Descending through cloud without a procedure
 

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?

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?

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

DFC,

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

Agreed.

DW.

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?

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.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
----------------

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.

"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.

while your on the subject!
 

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:

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.

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?

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.

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?

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.

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.

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

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

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:

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

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.

buster172,

If you wander over to the flyer forums, 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.

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?ca...90&pageid=5866

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.

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.

Thanks Flyingforfun, an interesting reply.

Rustle said:
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'.

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.

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.

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!

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

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

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.

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

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.

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

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:

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?

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:

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

The legal basis for FM Immunity requirements
 

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 states that, and I quote;

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

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;

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.

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.

DFC saysThe 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 and here 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 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."

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

Why - because so many are not FM immune?

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