ADF even if VORs are being used with GPS filling in the gaps between low level reception.

However legally, and particulaly in so far as let downs are concerned, the situation is more complex.

There are a few places with only NDB/DBE let downs. They are the least expensive let down aids available to an airport authority. Such airports are unlikely to ever be able to afford a localiser or have a VOR positioned on thier field.

I hear you say what about GPS approaches?

GPS approaches suffer from a significant limitation. They require an approved panel mount unit. Now we all know most people will "supplement" such an approach with a GPS (hand held or otherwise). However, strictly if the ADF is removed from the aircraft then these approaches will become illegal for most GA unless they invest in an approved panel mount unit.

The use of hand held GPS units for en route or approaches in not likely to be approved any time soon!

S-Works

12th Aug 2007, 09:08

Please don't demean others by assuming we all want progress in private flying.
And please don't demean private flying by holding it in the dark ages. If you want to be stuck in the dark ages sucking oil and experiencing the nostalgia of a bye gone age then it is your call.

However the reason we have dwindling pilot numbers, so few IR's etc is the modern nintendo generation have no sense of nostalga and all they see is old ****can aircraft with equipment that should have been sent to the skip decades ago.

I use my aircraft as a practical tool for getting me around Europe for business and leisure and flying over 400hrs a year I get to do a lot of instrument approaches.

The ADF IS OK as situational awareness tool, but I also have much better tools in my cockpit for the job and will not lament it's loss other than for listening to Virgin 1215, but even that has been replaced with my iPod....

Droopystop

12th Aug 2007, 19:42

I never said I wanted to hold GA in the dark ages. I happen to agree that some new airframes would do the flying schools a whole heap of good. I was merely trying to point out that not everyone in private aviation want their own private airline. Nor does every IR holder dispise ADFs.

Itswindyout

13th Aug 2007, 08:23

there are many countries that use adf/ndb facilities, that a UK PPL might visit.

Also they are a godsend, as situational awareness for ILS approaches.

I have just demonstrated the two NDB approach in Russia to a non believer.

He is also an american, who would not know an NDB if he fell over it.

Yes I know, I have a very high tech cockpit, but still when the chips are down like to think that I could conduct an approach with the little needley thingy.

In a former life I was able to navigate day and night over the UK, using the BBC transmitter location guide, also not forgetting Droitwich, centre of the known universe.

Please do not loose your basic skills.

its windy out

bookworm

13th Aug 2007, 09:44

Also they are a godsend, as situational awareness for ILS approaches.

You're winding us up windy... ADF for SA? Have you flown with a moving map?

Fuji Abound

13th Aug 2007, 10:00

In a former life I was able to navigate day and night over the UK, using the BBC transmitter location guide, also not forgetting Droitwich, centre of the known universe.

Low level using the football and other stadium lights works well also. Never understood why the lights arent marked on maps. You have just got to check that you coinicide your flight for when they are switched or otherwise they fade, a bit like the ADF needle.

IO540

13th Aug 2007, 12:09

Statements like

In a former life I was able to navigate day and night over the UK, using the BBC transmitter location guide

make me wonder how many trolls are in here.

Before the invention of controlled airspace, maybe. What's that, about 1950??

Sir George Cayley

13th Aug 2007, 12:23

I think the proposal from CAA is to remove the requirement, not to remove the equipment.

Therefore, should providers continue to support transmission, users who retain the onboard equipment can use it.

Far as I can see there is no move to take the NDB approach out of IMC training and testing as a result of GPS introduction.

And, it's only in UK airspace. No sign of Europe following suit.

So, lots exchanges about not a lot really.

Unless you won £35m this weekend and are about to order a Columbia 400!

Sir George Cayley

bookworm

13th Aug 2007, 13:50

So, lots exchanges about not a lot really.

Not unless you're currently paying thousands of pounds for the privilege of completely ignoring the ADF while flying IFR in controlled airspace, no.

mm_flynn

13th Aug 2007, 15:29

If ADF and DME could be replaced by GPS (as in USA). I would tomorrow junk my KNS-80 (for its DME) KN-53 and KR-87 for a 430 to match to my 530.

Itswindyout

14th Aug 2007, 03:45

I actually used Avonmouth docks, and the turning point, nice glow from the flare stacks at the chemical works.

The BBC Driotwich transmitter was my prime nav aid from Manchester to Bristol, at 3000 ft, and as it was turned off for a few hours every early morning, to be establised on track backtowards Brisol was critical, until the flare stacks ( or glow) were visible. NO motorway to follow like todays IFR pilots.

I currently fly the G550, and am quite happy with the moving map displays, however I also fly in less well fitted out cockpits, and the two ADF needles, are perfect to judge range and bearing to the abm, and even down wind positions. However Mr Garmen has not been teaching this technique recently.!!!!

In another life I also conducted aerial surveys, in a C172, and can vouch for the afternoon story, and womans hour, as perfect foils to a 2 hour orbit.

Until the world demolishes NDB and MW radio facilities, I shall continue to use ALL available facilities to assist SA.

windy

S-Works

14th Aug 2007, 08:30

Well I am glad you are a dying breed, lets hope you don't get a job with the CAA.....

Doing a type rating last few weeks in Canada, the guy teaching us was as old as the wright brothers and had a fascinating career flying everything from body bags in 172's across alaska using LORAN and ADF to Classic 747. He could see no place at all for ADF in this day and age and said that modern airliners that proclaimed to use NDB were actually just using the FMS to point at where the beacon should be. The Garmin can do that just as well.

ADF was a good tool when there was nothing better, just as carbs on cars were before fuel injection. Times change and if we don't change with them there will be nothing left of GA.

I for one won't miss the cost of maintaining a bit of kit that probably gets used twice a year and costs me a fortune to keep working. I have flown one NDB approach for real this year after arriving in Guernsey and the ILS was U/S in my friends Lance that only had steam kit (rectified now with a Garmin fit). The only other time I fly them is my ME/IR renewals.

Joining CAS at WCO is over half my airways joins and I won't miss the needle pointing miles off the track the GNS is giving. Guess what I have never missed WCO with the GPS but I would have many times with the ADF.

IO540

14th Aug 2007, 08:59

A and C

14th Aug 2007, 09:46

The big problem with GPS is that it is so easy to jam and with the goverment proposing a tax on the free movement of people or road charging as they call it GPS would seem to be the cheapest way to introduce such a tax.

If this comes to pass we will have a great number of people with a very real interest in jamming the GPS system.

So along with the fact that most modern airliners use DME to update the position in the FMS (the B737NG has 5 DME units) I see DME being around for a long time and the logical approach aid to go with this is an ADF located on the airfield as this is the cheapest answer to the GPS jamming issue.

We can also turn this on it's head and oppose the use of GPS for road charging on safety grounds not only for aviation but also for the other safety related uses that GPS has.

IO540

14th Aug 2007, 10:41

a great number of people with a very real interest in jamming the GPS system

Indeed, but the logical thing would be to use a very low power jammer, mounted in the actual vehicle.

Wholesale GPS jamming would stop GPS road navigation which many commercial vehicles rely on totally. It's also impractical; you would need a transmitter suspended under a baloon, or similar. Who is going to bother?

A 1 milliwatt jammer in your car would totally circumvent any road charging scheme but you would have to turn it off if you want to use a GPS for road nav yourself.

A and C

14th Aug 2007, 16:39

Point taken but what happens when three or four so equiped cars drive under the approach when you are on a CAT 1 WAAS GPS approach?

I dont know the answer but I don't want to find out by trying it !

IO540

14th Aug 2007, 17:08

IMV, universal road charging won't happen precisely because it would be so easy to evade, and road tax works very well.

Should tampering with GPS signals become fashionable, there are some easy countermeasures. I believe this (http://www.navcen.uscg.gov/archive/2001/Oct/FinalReport-v4.6.pdf)lists some of them.

mm_flynn

14th Aug 2007, 17:24

There is a slight problem: if overlay approaches were authorised in the UK (which would be great but is highly unlikely) then many IFR approved GPS installations would not be able to use them. My KLN94 uses a version of the Jepp database on which many tracks are missing, and often only the final approach track is shown.

"Overlay Approach" in the sense the FAA uses it is different from the "approach representation" that you have in your KLN94. An overlay approach is a new approach that has the same track as the underlying approach (so is quick to define and needs no survey) but has all of the key points defined in the database (IAFs, stepdowns, etc) so you can fly it with the GPS providing your only guidance.