Descending through cloud without a procedure

[Dude~]

I have a question about flying on top of cloud.

Pilot takes off in good viz with a layer of cloud 2000ft above the local terrain. Pilot gets a RIS and climbs on top for some general handling then decides to descend until in sight of the surface again. If in Class G airspace, and not using any procedure, but perhaps tracking a VOR and fairly certain of location, how low can you go, assuming the cloud base had lowered since climbing on top? Is this a judgment call or should it always be 1000ft above nearest obstacle? One can well imagine the temptation to try a little bit lower. Didn't Hill crash at Elstree doing that?

Could it still be acceptable to descend below MSA if you knew exactly where you are? If you were to unable to break cloud, presumably you'd have to divert to an airport where there is an instrument approach, but would ATC give you ILS frequencies or would you have to be carrying full approach charts everytime you go on top?

Yes I do have an IR, but no I have not really used it, and frankly find the idea of using it is daunting since the training for the IR was a entirely on pre-planned school routes.

Also, if you want to navigate out of sight of the surface, but there are no radio aids suitable to track, is it acceptable to dead reckon and back up with position fixes, or should you always be tracking a radio aid?

[dwshimoda]

Dude,

I may be way off the mark here, and if I am, I apologise. But if you are out of sight of the surface, and have no radio aids to track, how are you going to position fix?

[DFC]

dwshimoda,

One could have 2 VORs, 2 DMEs and 2 ADFs but if the track is not taking you to or from one of the VORs or NDBs within useable range you can not "track" them. You can however fix your position from the information they provide.

There is also VDF for the situation of having none of the above.

Failing that most of Europe has radar and some unit can give a fix.

----------
Dude~,

The answer is that provided you can fix your position using NDB(s) within the DOC, or VORs within the DOC and 50nm of the station, with DME if available, you should descend to not lower than 1000ft above the highest obstacle within 10nm of the indicated aircraft position (The 10nm being made up of the 5nm possible error and the 5nm you have to be away from obstacles).

The best place to be just after reaching MSA in your scenario and discovering that you are not visual is back up on top again. That makes the flying easier and gives you many oportunities for;

1. Calling the radar unit you used and finding out where the nearest hole is (if any) and what the weather is at various places.

2. Spotting a suitable hole yourself

3. Diverting to a suitable place where you can either descend to a lower MSA or to the same MSA but some pilot has reported a higher ceiling. Remember Fohn effect from the met?

4. Divert (radar vectors) to an aerodrome for an SRA........if you need more than a non-precision approach then you realy did get yourself in a pickle and if that is the case then ATC will pass the procedure details to you!

If operating on a DR track of any length, the allowance gets very big very quickly. Can't remember the exact figure but from memory when leaving the last fix, the area to be considered for obstacles quickly expands to 60nm each side and at some stage (I can't remember when) to 120nm.

You say that Yes I do have an IR, but no I have not really used it, and frankly find the idea of using it is daunting since the training for the IR was a entirely on pre-planned school routes.

Perhaps you should consider the school training provided as being the correct and safe way to operate. By that I mean do not go IFR unless you have planned the trip or part of the trip IFR and have the required charts, weather and planning completed.

If you like the idea of getting above the clag in the local area then take the time in the planning stage to check out the navaids you will use to define the area once above cloud. Make sure that you have a good MSA calculated. Carry diversion charts and fuel.

Don't push your luck with descending below MSA if the conditions are not right (and that includes visibility below cloud as well as ceiling!). Shame to spend 8 to 10K+ on an IR just to make a splat on some hill.

Regards,

DFC

[dwshimoda]

DFC,

Sorry - just reaqlised the difference in what Dude said, re tracking.

Agreed.

DW.

[Dude~]

Thanks DFC, so going for a jolly on top in the local area where there are stacks of radio aids around still needs careful planning and considerations, especially re diversions.

I didn't realise Radar might be able to help with finding a hole in cloud.

Thanks for the info about obstacle clearance when dead reckoning, any idea where that is written down?

[FlyingForFun]

Dude,

This question has been discussed many times, and no conclusion ever reached.

My own belief is that, legally, you are allowed to descend as low as you like. The reason I say this because you are exempt from the 1000' rule "as required for take off and landing". So if you argue that descending below 1000' is required for landing, then it is legal.

There are many others, though, who believe that this exemption only applies for a published approach. However, there is nothing in writing which confirms this. What's more, there was a proprosal by the CAA, a few years ago, to explicitly ban unpublished approaches. Although this proposal never came to anything, the fact that it existed in the first place suggests that the author believed that unpublished approaches (which is basically what you are talking about) are legal... otherwise he would have had no need to try to make them illegal.

If you agree with my legal point of view, the next question is the practical issue of how low do you actually go. That's something you can only work out for yourself.Yes I do have an IR, but no I have not really used it, and frankly find the idea of using it is daunting since the training for the IR was a entirely on pre-planned school routes.My suggestion is to go and fly some routes IFR. Take foggles and a safety pilot if it's a Cavok day. If it's not Cavok, and you're happy you can get into your home airfield safely (given what we've just been discussing) then leave the foggles off, because you want to start learning what real weather looks like. It's very rare you'll fly a whole route in solid IMC, for example, although this is all the IR has trained you for.

FFF
----------------

[PPRuNe Radar]

I didn't realise Radar might be able to help with finding a hole in cloud.


The help is actually totally dependent upon either another pilot or an adjacent airfield ATC unit who is able to report a hole (assuming the radar unit is socked in) :ok: ATC radars are not that great at weather detection since we process much of the clutter out so we can see the aircraft.

[IO540]

"Yes I do have an IR, but no I have not really used it, and frankly find the idea of using it is daunting since the training for the IR was a entirely on pre-planned school routes"

Speaks volumes about JAA IR training, doesn't it. I guess you are very familiar with the approaches at Bournemouth, Oxford, Cranfield, or Cambridge? :O

Best to do some flying with an IR pilot, doing some airways routes. You have an IR so you can be PIC. Pick some nice destinations in Europe and he'll be more than happy to come along just for the trip :O

Legally, it's not illegal to execute a DIY instrument approach, in a G-reg. (There are some complications doing this in an N-reg, due to a FAR regulation whose number I don't recall off hand)

How to do one satisfactorily depends on your attitude to risk. I'd use GPS plus VOR/DME fix and descend to 500ft over the highest obstacle within 5nm. Having got QNH from a nearby proper airport and verified it against the GPS derived altitude. This rule often yields an "MDH" of 1000ft or so. I've gone below that but wouldn't do it again.

As regards a position fix, well use your common sense. If you get it wrong, you will die, so it's desirable to get it right. (Actually personally spoke to one man who did a CFIT at an estimated 120kt but the angle was quite shallow and he is still here, having spent some time in hospital).

So, two independent position fixing methods, and obviously one of them should be a GPS or radar.

If you have no nav gear, a PAR approach is the #1 choice.

Next option: you can get a radar letdown from most military (LARS) units. They do it over nearby surveyed terrain and they will take you down to 1000ft over the obstacles. You just hope to be in VMC by then.

Next option is to get VDF from some airfield (most can do this) out over the sea and descend out there. I guess D&D on 121.50 can also give you a fix over the sea; I don't know if they like doing that. Obviously if you have enough fuel then a PAR approach is better because ending up over the sea under an OVC003 limits your options to coastal airfields with offshore wind :O

But surely you knew all this :O

Anybody who flies in IMC without nav equipment, and particularly a decent GPS, needs their head examined, IMHO.

[pipertommy]

Hi all,I have a an IMC rating and it was never actually covered about minmum equipment ie nav aids required to enter IMC conditions in non-controlled airspace?I currently fly a tomahawk with ADF and VOR/ILS but its not fm immune does this make it useless?I back this up with my own GPS pilot 3.By entering IMC i only mean to climb on top!Not to cruise in IMC.cheers:

[IO540]

pipertommy

Sounds like you have been listening to one of the countless old patronising farts who make up much of the UK GA airport scene and who say things like

"the IMC Rating is a get out of trouble Rating", or

"the IMC Rating is a get into trouble Rating",

"the IMC Rating is only a get out of jail free card, young man"

etc
etc
etc

Your privileges are IFR in Class D,E,F,G in UK airspace, and that includes all instrument approaches therein, subject to 1800m minimum visibility on the ground, and you can legally fly down to the approach plate minima.

It may be an idea to fly with a half decent instructor, or an experienced IR pilot.

The problem is that a monkey can be taught to fly a plane straight and level in IMC, so saying you won't fly en route IMC doesn't really help you. The instant you enter cloud (which a plain PPL must never do, of course :O ) you are facing the possibility of having to stay in it for a while, and fly an instrument approach to get back down.

Even flying VMC on top (which is everybody's preference, no matter how good they are, simply because it's so much nicer) means that you may have to fly an approach to get back down.

My suggestion, which is worth what you are paying for it, is that you need to get good enough to fly the common approaches i.e. VOR, NDB/DME, ILS. An ILS is the most important because it is the easiest to fly and will get you down and save your life even in the worst conditions.

FM Immunity is required only for IFR in controlled airspace which for you and in England means Class D. In Class G you are OK. I am not aware of any actual problems ever having been reported (and never met anyone who has) however. It is a theoretical measure to prevent interference from FM radio stations near the top of the FM band e.g. 104MHz, affecting VHF navaids such as ILS and VOR. Anyway, you can fly an ILS into say Biggin but not Bournemouth, well not legally anyway. Of course the schools that fly non-FM-immune planes never go to Class D airports IFR :O

If you fly an NDB approach then you need a working ADF. There is some debate about this if in Class G but I wouldn't go there. What I would do is use the ADF together with the GPS though, because a 30 degree error on an ADF is common.

Similarly with DME. However any approach which says "DME mandatory" obviously needs one. Sometimes there is a radar range substitute available if you don't have a DME.

I would also carry a very good moving map GPS and spare batteries, with a remote (window mounted) antenna.

[pipertommy]

Thanks!basically what i`m getting at is doing an ILS back into Cardiff which i guess is now ruled out:rolleyes: .I did SRA`s as part of my IMC training,would i be correct in saying i could use this as the let down?Oh and i have been told you must have two radios on board for class D or is this for flying actual airways?

[RatherBeFlying]

Lets just say that a GPS will teach you a lot about the accuracy of an NDB approach in your a/c.

You may want to have your compass properly swung after;) ;) ;)

Then go up and check it again on several bearings.

[bencoulthard]

Just a thought, which may be a crap one as I dont have IMC, is it worth practicing something which may kill you on flight sim software?

Surely its no disadvantage?

[justinmg]

pipertommy
FM Immunity is required only for IFR in controlled airspace which for you and in England means Class D. In Class G you are OK.
In class G you are only ok if you don`t need to make an ILS approach . If you do, then you have to be FM immune. I have taken this up with local RADAR units and the CAA for clarification, with very little progress or understanding from anyone.

[dwshimoda]

Just a thought, which may be a crap one as I dont have IMC, is it worth practicing something which may kill you on flight sim software?

Surely its no disadvantage?

Ben,

I found MS Flight Sim invaluable for my IMC training - but only really for practising the holds and approaches with different winds etc. There is no point trying to fly it as a real aircraft, as there is no feel to it.

The biggest element of learning to fly IMC is training yourself to ignore the fact you feel like you are banked at 30 degrees and climbing, and set up a really good instrument scan, and even more imprtantly - believe the scan, not your senses. This can't really be done on Flightsim, apart from building your scan, although none of the gauges on my flight sim are in the same position, nor look anythig like the ones in the aircraft I use!

As part of your PPL you will do a little IMC, including how to execute a 180 turn and backtrack - try and get an instructor who will do it for real with you, rather than with foggles / hood, etc.

DW.

[buster172]

I have to agree with Dude,

There are lots of bits outside the training that aren’t covered specifically, and it appears from some of the answers there are a few things less than black and white.

Are there any experienced IR pilots out there who might be willing to take someone like Dude or myself along with them to experience some 'real' flights?

Id like to say I’ll buy coffee, tea, lunch etc for the chance to see it all and provide as much input as I can. Might it even be a benefit to the other pilot having someone who can do it alongside to share a little of the workload?

Regards,

Buster

[IO540]

Equipment requirements for UK airspace, applicable to any aircraft registration, are in schedules 4 and 5 of the ANO

http://www.opsi.gov.uk/si/si2005/20051970.htm#sch4
http://www.opsi.gov.uk/si/si2005/20051970.htm#sch5

In class G you are only ok if you don`t need to make an ILS approach . If you do, then you have to be FM immune.

I'd like to see the reference for that. If it's not in the ANO then I don't see how it works.

I saved four figures in training costs by spending many hours on FS2002, as it then was (now FS2004). One doesn't even need the yoke; a joystick is good enough because it is the procedures and situational awareness one is learning.

The IMC Rating does need a general improvement in the calibre of instructors that teach it. But one could say the same of the PPL :O

[rustle]

The IMC Rating does need a general improvement in the calibre of instructors that teach it. But one could say the same of the PPL :O

You often make comments like that here, and I would (genuinely) like to know the sample-size you use to come to that conclusion.

Your earlier comment:

Speaks volumes about JAA IR training, doesn't it... was based on a sample of one.

I hope your comments about the pilot training industry in the UK are based on something more statistically significant than one? Have you a lot of anecdotal evidence or first-hand experience of lots of instructors?

While I have little sympathy for an fATPL or IR holder and/or flying instructor

Licence Type (eg CPL. Pilots only):
Frozen ATPL
Current a/c Type (eg B737. Pilots only):
PA28
Location:
Southern England
Occupation:
Flying Instructor

who doesn't know the "rules" about, or procedures for, descending through cloud, I think some of the throw-away comments are unnecessary too.

Just my 2p.

[Brooklands]

buster172,

Are there any experienced IR pilots out there who might be willing to take someone like Dude or myself along with them to experience some 'real' flights?

If you wander over to the flyer forums (http://forums.flyer.co.uk/index.php), and contact Timothy* I belive he offers to do this for people, as do one or two others.

Brooklands
*He does post here from time to time, but you'll get a much quicker response via the flyer forums.

[justinmg]

Equipment requirements for UK airspace, applicable to any aircraft registration, are in schedules 4 and 5 of the ANO
http://www.opsi.gov.uk/si/si2005/20051970.htm#sch4
http://www.opsi.gov.uk/si/si2005/20051970.htm#sch5
In class G you are only ok if you don`t need to make an ILS approach . If you do, then you have to be FM immune.
I'd like to see the reference for that. If it's not in the ANO then I don't see how it works.
The actual issue comes down to interpretation of table 2 of schedule 5. I have tried to get `round this` by interpretation, espescially as FM inteference is more of a theoretical problem than a practical one. Anyway.....it may force us all into flying with correctly equiped aircraft, which is a good thing.
http://www.caa.co.uk/default.aspx?categoryid=224&pagetype=90&pageid=5866

[IO540]

justinmg

In the CAA doc you link to the words "To conduct an ILS approach
inside or outside controlled airspace one (FM immune) ILS receiver is
required" do indeed appear. The question is where from; the CAA writes a lot of "guidance material" which has no legal basis.

Referring to Schedule 5, ILS (category G in the table) is required when

(c) when making an approach to landing at an aerodrome notified for the purpose of this sub-paragraph

I don't disagree with you at this point (though your view is suprising since a lot of people have looked at this before) but where can one find a list of aerodromes notified for the purpose of the table in Schedule 5?

rustle

My "sample size" of IMCR instructors is about 10, over say 5 years, of which none had a valid IR, and only about 1 or 2 ever held an IR. For various obscure reasons I flew with several myself, none of them being any good for teaching how to go places.

My comment on JAA IR training not teaching people how to get about on the practical UK IFR scene is confirmed by every JAA IR holder I have met; perhaps a dozen. The JAA IR training is wholly geared up for would-be ATPs. However, all of those I have met knew the stuff from previous experience, typically using the IMCR, so they were not in the slightest bothered and they just regarded the "IR" as a highly desirable airways ticket. The poster starting this thread seems to be an exception in that he seems to have got himself an IR without ever having done any real IFR flying, which is very unusual for someone who isn't an aspiring ATP (perhaps he is).

I can also add, from personal experience, that the FAA IR does teach you what you need to know to fly IFR/airways. Unfortunately it teaches this relative to the American IFR system. In Europe, airways route planning can be a nightmare, and in the UK pilots do stuff which Americans would be horrified at (like DIY approaches) but then the Yanks don't need to do them because most places over there have an IAP.

My comments on the general standard of PPL training being crap are based on a pretty large sample size of instructors. Also, every time I fly I see or hear somebody whose instructor should be spoken to.

I think a lot depends on the pilot's motivation. Probably the majority of punters just want to learn to fly for the fun of it, and post-PPL there is very little motivation. It's also difficult to rent reasonable quality planes and even when you can you cannot take it away for a holiday etc.

Those with firmer ambitions and suitable budgets become owners or part-owners and they have a strong incentive to push themselves beyond the training they receive. They do real long trips, navigate with better methods, and take extra time to learn the more advanced stuff. This applies to both the PPL and the IMCR level; an IMCR holder without proper access to something decent is going to chuck it in pretty soon too.

Unfortunately only a tiny minority of punters are in the above category, so the training business doesn't have to produce competent pilots. If they did, the PPL would be 100hrs min and few would bother. So I can comment but I can't offer a solution. If every punter turning up with a PPL came along in a modern spaceship and wanted an instructor who will teach him how to get about the UK and Europe, there would be mayhem.

[justinmg]

justinmg
Referring to Schedule 5, ILS (category G in the table) is required when
(c) when making an approach to landing at an aerodrome notified for the purpose of this sub-paragraph
I don't disagree with you at this point (though your view is suprising since a lot of people have looked at this before) but where can one find a list of aerodromes notified for the purpose of the table in Schedule 5?

Agree absolutely. I rang Humberside and Doncaster (SATCOs), and they were not sure but thought that they were included. I asked the CAA but they did not understand the question. Might try again.

[Dude~]

Thanks Flyingforfun, an interesting reply.

Rustle said:
The poster starting this thread seems to be an exception in that he seems to have got himself an IR without ever having done any real IFR flying

Too true Rustle, looking back at my logbook reveals an astonishing 10, yes juts ten IFR flights before taking and passing my multi engine IR. There were a few flights just doing approaches and the rest was in a sim. But I basically have no experience of real IFR flying, and even less of planning routes since it was all laid out on a plate (excuse the pun). I know several people who did their IRs at other schools and are in the same position as me.

Frankly I am in awe of people who can jump in a plane and fly long distance IFR 'off the cuff'.

While I have little sympathy for an fATPL or IR holder and/or flying instructor who doesn't know the "rules" about, or procedures for, descending through cloud

Its not that I don't know the rules, its that I was not tested or trained and have never had to descend through cloud in uncontrolled airspace. The only time I have descended through cloud has been on ILS and NDB approaches at familiar training airports with a zillion hours instuctor or examiner by my side.

I'm not looking for sympathy, I'm looking for advice, and I think quoting my profile shouldn't have any bearing on this. Just because I instruct doesn't mean I have to be a super proficient walking-IFR-rule-book-pilot. Bear in mind, I have only done 11 IFR flights the last of which was nearly a year ago.

[IO540]

Dude

It was actually me who wrote the first quote you attribute to rustle :O

The best way, perhaps the only way I can think of, of learning how to fly private-GA either in

a) airways around Europe, or

b) IFR around the UK (IMC Rating sort of thing)

is to fly around with someone who knows how to do it. And the two styles are significantly different.

I know of a number of serious-budget people who went to the USA, came back with an FAA PPL/IR, bought a brand new top-end IFR piston single, and "rented" somebody like that to fly with them to far away sunny places.

[3FallinFlyer]

Isn't IFR flying in controlled airspace just about filing a sensible route at a sensible level, picking up a clearance then either fly the route as filed if cleared or following headings and altitudes as assigned by ATC. In uncontrolled / class G you plan a sensible route and altitude/level and try and get whatever radar service you can along the route.

Its not really rocket science! I think the art is more pre-flight / groundbased in making the right go/no go descision based on forecasts, alternates and available outs with sensible fuel reserves for the conditions!

[DFC]

To look at the equipment requirements first.

There is a big difference between a requirement for certain certified and serviceable equipment to fly in certain airspace and a requirement to have certain certified serviceable equipment in order to complete a procedure that relies on that equipment.

For example and authority may require that all aircraft operating in certain airspace classes must have 75Mhz Marker beacon equipment. That does not mean that a) without a marker beacon receiver it is OK to fly in airspace of that class because there are no markers in that airspace. or b) that there will be any requirement to use the marker beacon equipment in certain airspace of that class.

That is simply that authority saying what equipment is required before flying in that airspace class.

In general in Class G, no equipment is required. However, if you decide to fly IFR in IMC with no serviceable certified nav equipment and either infringe airspace or have a CFIT or near CFIT accident, or get lost and run out of fuel then it probably goes without saying that the operation was reckless.

As for flying an ILS with non-FM immune equipment.

All ILS equipment is unserviceable unless is meets the requirements of Annex 10. Meaning that unless the equipment is FM immune then it can not be relied upon to fly an ILS.

Similarly information provided by a non-FM immune VOR receiver can not be relied upon because according to Annex 10 it is unserviceable.

NDB and DME equipment are not affected by the FM issue.

Can you rely on a non-FM immune VOR? - NO.

Why, because it is legally U/S.

Can you rely on a non-FM immune ILS? - NO

Why, because it is legally U/S.

There is nothing wrong with using a non-FM immune ILS or VOR in a situation where the actual position of the aircraft can be confirmed by other means eg visual. eg when training and the aircraft is in VMC but the student is behind screens.

When talking about non-FM immune VOR and ILS systems everyone seems to think along the lines of so what, the errors are mostly theoretical and as I am only using it enroute well above obstacles there will not be a problem.- Wrong!

VOR tracking is often used as the basis of procedural ATC separation. Using non-FM immune equipment could cause a loss of separation........which would be reckless would it not?

I am sure that no one here would try to fly an ILS with a U/S ILS system anywhere. For non-FM immune read U/S for IFR IMC purposes.

--------------

As for DIY approach procedures.

Yes indeed, the 1000ft within 5nm of the aircraft requirement does not apply when approaching to land. After all at touchdown the separation is 0!. Furthermore, when completing a published approach procedure, the obstacle clearance will be at times less than 1000ftand the area taken into account far smaller than 5nm from the aircraft.

So yes indeed there is nothing stopping someone at the moment from constructing a home made procedure. If that procedure does not comply with the requirements of DOC8168 then it is very easy to say reckless operation when something goes wrong.

There is one other fly in the ointment..........the navaid used must have been approved for use as an approach aid. One can not use an enroute VOR/DME as an approach aid. Such use as an approach aid requires a survey and a calibration flight..........all very expensive.

Thus the CAA are indeed quite happy for a person to construct a homemade procedure and do the obstacle survey, non-visual aid survey, flight checking by an approved checker, design of the procedure accordng to DOC8168 by a qualified procedure designer etc etc..........all for personal use to show that the operation is not reckless endangerment! :ok:

Otherwise, you could simply have a rule that you will be visual at the enroute MSA. As I am sure you will know that system has other benifits relating to the requirements to have alternates for IFR IMC flights.

Regards,

DFC

[JonWhitehouse]

I've just started IMC training, and one of the first things that was re-iterated from night rating days was that if (in Class G or in the Procedure) you're in IMC, you do not decend below your MSA or MDA, no matter how well you know your position.There aren't any rules regarding descent through cloud as such in Class G, so the normal cross country nav theory applies.
Regards
JonW

[IO540]

DFC

As is often the case, you mix up real stuff with your imagination, making it all sound very authoritative. I just hope that you are not an instructor! I have known a number like that; they make up stuff as they go along, all very convincing.

In general in Class G, no equipment is required. However, if you decide to fly IFR in IMC with no serviceable certified nav equipment and either infringe airspace or have a CFIT or near CFIT accident, or get lost and run out of fuel then it probably goes without saying that the operation was reckless.

The above is an example.

In any discussion of what is legal, one must totally separate what is legal, and what is sensible. Otherwise, the discussion descends into something totally pointless.

If you want an example of "reckless" look no further than the standard practice in the flight training industry where people go off flying having checked their fuel on board purely by reference to a piece of paper back at the school.

Can you rely on a non-FM immune VOR? - NO.
Why, because it is legally U/S.

Then, close down all flying schools. They train with non-FM VORs all the time :O Reference please for the words "legally U/S".

One can not use an enroute VOR/DME as an approach aid

Reference please, applicable to private flight.

JonWhitehouse

Very true about not going below the MSA but you have to land eventually. Obviously one would rather land at a proper airport with an ILS or whatever, but the point is that it is legal to fly a DIY instrument approach.

It goes without saying that one must do it very carefully but that is a whole different point.

One day, probably after a lot of the CAA have retired on their generous civil service index linked pensions, we might get GPS approaches into airfields that currently have no approach at all (and have no ATC which is a requirement for any published approach at present). Then, these discussions will be as moot as they are in the USA right now.

[DFC]

IO540,

To put it in simple words;

A non-FM immune ILS or VOR system is U/S. Put another way, it no longer meets the required standard for it to be used as intended.

It is not sensible or legal to use U/S equipment as a sole source of navigation information on an IFR flight.

What you say about the fuel issue is totally true and an unnecessary shoddy practice in this age.

Then, close down all flying schools. They train with non-FM VORs all the time Reference please for the words "legally U/S".

No. I said that there is nothing wrong with this provded that another appropriate way to confirm the position of the aircraft is available. You will find that most of those schools will do the IMC training in VMC and in visual contact with the surface.

You could very rightly say that charging someone a sum of money to do IMC radio navigation training with U/S equipment which legally can not be used as intended is not providing value for money.

Filters are relatively cheap and are a simple mod. They should have been fitted long before now. Perhaps EASA will replace the CAA bumbling with a simple sticker - U/S due Non-FM immune.

Please feel free to try and convince us that relying on U/S equipment is sensible. :)

Regards,

DFC

[JonWhitehouse]

Is there any relevence to the use of FM-immune equipment in class G airspace? the question put was simply asking if it was a good idea to descend below MSA in Class G whilst IMC. The answer is no! Not even if you think you know where you are. the MSA is there for a reason.
IO540, as you say, landing is a necessary occurance! it is not particularly relevent to the question, but a logical point to introduce nontheless. Each landing procedure has some kind of minimum imposed, even if it is a DIY, and each time, it is there for a reason. descending below it when IMC is asking for trouble.

[DFC]

Is there any relevence to the use of FM-immune equipment in class G airspace?

Yes.

If the MSA has to be calculated on a ceratin distance from the aircraft position, the ability to determine that position and how accurate the information obtained from various systems has an effect on the MSA calculated.

eg. DR position......one could have to use 1000ft above all obstacles within some 60 to 120nm from the aircraft depending on how long since last fix.

Using serviceable operating VOR equipment, I believe that the error is +/- 5deg. Thus at 60nm one will be +/- 5nm from the indicated radial.

ADF not as accurate, VDF, they tell you the accuracy with the bearing.

Thus what system is used and the servicability of that system as a great bearing on the MSA. A lower MSA reduces the probability of a diversion.

Regards,

DFC

[pipertommy]

Think you will find i asked the question about FM Immune,John
Simply because this is not covered in depth during the IMC course!!
Anyway it`s good to talk:ok:

[Fuji Abound]

Of course you might be able to descend over the sea.

Fortunately not too many sailing boat masts or bridges over 200 feet. :)

What height would you feel comfortable descending to if you were over the sea?

[pipertommy]

Guess that would be the old 500ft rule?Atleast your legal when you come face to face with Captain birdseye.Hope its not an a/c carrier:rolleyes:

[Fuji Abound]

The new QE2 seems to be "advertised" as the world's tallest at a little over 240 feet - slightly off topic I know.

[Charley]

Interesting to note the differing opinions on this. My own opinion is that one is legally required to use FM-immune ILS equipment when flying an ILS both inside or outside CAS in the UK.

The basis for my opinion is as follows:

This ORS (http://www.caa.co.uk/docs/33/ORS4_580.pdf) states that, and I quote;


1) The Civil Aviation Authority, in exercise of its powers under Article 20(3) of the Air Navigation Order 2005 ("the Order") hereby directs that:

a) where an aircraft is flying in the United Kingdom in circumstances in which it is required under Schedule 5 of the Order to be provided with specified radio
navigation equipment all such required equipment shall comply with the FM immunity requirements of Annex 10 to the Chicago Convention Volume I (Fifth Edition - July 1996 Amendment 80) and Volume III (First Edition - July 1995 Amendment 80);


Under the explanatory notes that accompany the ORS, it expands thus;


For non-public transport flights under instrument flight rules (IFR) in controlled airspace in the UK, the legal requirements include one VOR receiver (which must be FM immune). To conduct an ILS approach inside or outside controlled airspace one (FM immune) ILS receiver is required.

Now we're at the same point as has already been discussed. Is this guidance material with no legal basis, as suggested, or is this a legally binding requirement?

In my mind it comes down to Article 20(3) of the Air Navigation Order, which is a Statutory Instrument and therefore legally binding. This also explains my choice of emphasis in the first quote.

Artice 20(3) states;


(3) In any particular case the CAA may direct that an aircraft registered in the United Kingdom shall carry such additional or special radio communication or radio navigation equipment as it may specify for the purpose of facilitating the navigation of the aircraft, the carrying out of search and rescue operations or the survival of the persons carried in the aircraft.


It's a matter of personal interpretation but for me at least, this is the trump card. This statements suggests -- to me at least -- that the CAA have carte blanche to impose any additional requirements on our navigation equipment. In this instance, they specify that to fly an ILS inside or outside CAS requires FM Immune kit if performed under IFR and Article 20(3) of the ANO makes such a declaration legally binding.

This is my own interpretation, at any rate.

In summary, the rule I use for myself is that to fly an ILS anywhere in the UK under IFR requires an FM immune kit. If it ain't FM Immune, it ain't legal... unless flown under VFR, of course. That said, we are all free to draw our own conclusions.

[IO540]

Looks good.

Has anybody written to the CAA? My experience is that if you send them a precise question, and set out the context so there is no possibility of mis-interpretation, they reply usefully.

A bit of a bombshell, for IMC Rated pilots renting planes from flying schools................... !!

Would also upset not a few syndicates which contains members with the IMCR, but also some VFR-only members. Such syndicates (probably the majority of piston CofA syndicates) tend to gradually fall apart over stuff like this. One I know of, a nice plane too, ended up turning over most of its membership over a nonworking ADF.

[Spitoon]

DFC saysAs for DIY approach procedures.
Yes indeed, the 1000ft within 5nm of the aircraft requirement does not apply when approaching to land. After all at touchdown the separation is 0!. Furthermore, when completing a published approach procedure, the obstacle clearance will be at times less than 1000ftand the area taken into account far smaller than 5nm from the aircraft.The leg - Rule 5 - actually says "Exemptions from the low flying prohibitions
(a) Landing and taking off
(i) Any aircraft shall be exempt from any low flying prohibition in so far as it is flying in accordance with normal aviation practice for the purpose of taking off from, landing at or practising approaches to landing at or checking navigational aids or procedures at a Government or licensed aerodrome.
(ii) Any aircraft shall be exempt from the 500 feet rule when landing and taking off in accordance with normal aviation practice.
I leave it to you to decide whether what DFC says is normal aviation practice.
The straight answer to part of the original question is that for a non-commercial flight outside CAS it is not contrary to any part of the ANO to make an instrument let-down that the pilot creates. The CAA obviously doesn't like this - there are a couple of proposals that are being/have been consulted on here (http://www.caa.co.uk/default.aspx?categoryid=43&pagetype=90&pageid=1587) and here (http://www.caa.co.uk/default.aspx?categoryid=7&pagetype=90&pageid=6216) that make this clear. Although one of them is now quite old and doesn't seem to have led to anything I don't think it has gone away because I spoke with someone from CAA a week or two back and they said it is still under consideration.

As for is letting down in the circumstances that Dude~ first describes, speaking as a controller I would say that even if you stay legal it is unwise! There's a reason that proper IAPs need all that effort.

DFC also says There is one other fly in the ointment..........the navaid used must have been approved for use as an approach aid. One can not use an enroute VOR/DME as an approach aid. Not true at the moment. Lots of navaids used to have "Not to be used for instument approach" in their details in the AIP but its not there any more. If it was Rule 40 would cause you a problem because it says "the commander of an aircraft shall not make use of any radio navigation aid without complying with such restrictions and appropriate procedures as may be notified in relation to that aid unless authorised by an air traffic control unit."

[Fuji Abound]

"A bit of a bombshell, for IMC Rated pilots renting planes from flying schools................... !! "

Why - because so many are not FM immune?

[IO540]

Why - because so many are not FM immune?

Yes, most self fly hire spamcans aren't.

This is based on a sample size of 10-20 that I've been in. I don't think a single SFH plane I've been in was FM immune. In fact perhaps half of them had unserviceable instruments. I did my IMC Rating in several planes; one had a working VOR, another had a working DME (no ADF), another had a working ADF (and a duff but apparently working DME). None had all three working.

So I do quite enjoy ownership now :O

[DFC]

Spitoon,

At no time have I referred to the low flying rules. The 1000ft above everything within 5nm of the aircraft is an Instrument Flight Rule and nothing to do with rule 5.

You will find in the AIP that Enroute navigation aids are listed in the Enroute section. Approach nav aids are listed in the appropriate aerodrome section. Where for example a VOR is used as both enroute and aerodrome approach aid, this is noted in the enroute and aerodrome sections.

Ask about the regular flight checking of VOR and VOR/DME approach procedures. A very costly exercise for places that have them eg Cranfield. Do you think that such a requirement would be in place if it was not necessary because the average PPL with no knowledge of DOC8168 or the flight checking manual can construct an appropriate procedure and self check the signal quality available from the chosen navigation aid all while flying a typical club spam can in IMC..........give us a break!

Can those who can do all that please rush their CV to FR Aviation's Teeside office and get working on the checker asap. Doing all that with no backup must say that they are far more skilled than any checker pilot I know of. :D

Regards,

DFC

[pipertommy]

So basically i cant use my IMC!Sad,i enjoy doing some IF getting up into the blue sky when its a grey day below!So the outcome is i can`t use non-FM immune a/c in IMC.But why is this not stressed on the IMC course if it`s so important?If i didnt go on this site i would be none the wiser like loads of pilots out there!!!!!

[IO540]

Schools don't tell you lots of things, in the interest of revenue.

The #1 thing they don't tell you is just how restrictive self fly hire is. OK, you have a brain and should realise it, but the reality is that most students don't grasp it until they try to take the plane away for a few days.

The #2 thing they don't tell you is that most of the junk most of them have available for hire is unsuitable (and often illegal) for IFR flight.

As regards not being able to use non-FM immune kit in Class G, the situation is not clear cut.

You also still have the following navaids which are not affected by FM immunity requirements, and none of them is prohibited or in any way restricted from being used, at any stage of a flight:

ADF
DME
GPS

The crucial thing is that the regs specify what must be carried, not what may or may not be used.

Take a guess which of the above devices is the one chosen (as the main one, with the others used as a backup) by just about all pilots that fly seriously.

;)

[pipertommy]

Ah,i do have an ADF which i could supplement with my GPS for distance/moving map all may not be lost after all!

[chevvron]

You also have to carry a map, but many people with GPS don't bother.

[pipertommy]

As ever Chevvron:ok: Thanks

[Fuji Abound]

A reflection that most IMC / IR training is illegal or in VMC so a waste of time.

[IO540]

You also have to carry a map, but many people with GPS don't bother.

I have never met somebody that stupid. Perhaps they exist somewhere...

Of course if a pilot gets airborne without charts and without GPS that is less bad, yes??

pipertommy

You are either a true beginner, or you are a great windup :O Nobody on EARTH is going to use an ADF (which suffers from errors up to 30 degrees at the best of times) backed up by a GPS (which can position you within a few yards anywhere on earth). The other way round, yes.

A reflection that most IMC / IR training is illegal or in VMC so a waste of time.

I am trying to work that one out :O

[Fuji Abound]

Illegal if done on aircraft not correctly equipted and in IMC, legal if in VMC with the student in fogles, but then perhaps a waste of time :) .

I thought the FAA had just agreed to the "mapless" cockpit if the aircraft is properly equipted?

[DFC]

Fuji,

You will find that all aircraft used for the IR training have to be approved by the CAA. They have to be serviceable for IFR flights in Class A airspace.

------

Io540,

Actually unless the GPS is an approved panel mounted one with an up-to-date database, the ADF backed up by GPS is the only "legal" option. Never mind the CAA - just read the GPS manufacturers own statement regarding that one.

Of course the NDB must be within coverage which is very limited in most cases.

I laugh when people who can't track an NDB slag it off. ;)

-----------

Pipertommy,

You can still use the IMC rating. You just can not rely on the VOR or ILS indications as the sole basis for your departure, enroute navigation or approach. Of course you can not rely on an unapproved GPS as a [/B]sole[/B] means of navigation either.

---------

If anyone finds that when within the DOC with a calibrated serviceable ADF and a competent pilot that an NDB is providing information that is as inaccurate as IO540 describes i.e. well beyond the limits allowed then they should report the matter via an MOR. Silence in such a situation could cause another pilot to have an accident. Would not like to have that on my concience.

Regards,

DFC

[Fuji Abound]

DFC - yes, you are correct for IR training.

[IO540]

I thought the FAA had just agreed to the "mapless" cockpit if the aircraft is properly equipted?

Not heard of this.

But there is a common misconception in this area: a lot of people go around saying one has to carry the printed chart. This is not specified by any country I am aware of, not even the UK ANO. The wording tends to be like "all required navigation data" but even if the word "chart" is included it doesn't say it has to be the printed chart.

Obviously if one is displaying chart data on some electronic device then there are backup issues, battery life if applicable, etc, and if I was doing this personally I would want two different display devices with at least one of them having a battery life exceeding the fuel endurance, but that's obviously a different matter. Legally, printed charts do not need to be carried.

In the UK the whole GA scene is anally retentive in the extreme but in the much more affluent and modern USA the population of owner pilots flying spaceships equipped with nearly A4-sized displays running Jeppview or other chart products is quite significant. Just look at the aviation magazines they read over there, compared to the UK rags. So there is more discussion over there of flying without any paper, and it certainly isn't illegal.

Illegal if done on aircraft not correctly equipted and in IMC, legal if in VMC with the student in fogles, but then perhaps a waste of time

Well I suppose if you say that IMC training with foggles is nothing like as good as IMC training in real IMC, I would agree.

As regards IR training, this is done by only a few schools in the UK, all of them geared up for ATPL training. They keep reasonably decent planes, not least because the CAA-employed IR examiner wants to do the checkride in Class A. In the UK it isn't even possible to do any flight under ATC direction without going into Class A. This is a world apart from IMCR training.

The funny thing is that a properly trained IMCR holder is perfectly capable of flying IFR in Class A... the only real difference from Class D is that you have to stuff the flight plan through the CFMU website, then talk to London Control, and there isn't much to do en route.

If anyone finds that when within the DOC with a calibrated serviceable ADF and a competent pilot that an NDB is providing information that is as inaccurate as IO540 describes i.e. well beyond the limits allowed then they should report the matter via an MOR. Silence in such a situation could cause another pilot to have an accident. Would not like to have that on my concience.

:ugh: :ugh: :ugh: :D :D :D

I will let you in on a closely guarded secret, DFC. Fly to the start of the EGKA 20 inbound track, say 6.5D out, fly a precise inbound track (using a GPS of course :O ) and plot the RMI reading as you go in.

The good news is that as you track the NDB in, 25-30 degrees off the "real" track, you won't get embedded in the hill provided you stick to the DME stepdowns. That, no doubt, is why the DME is mandatory. All that happens is that if flying it to something like the minima, you may not be able to land because you will be too far off the inbound track.

;)

[pipertommy]

Well if i used GPS then ADF that would be illegal?The GPS i use is not approved for IFR use ONLY VFR as it states on my unit on start up.And yes i am not very experienced in IMC/IFR flying thats why i`m on here,so thanks for stating that:D ,remember the days when you first started and the questions you had? All i want is the knowledge to use my IMC in a legal way but most of all in a safe manner with the limited kit to hand.I feel this was not fully covered in the IMC course:ok:

[tmmorris]

You can still use the IMC rating. You just can not rely on the VOR or ILS indications as the sole basis for your departure, enroute navigation or approach. Of course you can not rely on an unapproved GPS as a [/b]sole[/b] means of navigation either.

What you are forgetting is that in class G you can rely on dead reckoning as your primary means of navigation, with GPS as a backup.

Can't you?

Tim

[IO540]

pipertommy

I don't think any UK legislation states what equipment you must use. It lists what you must carry.

Everything else is conjecture and perhaps wishful thinking.

Sometimes wholly plausible conjecture (like you are supposed to fly an ILS with an ILS receiver and not by dead reckoning) but at other times it is certain nonsense (like not allowed to use a certain type of GPS when IFR in Class G).

An "IFR GPS" is a specific category of GPS which you need to have if flying on BRNAV routes, above FL095 in Europe. In the UK these are all in Class A anyway.

As tmorris rightly says, you can legally use dead reckoning in IMC. That is about the least accurate and least safe way to do anything, so anything will be better.

You can use any GPS for primary navigation ("primary" is another term not defined in legislation but widely touted by amateur aviation lawyers) anytime.

So I think you worry too much. Get yourself the very best moving map GPS you can afford, make sure it comes with an external antenna which you can clip to a window (for a decent view of the sky) and enjoy yourself!

Around the UK, one can do most flying in Class G.

[pipertommy]

Cheers!Thanks for the advice.Happy flying:ok:

[Spitoon]

I don't want to turn this into a spat but.....At no time have I referred to the low flying rules. The 1000ft above everything within 5nm of the aircraft is an Instrument Flight Rule and nothing to do with rule 5.I'm afraid that rule 29 - the Minimum height rule and, yes, one of the IFRs - does have something to do with rule 5. Rule 29 says you always have to comply with rule 5 too. It also says that you do not have to maintain 1000ft obstacle/terrain clearance "if it is necessary for the aircraft to do so in order to take off or land". We each may have an interpretation of what would be neccessary - I guess the only person who really gets to make that judgement is a judge in court - but in my view descending, effectively en-route, in order to make a visual approach is not necessary.
You will find in the AIP that Enroute navigation aids are listed in the Enroute section. Approach nav aids are listed in the appropriate aerodrome section. Where for example a VOR is used as both enroute and aerodrome approach aid, this is noted in the enroute and aerodrome sections.Again it's an interpretation of words but rule 40 refers to "restrictions and appropriate procedures" and unless the AIP explicitly says "thou shalt NOT" it is not a restriction. And as far as I know at the moment there is no such explicit limitation on the use of navaids.
For what it is worth the AIP does say (page AD 1-1-18 if anyone cares)Aerodromes without published Instrument Approach Procedures
For an aircraft landing at an aerodrome without an instrument approach procedure either:
a A descent should be made in VMC until in visual contact with the ground, then fly to the destination;
b An IAP at a nearby aerodrome should be flown and proceed as in (a); or
c If neither (a) nor (b) is possible, first obtain an accurate fix and then descend not lower than 1000 ft above the highest obstacle within 5 nm (8 km) of the aircraft. If visual contact (as at (a) above) has not been established at this height, the aircraft should divert to a suitable alternate with a published instrument approach procedure.

Strangely enough, I am fairly familiar with flight checking requirements and I agree there's a good reason for all of the checks....but that doesn't mean there isn't a loophole in the legislative framework at present.

[IO540]

but in my view descending, effectively en-route, in order to make a visual approach is not necessary.

I can't see this. A descent to land is clearly necessary.

If you have legislation banning an IFR approach unless it's a published one (like the FAA has) that's something else. But until you have, what else is one supposed to do in order to land?

[PPRuNe Radar]

I0540

An "IFR GPS" is a specific category of GPS which you need to have if flying on BRNAV routes, above FL095 in Europe. In the UK these are all in Class A anyway.

Not all, have a look at airspace North, and Northwest, of the Manchester area :ok:

[DFC]

PPRuNe Radar

And in the Cardiff area!.

-------

IO540, explain to me exactly how you set up your GPS when flying the Shoreham NDBDME procedure you talk of. WGS84 coordinates? tracking to the NDB? on the final approach QDM or tracking to EGKA on the runway QDM?

Seems to me like your ADF tracking could be out. Remember that approach only gets you down to circling altitude so having to manoeuvre all round the circuit should not be a problem! The 02 approach gives you lower circling minima even without DME!

Regards,

DFC

[IO540]

DFC, I give up. A 30deg NDB error is 1-2 miles off track.

Anyway, such errors, caused by terrain contours and/or coastal effects, are common knowledge to pilots who fly these approaches for real.

[Fuji Abound]

IO540 - oh no dont do that, dont take the bait. I have already got that sinking feeling. :)

Here is the question though. EGKA - you have to land, some "unexpected" emergency, the base is 400 feet - below minima and for same unexplained reason you can use either the GPS or NDB / DME but not both. Which one would you prefer?

Dont know if you read Flying - there was a good article on the paperless cockpit and the circumstances in which the writer held the view the FAA would be happy if "you left the paper maps at home". I cant remember if it was just his view or he had got an official pronouncement from the FAA. I wil try and dig out the article.

[homeguard]

I've read all the posts carefully and wonder at why so many are so keen to venture into the legal world of so many things when i doubt whether the lawyers amongst us would be willing to define an absolute in all of this at all.
Class 1 VHF navigation radio is tested for many standards, FM immune protection being just one.
Class 3 equipment is usable at all times unless it is stipulated that the use of such equipment is MANDATORY!
Currently it is only within certain controlled airspace that, for a particular purpose, the use of the equipment is stipulated to be mandatory.
It is not stipulated to be neccesary anywhere outside of controlled airspace. I have noted a number of personal interpretations of the JARs. There has been some qualified advice that the use of Class 3 equipment outside of controlled airspace (class G) when undertaking an ILS in IMC is illegal. The arguement here is that because you cannot do an ILS without using the ILS receiver equipment then it must be mandatory equipment. That is not neccessarily the correct us of 'mandatory'. The word mandatory leads to the action that must be followed following the issue of a mandate. No such mandate has been issued to date with regard to the use of class 3 equipment outside contolled airspace.
Class 3 equipment must as with Class 1 be tested and signed off as being within limits and FIT for its purpose and therefore must be complient with the JARs. Or, do we have a double standard!

[IO540]

Fuji

In an OVC004 I would divert to some place with an ILS and a low enough DH e.g. Bournemouth (from memory). In an emergency (below minima for even an ILS) I would pick any ILS with no high terrain nearby, which is most ILS runways in the south.

But if I had to get into Shoreham under OVC004 (can't see why in reality) I would fly the existing 20 or 02 NDB/DME procedure, as depicted in my GPS database, using the GPS. Much more accurate.

Regards paper charts, I don't think there could be a serious debate as to the legality of flying without them. It's always been legal (Part 91, or UK private flight context). One can debate the wisdom indefinitely, like most things in this business :O IMHO getting the FAA to say it is OK to fly without paper charts (if you carry them in some electronic form) is a bit like getting the CAA to say GPS isn't illegal.

I do get Flying, a good mag, but don't recall reading about this.

Homeguard

I too think that there has to be more to this than "can't fly an ILS in IMC if not FM immune". So many flying school planes, and most rental planes, are not FM immune and the CAA would have done a few people by now. They've had a number of years to get around to it. I know it's said that IMC Rating training can be done in VMC but all the smarter instructors do at least some in IMC - as indeed they should.

[englishal]

A non-FM immune ILS or VOR system is U/S. Put another way, it no longer meets the required standard for it to be used as intended.It is not sensible or legal to use U/S equipment as a sole source of navigation information on an IFR flight.
Out of interest, is it only the UK / Europe which insists on FM Immunity? Does this mean that my 00's of approaches done in N registered aeroplanes in the US have been dangerous?

The FAA say that you no longer need to carry paper charts in a suitably equipped aeroplane (G1000 etc....). I did have a reference but can't find it at the moment, so don't ask me for it :)

[Fuji Abound]

"In an OVC004 I would divert to some place with an ILS" of course.

That was why it was hypothetical. My point was that I as you would far rather fly the gps than the NDB / DME. Simply a follow up to the earlier point.

"The FAA say that you no longer need to carry paper charts in a suitably equipped aeroplane (G1000 etc....). I did have a reference but can't find it at the moment, so don't ask me for it"

Yes that was what I thought - they had specifically sanctioned it.

"Can you rely on a non-FM immune VOR? - NO.

Why, because it is legally U/S."

Reference please. For flights under IFR the requirement is one FM immune VOR WITHIN controlled airspace. Where does the legislation specify an FM immune VOR is required OUTSIDE controlled airspace or for that matter where does the legislation state in these circumstances the receiver is u/s?

I would also be interested in the specific reference to the G/S FM immune requirement for approaches outside controlled airspace.

I gather the CAA have not yet completed their report on the FM interference risk, however whilst theoretically it exists I dont think there has yet been a single reported case of FM interference.

[Charley]

Hi Fuji

I would also be interested in the specific reference to the G/S FM immune requirement for approaches outside controlled airspace.

I'm not sure what you mean by this; if you want to see a reference to ILS approaches outside controlled airspace, I have given one back on page 2 although it's up to each of us to decide on its relevance.

If you specifically mean a reference to the FM Immunity (or lack thereof) of glideslope receivers, then I suspect you'll never find one. Glideslopes work on UHF and therefore are not susceptible to FM interference. It is the VHF localiser which is, if only in theory.


Hello Homeguard

It's interesting that you mention the LA Class 1 and Class 3 approvals. I spoke with an engineer I know last year and had been led to believe, perhaps wrongly, that these classifications of kit can be somewhat bogus under the JAR/EASA schema. Perhaps I had misunderstood what he was saying.

This page (http://www.caa.co.uk/application.aspx?categoryid=33&pagetype=65&applicationid=11&mode=detail&id=57) and this one (http://www.caa.co.uk/default.aspx?categoryid=220&pagetype=90&pageid=672) both hint that these definitions might not be entirely relevant to aircraft issued with CofA's by EASA, for example. Specifically, from the former page;

With effect from 28 September 2003, for the purposes of new certifications [of avionics equipment], BCAR Section R is applicable as a requirement only to those aircraft which are excluded from the coverage of Regulation (EC) No. 1592/2002. For a definition of these aircraft, see CAP 455 Airworthiness Notice No. 1.

Needless to say that most club/school spam-cans are indeed covered by EC1592/2002. Permit aircraft and some older rarities are not.

From the second source;

Volumes 1 and 2 of CAP 208 - Aircraft Radio Equipment, are now considered to be obsolescent in that these volumes no longer represent current minimum performance requirements or complete and definitive records of aircraft radio equipment approved by CAA. Volume 1 of CAP 208, listed certain ICAO standards (for example, ICAO annex 10 requires VHF communication transceivers to have a frequency stability operation of plus or minus 0.003%), whcih have been superseded by later requirements.

If the CAA themselves are suggesting that their own requirements have been 'superceded', is it not possible that this may have occurred in the ORS that states avionics equipment must be FM Immune (i.e. equivalent to LA Class I) in order to fly an ILS approach inside or outside controlled airspace?

I ask this as a genuine question. If the Class I/Class III distinctions are still valid and meaningful for all UK registered aircraft then fair play. But if they are only meaningful for those aicraft still maintained under national airworthiness rules (as opposed to JAA/EASA) then it muddies the water a bit.

All a bit of a mess really.

[DFC]

ICAO Annex 10 is the reference and it applies worldwide.

The FAA may not have such a requirement at the moment within the CONUS because they may have restricted the FM spectrum to avoid the problem. However, FAA aircraft operating outside the US are required to conform to the requirments.

The GS being UHF is not affected.

What are you saying Fuji? using the GS without a LOC? :rolleyes:

Everyone is still getting confused by the requirements to carry certain equipment to operate within certain airspace (it has to be fitted, and serviceable. It does not have to be turned on unless being used!) and a totally separate requirement to have a serviceable VOR or ILS equipment in order to use VOR or ILS information.

Ask anyone if they will try to fly an ILS with equipment that is placared as "U/S" or even "unreliable". I can guarantee that no sensible pilot will use such equipment in IMC.

Ask an avionics engineer to certify a non-FM immune instalation as fit for making ILS approaches and you will get a prompt no!

I feel it is only time before we have someone trying to fly using GS on nav 1 and the NDB to somewhere like Blackpool. :( Accidents waiting to happen is the term I believe.

Regards,

DFC

PS: No explanation of the set-up you use for the GPS yet IO540?

"A 30deg NDB error is 1-2 miles off track" is bo:mad: ox

[Fuji Abound]

Charley - I share your views and should have read your earlier post properly. I would agree it is a requirment the G/S must be FM immune whether in or outside controlled airspace. I think I am corect that the VOR is only "required" to be FM immune within controlled airspace. Presumably, subject to the afore, there is no issue with the schools etc operating IFR outside controlled airspace and engaging on all forms of approach except an ILS.

[DFC]

Fuji,

To put it in very very very simple terms for you;

In ceratin classes of airspace your aircraft needs to be equipped with certain serviceable equipment.

In class G there is no requirment for the aircraft to have a serviceable VOR even when flying IFR in IMC.

That means that you can fly an aircraft with a VOR that has 60 to 80 degree errors perfectly happy in class G provided that you do not rely on the accuracy of the VOR to ensure separation from terrain, controlled airspace or other aircraft.

Do you now understand the difference between a requirement to have equipment fitted and the requirement for equipment to be serviceable before using it?

I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT".

It is a commonsense safety issue!

Regards,

DFC

PS: Reputable schools do not rely on non-FM immune equipment.

[Fuji Abound]

DFC

I wanted to clarrify Charley's interpretation which I guess you have done.

The position would seem to be you are not required to have an FM immune VOR outside controlled airspace to operate IFR.

My understanding is that the VOR has to be placarded "not FM immune". I know of many aircraft with this wording so I assume the avionics chaps know what they are doing. The placard does not say the equipment is unserviceable. In exactly the same way the comms boxes may not be FM immune, but in that case there is a specific exemption permitting their use in controlled airspace. In my opinion your comments are therefore misleading becasue you are legally entitled to use the VOR other wise the legislation would be worded in the way it is for the G/S. An all together different debate is whether you should rely on a non FM immune VOR as the sole means of navigation. I guess their are many aircraft with the G/S FM immune but not the second nav box for example. Equally there are those perhaps with neither FM immune but with a GPS. Perhaps again there are those that understand how to fly a DME arc.

[englishal]

That means that you can fly an aircraft with a VOR that has 60 to 80 degree errors perfectly happy in class G provided that you do not rely on the accuracy of the VOR to ensure separation from terrain, controlled airspace or other aircraft.

Do you now understand the difference between a requirement to have equipment fitted and the requirement for equipment to be serviceable before using it?

I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT".
Now you are just being dramatic.

So we may as well rip out all our Nav gear and bung it in the bin according to you.
:ugh:

[Fuji Abound]

I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT.

Well the CAA obviously think it is OK so far as the VOR is concerned. I guess they could have just as easily required FM immunity in class G for the VOR as they did for the G/S. The fact remains they did not. I wonder why?

[IO540]

ILS (LOC actually) frequencies are lower down the VHF scale, thus nearer to the FM broadcast band?

Still, nobody I have ever met has ever known of a case of actual interference. For all the grief and expense this has caused... how long has ILS and VOR been about, how long has the FM broadcast band been about? You would think that if there were any problems it would have been glaringly obvious by now. We are talking about 2-3 decades in which to demonstrate a problem.

[Fuji Abound]

"We are talking about 2-3 decades in which to demonstrate a problem."

Correct. 1979 was the year in which it was agreed the 105 to 106 Mhz part of the band could be used by commercial radio stations from which the "fear" derives of possible interference. As I stated previously I understand there has not been a single reported case of such interference but the theoretical possibility exists. I am not sure how many stations actually use this part of the spectrum anyway but this gives a flavour http://www.electricbluesclub.co.uk/uk_radio_stations.html

Interesting that the whole of the USAF AWACS fleet was operating "with defective brakes" (non FM immune) until 1999 under certificates of exemption and only then ceased to do so becasue the EU refused to issue any more certificates.

[DFC]

No. The agreement made was that from about 1997, the FM band would be expanded. The reason for giving away the protection was that it was expected that technology such as MLS would remove the requirement for ILS.

Unfortunately, technology did not go as expected and the solution was to require instalation of filters on current technology equipment.

------------
Englishal,

So we may as well rip out all our Nav gear and bung it in the bin according to you

No you could have a cheap easy to install filter fitted and then your equipment would be FM immune.

--------

Fuji/IO540,

Just because the CAA does not require certain equipment to be carried and be serviceable in Class G airspace it does not not not mean that they are saying it is OK to rely on equipment that does not meet the required standard.

The CAA does not set any standard for some required items in aircraft. Do you think that you could safely claim that the elastoplast stuffed into the seat pocket is the first aid kit.......or that the bottle you peed in was the fire extinguisher? :)

If the DME was labled as "unreliable" could you use it to complete an approach in IMC? NO. and that goes for FAA/CAA/JAA or any other authority. For not FM immune read unreliable. No mention of airspace there!

Of course ther will always be the idiots who fly with U/S equipment and rely on unreliable fuel gauges among other things.

Regards,

DFC

[Fuji Abound]

GASIL 1/2001 - "as a result of the 1979 world radio conference the decision was taken to allow FM broadcasters to use the 105 to 108 Mhz .. .."

http://www.wws.princeton.edu/ota/disk3/1982/8221/822104.PDF#search='world%20radio%20conference%201979'

I wonder why the CAA granted exemption certificates until 1999 - 20 years after FM broadcasters were permitted to use these bands? Were these certificates the work of idiots or did the CAA have reasonable grounds for their grant? What has changed since 1999? Why did the CAA not prohibit the use of non FM immune VORs? They were clearly capable of prohibiting the use of non FM immune loc.

I suspect the real reason is the CAA and other national organisations within Europe realised there was a very small but never the less real risk FM broadcasts could make the integrity of loc unsafe which in itself presented a serious safety hazard whether in controlled or uncontrolled air space for obvious reasons. Never the less they felt the risk sufficiently small to grant the exemptions that were given (or maybe they gave in to the political pressure) or maybe they realised that the USAF would not be relying solely on loc approaches. They also realised that outside controlled airspace given the widespread use of other means of cross checking position it remained "safe" to use non FM immune VORs.

I would be interested to know the effects of FM interference. What would be the indicative signs. Would a half competent pilot have ample warning that all was not well. Would he in any event be cross checking his VOR with GPS, NDBs, DME, radar, dead reckoning. I would have thought so. If tracking two VORs would both be effected at the same time - I would have thought not. I find it hard to imagine that a pilot would not see some warnigns signs that all was not well and have plenty of time to resolve the issue.

I am not advocating flying with non FM immune equipment. The fact remains that there are many aircraft without, including those used for IMC training. Are they operating illegally or irresponsibly? I am far from convinced they are.

[englishal]

No you could have a cheap easy to install filter fitted and then your equipment would be FM immune.
So where do I get one? If they are that cheap, then I might as well fit one so the aeroplane is IFR certified.....

If the DME was labled as "unreliable" could you use it to complete an approach in IMC? NO.
No, if the approach required DME. However more sensible rules would be to allow GPS in place of DME, as some administrations do.

The only time I have seen glideslope distortion was when a 767 taxyed across the threshold of a runway which I was approaching on the ILS. It was quite a marked distortion.

Anyway, all this is academic. In a few years we'll be able to buy one box of tricks (called a GPS) which will do for DME, position fixing, precision approaches and NPA's.........at least I hope so ;)

[DFC]

Fuji,

Perhaps I did not make myself clear.

The agreement in 1979 regarding the expansion of the FM band and the increase in radiated power did not have immediate effect. The expansion was planned to start in the late 1990s.

That is why between 1979 and the late 1990's there was no problem with non-FM immune equipment - the problem was not yet there.

The 20 year lead time was to allow technology that was to replace ILS etc to be developed. That technology did not happen for various reasons and we ended up in the position of not having suitable technology but having already promissed to give away the spectrum.

The solution was simply fitting filters to existing equipment.

You will find that technology developed in the 1990's is FM immune because the designers had to meet the requierd specs which included FM immunity.

Remember that radio stations are licensed. The authorities can base FM immunity requriements at any particular time on what FM stations are licensed and the conditions of those licenses.

------------

Englishal,

Ask your friendly avionics engineer for info.

A chat with the following company who have an approved filter will also help you;

http://www.chelton.co.uk/

Regards,

DFC

If people had paid attention to what was going on and simply put £1 per flight hour aside since 1979, the average spam can could have dual GNS430 or similar with the cost of instalation paid for and some money left for updates!

Ok so not many here remember back that far but the aircraft they fly do!

[IO540]

The filters are not cheap, about £1000 plus fitted. Very few owners fit them in reality, for various reasons.

[Fuji Abound]

So come on some one must have a view about how FM interference would manifest itself while tracking a VOR and whether the pilot would spot the problem and what he would do about it.

The aircraft I fly is FM immune, it also mode S all done before any of this became mandatory and all at substantial cost. I sometimes wonder why particularly when I often ask for verification of my mode S and have yet to find anyone able to do so - the usual comment is "we only wish we could".

If I rented an aircraft and found the VORs were placarded not FM immune and I had to fly IFR outside controlled airspace would I - I think I would :) .

[Longbow55]

Dude, here is my take on your question. I am nowhere near an expert, and will never say I am. But if I am flying along, and not on an IR flight plan, then I have to ask for a specific clearance (FAA IR Rated) to desend below the clouds, and no I cannot go below MSA(My view of going below MSA is not favorable). so what would I do. if the airport has an IAP then I would request the approach from present position or fly to an nearby airport that has an approach and shoot the approach to a missed with instructions or request to stay below the cloud layer toproceed to my destination. I now carry current plates for England. The plane I also fly doesn't have ADF so I am limited to ILS, LLZ and VOR approaches. It does have a very nice in panel IFR certified GPS.

This is my view, not necessarilly correct.

Always looking for new folks to fly with, so contact me if you want to go shoot some approaches at different airports.

[IO540]

Longbow55

You don't need ATC clearance to descend "below clouds", here or in the USA.

In the USA, FAR something.something appears to prohibit an instrument approach other than a published one. In the UK there is no such rule (yet).

But if you happen to be able to do a visual approach from some level which you can get an IFR clearance to fly at then obviously you can then land under VFR. You can call this a DIY instrument approach with a MSA of 1000ft AGL or more :O Or you can call it "cancelling IFR". Same thing.

In the UK this is a bit of a non event anyway because in Class G you won't normally be receiving a radar control service so you can fly under own navigation as you wish. The only case I know of of a RCS in G is a low level letdown which is basically a radar vectored descent over a surveyed bit of ground, down to 1000ft AGL, but even then you can ask to switch to own navigation at any time.

The question then becomes: how low will you go? Flying at the MSA (or your MOCA; I have the FAA IR too) gives you an IAP with a DH of 1000ft - not unreasonable over open flat country. Of course Americans have never discovered this ;)

It all gets much more tricky if trying to get below say OVC005.

[Longbow55]

Longbow55

You don't need ATC clearance to descend "below clouds", here or in the USA.

In the USA, FAR something.something appears to prohibit an instrument approach other than a published one. In the UK there is no such rule (yet).

But if you happen to be able to do a visual approach from some level which you can get an IFR clearance to fly at then obviously you can then land under VFR. You can call this a DIY instrument approach with a MSA of 1000ft AGL or more :O Or you can call it "cancelling IFR". Same thing.

In the UK this is a bit of a non event anyway because in Class G you won't normally be receiving a radar control service so you can fly under own navigation as you wish. The only case I know of of a RCS in G is a low level letdown which is basically a radar vectored descent over a surveyed bit of ground, down to 1000ft AGL, but even then you can ask to switch to own navigation at any time.

The question then becomes: how low will you go? Flying at the MSA (or your MOCA; I have the FAA IR too) gives you an IAP with a DH of 1000ft - not unreasonable over open flat country. Of course Americans have never discovered this ;)

It all gets much more tricky if trying to get below say OVC005.

IO540, Not to argue because I don't want to. but if you are flying VFR and flying under VFR rules(FAA Only I am talking about), you must stay clear of clouds, that is in Part 91, even under SVFR same applies. it happens in the states, and the control centers help the pilots down, and there are some that just descend anyhow. Now I kinda like the idea what you talked about in the UK. and if I ever have to do that, the sectional will come out and see were the obstructions are. I do agree with the Class -G airspace, pretty much the same inthe states for rules. but you can get radarflight following in there if work load is not to high for the controller.

Now I just read somewhere, Can't remember, that the different ICAO states are trying to make the rules and regs equal, so if you fly in Europe, UK, US you know what the rules are. This is new info for myself, maybe old for some others.

[slim_slag]

IO540.

Please don't say "Americans have never discovered this" as your post demonstrates you are quite confused about the American system yourself and you are misleading people. You should stick to stuff you know about, like fuel flow meters. It is a very brave man who only held an FAA IR for only a few months & has only flown there once, to say "Americans have never discovered" something when it comes to flying in America.

[Gerhardt]

I think IO540 said that tongue-in-cheek. He's just having a little fun in a thread that seems to have a lot of pilots worked up.

[BTSM]

You could always call 121.5 and distract all the real pilots out there.

[IO540]

longbow55

I agree, but as we were talking about DIY instrument approaches I assumed you were talking about somebody flying under IFR. Then, if you have legally descended sufficiently to become visual with the airport, you can cancel IFR and land there.

That is the bit which I was suggesting Americans have discovered too :O

There is no practical difference between that, and landing somewhere on a DIY IAP with a 1000ft DH.

In the UK, the only difference is that you don't need to cancel IFR because, in Class G, nobody much cares what rules you think you are flying under at any given moment.

I wasn't suggesting a flight that's illegal (outside one's license privileges) to start with, but now that you mention it:

I don't know how many Americans do the obvious illegal thing which is to fly VFR, perhaps on a plain PPL, and just drop into their home base through a bit (or a lot) of cloud. With the large number of highly equipped GA spaceships flying out there, some capable of flying a "virtual ILS" on autopilot, I would be rather suprised if nobody out there has discovered this option which would surely have the last 10 FAA administrators revolving in their graves at 2575 RPM. Of course no plain PPL in Europe has discovered this either...

But there are two very big differences: in the USA many small fields have an IAP of some sort (often GPS) and the FAA IR is far more accessible to private pilots without commercial aspirations than the JAA IR. So I would suspect that DIY approaches are a lot less common out there.

[Fuji Abound]

"In the UK, the only difference is that you don't need to cancel IFR because, in Class G, nobody much cares what rules you think you are flying under at any given moment."

I am not sure I entirely agree.

If you are working a station in class G and report IFR, at FLX then I think both the controller and other users are entitled to expect you to remain at that level unless you agree a new level.

[DFC]

I would say the same as Fuji but for a different reason.

Not an uncommon situation to be in flying VFR below a 2500ft overcast and knowing that the tops are about 3500 to 4000ft and hearing a pilot announce that they are flying VFR through the same area at 3000ft.

Seriously bad practice not to let an ATS service know of any change in flight rules because while it may be class G and a free for all out there, there are many rules and requirements that change as the flight rules change and some of those affect other airspace users.

It can also fool pilots into thinking that they will be VMC at a particular level when they will not!

Regards,

DFC

[Longbow55]

longbow55

I agree, but as we were talking about DIY instrument approaches I assumed you were talking about somebody flying under IFR. Then, if you have legally descended sufficiently to become visual with the airport, you can cancel IFR and land there.

That is the bit which I was suggesting Americans have discovered too :O

There is no practical difference between that, and landing somewhere on a DIY IAP with a 1000ft DH.

In the UK, the only difference is that you don't need to cancel IFR because, in Class G, nobody much cares what rules you think you are flying under at any given moment.

I wasn't suggesting a flight that's illegal (outside one's license privileges) to start with, but now that you mention it:

I don't know how many Americans do the obvious illegal thing which is to fly VFR, perhaps on a plain PPL, and just drop into their home base through a bit (or a lot) of cloud. With the large number of highly equipped GA spaceships flying out there, some capable of flying a "virtual ILS" on autopilot, I would be rather suprised if nobody out there has discovered this option which would surely have the last 10 FAA administrators revolving in their graves at 2575 RPM. Of course no plain PPL in Europe has discovered this either...

But there are two very big differences: in the USA many small fields have an IAP of some sort (often GPS) and the FAA IR is far more accessible to private pilots without commercial aspirations than the JAA IR. So I would suspect that DIY approaches are a lot less common out there.

IO540, Yep I think we are thinking of two different types. I am on line now with what is being said:ok:

[mm_flynn]

Seriously bad practice not to let an ATS service know of any change in flight rules because while it may be class G and a free for all out there, there are many rules and requirements that change as the flight rules change and some of those affect other airspace users.

I am struggling to think of any rule/requirement changes that are going to be material to ATS or other pilots between operating IFR and VFR - other than quadrantial rule(but typically not relevant due to being below the transition level) and 1000 foot above nearest obsticle (which I struggle to see the impact of on ATS or other aircraft)

[Droopystop]

So in summary:

One cannot descend below 1000' above obstacles within 5nm, except to land/take off (rule 29), but:

One cannot descend below 1000' aal unless the actual weather is above the notified aerodrome operating minima (approach ban, article 49).

Where there is no notified aerodrome operating minima, one can calculate the AOM using the approved method (based on the Obstacle clearance height applicable to your aircraft type and the system minima) (para 7, article 49).

In other words the simple answer is one has to be visual at MSA to continue approach or shoot a published instrument approach. As far as I can see, a DIY approach is pretty much unfeasible to GA, unless of course one is referring to an approach with a 1000' MDH, which isn't really an approach, it is more a descent enroute.

[bookworm]

In other words the simple answer is one has to be visual at MSA to continue approach or shoot a published instrument approach.

Nope, that's not what it says:

"(4) Without prejudice to [Cat II/III approaches] an aircraft to which this article applies when making a descent at an aerodrome to a runway in respect of which there is a notified instrument approach procedure shall not descend from a height of 1000 feet or more above the aerodrome to a height less than 1000 feet above the aerodrome if the relevant runway visual range for that runway is at the time less than the specified minimum for landing." (my italics)

No notified IAP, no approach ban.

[IO540]

Thank you Bookworm, yours is a much more precise mind that mine :O

Droopystop

unless of course one is referring to an approach with a 1000' MDH, which isn't really an approach, it is more a descent enroute.

Yes and no. To make a typical visual approach (not a 3deg ILS type of thing) you want to be say 1000ft AGL 3 miles before the runway. I wouldn't call that an en route descent. The entire length of such a "procedure" will be no more than any published one.

I wouldn't descend to 1000ft above the runway elevation say 20 miles out. Not many runways have zero obstacles that far back. So there is a lot more opportunity to hit something that you have missed.

[Droopystop]

Bookworm,

So how is para 7 in article 49 supposed to be interpreted?

In this article “specified” in relation to aerodrome operating minima means such particulars of aerodrome operating minima as have been notified in respect of the aerodrome or if the relevant minima have not been notified such minima as are ascertainable by reference to the notified method for calculating aerodrome operating minima.

Does that not say if there is no notified minima, you have to calculate them yourself?

And on the generation of DIY approaches, the AIP defines what radio aids are used for (enroute or aerodrome, including relvant IAPs) so can one assume that rule 40 prohibits their use for anything else?

[bookworm]

So how is para 7 in article 49 supposed to be interpreted?


It's supposed to be interpreted as defining "specified" in the context that the word is used. And it's used in the context of runways with notified IAPs.


And on the generation of DIY approaches, the AIP defines what radio aids are used for (enroute or aerodrome, including relvant IAPs) so can one assume that rule 40 prohibits their use for anything else?
The AIP, in which the notification is made, makes the intention perfectly clear, IMHO.


"3.7 Those procedures at aerodromes which lie within Controlled Airspace are notified for the purposes of Rule 31(3)(a)(ii) of the Rules of the Air Regulations 1996. Those procedures at aerodromes which do not lie within Controlled Airspace are notified for the purposes of Rule 40 of those Rules.

These Rules require that, where an aerodrome is provided with one or more notified Instrument Approach Procedure, unless otherwise authorized by ATC, pilots requiring to use an Instrument Approach Procedure shall use only such notified procedures. This applies irrespective of whether the aerodrome is situated inside or outside Controlled Airspace." (my italics, again)


There is also an issue over the interpretation of "requiring to use an Instrument Approach Procedure".
While the words "Instrument Approach Procedure" are not used, I think there's a clear difference in intent between:


"Art 47(9) An aircraft [registered in the UK flying for public transport] when making a descent to an aerodrome, shall not descend from a height of 1000 feet or more above the aerodrome to a height less than 1000 feet above the aerodrome if the relevant runway visual range at the aerodrome is at the time less than the specified minimum for landing."


"Art 48(6) Without prejudice to paragraphs (4) and (5), [registered outside the UK flying for public transport], when making a descent to an aerodrome, shall not descend from a height of 1000 feet or more above the aerodrome to a height of less than 1000 feet above the aerodrome if the relevant runway visual range at the aerodrome is at the time less than the specified minimum for landing."


and


"Art 49(4) (4) Without prejudice to paragraph (2) [a non-public-transport aircraft] when making a descent at an aerodrome to a runway in respect of which there is a notified instrument approach procedure shall not descend from a height of 1000 feet or more above the aerodrome to a height less than 1000 feet above the aerodrome if the relevant runway visual range for that runway is at the time less than the specified minimum for landing."

[BillieBob]

An interesting, lengthy and, ultimately, futile discussion. Consider two things:
Rule 29 of the Rules of the Air Regulations 1996 -

Without prejudice to the provisions of rule 5, in order to comply with the Instrument Flight Rules an aircraft shall not fly at a height of less than 1000 feet above the highest obstacle within a distance of 5 nautical miles of the aircraft unless:

(a) it is necessary for the aircraft to do so in order to take off or land;

(b) the aircraft is flying on a route notified for the purposes of this rule;

(c) the aircraft has been otherwise authorised by the competent authority; or

(d) the aircraft is flying at an altitude not exceeding 3000 feet above mean sea level and remains clear of cloud and in sight of the surface.

Clearly, in the case of a 'self made' procedure, one is relying upon Rule 29(a) but, since GPS is not yet approved as a Class 1 aid in the UK, any legal procedure must be based upon a radio navigation aid and Rule 40 states that:

(1) Subject to paragraph (2), the commander of an aircraft shall not make use of any radio navigation aid without complying with such restrictions and appropriate procedures as may be notified in relation to that aid unless authorised by an air traffic control unit.

(2) The commander of an aircraft shall not be required to comply with this rule if he is required to comply with rule 31.

Therefore, any approach procedure that is not notified in accordance with Rule 40 is, unless authorised by an air traffic control unit, by definition, illegal.

Whilst anyone who thinks it is OK to conduct a 'self-made' instrument approach procedure is no loss to the aviation industry, the consequent loss of a perfectly serviceable aircraft, not to mention the innocent victims of such crass incompetence, is to be deplored.

[bookworm]

Whilst anyone who thinks it is OK to conduct a 'self-made' instrument approach procedure is no loss to the aviation industry, the consequent loss of a perfectly serviceable aircraft, not to mention the innocent victims of such crass incompetence, is to be deplored.

It sounds laudible, BillieBob, but hides some oversimplifications about risk management and regulation.

Where notified IAPs exist, there would be little point in not using them -- and the law requires that they are used.

At airports where IAPs do not exist, however, the situation is more complex. Scud-running in poor vis for 30 mins to make an under-the-deck VFR arrival is certainly legal, but not usually safer than a carefully planned and executed let-down which has not been notified as an IAP by the CAA.

The law currently recognises that. The only notification for the purpose of Rule 40 is in ENR 1.5 in the passage that I have already quoted, and the intention appears very clear from the second paragraph.

[Fuji Abound]

"(1) Subject to paragraph (2), the commander of an aircraft shall not make use of any radio navigation aid without complying with such restrictions and appropriate procedures as may be notified in relation to that aid .. .. .."

Forgive me if I have not correctly followed this thread but what restrictions and procedures apply to a VOR in open FIR that it is being suggested would prevent that VOR being used for a cloud break without air traffic consent. For example at GWC there used to be a published approach procedure I believe. At least one operator on the airfield has CAA approval to continue to use that procedure. However, for someone flying the "procedure" without CAA approval what restricitons prevent using the procedure for a cloud break?

[IO540]

There are loads of such "private" IAPs around the UK, based on some nearby navaid. Most airfields with an on-site or nearby navaid either have one, or had one when they had full ATC.

[DFC]

However, for someone flying the "procedure" without CAA approval what restricitons prevent using the procedure for a cloud break?

How about the posibility of collision in IMC with the oporator approved to complete the procedure?

There is no ATC to provide separation or organise an approach sequence.

Very much one operator at a time being very cautious.

If I found that I was about to start an approved cloudbreak into a base aerodrome only to find another unapproved private operator already in the procedure, it would be a case of;

1. MOR and

2. Report to company that someone outside the business has obtained a copy of the confidential parts of the ops manual.

Regards,

DFC

[Fuji Abound]

DFC you have missed the point.

Whilst what you say is of course correct the poster said

"shall not make use of any radio navigation aid without complying with such restrictions and appropriate procedures as may be notified in relation to that aid"

my question was what are the restrictions and appropriate procedures applicable to any VOR in open FIR.

[Keef]

But, after all the shouting's over, why would you want to do it? Whether the law does or doesn't ban (or allow) specific classes of approach ... what makes sense?

ADF is notoriously inaccurate: I flew an NDB procedure on my FAA IR checkride, with the needles in the right places all the way to the MAP. After I'd done the missed procedire and got to the holding fix, the examiner asked me how far left or right of the centreline I thought I was at the MAP. I said I thought I was ON the centreline. He agreed that's what the instruments showed, and said that in fact I probably wouldn't even have seen the airfield, which was a good half mile to one side. We then had an "examiner debate" about ADF errors, when I surprised him by telling him about Coastal Effect - I suppose they don't get a lot of that on NDB procedures in the USA.

I've flown an NDB procedure "in anger" just once - the 02 at Shoreham. I was very glad indeed that I had the GNS430 running alongside, with the 02 NDB procedure displayed. (I've flown countless NDB procedures in training and "renewals", under the hood, but that's a lot easier).


Stuck above an overcast, with 400 foot cloudbase all around? I'll go (above MSA) somewhere with an ILS and vis above minima, thank you very much. Cowardice Prolongs Active Life and all that.

[IO540]

Well yes I don't think even pretty bold pilots would do a DIY letdown through OVC004.

Over the sea, perhaps, but that only gets you into a runway which is right on the coast.

It's a question of degree. Many, myself included, would be happy to do it through OVC010 but one has to study the chart and also Ordnance Survey maps of the area very carefully beforehand.

There is no suggestion, I hope, of doing this with an ADF. That's a great way to get killed. A GPS plus VOR/DME would be my minimum equipment i.e. two unconnected position fixing methods.

Incidentally, ADF is affected not only by coasts but also by high terrain close to the aerial. At Shoreham you get a huge error, 30 degrees easily, on the 20 approach even if approaching more or less perpendicular to the coast (when any coastal effect should be symmetrical).

Sometimes NDB approaches can't be avoided. Like Berlin Tempelhof (EDDI) right now - ILS inoperative, the runway with VOR approaches is closed, so all you have is NDB/DME. I can just imagine somebody going in there IFR/airways and expecting for the customary radar vectored ILS :O And I bet more than 50% of professional (e.g. bizjet) pilots would have made that mistake.

[BillieBob]

I have to say that I am astonished that a thread on a 'Professional' pilots' rumour network, even in the 'Private' (a.k.a. amateur) forum, entitled "Descending through cloud without a procedure" could have streched to 6 pages. The whole concept is wrong, stupid and, as Graham Hill, among others, discovered, ultimately fatal.

[IO540]

I have to say that I am astonished that a thread on a 'Professional' pilots' rumour network, even in the 'Private' (a.k.a. amateur) forum, entitled "Descending through cloud without a procedure" could have streched to 6 pages. The whole concept is wrong, stupid and, as Graham Hill, among others, discovered, ultimately fatal.

The problem with attending too many CAA safety evenings and listening to too many of the boring righteous old farts who take up so much space in UK GA is that it all dulls one's brain. The result is that one stops asking intelligent questions and stops seeking intelligent answers to them.

Critical analysis is what keeps one's brain going into ripe old age.

If every GA airfield has a GPS approach then you might have a point.

[Croqueteer]

:D BB, don't even think about trying a logical discussion with IO540. His chances of becoming a "boring old fart" are not good!

[IO540]

"I have to say that I am astonished that a thread on a 'Professional' pilots' rumour network, even in the 'Private' (a.k.a. amateur) forum, entitled "Descending through cloud without a procedure" could have streched to 6 pages. The whole concept is wrong, stupid and, as Graham Hill, among others, discovered, ultimately fatal."

= "logical discussion"

???

[Islander2]

BillieBob, it's not the 'descending through cloud without a procedure' that's ultimately fatal, it's the 'getting it wrong'. And that applies equally to 'descending through cloud with a procedure, as countless 'professional' pilots have discovered to their cost.

Graham Hill did not have the benefit of an IFR-approved GPS, which arguably makes a carefully-considered NPA (using cautiously-high minima) to an airfield without a published approach actually safer than an NDB approach into some airfields that have a published IAP (maybe with only timing for distance-to-go reference). I have no doubt as to which I would choose in certain circumstances.

[Fuji Abound]

""I have to say that I am astonished that a thread on a 'Professional' pilots' rumour network, even in the 'Private' (a.k.a. amateur) forum, entitled "Descending through cloud without a procedure" could have streched to 6 pages. The whole concept is wrong, stupid and, as Graham Hill, among others, discovered, ultimately fatal."

Personally I has always thought amateur means "doesnt get paid for" and professional "does". That saves any confusion about there being some amateurs better than professionals and vica versa :) .

Safe aviation is about assessing risk. If I really had to would I rather descend with an NDB / DME or with a GPS. Maybe there might be a situation in which I need to make a cloud break - what are the factors I should consider? The aircraft is not FM immune but I have managed to get into IMC - what are the consequences? IMHO that is one of the reasons we enjoy this type of debate.

There are always those who come along and say blindly - ah, you cant do that becasue the ANO says so, or convensional wisdom is agin it. I worry more about those pilots because they think within the box.

[drauk]

BB wrote:

I have to say that I am astonished that a thread on a 'Professional' pilots' rumour network, even in the 'Private' (a.k.a. amateur) forum, entitled "Descending through cloud without a procedure" could have streched to 6 pages. The whole concept is wrong, stupid and, as Graham Hill, among others, discovered, ultimately fatal.

Surely the fact that the discussion has stretched to 6 pages shows that it isn't as clear cut as just being "wrong, stupid and ... ultimately fatal"?

What IO540, and others, are trying to do is to gather as much of an informed opinion as possible on something that you can't just pick up in a book. What with all the legislation, the old-school "you young kids with your fancy GPS don't know what you're talking about" and flying schools operating on ever tighter margins with shrinking numbers of customers, it's incredibly hard for people who enjoy flying to get good, useful and valuable information. So, whilst you're astonished the rest of us will go on trying to learn and happily debate the pros and cons of, say, descending through cloud using the various means we have of avoiding hitting the ground.

[unfazed]

Descended through cloud a couple of days ago whilst getting a FIS from LARS - controller got a bit twitchy but we used a VOR radial and DME to find our way and set a local area MSA which provided sensible seperation from high objects and ground in local area, we also had a backup plan for divert in case we could not get visual

All worked a treat ! No safety compromised and can't think of another way to get in to an airfield with no formal approach procedure. :)

[Droopystop]

Is there really such a glaring loophole in the ANO that allows a private pilot to make up their own DIY approach to an airfield with no IAP and choose their own minima?

[IO540]

Yes, it's called "pilot with a brain".

For most purposes, this presumption is adequately validated by getting the candidate to sit half a dozen PPL exams, plus one more IMCR exam, plus (for those who have an IR) one more IR exam (if FAA IR), plus 10 or so more IR exams (if JAA IR). Plus some flight training.

But seriously, it is actually quite normal during IFR operations to be in IMC. During this time, one might be climbing, or one might also (shock, horror) be descending. If, when descending, one becomes visual with the ground, then one is in a position to do a visual approach.

It's awfully difficult to draft legislation which bans descent during IFR!

The question which one could debate is how low one should go. Going down to what on the UK scene is called "MSA" amounts to a DIY instrument approach with a DH of 1000ft.

Sorry to sound patronising but by writing

Is there really such a glaring loophole in the ANO that allows a private pilot to make up their own DIY approach to an airfield with no IAP and choose their own minima?

you walked straight into that one.

:O

[Droopystop]

I never had an issue with descending to MSA in IMC. All perfectly normal avaition practice. My question goes beyond the MSA stage. So I will ask the question again: Is it legal for a private pilot to descend (in IMC) to say (for the sake of this thread) 400' MDH on a DIY approach?

Do not assume my level of experience or qualifications from my posts here, I choose not to advertise them. However they are such that your patronising tone is amusing. My only fault here is my ability to express myself, but then we all fall foul of that on these forums from time to time.

[jayteeto]

Unfazed and others... The concept of a home made GPS/VOR/NDB approach is alien to some people, although I now accept it could have its uses. The problem a lot of us older pilots have, is the one about being in cloud without a radar service...... You rely on the Big Sky theory, in other words that no-one else will be in your cloud. This will work 999,999 times out of 1,000,000. Then you have to think like the national lottery, it COULD be YOU!!
I have flown in many nasty places, often without radar cover in very poor weather. We had an emergency letdown GPS procedure that was just that... An EMERGENCY plate.
Risk assessment is part of life these days, the chances of a mid-air collision are not great, but they are there. So "Do you feel lucky??"

[unfazed]

So I will ask the question again: Is it legal for a private pilot to descend (in IMC) to say (for the sake of this thread) 400' MDH on a DIY approach?

Common sense would dictate that you do not descend below 800 feet which is the non-precision system minima plus 200 for luck (and then sanity check that against the local terrain and obstacles within 25 miles circumference).

Also agree that you should not play "cloud roullette" but should get a RIS OR RAS.

Other caveats - Have at least an IMC rating, preferrably IR, be current and proficient, have a plan B and a Plan C (i.e. know where your alternates are and make sure that you can reach them and that they have VFR weather or a precision approach which is forecast to be well above minimums (legal and personal).

Plan well in advance and don't get caught out !

[bookworm]

The problem a lot of us older pilots have, is the one about being in cloud without a radar service...... You rely on the Big Sky theory, in other words that no-one else will be in your cloud. This will work 999,999 times out of 1,000,000.

How do you cope with aerodromes outside controlled airspace with IAPs and procedural approach control, then? Or indeed for that matter, with enroute IFR outside controlled airspace where no radar service is available?

There is, unfortunately, no such thing as "safe" in aviation, only "safer". Risks are always relative, and there's a strong argument to suggest that without a radar service you are safer overall in low-traffic-density cloud than in high-traffic-density VMC, as see-and-avoid is imperfect.

Of the risks to be assessed in any DIY instrument let-down, I would have thought that the risk of collision with obstacles or terrain vastly outweigh the risk of mid-air collision.

[unfazed]

Bookworm

You are quite right there is nothing to stop you flying without a RIS or RAS outside of controlled airspace, hopefully everyone is sticking to the correct altitudes however you must admit that there is a risk of collision with some other IFR aircraft who is sharing the same cloud as you are and not talking to anyone else

I can only advise what I would do, as I am not prepared to take risks like that when I don't need to, that's where I choose to draw my own personal line. You can ask for a service (FIS) outside CAS but it is subject to radar cover and workload. I can only advise that you eliminate as much risk as you can and then check to see how important the flight is.

Hope this helps

[IO540]

When it comes to someone's personal attitude to risk, there is no arguing with that. Each to their own, and it cannot be objectively faulted.

What one can always debate is relative risks and how to minimise them.

The magic number which one could descend to on a DIY approach is a good one. 1000ft (the traditional UK MSA) is reasonable as one would expect the obstacle rules used in the production of the CAA VFR charts to protect you. How low can one go while still having this protection? I can't remember the exact rules the CAA uses to depict each bit of the terrain, and also if I recall correctly there can be uncharted obstacles up to 299ft above the ground.

Perhaps somebody can illuminate this.

The proper way to do this is to get out the 1:25k or 1:50k Ordnance Survey map and look at the contours very carefully. It should have man-made obstacles on it, and should be as up to date as the CAA chart which can itself be over a year out of date. If I was planning an approach I would use both charts, GPS+VOR+DME, and descend to 700ft above known obstacles. This is reasonable given that many NDB/DME approaches have a DH of that much but with far less accuracy in azimuth. 400ft is lower than I would do.

As regards a radar service in IMC, again I respect anybody's view that they would not fly in IMC without it but this hugely conservative attitude is unsupported by mid-air collision data (how many mid-airs have occurred in IMC?) apart from making IFR OCAS impossible most of the time. The most dangerous thing has to be trying to get into Wellesbourne or Stapleford on a sunny Sunday preceeded by weeks of bad weather; people cut you up on the inside, below you, above you, a total free for all at times.

In fact a very real problem in this department is caused by all those pilots who fly around without a transponder; this renders a radar service mostly useless because the ATCO is forced to report all horizontally conflicting traffic even if you are at FL070 and the non-transponding traffic is probably somebody at 1000ft.

Have at least an IMC rating, preferrably IR,

I hope nobody is assuming otherwise; if they do it would explain some of what has been written!

[unfazed]

The magic number which one could descend to on a DIY approach is a good one. 1000ft (the traditional UK MSA)

I think that it would be a good idea to clarify what this means ? I think you mean 1000 AGL (or above highest obstacle in vicinity?)

[IO540]

I think you mean 1000 AGL (or above highest obstacle in vicinity?)

Yes; the traditional UK MSA calculation.

If I recall right (gave away the books recently) even Trevor Thom says this is OK, and he must be right! :O

I'd still like to know the rules of terrain depiction on the CAA charts.

[Fuji Abound]

There are I guess not that many procedural approaches outside controlled airspace in the UK. There are a whole lot more in the States. Presumably we may end up with more, if GPS approaches are ultimately approved.

Separation implicitly relies on pilots doing what they are told. There is clearly no backup so far as vertical separation is concerned whilst in the hold. I suppose ATC does have some indication of where the aircraft is from DF so that if for example the aircraft reports beacon outbound and isnt an alert ATC might spot a problem.

I recall one of two close misses I have had; whilst in the hold without radar. briefly I became VMC and almost immedaitely spotted another aircraft far too close for comfort. It turned out they were working Dunsfold (in the old days when Dunsfold provided a LARS) and yet had managed to be allowed to fly straight through the ATZ in IMC. Not surprisingly there was a rather terse telephone call between the two ATCs.

Sadly it seems to me the biggest risk is just this - other aircraft flying through the ATZ in IMC oblivious to the fact the "local airport" provides an apporach service. Also whilst the big sky theory is comforting unfortunately our arrangement of airspace provides far to many choke points.

Personally I feel 1,000 feet AGL is entirely reasonable, but no lower. From experience it is a hard IFR day when there are no cloud breaks at all to enable a visual descent albeit that does require a sound technique for maintaining a visual descent in a small break. I would feel that if you find yourself in such hard IFR conditions unless the forecast was seriously inaccurate you had no business setting off in the first place without having recourse to a procedural approach.

[High Wing Drifter]

I'd still like to know the rules of terrain depiction on the CAA charts.
More or less as you say, just search for 299 here: http://www.caa.co.uk/docs/33/SRG_GAD_WEBSSL5.PDF

[ShyTorque]

"Of the risks to be assessed in any DIY instrument let-down, I would have thought that the risk of collision with obstacles or terrain vastly outweigh the risk of mid-air collision."

Not sure about that, Bookworm! It is perfectly possible to plan an IMC approach taking into account the terrain and other obstructions. I am NOT advocating this to be done in the air - rather a proper plan in place with a survey done first! However, encountering another aircraft in IMC can be an unquantifiable risk.

Speaking as someone required to spend a fair amount of time IFR/IMC in Class G airspace, it is becoming increasingly worrying how many aircraft are IMC but apparently NOT talking to an relevant ATC unit for any kind of separation service. The really worrying ones are those not transponding mode C (possibly not equipped and therefore not supposed to be flown in cloud). They really are taking a big risk, if not in receipt of an ATC service (and therefore not communicating their altitude) especially those under the London TMA when it isn't possible to fly quadrantals. We seem to encounter them increasingly often; my most recent encounter was last week when the radar unit we were working advised of a "contact left to right, 2 miles, no altitude information". We already had the contact on TCAS but it had no altitude tag. We therefore reasoned that it was VMC beneath cloud. As it turned out, we were wrong! It was an R-44 helicopter flying in and out of cloud about 4 miles north of Denham. It passed only a couple of hundred feet below and almost directly beneath us, according to my co-pilot. As far as I know, there are no R-44s clear to fly IFR in UK...... not least because they are single engined!

The big sky theory regarding no mid-air collisions IMC generally works but only because outside regulated airspace there are often fewer aircraft in cloud than not! The small minority of pilots who fly in cloud whilst not speaking to a radar unit and don't have TCAS quite possibly believe there is a tiny risk simply from past experience, because they are likely to be blissfully unaware of other aircraft in their close vicinity - until one day when they will possibly be part of an accident.

[IO540]

The problem, ShyTorque, is that much of the time one cannot get an RIS (OCAS) and when you do the controller has to report loads of returns from non-transponding targets.

If Mode C transponders were mandatory that would be something else.

And without radar, ATC service is meaningless. "27 aircraft known in the area"....

If only as much time was spent by the training industry telling pilots to fly with Mode C ON as they spend getting everybody to pointlessly call up London Info....

HWD

That PDF you refer to is just a leaflet on VFR flight planning.

[High Wing Drifter]

IO540,
That PDF you refer to is just a leaflet on VFR flight planning.
The issue of VFR or IFR has nothing to do with what is charted and what isn't. Clarify what rules you are looking for.

[IO540]

I was looking for rules the CAA mapmakers use to determine the elevation steps at which they change colour, and what rules they use to decide whether to show say a 530ft obstacle and perhaps not a 500ft one a mile away.

Obviously they must have rules on which obstacles to show, when others already shown are in specific proximity. Looking at the chart, the relevant distance is probably a few miles - unless they are exceptional man-made obstacles in which case (say, two tall towers close to each other, like those easy of LCY) they show them all.

[Chilli Monster]

If only as much time was spent by the training industry telling pilots to fly with Mode C ON as they spend getting everybody to pointlessly call up London Info.....

Amen to that!

[ShyTorque]

[QUOTE=IO540]The problem, ShyTorque, is that much of the time one cannot get an RIS (OCAS) and when you do the controller has to report loads of returns from non-transponding targets.
If Mode C transponders were mandatory that would be something else.
And without radar, ATC service is meaningless. "27 aircraft known in the area"....
If only as much time was spent by the training industry telling pilots to fly with Mode C ON as they spend getting everybody to pointlessly call up London Info....QUOTE]
I agree with most of that, the use of London Info is often not the most intelligent use of R/T. I think some pilots use it as a "coverall" frequency to avoid having to speak directly to other airfields near to their route.
Unfortunately, the amount of LARS radar coverage in UK does seem to be decreasing with the demise of some military bases but .
The altitude details of a non transponding aircraft, where given to a more appropriate ATC unit can be passed to other pilots using the service. When this is done for me, I will change altitude if appropriate to give some vertical separation. Our aircraft carries TCAS but as you say, it's not a lot of use if the other aircraft don't have Mode C or don't use it (for the info of those who don't know, TCAS isn't so good in azimuth and can't be relied on to give positive lateral separation from a non-mode C contact).
The thought of meeting up with unannounced aircraft in cloud scares the pants off anyone wth a modicum of common sense. In the last five years this has happened to me on at least three occasions in class G, one of them under the London CTA. Two of these aircraft were known to the ATC and working the same unit as us. Both, having announced their altitude and "VMC" suddenly climbed into cloud without saying so, causing a conflict.... Both of these were "professional pilots" flying twins; one of them on an instructional flight and one supposedly watching the traffic. :rolleyes: I no longer subscribe to the "big sky" theory (neither does the UK helicopter pilot who has miraculously survived TWO mid air collisions).

[IO540]

I think you can get overly paranoid over TCAS reports.

The statistical picture for IMC mid-airs over the last 50 years clearly supports the big sky theory. You might get a dire looking warning of traffic say 1000m away but if your wingspan is say 10m (PA28 type of plane) and the airframe is 2m high then your frontal profile is 20 sq. m. The other plane is say also 20 sq. m. If it is 1000m away and at exactly the right level the probability of a hit is just the ratio of the wingspan to the horizontal separation, which is 1/100, but nobody can fly the height that accurately - even below the LTMA :) - so let's take a 200ft level difference (say 50m to keep the numbers easy) then the 1/100 chance improves by the ratio of 2m to 50m i.e. 25x i.e. to 1/2500.

So your dire looking TCAS warning was actually a 1/2500 chance of a hit.

So if the two planes flew those reciprocal routes every day, there might be a hit after 2500 days.

These are just back of a fag packet figures but they indicate the magnitues.

If this was on a common commercial-traffic route, such as one finds in CAS (airways) then you would have plenty of hits (esp. with the much more accurate autopilots in use, and the virtually universal AP usage during the whole en route and approach segment) but that traffic flies under radar separation. Hence the old joke about the job of ATC being to pack everybody into a small space and then keep them from colliding :)

I won't claim that the existence of CAS protects anybody much because a lot of people infringe anyway and if they are not Mode C (which they aren't either because of the expected strong correlation between "bimblers" and non-equipped planes, or because they turned the transponder off in case they bust airspace) then ATC has to assume they are OCAS below it. However, CAS must reduce the chances because most pilots do keep out of it - despite their wonderful map+stopwatch PPL training :)

When we get to OCAS, the traffic density is far lower. The UK is actually quite busy; you can fly the entire length of say Italy and not see or hear another plane. On a typical UK flight, say 200nm, one might see 5-10 planes but they are very far away.

The chances of a hit en-route in VMC is miniscule (a hit, as I show above, is not the same as a near miss, the difference in probability is of the order of 2-3 orders of magnitude) and much lower still in IMC.

In 500-600+ hrs of flying on my own I have been within 100m of somebody maybe 3x, both being below 2000ft. Assuming 100m x 50m separation is 1/250 that puts the risk of a mid-air for me at about 600x250= 1 in 150,000 hours and that assumes I fly in those places every time I fly, which I don't, not by a very long way. One was on right base to Le Touquet (with a French pilot having been cleared for a concurrent left base in French), one was N of the Isle of Wight at 1900ft, one was at 2400ft over MID. Only the last one might have been likely in IMC. I am not counting various "proximity cases" trying to get into Stapleford or Wellesbourne because that was VMC and if you go there you take your chances! Of course those are just the ones I know about but even adding a factor of 10 to it still gives a hit every 15,000hrs and that's with the same assumption (flying in the dodgy places all the time).

The figures indicate that one could fly around 24hrs/day and would still die of old age before hitting something. Just don't try to go to Wellesbourne or Stapleford on a nice day unless you can hack it with the locals :O

Of course I am happier with a RIS, VMC or IMC, but all those ********** without transponders make the service practically worthless much of the time.

[englishal]

Lies, damn lies and statistics :)

Seriously though, although the chance of a mid air is incredibly low, chances are that the two aeroplanes are exactly in the right spot. It is called Sods' Law ;)

I think there is a difference between shooting a home made approach somewhere you may not have been for a while, and one at your home field to get you back in after a days flying. Assuming you depart your home field in the morning in VMC, and there is nothing obvious in the vicinity (new chimneys and the like), then you're probably pretty safe coming down to 500' on your way back in. If you're luckily enough to fly from somewhere like shoreham, there is no danger making up a GPS approach which takes you out over the sea and descends you to 500' before coming inbound again, and I would argue that it is probably safer than the NDB approach for a number of reasons.

I wouldn't shoot a home made approach without first surveying it in VMC, though have carried out a number of home made SID's using GPS.....

[IO540]

chances are that the two aeroplanes are exactly in the right spot

Having just cycled for an hour along a very busy dual carriageway, I wouldn't like to guess which is going to get me first ;)

Life is not without risk.

[bookworm]

"Of the risks to be assessed in any DIY instrument let-down, I would have thought that the risk of collision with obstacles or terrain vastly outweigh the risk of mid-air collision."
Not sure about that, Bookworm! It is perfectly possible to plan an IMC approach taking into account the terrain and other obstructions. I am NOT advocating this to be done in the air - rather a proper plan in place with a survey done first! However, encountering another aircraft in IMC can be an unquantifiable risk.

I agree. The risks are fundamentally different in nature. What I was thinking was that if we announced a national "fly your own IAP" day to the GA community sometime, we'd probably end up with more aircraft in the sides of hills than we would aircraft entangled with each other. :uhoh: But flying a properly designed IAP is a low risk activity.

[ShyTorque]

IO540, You seem to quantify collision risk differently to myself; each to his own.

My own reasoning is based on experience gained from flying in a professional capacity since 1977 and a few years privately before that. In that time, I have experienced a number of other "mid-air conflict" situations where I would probably not be here taking part in this discussion, had I not taken avoiding action, as in the two previous cases I mentioned.

One of those more recent "encounters" in cloud allowed us to view the expression on the other pilot's face as we banked hard away from him. He was head on at exactly the same altitude (same QNH) and he was alone in the cockpit and looked wide-eyed and terrified - I sincerely hope he learned his lesson. He passed S + L, very close indeed on our left side, presumably not having any chance to take any action himself. Inexplicably, he had just confirmed to ATC that he was remaining VMC and 900 feet below us.

The recent provision of TCAS (in the last eight years in my case) has proved to myself and my colleagues just how many times aircraft DO come dangerously close to each other, both VMC and IMC in Class G airspace.

Often, having spotted another aircraft in VMC, we notice the "other" pilot takes no avoiding action, when required to by rules of the air - which makes me think that the lookout/awareness of some pilots is inefficient. Unfortunately, a pilot who doesn't see conflicting aircraft, doesn't talk to ATC and doesn't have TCAS is likely to think that "other aircraft" aren't actually there and may be further inclined to be unduly complacent on another occasion!

I note that your stats take no account of the fact that aircraft fly between ground features in VMC and other waypoints when IMC. Whatever, the likely severity of the possible outcome surely means that merely relying on chance and/or statistics is unacceptable in aviation. Otherwise, having ATC and rules of the air are probably a complete waste of time....

BTW, I certainly don't see myself as paranoid, in fact I would be seen as highly irresponsible to take any other viewpoint. All I'm trying to do is safely reach retirement. ;)

[unfazed]

I0540

What you also need to factor in to your calculations are the following

1 - Every man and his dog wants to fly at 2000 due to London TMA and high masts
2 - All tracking to and from same pinch points over beacons
3 - All routing around Hrow, Stanstead, Luton etc

I would suggest that your odds of a hit are now much improved:)

[Fuji Abound]

"And without radar, ATC service is meaningless. "27 aircraft known in the area"....

I dont entirely agree.

There is an increasingly held view that it is a waste of time talking to London info.

The fact of the matter remains there are significant parts of the country were there is no RIS or LARS and no other meaningful service.

Never the less I still find some of the traffic information that can be provided by London info or ATC useful.

For example, I can think of many occasions where the call is bla bla bla expecting the SFD at 10.45 at FL45. That is useful if I am going to be in that vicinity at a similar level at a similiar time. There are many other examples. If pilots give up talking to any of these service providers then all that information is lost and after all whilst flying in much of France is very peaceful it also seems pretty quite after a while :) .

[drauk]

All tracking to and from same pinch points over beacons

That's another good reason to use a GPS in IMC. Even a handheld one (backed up by traditional instruments) will do the job of allowing you to route easily avoiding this type of hot spot.

[jayteeto]

Enroute IFR generally still has the protection of being controlled airspace. You operate procedurally, still with a system designed to stop collisions. Read my post again, I am not saying don't do it under any circumstances, just highlighting that there are risks involved.

[Droopystop]

Shy Tourque's experience is somewhat worrying. Is it the case that since the instrument requirements for the PPL have increased, instructors are increasingly (illegally in some cases) taking students into IMC to make use of the undoubted benefits of experiencing it for real? Of course when instructing, the radio can be a bit of a pain, especially if having to provide the long speil of filing an airbourn flight plan, so they just don't bother and rely on the big sky theory. Except that in certain parts of the country, the sky is not that big. It would also be interesting to see if the level of IFR traffic OCAS is on the increase. Certainly the ever increasing numbers of smaller airports (OCAS) being adopted by low cost airlines is not helping but are there more and more people using small twin IFR helicopters, biz jets and private pilots trying to go by air rather than being stuck on the roads?

[Chilli Monster]

There is an increasingly held view that it is a waste of time talking to London info.
The fact of the matter remains there are significant parts of the country were there is no RIS or LARS and no other meaningful service.
Never the less I still find some of the traffic information that can be provided by London info or ATC useful.

I don't think the view is increasing - it's more that there are a lot of people calling who don't really need to who are, by dint of clogging up the frequency, preventing them from doing their main tasks and preventing those with a higher priority requirement to call them from getting what they need.

This has been spouted many times before, but the main priorities for London information are:

1) Dissemination of information required for the safe conduct of flights (weather, danger area activity, TDA activity etc).

The calling for a pseudo ATC service, which is not actually provided, does not fall within that remit

2) Receipt of airborne flight plans, and issuing of ATC clearances when that clearance cannot be obtained from an ATC unit

How can they do that when the frequency is clogged by people who are calling for the pseudo ATC service mentioned above.

3) Provide Alerting service

If you're over the English Channel, Irish Sea, Middle of Wales you want a safety net just in case it all goes quiet. That is a servce that is seriously downgraded when every cretin from here to kingdom come is calling for a supposed "Flight information Service" (Read - "I want someone to talk to because that's what I was taught to do"). If you're over the south of England, in good VMC, do you need to make that call?

NO - look out of the damn window - it's going to serve more use!

[Fuji Abound]

Chilli

Whilst I have some symphathy for your comments the CAA would seem to take a different view. AIC 48/2004 offers some specific guidance about what an ACC FIS is intended to provided which specifcally (there use of words) includes "general traffic information" and "general information about traffic reported as operating in the same area".

Outside of controlled airspace in IMC I know of no other service that can provide traffic information. A visit to SFD on IMC days will tell you there is a fair bit of instrument training traffic around and some en route traffic who doubless should be at the correct level but are often not. I am pleased to have an idea who is around and what they are doing, VMC and IMC whilst also looking out of the window.

I find if you have a serious problem a Pan tends to grab everyones attention, with the resultant peace and quite that follows. Of course as you know D and D are probably a better alternative in these circumstances, as presumably you will be after a fix as soon as possible.

Personally I have never had a problem getting the information you indicate. I accept that there are occasions when it may take several minutes to get a call in, but there again as long as you are thinking ahead I dont see that as a problem. I would however suggest that if only pilots were trained better the vast majority of calls could be a great deal shorter if only by cutting out all the ums and ahs. Some calls make us all cringe.

Think before you speak, and that way you will know what you are going to say.

In so far as the thread is concerned, again I would quite like to know from London info or anyone else for that matter if an aircarft is "attempting" a cloud break where I am.

[pipertommy]

One last question!Whats is the cockpit equipment requirement for an SRA in class D airspace.As i said before on here i done a few during my IMC training(vfr-foggles) but slightly unsure of exact requirement for the A/C?But happy with the actual procedure.Checked through my training books but they just give information on flying side of things.

[High Wing Drifter]

Have a look at the tables in Schedules 4 and 5 of the ANO. Amongst other things, the requirement is based on IFR in CAS but not the type of approach.

[IO540]

There is a lot of confusion on this issue because a) PPL students are told nothing about the equipment carriage rules and b) schools like to "economise" by flying practice approaches under pretend-VFR whenever possible, and the rest of the time they rely on the fact that ATC will never ask the question whether the plane is legal for IFR in CAS.

[pipertommy]

Yes!I think i`ve been had by the VFR foggles gag!Poor show that the equipment required is not covered in any of the course manuals!

[unfazed]

I think you mean 1000 AGL (or above highest obstacle in vicinity

Just realised that if not descending below 1000ft above the highest obstacle within 5 nm of track means not descending below approx 1500ft (or higher) in my part of the London TMA

Example - Planned descent to 1000ft, ATC advises Tower 3nm ahead of track up to 750 agl (which you know about and have planned for) - although
you are navigating clear of the tower you will now need to maintain 1000 ft above that tower to remain legal in IMC (Not below 1000ft above the highest point within 5nm). So you cannot now descend below 1,000 + 750 + elevation at tower (lets say 2000 ft)

I realise in hindsight that my descent to 1000 ft to break cloud "near" the tower (even though there was awhopping great VOR prior to twr which was my turning point) was technically :mad: illegal.

Lesson learned (measure 5nm each side of intended track and be more conservative with min descents, this will ensure that you remain legal and safe but will require more planning as you now need to ensure that you can break cloud prior to destination and any obstructions on route will keep you high