UK IMC Rating Minima

[Snigs]

I was asked a question yesterday that I didn’t really know the answer to…but should have!

In the UK IMC rating the pilot should add 200ft on to the OCA/H for his minima for a non-precision approach. Does the extra 200ft apply to OCA/H for a circling approach to land on a different r/w, as by definition you should be VMC?

[bluskis]

I would think that your MDA/H would be the criteria for the non precision approach, not forgetting the 'not less than 600 ft' criteria

The cloud base may well be lower than these MDAs in which case the visual manouvering height will not be applicable.but a missed approach will

I do not believe anything has to be added to the VM height if the conditions become VMC

[DFC]

The problem is in the wording.

It is "recomended" that 200ft is added to the published approach minima.

However, the absolute minima for a non-precision approach is 600ft (MDH).

Circling is part of a non-precision approach.

Personally, for IMC rating flying, I would addd 200ft to the circling minima. If one was to use the IMC straight-in minima, one could fall foul of a higher circling minima.

Regards,

DFC

[homeguard]

Circling to land is not part of the non precision approach. Circling to land may follow any kind of approach and is undertaken visually.

A factor of +200ft need not be applied.

[bookworm]

In the UK IMC rating the pilot should add 200ft on to the OCA/H for his minima for a non-precision approach. Does the extra 200ft apply to OCA/H for a circling approach to land on a different r/w, as by definition you should be VMC?

It would be utterly daft not to, wouldn't it? This is the toughest bit of most IAPs, in which it's only too easy to make a misjudgement. If you're going to add 200 ft to the easy straight-in bit, why wouldn't you add 200 ft to the bit where you're fumbling around in the clag a few hundred feet above obstacles trying to keep the runway in sight as you make what are, for conditions unlikely to have a distinct horizon, quite lively manoeuvres?

[Snigs]

bookworm, that's what I thought, and advised. But judging by the response (thanks all) there is still a bit of uncertainty.

[martinidoc]

I agree that once you have broken cloud using the procedure and become VMC, that the circling minima is appropriate, not the addition of an extra 200 ft for the IMC rating

Consider my base airfield EGNT The AIP gives for a Cat A non-precsion approach NDB/DME 25 an OCH of 371 ft labelled for the procedure. However it also gives a VMC OCH for the total area of 534 ft. If the AIP states that the minima is for a VMC circling procedure for the total area, then no IMC Xs should apply because by definition that minima applies to VMC!

Let us say that an IMC pilot decends to his mdh of 600ft, having broken cloud at 700ft. It would be illogical to expect him to climb back to 734ft, and lose visual contact with the runway and have to execute a MAP.

We teach slow safe cruise/tight bad weather circuit specifically to deal with the bad weather/poor vis. If that can only be done at or near the normal circuit height it kind of defeats the object of the exercise.

http://www.ais.org.uk/aes/pubs/aip/pdf/aerodromes/32NT0810.PDF

[homeguard]

No uncertainty at all.

Martinidoc is absolutely correct!

[Snigs]

OK, ta, that clears it up!

[homeguard]

If I could add another thought Snigs.

It maybe that your IMC MDH, say 750' QFE is higher than the VMC OCH, say 550'.

A cloud break is not required, only that you have visual reference with the runway i.e. the associated lighting. You may be still well within cloud on the approach when the lighting is identified, very common nowadays with high intensity white approach lights. When turned up high they can penetrate through a lot of cloud. With such reference you may continue the approach below your minima to the visual circling minima or land ahead of course. Don't forget the 1800m viz requirement that you must have for landing before you commence the proc.

[bookworm]

Well Snigs, a lot of the uncertainty comes from the terminology.

VMC means "visual meteorological conditions".
VM(C) means "visual manoeuvring (circling)".

A circling manoeuvre at the end of an instrument approach need not be carried out in VMC. For example, in 3000 m visibility in a class D CTR, the conditions would most definitely still be IMC, and a flight would remain operating under IFR. But a circling approach within the VM(C) area is still permitted.

The VFR minima, which define VMC, are irrelevant to a circling approach. Of course you *can* cancel IFR and proceed VFR if you are in VMC and can maintain it, and, provided you can satisfy the judge that the VFR circling manoeuvre was part of "taking off or landing in accordance with normal aviation practice", you may not even have to satisfy Rule 5 in choosing the level at which you do so. But generally speaking, ATC is expecting the manoeuvring to be carried out under IFR, and must provide appropriate separation.

I have to take issue with martinidoc's example:

Consider my base airfield EGNT The AIP gives for a Cat A non-precsion approach NDB/DME 25 an OCH of 371 ft labelled for the procedure. However it also gives a VMC OCH for the total area of 534 ft.

Consider carrying out the procedure as an instrument-rated pilot. The MDH for the straight-in approach is 371 ft. The MDH for the circling manoeuvre is 534 ft. In descening on the IAP intending to circle to land on 07, you would not descend below the 534 ft MDH for circling, despite the lower straight in MDH. There's no question of climbing back up to 534 ft. If you need to descend below 534 ft, you should either be making a straight-in approach, or you should be going around.

The same principle should apply to an IMC-rated pilot. Because the increments are recommendations, I can't use the word must, but if you feel you need a 200 ft buffer for the straight in part of an instrument approach where you can focus entirely on the instruments, it would be very brave to abandon that buffer for the circling manoeuvre where your attention is split between the external environment and the instruments. Most commercial operators would regard this as the most dangerous stage of flight.

For what it's worth, the minimum obstacle clearance afforded by:

a non-precision approach with FAF is 246 ft
a non-precision approach without FAF is 295 ft
a visual manoeuvring (circling) area is 295 ft

You have a similar buffer between you and the obstacles in each case. If you're unsure of your ability to hold altitude, add something in each case.

[DFC]

Bookworm has it.

I can understand why there is a problem with the circling minima. It is because the explanation given in some text books get it wrong.

From a practical point of view, let's use Newcastle NDBDME 25 and assume that there is no approach available at the other end.

We will apply the recomended 200ft addition to the IR minima.

In this example, the IR minima are;

OCH 371 for straight in

OCH 534 for a circle to runway 07

That makes the IMC minima

OCH 600 for straight in; and

OCH 734 for a circle to runway 07

If we intend to circle, we will level at our OCH of 734ft. If we are not visual at the MAP, we will execute a missed approach.

The biggest reasons for not descending to the straight in minima and climbing back to the circling minima are;

a) We could be below the height of obstacles to the side of the runway; and

b) With the nose in the climb attitude, our view is reduced forward. i.e. Having spotted the runway ahead in a low wing aircraft, the last thing we want to do is a climbing right turn.

I would also recomend that pilot considdering a circling manoeuvre considder adding something to the visibility minima. Trying to circle at an unfamiliar field in 1nm visibility is hard work especially for the inexperienced.

Also be sure that one knows how to start the published missed approach procedure from anywhere in the circling procedure.

Finally, if using 600ft OCH, one will reach that height 2nm from the runway on a 3deg approach path. With 1800m visibility, one will not see the runway from that height until 1nm from touchdown. Can you safely land straight in using your aircraft starting descent from 600ft 1nm to the threshold in poor visibility. Try it VFR and see how hard it is! Note I am not saying that you should use 3600m but perhaps 1800m would be challenging initially. :)

Regards,

DFC

[Chilli Monster]

Martinidoc and Bookworm - I suspect you're agreeing with each other, just putting it in different ways. Consider carrying out the procedure as an instrument-rated pilot. The MDH for the straight-in approach is 371 ft. The MDH for the circling manoeuvre is 534 ft. In descening on the IAP intending to circle to land on 07, you would not descend below the 534 ft MDH for circling, despite the lower straight in MDH. There's no question of climbing back up to 534 ft. If you need to descend below 534 ft, you should either be making a straight-in approach, or you should be going around.

The same principle should apply to an IMC-rated pilot. Because the increments are recommendations, I can't use the word must, but if you feel you need a 200 ft buffer for the straight in part of an instrument approach where you can focus entirely on the instruments, it would be very brave to abandon that buffer for the circling manoeuvre where your attention is split between the external environment and the instruments. Most commercial operators would regard this as the most dangerous stage of flight.
Ok - let's take this example and instead of baffling each other with words let's look at it as a logical sequence of events.

IMC holder flies non-precision approach down to IMC minima (600ft QFE or OC(H) +200ft, whichever is the higher). At this point he looks up, sees lights and runway environment and continues visually for the circling approach.

(Let's forget IFR/VFR here, you're just confusing everyone with semantics).

Now, VM(C) is minimum ht. for the manoeuver. All this is is the level below which you must not descend until established on the final approach for the runway required to give safe obstacle clearance in the manoevering area. You are flying visually at this point, with reference to the altimeter only as a guide to make sure you don't descend below VM(C), the workload is high, but not impossible providing you look out of the window.

So - you fly according to VM(C) (not VM(C) +200ft, as long as VM(C) is less than the non precision MDH) providing you fulfill the criteria which is to remain in sight of the runway environment.

Obviously if VM(C) is greater than Approach minima then that becomes MDH, planning here is the name of the game.

At any point that you lose that visual reference to the runway you must execute the published missed approach procedure - no ifs, no buts.

[bookworm]

No, sorry Chilli, I'm not agreeing with that.

You seem to be agreeing with the AIP that IMC-rated pilots should add 200 ft to the obstacle clearance that they get from the standard approach minima. Presumably, this is because they aren't very good and holding their altitude while doing other stuff associated with the approach. OK.

But now we come to the manoeuvre that is probably the toughest thing we do in instrument flying, a feature that many pilots have found out the hard way, sometimes literally. It's sufficiently tough that many airlines ban it, or impose minima way above the statutory minima. It's an instrument/visual transition, with some fairly abrupt turns, at low level, in potentially windy conditions (where was that downwind turn thread?), with a crappy horizon, and instead of having a nice set of lights to aim at, we turn away from the lights. I'm almost tempted to say that if you haven't frightened yourself in a circling approach, you need to go and do some in nastier weather.

But for this suddenly the altitude holding gets easier, and the IMC-rated pilot needs only the same buffer as the instrument-rated one? I beg to differ.

[homeguard]

Snigs asked a simple question for fact. Personal limitations should always be taken into account but that is not his question.


In regard to VM(C) ICAO states that the minimum height above a runway or obstacle must be; for CAT 'A' aircraft no lower than 394'. The in-flight viz must be no less than 1nm. For each procedure the Height and Viz varies and is specific and published and must be complied with. Check the approach plate.

The manouvring area is defined by ICAO but the flown pattern is not determined although flight must remain within the published area. Therefore the circle to land may be achieved by flying through and joining for a downwind pattern or breaking right or left to a downwind, base leg or circling final approach. Perhaps a tear drop. A climb from MDH to VM(C) in order to do this is not prescribed. The pilot must at all times remain visual with the runway or its environment (lighting).

[bookworm]

I'm not sure, homeguard, that Snigs's was a question of fact. The 200 ft increment for IMC-rated pilots is a recommendation. Whether a 200 ft increment should be added to MDH for circling by a similarly rated pilot seems to me a matter of judgement, not of fact.

In regard to VM(C) ICAO states that the minimum height above a runway or obstacle must be; for CAT 'A' aircraft no lower than 394'. The in-flight viz must be no less than 1nm.

You appear to be reading a different version of PANS-OPS from me.

[FlyingForFun]

I'm following this thread with interest, having never done a circling approach.

Bookwork, your last post but one seemed, at first, to make a lot of sense. But then I got thinking.The IMC-rated pilot needs only the same buffer as the instrument-rated one? I beg to differ.Why? Because the IMC-rated pilot is less qualified?

Question (which I genuinely don't know the answer to, because I haven't done it yet): do IR students get to practice circling approaches? (If they do, I'd guess it's not always in the crappy conditions with no horizon and the barely-visible runway lighting that you're talking about, because how would the instructor ensure these conditions were available?)

If they don't, is there not an argument which says that the newly-qualified IMC-rated pilot is no worse-qualified to perform a circling approach than the newly-qualified IR holder? And that the minima should be the same for each? (Although obviously the IMC-rated pilot should acquire visual reference before descending below his (higher) MDA/DA.)

(This argument does not, of course, hold true for straight-in approaches, which both student pilots will have practiced during their training, but the IR student will have practiced right down to the lower minima.)

I'm just thinking aloud really, rather than agreeing or disagreeing with anyone... so what do you think?

FFF
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[DFC]

FFF,

The criteria are not set by how much practice was done during the training. They are set on the basis of the standards to which in general the pilots should be able to operate on a regular basis.

IMC pilots are not as qualified as IR pilots. 15 hours of training can not equate to 50 hours.

Both IR and IMC pilots are reminded to increase their minima if they are not current and the AIP tells us what being current means. Since few IMC pilots will make regular weekly IFR approaches in IMC to minima, to disregard the recomended 200ft increment seems questionable.
---

Chilli,

Are you saying that you do not add the recomended 200ft to the published OCH?

If that is true then you can use the absolute minima of 600ft provided that the IR OCH isn't more than that.

If however, you follow the CAA's advice and add 200ft to the published IR minima for the particular approach then why do you not follow your own criteria for another particular approach?

This would be similar to a pilot adding 200ft to say an NDB approach but not bothering for a VOR approach.

Perhaps your response highlights wht I believe to be one of the dangers of the current IMC minima. Too many pilots simply use 600ft non precision and 500ft precision without really taking into account all the requirments.

As for a circling manoeuvre being visual flying. It is true to say that navigation is by visual means but I can assure you that control of the aircraft is more than 50% by instruments until turning onto final approach.

Regards,

DFC

[homeguard]

Bookworm

The CAA words actually say "should" add 200' to the MDH/DH as published with 600'/500' as absolute minima for IMC rated pilots.

In all CAA definitions of the word "should" it is said to mean 'must'. Where have you read it is only a recommendation?

[Chilli Monster]

DFC Are you saying that you do not add the recomended 200ft to the published OCH?

If that is true then you can use the absolute minima of 600ft provided that the IR OCH isn't more than that.

If however, you follow the CAA's advice and add 200ft to the published IR minima for the particular approach then why do you not follow your own criteria for another particular approach?

This would be similar to a pilot adding 200ft to say an NDB approach but not bothering for a VOR approach. No - I'm not saying that at all and I'm well aware of what to add to the approach minima published - to the extent of editing my post to reflect that. Hope that clarifies matters - if not then you obviously have problems with the language which I can't be bothered to redress here.

[bookworm]

The CAA words actually say "should" add 200' to the MDH/DH as published with 600'/500' as absolute minima for IMC rated pilots.

In all CAA definitions of the word "should" it is said to mean 'must'. Where have you read it is only a recommendation?

The relevant wording is in AIP AD 1.1.2 para 3.3.2.1

"Pilots with a valid IMC rating are recommended to add 200 ft to the minimum applicable DH/MDH, but with absolute minima of 500 ft for a precision approach and 600 ft for a non-precision approach."

Where did your "should" come from? And where did you read the definition as 'must'? It doesn't seem to appear in the 'Interpretation' article of the ANO?

(My opinion on the recommended vs mandatory aspects of IMC-rated pilot minima have been set out in a number of different forums, and I don't want to drag it in here.)

Why? Because the IMC-rated pilot is less qualified?

Question (which I genuinely don't know the answer to, because I haven't done it yet): do IR students get to practice circling approaches? (If they do, I'd guess it's not always in the crappy conditions with no horizon and the barely-visible runway lighting that you're talking about, because how would the instructor ensure these conditions were available?)

An excellent point FFF. I have been asked to demonstrate a circle to land on several proficiency checks (IR-SPA-SE). AFAICS, it's not an obligatory part of the IR reval. And as you say, the weather rarely obliges with the necessary clag.

I do feel that someone whose instrument flying skills are "proficient" will make a safer job of a circling manoeuvre than a less proficient instrument pilot. Whether an instrument rated pilot is truly more proficient than an IMC-rated pilots depends on a lot of factors, including currency and experience. But if you're going to add these "cushions", it makes sense to add them for all IF-related critical situations.

[Tinstaafl]

FFF, speaking for Oz, circling approaches are a fundamental part of the IR training & flight test. They're used every day in Oz (perhaps less so now with the rapid rise in the number of GPS runway approaches available)

[DFC]

I had to search a bit but I have found a UK approach that could help with this discussion.

Have a look at the NDB approach into Gloucester.

The final approach track is not aligned with any runway and consequently only circling minima are published. i.e. This is a circling approach no matter what runway you intend to land on.

The published OCH is 649 if you intend to circle in one direction and is 899 if you intrend to circle the other way.

An IMC rated pilot is recomended to add 200ft to the published minima for an approach. That makes it 849 or 1099 OCH depending on the intended circling direction.

If one does not add the 200ft then one is using IR minima. The IMC rating does not qualify the pilot to make approaches to IR minima.

I hope that everyone agrees that one can not descend to 849 on the approach and then climb back to 1099 for the final circling element.

I also hope that every one realises that even at the OCH plus 200ft height of 849ft, one is too low to safely circle in the other direction.

Of course the fact that pilots flying VFR circuits at Gloucester may fly at 800 QFE for normal circuits and 500ft for a bad weather circuit but that has nothing to do with the minima for an instrument approach.

Finally, the time to decide on the correct OCH to be used is in the pre-flight planning. If this is not done then how can one decide what the weather (ceiling and visibility) requirements are?

Regards,

DFC

[Tinstaafl]

Damned easily.....in Oz! Every instrument approach there has an 'alternate minima' published on the approach plate. If either the ceiling or vis. is less than specified then an alternate is required. :ok:

[Snigs]

DFC

Have a look at the NDB approach into Gloucester.

This is my home base, so unfortunately I have to make a few slight corrections :\

The final approach track is not aligned with any runway and consequently only circling minima are published.

Not true I'm afraid, the published charts (amongst others) are for NDB/DME for 27 and 09, with the option of circling to the others.

So for 27 approach the OCA(H) is 600'(513) plus 200' for the IMC qualified pilot.

For a circling approach the VM(C) OCA is 1000' unless you circle north of 04/22 and 09/27 then it is 745'

So, and this is specifically why I was confused and hence I asked the question.

As an IMC qualified pilot if you intend to do the approach into 27 on the published procedure then you can descend to 800' (600+200), if not visible by the MAP then go around. But if you decide that this is a let down approach to circle north to land on 22 then can you descend to 745' before needing to go around? Or should the IMC minima for a circling approach be 945'?

You see the dilemma?

Of course the fact that pilots flying VFR circuits at Gloucester may fly at 800 QFE for normal circuits and 500ft for a bad weather circuit

For your info normal circuit height is 1000' QFE (bad wx 500')

[FlyingForFun]

Snigs,

I believe that DFC is refering to the NDB procedure (http://www.ais.org.uk/aes/pubs/aip/pdf/aerodromes/32BJ0805.PDF), not the NDB/DME procedure (http://www.ais.org.uk/aes/pubs/aip/pdf/aerodromes/32BJ0804.PDF).

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

[Snigs]

Ahh, ok point taken, sorry DFC.

My point on the NDB/DME approach still stands, though. Surely you must add 200' to the circling approach minima....???

[DFC]

Thanks FFF.

Snigs,

Absolutely. That is what I was trying to get people to beleive by using the NDB only procedure described. If only circling minima are published then people don't seems to have a problem with adding the 200ft.

However, some appear to be confused when they have a choice between a straight in approach or a circling approach.

To me, the 200ft is added to every minima. Otherwise it is hit and miss (and the hit can hurt in IMC!).

regards,

DFC

[homeguard]

Bookworm, my apologise to you. The wording is indeed 'recommend'. My reference is way out of date and I note that such words as 'should' appear to have dissappeared from the tomes, hopefully forever.

However, it is my believe that if a licence priviledge allows flight to a minima, either the system minima or 600'/500' as appropiate, then that is the standard that must be trained for and subsequently tested. A 'recommendation' follows subsequent to rating issue.There is no such recommendation to add 200' to the VM(C) and as some have already said it could be impracticable to do so.

It must always be the the correct action of a private pilot to set a increased personal margin of safety as they see fit without rancour from anyone. Although, as Instructors and Examiners we should ensure that the abilities following training and testing match the actual privilege the Pilot will have endorsed on their licence. To do anything else is patronising and leads to confusion which leads to accidents.

[DFC]

Homeguard,

If a pilot adds 200ft to the published minima for an approach. Why would they suddenly disregard their safe buffer when completing a circling approach?

The approach example I gave above only provides circling minima. Are you saying that if one completes an NDB/DME approach to Gloucester then one is recomended to add 200ft but if one completes the more difficult and less accurate NDB only approach, one would not add that same 200ft buffer.

Inconsistency can be dangerous.

Are you saying that IMC students should be tested to IR minima because if you don't permit them to add on the 200ft buffer then that is what you are doing when the OCH is 600ft or above?

As an IR holder the AIP details what being current means and makes recomendations with regard to approach minima. If I decide to add on 200ft/500m because I an not suficiently current, I will add it to all approach minima and most definitely includes circling.

In fact the AIP recomends that pilots who are not current should avoid making an instrument approach. This includes probably 75% or more of IMC rated pilots.

Regards,

DFC

[homeguard]

An Instructor or Examiner, I believe, has a responsibilty to ensure that at the time of training and testing the student is able to perform to the standards of the rating or licence to be issued.

The approach down the slope is IMC.The VM(C) is visual flight and the pilot therefore should be more than capable of safe flying that sector prior to landing. Indeed must be able to be.

The IMC Rating standards for the final approach make no allowance greater than that for an IR Pilot, other than the 600'/500' minimas. The ability between the IR and Non-IR Pilot to fly VMC, following the appropiate training, should not be any different.

Any common sense and safety caveats such as the 'CAA Recommends that...............etc'. It is my opinion that ..............etc. is an important but seperate issue - which too often evokes disprit and confusing arguement which cloud the real facts. Although I accept that, "out of the darkness comes the light" snigs clearly wanted to ensure that he told his student the full facts by asking the question for which he needed an answer. I'm sure snigs will as others, have the common sense to discuss with his student the wider issues.

It was clearly not decided by the CAA for it to be necessary to legislate for the IMC Rating standards tighter than they have. Others will have an opinion of their own. The excellent safety record of valid IMC rated Pilots over the years tells it's own story which is why the CAA tried so hard to sell it to the JAA.

[DFC]

An Instructor or Examiner, I believe, has a responsibilty to ensure that at the time of training and testing the student is able to perform to the standards of the rating or licence to be issued

I agree totally.

However, does one ever ask PPL students to operate to the flight manual figures for airfield performance or does one ensure that every student uses the recomended CAA safety factors?

The principle is the same.

If the approach has an OCH of 350ft then the pilot will use 600ft thus providing an extra 250ft safety buffer. However, as the height of obstacles increases, this extra buffer reduces meaning that with and OCH of 600ft the extra safety buffer is gone.

Would you use the CAA safety factors for landing on big airfields and then disregard them as the airfield got more challenging?

If not then why not use the recomended 200ft CAA addition?

The excellent safety record of valid IMC rated Pilots over the years tells it's own story which is why the CAA tried so hard to sell it to the JAA

Or one could take a slightly different view that while the IMC rating has prevented a number of scud running CFIT accidents, the number of VFR departures which due to poor planning had to make an unscheduled climb into IMC during the flight go unrecorded.

I agree that the IMC is a good rating provided that it is current and flights where it is going to be used are planned as IFR flights.

Regards,

DFC

[goddammit]

I think DFC pretty much nailed it on the 18 march:ok:
But with a minor exception, the circuit height at glos is 1000ft not 800.(one hopes snigs spotted this and merely elected to remain on thread!!) This should not detract from his otherwise excellent explanation.

I was a little confused by chilli on 17 march, won't the straight in minima always be less than the circling minima?
Incidentally, i think they all qualify as approach minima!

[homeguard]

DFC, our sentiments are undoubtably aligned, but!


You can of course control the minima to that which is RECOMMENDED by the CAA during the training of the student. However you cannot control the licenced pilot. The law does that.

If the CAA only recommend a minima it follows that while the recommendation should, on good advice, be followed the Pilot is under no obligation to follow that advice.

I'm sure that you would agree that many factors require a greater skill, technique and understanding the lower the minima flown during an instrument approach. If a pilot is legally able to fly the published minima then we should ensure that they are trained to do it safely. Applying common sense and the recommended limits must also be strongly advised.

We operate at a full instrument airport with 2200m of concrete that is 40m wide. We train our students to fly the correct speeds in accordance with the aircraft manual and land on the centre line, nothing less. Our land-aways are to smaller tarmac and grass uncontrolled aerodromes. The purpose is to ensure that the importance of flying to the correct standards is always understood.

The first class safety sense leaflets published by the CAA have a particular relevance where an aircraft manual provides insufficient information to the pilot. The CAA would not expect the leaflets to overide the aircraft manual.

In all seriousness, apply the factors required of JAR-OPS, being in most cases in excess of the aircraft manual, then many aircraft would not be able to take off and land from their base airfields. Netherthorpe perhaps being a good example. To train to JAR-OPS and demand complience will in many cases simply bring your good advice unfortunately but never the less into contempt. The expert in the bar will have a greator influence.

[FlyingForFun]

Homeguard,

The CAA recommend that you contact the controlling authority for permission before penetrating a MATZ. But there is no law to stop a licensed pilot blundering into a MATZ without talking to anyone. Are you suggesting that instructors should train students to do this, just because they are legally allowed to do so once they get their license?

IM(V)HO, instructors should train students to safely do things which they might be expected to do after they obtain their license/rating. In the case of an IMC rating, I don't believe that anyone would expect a newly-rate pilot to fly an approach to the legal minima, even though he is licensed to do so. But it is entirely reasonable to expect him to fly an approach to the recommended minima, assuming he is current. Therefore, that's what he should be trained to do. IMHO.

FFF
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[homeguard]

I would hope that no Instructor trains anyone to blunder into anything!

I would also hope that if you are an Instructor that you teach your students the facts in regard to the law and the status of a MATZ and in addition ensure that they, the student, have the ethics of good airmanship plus the knowledge of the correct MATZ penetration procedure - and any other recommended procedure, always at the foremost of their mind.

Teaching standards are an interesting, important and productive but arguable matter that have so far been instructive on this issue as well as being engaging. Infantile comments do little to assist.

[bookworm]

homeguard

I sincerely admire the sentiments that you've expressed. I agree it's important to train students for the realities that they'll face when they are licensed/rated and in the real world. There seem to be three different issues here:

1) What minima should you train IMC-rating students to?

There is no doubt in my mind that you serve them best if you train them to standard (IR) minima, and then instil in them the importance of a safety margin. That, I think, is quite analogous to teaching them short field landings in the minimum distance but making sure that they plan for field performance with a sensible margin for safety.

2) What are the legal IMC-rating minima?

Well I tried to stay away from this one :) but it is my opinion that both the 200 ft increment and the absolute 500ft/600ft MDH are recommendations. The IMC-rated pilot is legally entitled to pick the same DH/MDH as an instrument rated pilot. The 1800 m minimum visibility for take-off and landing is without question a mandatory licence privilege.

3) Should an IMC-rated pilot add 200 ft to circling MDH in the same way that he "should" for straight-in non-precision MDH?

This has to be a judgement call. My opinion is that it would be consistent to do so, though I note the counterargument (best put, I think, by FFF) that circling is a skill that is less likely to be differentiated in proficiency between an IR-pilot and IMC-rated pilot. Perhaps I'm just a chicken when it comes to circling approaches on dark and rainy nights. :)

[homeguard]

Bookworm, would you clarify the statement;

"but it is my opinion that both the 200 ft increment and the absolute 500ft/600ft MDH are recommendations. The IMC-rated pilot is legally entitled to pick the same DH/MDH as an instrument rated pilot."

The 200' bit is now well argued but the rest of your statement please, i'm curious.

[bluskis]

Sniggs

I am curious to know if, after such a lengthy set of opinions and answers to your question,you are more or less clear what the answer is?

[bookworm]

OK. Let me repeat what it says in the AIP as reference:

AD 1.1.2 para 3.3.2.1

"Pilots with a valid IMC rating are recommended to add 200 ft to the minimum applicable DH/MDH, but with absolute minima of 500 ft for a precision approach and 600 ft for a non-precision approach."

Many if not most people seem to interpret this word absolute as meaning mandatory, and thus that it is illegal for an IMC-rated pilot to use an DH/MDH lower than 500/600 ft respectively. I don't believe that is the intention, and I offer four arguments in support:

1) Lexical

absolute in the dictionary (e.g. COED) means not relative. The recommendation is in two parts: the incremental, relative 200 ft addition, and the absolute, non-relative 500/600 ft. There is no context in which absolute means mandatory or not advisory.

2) Contextual

Licence privilege restrictions are set out in Schedule 8 of the ANO. Among them, in Part B are explicit limits on the minimum visibility for take-off and landing and SVFR for IMC-rated pilots. If restrictions on DH/MDH were prescribed, they would be there, not in the AIP.

3) Historical

AD 1.1.2 derives its authority from Art 40 of the ANO, which enforces the specified (notified) DH/MDH for non-public-transport flights. Prior to the introduction of Art 40 (around 1990 I think) AD 1.1.2 (or in fact its equivalent in the RAC or AGA sections) had no legal enforceability for non-public-transport flights. Yet the same or similar wording (absolute) was used.

4) Logical

Interpretation of absolute as mandatory leads to the following absurdity. With an OCH for a non-precision approach of more than 600 ft, the specified MDH mandated by Art 40(3)(b) is clearly intended to be the very lowest MDH anyone would use on the approach, if the OCH were greater than 900 ft, using a MDH of 600 ft even with perfect accuracy would likely result in CFIT. If you regard the absolute in AD 1.1.2 para 3.3.2.1 as meaning mandatory, it overrides the absolute MDH specified elsewhere -- there is no mention of "600 ft or the IR-pilot's MDH whichever is higher". In fact the "whichever is higher" part is the intention of the juxtaposition of the two parts of the recommendation, the incremental and the absolute.

Whether it is smart for an IMC-rated pilot to use DH/MDHs below 500/600 ft is entirely another matter. But I contend that it is legal, on the basis of the case I outline above.

[homeguard]

Bookworm

I thought that was what your arguement would be and I for one cannot see reason why you are wrong.

The responsibilties of an Instructor and Examiner, as I see it, determine that we should think seriously about the standards to which the student/candidate is legally and lawfully permitted to exercise the privileges of their licence. We are legally bound to undertake our roles and responsibilies to them accordingly.

It may be that if as Instructors/Examiners we do not fulfil our function to train our student to the standards that they will later be entitled to exercise or subsequently test to the flying standards permitted it may be considered that we have, to put it mildly, fallen short of our professional duty to the student/candidate.

[bookworm]

I think you've hit the nail on the head, homeguard. There's a fine line to tread between instilling too much confidence in the student and not instilling enough competence.

The downside of teaching someone to fly ILSs to 200 ft is that they may believe they can do so by themselves in extreme conditions some 11 months after their last experience of instrument flying. If they do they're in for a rude shock. But I don't think you can regulate against stupidity. Let them try it in training.

I fully support teaching circling at the true circling MDH -- that was the way I was taught my IMC rating many years back. I just feel that students should be aware of the difference between flying a "bad weather" circuit at 500 ft on a nice calm summer's afternoon, and flying a night circling approach at an unfamiliar airport with a howling wind with scraps of cloud at or below MDH in poor vis after a non-precision approach. They're very different games, as you well know.

[DFC]

Perhaps there is a very good argument for the CAA to amend the rules for IMC pilots to something like;

Shall add 300ft and 1000m to all published approach minima.

Simple, unambigious and appropriate.

So if the minima are DH200, RVR800 (best for single pilot ILS), then the IMC pilot would use DH500, RVR1800m. Simple.

Regards,

DFC

PS, was not aware of the circuits height at Gloucester so used 800ft purely as an example. Thanks for the info that it is 1000ft. :)

[Snigs]

Thanks all for your input, an interesting debate, which has certainly opened my eyes to the various sides of the argument (particularly the legal issues).

In my earlier example (Glos NDB/DME Rwy 27) I suggested if you elected to commence an approach to circle and land on 22, i.e. a published OCA of 745' (no 200' added). However if you elected to commence an approach to land on 27 then the recommended OCA would be 800' (the published + 200')

Let's say the cloud base is at 770'. The wind is 245/10. (equal crosswind for both runways)

So, for the approach to 27 the IMC pilot would have gone around at 800' but for the circling approach the pilot could have continued, and landed on 22. (which in itself doesn't seem logical)

So, can the pilot, at say 750' change his mind and elect to land on 27, because that is the runway he's lined up on? Surely that would be safer, but wouldn't he then have "bust" the recommended minima...?

I hope that makes sense.... :confused:

bluskis the one thing I am sure of, it that this is not as black and white as I thought!! :)

goddammit I did mention the Glos circuit height in my earlier post

[bookworm]

Now you see why they're recommended... Don't confuse what's sensible with what's legal.

[goddammit]

snigs

So you did, i completely missed that post as i flicked through the thread.
So after all this, will you be teaching your imc students to add 200 ft to the minimum applicable DH/MDH as recommended atAD 1.1.2 para 3.3.2.1

or do feel, like some, that only applies to the straight-in approach??

[Snigs]

goddammit, the $64m question eh!!

I'm leaning towards a consistent approach. Do it for all.

A student will take in a blanket rule easier than the rule plus exceptions, however, if the student is eminently capable and switched on then.....

Like I said, it's not black and white anymore....:confused:

[DFC]

It is impossible for the circling minima to be lower than the straight-in minima.

Thus one could never end up in a situation wher the straight in minima was say 700ft and the circling minima was 600ft.

In an exceptional case, the circling minima may equal the straight in minima however, this would be unusal.

The reason why circling minima are greather is that the area considered for obstacles is much larger and displaced arround the runway. Thus in a totally flat terain, with absolutely no obstacles, if the och for a straight in approach was 700ft then the circling approach could in theory also be 700ft but it could not be less.

Does that explain the situation?

Regards,

DFC

[goddammit]

DFC

I am almost certain i agree with you on this topic, i only started to get confused on the whole issue when i started reading this thread.

Once an imc individual has the IR pilots MDHs for straight-in and VM(C) approaches, why would they elect to add the recommended 200' to one and not the other? I accept it's a recommendation, but surely one is either going to ignore it or follow it. :{

[homeguard]

CAP507 while recommending that the IMC Pilot adds 200' to the approach minima together with the 500'/600', it is specific that such a recommendation does not cover the VM(C). For the simple fact that while on your approach within imc your only reference is to your instruments and radio indications, the work load is high. Circling to land you are visual and therefore can be more certain of maintaining the required flight path and not hit anything.

A major reason for confusion here is that so many wish to interpret the rules in a way that they wish it to be. There are no shortage of comments to the effect that; an IMC rated Pilot is not as good as a IR Pilot and so must add the 200' for that. Rubbish, the same standards applied to flight in imc for the IR and IMC Pilot are the same.

The 15 hour IMC course is a minima not an absolute. The hours required to train are those required to meet the standards. The major differences between the IR and the IMC are of course the exams, airways flight (so what) and most effectively the requirement to train and demonstrate RADAR,ADF and VOR/ILS procedures within the one test.

The IMC course may be completed using only ADF/Controller Procedures or VOR/Controller Procedures or VOR/ILS/Controller or Controller Procedures alone, RADAR if there is any, make a choice. The IMC test only requires that one procedure is examined.

The length of the IMC course reflect these differences. The duration of the training should not be a compromise. It cannot be acceptable that the standards trained to are good enough only for the higher minimas but not good enough for the full procedure to which they will be licenced! "Look mate don't think that what we have just trained for is anything that you should really consider doing in real life - it's a get yourself out of trouble thing, that all". That kind of scenario cannot be correct.

The addition of 100' increments for lack of currency and practice is recommended to all Pilots, IMC or IR holders.

Whatever I have said throughout this debate, Safety, of course, is paramount!

[BEagle]

Since the lowest recommended MDH for a non-precision approach flown by an IMC rated pilot is 600ft, I examine their ability to fly a bad weather circuit at 600ft on the IMC Rating Skill Test. Normally one would reach MDA/H, maintain it until reaching the missed approach point (unless you are one of those airliner drivers who insists on treating MDA/H the same as DA/H by going around immediately upon reaching it if they don't have landing criteria), then carry out a missed approach if visual criteria have not been achieved. For the test I get the applicants to fly a radar-vectored ILS to assess their ability to work with ATC, monitor their position and fly a good approach - then to carry out a go-around. I then position the aircraft where I want at 600 ft in the bad weather configuration whilst the applicant doffs the foggles (I refuse point blank to use those damn dangerous tin screens so beloved of CAA IREs) - then I task them to fly a 600 ft bad weather circuit to land.

[homeguard]

Sounds good to me BEagle!

[vfrflyer]

CAP507 while recommending that the IMC Pilot adds 200' to the approach minima together with the 500'/600', it is specific that such a recommendation does not cover the VM(C).


so does it differ from the AIP which says

add 200 ft to the minimum applicable DH/MDH

which doesn't distinguish between the MDH for straight in approaches and the MDH for Visual Manoeuvring(circling) approaches?

[homeguard]

VM(C) is seperate from the Minimum Descent Height/Decision Height which pertains to the approach only.

VM(C) is often higher than the MDH/DH owing to the fact that obstructions not affecting the approach profile or Missed Approach Procedure are to be considered when circling.

[vfrflyer]

VM(C) is Visual Manoeuvring (circling)

MDH is minimum descent height.

Is the MDH not calculated using the appropriate OCH, which if one where going to be VM(C) would be the VM(C) OCH that appears on the approach plate?

Surely that must be the case. Otherwise, how would an individual calc an MDH for , say, the procedure sniggs used, the gloucestershire NDB(L) AERODROME, which only has VM(C) OCA (OCH AAL)???:E

[homeguard]

vfrflyer

Of cause they can be the same but not always, as I stated;

'VM(C) is often higher than the MDH/DH owing to the fact that obstructions not affecting the approach profile or Missed Approach Procedure are to be considered when circling.'

An obstruction affecting the approach profile may not also affect the area designated for circling. The circling areas around an airport may differ N,S,E or west and anywhere in between. i.e. An obstruction to say the west of an airfield may not affect circling to the east of it. Therefore the VM(C) area's surrounding an airfield may also differ, one from another.

[vfrflyer]

I am not saying they are the same.

When carrying out an NDB procedure one will have preplanned an MDH, whatever one's intentions may be.
If one intends to land on a suitably orientated runway from a straight-in approach this MDH will be calculated using the OCA.
If one intends to visually manoeuvre then this MDH will have been calculated using the VM(C) OCA.
In both cases one must have an MDH.

It is then a matter of deciding whether one wishes to follow the recommendation and add 200'.


VM(C) is an action, MDH is a minima therefore they are
;)never the same thing.

[homeguard]

vfrflyer

You appear to answering your own question. Interpreting the law is difficult enough. If we start getting into semantics we will be doomed from ever getting clarity, however long the debate.

[vfrflyer]

I'm not getting into semantics.

I am disagreeing with your view that the 200' recommendation only applies to the MDH for straight in approaches.

It is a recommendation to apply to ALL MDHs.

Is the MDH not calculated using the appropriate OCH, which if one where going to be VM(C) would be the VM(C) OCH that appears on the approach plate?

Surely that must be the case. Otherwise, how would an individual calc an MDH for , say, the procedure sniggs used, the gloucestershire NDB(L) AERODROME, which only has VM(C) OCA (OCH AAL)???

[goddammit]

vfrflyer

As far as the UK AIP goes you are absolutely correct. Unless the CAP 507 is different, homeguard wrongly believes the recommendation only applies to straight-in approaches.

I can't imagine how he would come up with a MDH for the glos NDB, as he doesn't seem to use the VM(C)OCA to calculate his approach minima!!

Oh, and do let him repeat himself, it gives me something to laugh at:ok: :D :D :D

[Chilli Monster]

Would someone actually like to 'quote' the CAP507 for those of us who don't have it and put us all out of our misery! Otherwise this is just going to be b:mad: y tedious!

[homeguard]

I don't know Gloucester but I've looked up the NDB(L)DME RWY 27 procedure.


The OCH for the approach is 513',

VM(C) (OCH AAL) Total Area - 899' but to the North of RWYs 04/22 and 09/27 - 644'.

The only MDH that i've heard of in association with and following a circling approach is concrete.

Ciders good in Gloucester then!

[vfrflyer]

The reference was to the NDB not the NDB/DME.
What would you base your MDH on for the NDB? Because of course, you wouldn't fly an NDB approach without having an MDH otherwise you wouldn't know when to stop descent without the required visual reference!!

[DFC]

Homeguard,

I pray that you don't have an IMC.

You said;

VM(C) is seperate from the Minimum Descent Height/Decision Height which pertains to the approach only

and

An obstruction affecting the approach profile may not also affect the area designated for circling

and

The only MDH that i've heard of in association with and following a circling approach is concrete

If you are doing an approach where you intend to circle. At what height will you stop descending and if not visual execute a missed approach. The procedure designers call that height the MDH.

Look up the definition of MDH.

How can you say that an obstruction affecting the straight in approach does not affect the circling approach.........how could you continue the approach to the missed approach point and then circle if the procedure designer had not considered all the obstacles?

All this talk of circling seems to come from people who have never done it. Circling is far harder and more prone to CFIT than the straight in approach. That is why professional pilots try to avoid doing them.

During the circling manoeuvre, you may be navigating visually i.e. there are no non-visual aids to guide you but that does not mean that you can fly the aircraft visually since there will be little or no natural horizon reference and having left the final approach track, one no longer has approach lights to provide both lateral and longitudinal reference.

There is also the high probability that one can loos the visual reference and must execute a mussed approach - not good if you are folling homeguards system of scraping the concrete somewhere outside the airfield perimiter.

---

BEagle,

Airlines who use the stabilised constant descent approach on non-precision approaches as opposed to the dive and drive method do not use the MDA(H) as a DA(H).

While the DA is the point where you descide and the precision procedure includes an amount of descent below that height during the initiation of the MAP, the same can not be said of the MDA(H) on a non-precision approach.

For info, when using such a profile, the procedure will use a height above the MDA(H) so that the descent during the initiation of the MAP does not take the aircraft below the MDA(H).

If IMC pilots were to use that procedure, they would require 3600m visibility or more for non-precision approaches otherwise they would nexver see the runway from 600ft.

Of couse the airlines can not use that procedure for circling approaches since there is always going to be the drive element during the circle to land.

Regards,

DFC

[homeguard]

DFC

The MDH is as I have said, it is the approach minimum height following a descent within a non-precision approach prior to becoming visual. Circling is undertaken when visual and will have it's own minimum height and is flown at a constant height until the point is reached, determined by the pilot, to descend further to land.

The concrete to which I refer is the runway for although circling is flown at a constant height you must at some time descend for landing. My little attempt at some humour obviously fell on stoney ground.

Different sectors around an aerodrome may have different minimas not coincident with the instrument approach path. Gloucester, as it has been mentioned, is one of those.

I don't see your problem with that.

[vfrflyer]

Homeguard,

what approach minima would you use for, say. the gloucester NDB approach? (not the NDB/DME)

[goddammit]

DFC

How right you are about homeguard, especially if you read his contributions on the 'visibility' thread.

As for this thread, vfrflyer has been trying to steer homeguard in the correct direction, but homeguard just ignores the questions.

What can be done with such people??:{

[homeguard]

goddammit

All I can do for you is say this, since rudeness is your meter, and qoute Freud.

You are born with two eyes, two ears and one mouth. Use them in that proportion and the world will be a better place.

[goddammit]

:O :O :{ :{

HOMEGUARD !!

You have repeatedly demonstrated your ignorance of the principles of approach minima, refusing to 'use your eyes' to read the appropriate literature or follow the guidance of VFRFLYER and DFC, deciding instead to repeatedly voice your uneducated views.

Take your own advice:ok: And do some bookwork!!

It's ignorant people with your attitude that are destroying the reputation of private flying, and that irritates me no end!

[pilotbear]

Homeguard,

HA HA, :O as usual when people on here have their views (usually exRAF) challenged, whether you are right or wrong, they resort to personal insults or implied bad language.....as for ironic humour...it goes over their heads - (probably at circling altitude)

Simple safety...add the 200' to all minima unless you are very sure of your ability. :ok:
All the IMC and IR students I have taught can do low level 'bad weather' circuits holding their altitude exactly remaining within 1500m of the rwy. Why? because I make them do it at every opportunity, and flying at low level in poor vis is probably what the average IMC pilot is going to try and do whatever you recommend.
You are right; some airports do have different circling minima depending on which side you are, If you have planned a circle to land then your Circling Altitude becomes your MDA. You should not descend from circling minima until on final approach. :ok: