VOR/ADF Position Fixing

[twistedenginestarter]

I did an ADF let down the other day as the airfield concerned had no other aids, my GPS was in the bag and the cloud was down to 900 feet. The instructor I was with made the call. I was a bit surprised as the field didn't have ATC so this was illegal.

I think you should be able to manage ADFs. If you can't it suggest there's a big hole in your general navigation. MS FS is a perfectly good way of getting back into practice.

[Julian]

My view is use everything that is availiable to yourself, eyes, map, GPS, VOR, ADF.

Dont just rely on one piece of kit and use the others to cross check what the one you are looking at is telling you - it may be lying!!!!

J.

[samuelwmartin]

Yes my reason for asking the question in the first place was because I want to be able to know and fully understand all the basics inside out and not rely on electronics such as GPS, etc.

Because one day you just know you're going to need it (and also I've been in a situation where I wish I did know how to use it and it ended badly so this time round I want to know everything inside out - PRESSURE!).

[IO540]

I was a bit surprised as the field didn't have ATC so this was illegal.

It's not illegal, in a G-reg plane.

You can descend to any height for the purpose of a landing, on an unpublished instrument approach.

It is only airfields that have published instrument approaches which need full ATC.

[tmmorris]

IO540 - don't let DFC catch you flying NDB approaches on a GPS.. he'll have a field day!

Learning how to NDB track is also useful if you ever find yourself dependent on tracking towards/away from a VDF (like the almost defunct VDF approaches) because the theory is the same - i.e. bearing to beacon increasing - turn left; bearing to beacon decreasing -turn right; and the plus 10/minus 10 mantra works, too. Something which might save your life if you end up in IMC with no working nav kit but a serviceable radio. (Though obviously a radar approach would be preferable!)

Tim

[DFC]

You can descend to any height for the purpose of a landing, on an unpublished instrument approach

Provided that the instrument approach is in accordance with the appropriate requirements i.e. ICAO Doc 8168. It would then have an appropriate DA(H) or MDA(H) so you could not "descend to any height".

Of course the approach ban would apply if there was not the required minima for the approach and thus unless there was met reporting at the destination, the (expensive) approach procedure could not be started.

I wonder why there are so few "private" instrument approach procedures.........could be that the cost of the navigation aid, the design of the procedure, the flight checking and the met reporting simply make it not worthwhile for the few times it would be used in anger.

With no instrument approach meeting the ICAO requirements then -

IFR rule = 1000ft above everything within 5nm of the aircraft.

Not applying when visual below 3000ft amsl or when taking off or landing.

If visual, you can see where you are going and you don't need ADF or GPS.

If taking-off or landing I hope you are visual unless you have a private CAT3 ILS system.

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The one consistent argument from IO540 in support of GPS is that IO540 finds (in this case) ADF tracking and setting the DI too difficult, it is outdated and something for those morons who can actually do it.

Even the UK uses both Transverse Mercator and Lamberts Conforman Conic for the CAA VFR charts so one needs the know those two projections hust for UK VFR operations........perhaps we will leave the others and sad things like grid navigation to us morons who actually go places.

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To answer the original question;

S-I-D = Select, Identify and Display

For crossfix -select navaid closest to along track as possible first and plot.

Regards,

DFC

[IO540]

IO540 - don't let DFC catch you flying NDB approaches on a GPS.. he'll have a field day!

and you were right, TMorris

He must get through a lot of those Russian stopwatches which all the pilot shops sell these days. He must have flown around 165 NDB holds in that response time.

[twistedenginestarter]

IO540 and DFC

Are we then agreed it is illegal to make an instrument approach to 900 feet without ATC?

[DFC]

Are we then agreed it is illegal to make an instrument approach to 900 feet without ATC?

That is not 100% true.

If there is a published procedure then there must be ATC.

Some commercial operators have procedures approved by the CAA and included in their ops manual. Examples being operations to some of the Highlands and Islands airports or for example Blackbushe where companies have had procedures approved just for their own use and with only AFIS service.

However, those procedures will be the exact same as the published ones i.e. will have had the exact same design, approval and checking process as published procedures.....an expensive thing.

Home made GPS (or any other) instrument procedures will not meet the same standard and thus among other things could be classed as reckless endangerment.

A mis-conception among pilots is that if for example there is a VOR on or near the field then they can construct an instrument approach procedure based on it. However, the instrument approach procedure relies not simply on good professional survey and design but also on having the approach aid certified as fit for more than enroute use plus flight checked. The AIP navaid listing shows what each VOR navaid is certified to be used for. Enroute means enroute and no more.

Regards,

DFC

[mostlytossas]

You should learn to do what we do down here in OZ while flying over the long expanses of country. Turn on the ADF and tune to a local AM radio station within 200NM. Listen to the music. Turn on the GPS and follow your entered flightpath. Before all you excitable instructors out there have a hernia remember we live down under so all our flying is uphill.

[SNS3Guppy]

Your ADF is also useful as the "poor man's strikefinder," in identifying thunderstorms and lightening. Tune to a low frequency and listen; you'll hear the lightening discharges and see the needle jump often before you'll see or hear the lightening with your eyes, and at a much farther distance.

[IO540]

Your ADF is also useful as the "poor man's strikefinder," in identifying thunderstorms and lightening. Tune to a low frequency and listen; you'll hear the lightening discharges and see the needle jump often before you'll see or hear the lightening with your eyes, and at a much farther distance

Jesus christ if you believe that as an indicator of anything even remotely reliable you believe anything

What kind of kit is this on??

[tmmorris]

It's safe to say, twistedenginestarter, that we aren't agreed on that at all, but I don't think we should resurrect the argument now as it's been done to death before.

Tim

[llanfairpg]

1. Tune ADF
2. Turn up volume to hear you have NDB Station
3. Set heading accurately to where needle points
4. Fly heading

Sam that is the logical sequence but with a NDB you need to be bit more careful than that. I have known many cases were on the edge of range the needle is pointing but not to the beacon you want to get to, yet you can still hear the ident.

The first thing to be aware of is the protected range of the beacon(AIP) Never trust NDB bearings outside protected range or around thunderstorm activity and even then be very careful.

You also need to consider with some smaller airfields hours of operation as I have known some not to be 24 hour.

There is an old saying in flying that goes like this;

Never trust one man, one gauge, one engine or one instrument. I have seen the truth in it several times unfortunately.

On that basis I would need some type of duplicate or back up check that when the needle falls I am actually over the beacon I think I am. VOR check ATC etc etc.

You also need to monitor the ident throughout the approach if you are only using one ADF.

I worked with a pilot once who was based at an out of the way airfield with a public transport Aztec. He was returning one claggy night, went to the overhead and started the procedure, half way round he noticed the ADF had failed and there was no ident so diverted to another airfield. He subsequently found out that the barman at the club had heard an aircraft overhead and went and turned the NDB off. When later questioned he said that he had heard an aircraft overhead and thought. 'why should enroute aircraft use our airfield NDB', amazing but true, he of ,course never realised that Steve was about to let down on it as club flying had finished much earlier in the day and there had not been a movement all afternoon.

[echobeach]

It's not illegal, in a G-reg plane.

You can descend to any height for the purpose of a landing, on an unpublished instrument approach.

IO540
Can you clarify this comment regarding unpublished approaches in IMC
If the runway at destination is on a radial from VOR, the cloud base is 1500 ft and the MSA is 2000 ft I would have thought that you should not descend below MSA in uncontrolled airspace whatever the level of ATC at the airfield.

I thought that if there is no published procedure at the destination airfield that one should cloud break using a published approach at an alternate airfiled and then transit VFR in VMC below cloud base if safe to do so. If this is not possible then one cant land at destination airfield.

This comment suggests that it is legal to use an unpublished approach to cloud break below MSA.

[llanfairpg]

You can descend to any height for the purpose of a landing, on an unpublished instrument approach.

VFR yes but IFR you need to be at least 1000ft above the highest obstace 5 nm either side of track in the same way as if you were tracking the same aid enroute. Thats my understanding.

[llanfairpg]

It's not illegal, in a G-reg plane.

I dont think reg has anything to do with it, you have to adhere to the rules of the member state you are fllying in thats why we have different Cat 3b rules in different countries.

[echobeach]

that is my understanding also. The previous post had suggested that an unpublished approach to an airfield in uncontrolled airspace below MSA in IMC was possible and this did not seem correct to me.

[mm_flynn]

IO's comment reflects a specific interpretation of rule 33 of the ANO (minimum height). Which says broadly IFR flight must be above the MSA and then lists 4 exceptions to this general principle. Exception a) says "Unless it is necessary for the aircraft to do so in order to take off or land".

It does not qualify, as it does in other exceptions to rule 33, any minimum viz, a requirement to be on an approach (published or otherwise), in sight of surface, or anything else. Hence the argument that a flight in cloud, below the MSA while approaching to land at an airport with no approach does not contravene rule 33 of the IFRs

This interpretation is reasonably common and is consistent with operations of which the CAA is no doubt aware. Even more odd is the CAA appears to have considered changing this but declined, and only last year 'had the hood up' on this particular rule to introduce a minimum viz requirement on another one of the exceptions.


The FAA equivalent rule does specifically qualify the landing element as only valid when following a published approach (and you could argue that an N-reg aircraft in the UK would be bound by this stricter interpretation, although I believe the specific FAR is restricted in applicability to US airspace)


However, the interpretation as given is subject to extensive debate if you look in the archives.

[Chuck Ellsworth]

Just to give myself an edge on the rest of you navigators I'm going to have a BFO installed in my GPS.

And I yearn for the twilight zone flying the Radio Range and remembering finding the cone of silence still gives me a woody.