IMC Uncertainties

[Callsign Kilo]

I am an IMC rated PPL holder who is hoping to clear up a few uncertainties that I have regarding the rating. The way that I look upon the rating is that it provides greater piece of mind to the private pilot by increasing the priviledges of his/her licence. However where I am unlcear is how does flying under 'IFR' work with an IMC rated pilot?
I know the rating is restricted to the UK, however in what way is it practiced? Can you file IFR flight plans, even though you cannot fly in airways? Can you upgrade to IFR from VFR if the weather starts to get below VFR minima or if you need to decend through cloud to get into an airfield? What are the DH/MDH minimas for an IMC holder. For my test I was told to add 500 ft to the published minima + the Pressure Correction error for my aircraft. Does this still apply?

I would be grateful to anyone could help to clear up my issue. Many thanks

[stuartforrest]

As far as I am aware the answers are yes you can file and yes you can upgrade and the decision heights are not plus 500ft but down to a minimum of 500ft (200ft on IR) I think but that depends on the airfield as some will be higher.

I am sure I will get roasted now off the experts but it is pretty much something like that.

[JUST-local]

The holder of an IMC rating can fly IFR in uncontroled airspace and controlled upto class D. You can file an IFR flight plan or request an IFR clearance on route if you know what you want and ensure you are not directed through/via an airway or airspace above class D.
When I initially trained for the IMC rating I was told minimums of 1800 meters viz for departure and a cloud base not less than 700 feet? I think, Minimum for an approach procedure I was told was 700 feet for a non precision and 500 feet for a precison approach.
However another examinar told me that this was not in the air navigation order so was only advisory and you could effectivley use lower minimums if required, (he also said don't be a fool and ensure you are in current pracise, aircraft is properly equiped etc.) but I am unsure where the definitve answers can be found, hopefully someone can put a link up!

[Fuji Abound]

CK - I regret that these issues were not covered during your IMC training - becasue they should have been. Unfortunately this would seem too often the case.

There is a suggestion from your post you may not be clear on the difference between IMC and IFR. Any pilot can conduct an IFR flight however for that flight to continue into IMC then the pilot must have an IR or IMC rating.

You can file an IFR flight plan within the UK which may include flight in IMC and you can change from visual to instrument flight rules in flight because you have entered IMC.

Your landing minima are the same as the minima for IR holders (although this has been widely debated and there are those that would disagree.) Whether you should operate to these minima is another matter.

The rating is restricted to the UK but it does "lift" the requirment to remain in sight of the surface outside the UK - commonly know as VFR on top.

You are entitled to operate in IMC in all UK classes of airspace except for all types of class A.

Flying a solid IMC sector with an approach to or near minima followed by a possible diversion is not something the IMC rating has probably trained you to do safely (although it is within your priviliges) but there are many IMC rated pilots who with further training and experience do exactly this.

[rustle]

Originally Posted by Fuji Abound

Your landing minima are the same as the minima for IR holders (although this has been widely debated and there are those that would disagree.) Whether you should operate to these minima is another matter.

You are entitled to operate in IMC in all UK classes of airspace except for all types of class A.

Er, no and no

You can fly down to IR minima cloudbase (but are advised by AIPs/Thom etc. to add 200' to any "IR minima").

You cannot land or take off if the viz is less than 1800 meters. (Whereas single pilot IR can takeoff in 0 and land in 800)

IFR (or IMC, which implies IFR) up to class D only. Not classes C, B or A.

[Fuji Abound]

Of course you are correct Rustle but CK asked about DH not landing viz.

I guess there is some C and B airspace in the UK but I have yet to come across it.

[FlyingForFun]

Callsign Kilo,

From your post, it seems there are some very large gaps in your knowledge. This is a pity, and my guess is that the root of the problem is that you were taught to pass the IMC test, rather than fly in IMC - probably by someone who believes the rubbish that an IMC rating should only be used to get you out of trouble.

To answer your questions as fully as I can on a forum like this:

However where I am unlcear is how does flying under 'IFR' work with an IMC rated pilot?

In the UK, you may fly IFR outside controlled airspace, using any combination of approved navaids. Probably the most common navaids for en-route navigation are VOR and GPS. You must comply with the rules of IFR flight - that is being 1000' above the highest fixed object within 5nm, and following the quadrantal rule if above 3000'. Assuming your aircraft has minimum level of equipment as required by the ANO, you can ask for, and may get, an IFR crossing of Class D/E controlled airspace such as control zones or control areas, but most of your en-route flying will take place outside of controlled airspace, where you should make use of whatever radar services you can get if you are in IMC.

I know the rating is restricted to the UK, however in what way is it practiced? Can you file IFR flight plans, even though you cannot fly in airways?

You can file a flight plan for any flight. You must file a flight plan if you are crossing the UK FIR boundary, and also if you plan on flying on airways. You are recommended to file a flight plan if flying in remote areas or over large bodies of water. You can file a flight plan for any other flight if you wish. As an IMC-rating holder, you do not need to consider flight plans any more than you did as a basic PPL holder. What I mean by that is that, if you are flying to France, you would have to file a flight plan whether you plan to use your IMC rating on the British portion of the route or not. On the other hand, if you are flying from Cranfield to Shoreham, you do not have to file a flight plan if you are flying VFR (although you may if you want), and you also do not have to file a flight plan if you are flying IFR (although, again, you may if you want).

Can you upgrade to IFR from VFR if the weather starts to get below VFR minima or if you need to decend through cloud to get into an airfield?

Yes. Outside controlled airspace, you can switch between IFR and VFR as often as you like, without having to inform anybody (although you might like to ask for, or cancel, a radar service). Inside controlled airspace, your clearance will be either VFR or IFR, and you must inform ATC if you wish to change flight rules.

Having said that, with limited experience, trying to plan an IFR route (or even half a route) on the hoof is not to be recommended. If there is even a slight chance of the weather being IMC, I would suggest planning the whole flight as IFR right from the start, then downgrade to VFR during the flight if appropriate. As you get more experience, you will become more comfortable with the idea of upgrading to IFR part way through a flight with minimal prior planning.

What are the DH/MDH minimas for an IMC holder. For my test I was told to add 500 ft to the published minima + the Pressure Correction error for my aircraft. Does this still apply?

I hope that's a typo. The recommendation is to add 200' to the published minima (plus PEC for a precision approach), and then to round this up to a minimum of 500' above ground for a precision approach, or 600' above ground for a non-precision approach. (If you prefer to fly instrument approaches on QNH - probably the most common scenario - rather than QFE, this takes a little bit of maths.) This is just a recommendation, but one I would suggest you stick to until you have more experience. (In any case, if you are flying a single-engine aircraft, would you really want to be flying if the cloudbase was below 500'???) This is described in detail in both the AIP and Trevor Thom book 5.

However, Fuji is wrong when he says "Your landing minima are the same as the minima for IR holders". [Edit to note that Rustle got in before me in spotting this.] Although the increase DA/MDA I've described above is just a recommendation, the increased visibility for IMC ratings vs IR is mandatory. It is 1800m for both take-off and landing. In the case of landing, what this means is that, on an approach, you may not descend below 1000' agl if the vis is less than 1800m. However, once you have descended below 1000', if the visibility subsequently deteriorates to below 1800m, you may still continue the approach, and you may land if you have acquired the necessary visual reference before DA or MApPt.

I hope that helps, but it really does sound, from your post, that you have been left with big enough gaps in your knowledge that you really need to spend some time with a competent instructor and/or experienced IMC-rating holder before attempting to use the rating in anger.

Good luck in acquiring the necessary knowledge, and using your rating's privileges!

FFF
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[Callsign Kilo]

Thanks to everyone who has helped me out here!! Some valuable knowledge has been gained!

FFF and Fuji, I would admitt yes, I realised a bit of a void was left after I got my rating. I understood what was required to pass the IMC test, and I would also like to say that under the guidence of my instructor I was prepared to do this to a good standard. Practicing in the aircraft, along with the use of Flight Sim (plus the added benefit of my ATPL Radio Nav Textbooks) helped me get to grasp with the IMC course and impress the examiner enough to pass the skill test.

Whilst I would never look to intentionally use my rating in anger, I never actually know when it may or could be called upon. It has given me a little bit more confidence and piece of mind in my flying and has provided me with an appreciation for what is involved in the IR course (which I intend embark upon very soon). However as rightly noted, I didn't really have the knowledge of what a private pilot is entitled to with the IMC!

I am looking forward to investing a little time in refreshing my skills with an Instructor at my local club. It won't do any harm! Thanks once again

[IO540]

Oh dear this is going to be a long thread

I know the rating is restricted to the UK,

The IFR privileges are limited to UK only, but the removal of the requirement to remain in sight of the surface when flying under VFR is valid worldwide (I have this in writing from the CAA).

however in what way is it practiced? Can you file IFR flight plans, even though you cannot fly in airways?

Yes, though it is fairly pointless except for search/rescue purposes. An FP is mandatory only outside the UK, but you can't fly IFR outside the UK.

It's possible to file IFR flight plans with a route that keeps you below Class A but the UK doesn't really have a meaningful "system" for that, other than addressing such an FP like it was a VFR one, i.e. nobody en-route knows about you and you don't get any clearance into CAS other than what you are permitted as you progress along the route. The UK also has no enroute ATC service below the airways (mostly Class A) that is of any value; you can get a radar service from bits of LARS here and there but that's more or less it. So - if you still really want to file a flight plan - you may as well file a VFR one and then change to IFR when you feel like it (or when you see IMC ahead).

Perhaps the best use of filing an IFR FP is if you are heading for a major airport (in Class D or lower, obviously in your case) to land with an instrument approach; they will be more impressed than if you just turn up VFR and ask for an ILS - in fact some like Cranfield will refuse the ILS if the weather is actually VMC.

IFR flight plan filing is a big science / black art and if you get too smart and try to file an FP which looks like an airways one but is in fact below Class A, and that FP gets addressed to Eurocontrol (which controls airways routings in Europe) then it all gets very messy. In the UK, the Class A service is totally separated from all the dross flying below and they will assume you have an IR and can just send you off into Class A, and get totally confused if you refuse. The IMCR is to be used and enjoyed to get from A to B while legally drilling holes in clouds, not for flying pretend-airliner routes

Can you upgrade to IFR from VFR if the weather starts to get below VFR minima or if you need to decend through cloud to get into an airfield?

Yes, in the UK, outside CAS (OCAS), the VFR v. IFR state is entirely in your mind and you can change anytime. You can fly non-radio too! The only time it really matters is if you enter Class D; then you need clearance for a transit which will be authorised according to what you ask for (VFR or IFR) and you need to be clear about that.

In general you are more likely to get a radar service if you call up some radar unit as "IFR" But slick radio will also help.

What are the DH/MDH minimas for an IMC holder. For my test I was told to add 500 ft to the published minima + the Pressure Correction error for my aircraft. Does this still apply?

No, that's standard CAA disinformation. It's a recommendation, like so many things that take up bandwidth on pilot forums. The law (the ANO) does not restrict an IMCR holder over an IR holder on the minima. You need 1800m+ vis for departure or landing (or better if the aerodrome has its own vis minima). There are some extra SVFR privileges over a plain PPL but I never (knowingly) use SVFR so I don't know them.

Now, to fly an ILS down to 200ft you need to be pretty good and current, not the usual UK 10 hours/year average PPL (or whatever it is), as well as flying something a whole lot better than the standard piece of rental junk in which half the panel is duff - but we are talking legality here, not practicality

When you ask for an IFR clearance through some bit of airspace, on occassions you will be offered a transit through Class A. You have to refuse that with something like "unable to enter Class A" - they will then realise you have an IMCR and not an IR. This is rare however.

From your post, it seems there are some very large gaps in your knowledge

His instructor's knowledge, evidently.

you may fly IFR outside controlled airspace, using any combination of approved navaids

There is no specification on how navigation must be done, on private flights in the UK (or anywhere else I know of), VFR or IFR. It's true that IFR pilots tend to use GPS backed up by navaids i.e. VOR/DME and ADF and plan the route to use these as much as possible.

You must file a flight plan if you are crossing the UK FIR boundary

Perhaps worth a mention that one doesn't need an FP between England and Scotland for example, even though one is crossing an FIR.

and also if you plan on flying on airways

You must mean the very few bits of airways which are in Class D.

Would ATC treat that as an airway or as just a piece of Class D into which somebody who has just appeared (don't forget the IFR FP will not generally be addressed to enroute ATS units) has asked for transit of, along a route which just happens to be an airway higher up?

For Class D, no need for a filed ICAO FP. The IFR clearance request/granting is equivalent to filing an airborne FP. (One can do that for Class A too, on some occassions, with a full IR).

The plane needs to carry quite a bit of working equipment to be legal for IFR in CAS. I am sure the majority of rental spamcans are illegal for IFR in CAS.

As to realities:

I would suggest planning the whole flight as IFR right from the start

IMHO it is sensible to plan every A-B flight as IFR, and regard VMC enroute as a bonus

One nice advantage of flying IFR is that ATC doesn't ask you to go to some VRP which nobody except the local sheep farmer knows where it is (the "Nokia Factory", etc). You can navigate using IFR waypoints: navaids, airways intersections.

Whilst I would never look to intentionally use my rating in anger

Why not? You have the legal privileges; you paid for them, so use them. A bit at a time, with another experienced pilot perhaps, then some more. All those old farts who say it is a "get you out of trouble rating" etc etc should be drawing their Civil Service pensions by now.

[DFC]

Originally Posted by FlyingForFun

Although the increase DA/MDA I've described above is just a recommendation, the increased visibility for IMC ratings vs IR is mandatory. It is 1800m for both take-off and landing. In the case of landing, what this means is that, on an approach, you may not descend below 1000' agl if the vis is less than 1800m. However, once you have descended below 1000', if the visibility subsequently deteriorates to below 1800m, you may still continue the approach, and you may land if you have acquired the necessary visual reference before DA or MApPt.

FFF,

You seem to have confused the approach ban and landing minima. They are two separate things.

An IR holder requires the RVR to be above the applicable minima before commencing an approach or descending below 1000ftAAL. If after passing the 1000ftAAL or equivalent point the RVR reduces, the IR holder can land provided that at DA or MDA, they have the required visual references. Thus the IR holder while limited in RVR to commence an approach can actually land in any RVR provided the visual references are available.

The IMC Rating holder on the other hand is also limited by the requirements of the approach ban (note some approach minima may be greather than 1800m RVR eg circling). But the IMC rating holder is also legally required by the ANO to have 1800m to land.

Thus for the IMC holder, the RVR reducing below 1800m even when below 1000ftAAL will require that a landing is not made.

In fact should the IMCrating holder become "visual" at say 1000ft but find that the flight visibility below cloud is only 1500m then since they do not have 1800m, they can not legally land despite perhaps having the threshold in sight.

Regards,

DFC

[IO540]

You are probably right, DFC, but the 1800m min for the IMC pilot is reported met visibility, IIRC. The pilot himself has no way to tell if vis is 1000, 1500 or 2000m.

This figure is unlikely to change from say 2000m to 1500m as he descends down the approach.

It might do, but would the new value be reported to the pilot on his way down?

Also there won't usually be a reported vis at a non-ATC field. This brings us to the subject of DIY instrument approaches (which are legal)...........

So I don't think this is a practically enforceable detail.

[FlyingForFun]

Interesting, DFC. I have to admit I never thought of it that way.

The relevant part of the AIP - AD1-1-6 - is not on-line, so I can't check right now. If I get a chance at work today, I'll look up the exact wording.

FFF
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[DRJAD]

Originally Posted by IO540

and also if you plan on flying on airways
You must mean the very few bits of airways which are in Class D.

I believe there is some confusion amongst some, who refer to Class F Advisory Routes as (pseudo) airways. One can, of course plan as an IMCR holder to fly on these.

[IO540]

Does anybody actually use VFR advisory routes in the UK? It seems utterly pointless. Any pilot should be able to get the map out and plan a route which is outside Class D. One needs nothing less, nothing more. Sometimes a transit of D is worth asking for, but if one doesn't get it then one has to fall back to the original plan.

It's different outside the UK (where CAS transits of C or D are generally much more freely given) but an IMCR holder can't fly IFR there anyway.

[bookworm]

Originally Posted by IO540

Does anybody actually use VFR advisory routes in the UK?

Who said anything about VFR advisory routes? Class F routes are helpful in providing separation for particpating IFR traffic.

[IO540]

Sorry bookworm I misunderstood. I just don't recall ever seeing class F routes anywhere.

[DRJAD]

Try Scotland!

[FlyingForFun]

Earlier, DFC discusses whether the 1800m visibility restriction for an IMC holder is to be interpreted as being applied for the purposes of the approach ban in the same way as an IR-holder would use the published minima, or whether the restriction applies even once an IMC holder has passed below 1000' on an approach.

I couldn't find anything in the AIP, but I did find the relevant legislation in the ANO.

Schedule 8 Part B contains the privileges of the IMC rating. Included in this is the following:

(2) The rating shall not entitle the holder of the licence to fly:

(b) when the aeroplane is taking off or landing at any place if the flight visibility below cloud is less than 1800 metres.

Note that it does not ban you from taking off and landing; it bans you from flying under certain conditions.

The legislation relating to the approach ban for non-commercial aircraft is in the AIP, and it's also in the ANO Part 5, paragraph 49(4):

(4) Without prejudice to paragraph (2) 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.

I don't think there's any doubt that the 1800m is "relevant", although it is a vis, not an RVR, so might not apply for the purposes of the approach ban? Also, I don't see anything in the approach ban which would override the general ban on flying when landing in less than 1800m vis.

So, in conclusion, I'm not really sure, but I think DFC is probably right. But, as IO540 says, it's completely academic in any case.

FFF
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[rustle]

Originally Posted by FlyingForFun

So, in conclusion, I'm not really sure, but I think DFC is probably right. But, as IO540 says, it's completely academic in any case.

FFF
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I don't believe it is academic:

Class D airport, say Bournemouth for example.

IR pilot cleared on an approach passes through height 1000' descending, ATC may pass further viz/RVR and even if they do and it has dropped below 800m the pilot may continue the approach.

IMC rated pilot cleared on the approach passes through height 1000' descending, ATC may pass further viz/RVR and if it drops below 1800m the pilot must go around.

[IO540]

I think the real issue with the 1800m is for departures from an ATC airfield. The conversation gets recorded and also lots of people routinely listen in on handheld radios, including those who know you only have the IMC Rating

That said, I have never heard of anybody getting done. There must be bigger fish to fry.