IMC in practice

[picky]

Can anyone offer some example uses of the IMC rating, in particular with airfields which don't have ILS or even any radio navigation aids? For example, if you're planning from flying from airfield A to airfield B but it is overcast at 1000ft would this be possible with an IMC rating even if the destination doesn't have ILS?

Incidentally, I've been reading the IMC diary by OBS Cop and others which has been most enjoyable and informative reading - well done chaps and keep it up.

[2Donkeys]

If you are confident that airfield B can be approached and landed at whilst maintaining VMC, then you could certainly do that.

If you are going to find yourself in cloud as you approach B, then you are going to need some form of approach aid to get you below MSA for a visual approach.

[picky]

Can't you simply position yourself above the airfield using radio navigation aids and then 'drop' down into the circuit?

Can an NDB used as an approach aid?

Say for example your destination was Caernarfon just west of Snowdonia with an MSA of 4,800ft. If there was a low cloud base would you still be able to land there?

[tmmorris]

One thing I've found it very useful for this winter, with lots of inversions trapping cr@ppy viz, is to shoot an ILS in visibility of 4000-6000, when VFR is possible & legal but not much fun or very safe; an ILS is much easier.

Tim

[Chilli Monster]

Say for example your destination was Caernarfon just west of Snowdonia with an MSA of 4,800ft. If there was a low cloud base would you still be able to land there?


First - go do some reading. CAP393 (ANO and Rules of the Air) Rules 28 to 32. Minimum Height Rule especially

If you were over the sea, and knew you were over the sea, then no reasons why you shouldn't descend to 1000ft amsl.

The beauty of the IMC rating is it gives you options. If you can't get into the original destination (for example, Caernarfon) there's nothing to stop you :

a) asking Valley for an instrument approach and then, once VMC below continuing VFR to destination

b) if the weather is that bad that you can't achieve the above then you just land where you did the instrument approach and continue to original destination by road.

It also gives you reduced VFR minima, and allows you to fly on top - both extremely handy.

As for 'dropping into the circuit' - if you get down to 1000ft above the airfield and you still can't see the ground then - how much further are you prepared to descend? How do you know what the cloudbase is? Are you certain you know the surrounding terrain sufficiently well to continue lower?

CFIT will always be a killer :uhoh:

[IO540]

The great thing about the IMCR is as CM says - it gives you options. It gives you the IFR option, which in the UK is priceless. If you planned flights say 3 days ahead at random, you'd have to cancel perhaps 50% of them if you had to fly VFR (maybe less in the summer, nearer to 95% in the winter).

With an IFR option, this might fall to somewhere between 5% and 20% depending on whether you fly to airfields with an ILS for example.

The limiting factors that remain are

Currency (costs time and money)
Availability of a decent aircraft (costs money)
Icing conditions in IMC and below the MSA

and.....

Picky has picked on the #1 problem with instrument flight in the UK: the majority of airfields don't have official instrument approaches.

If the destination has

1) a confirmed cloudbase 1000ft AGL (say there is an ATC airfield 10 miles away, the weather is uniform, and you get their ATIS) and

2) there is no terrain for miles around and

3) one can do a position fix using at least TWO completely independent methods (of which a moving map GPS should be one) and

4) one can get a reliable QNH, say from a nearby ATC airfield

then I would be happy to descend, on QNH, to say 700ft AGL, and that would be my decision height.

600ft is the lowest I've been and I would never do that again - not because it was dangerous but because it was pointless; my alternate airport with ILS was 10 miles away and I had the plates, the ILS set up, and everything ready.

I've seen people go a lot lower. Over open flat countryside, or over the sea, they will get away with it.

A number of airfields have unofficial instrument approaches, using a navaid on the airfield or perhaps a few miles away. That's superficially a better way but is no different to the above rules.

1500ft cloudbase is a LOT better :O Especially as a 1000ft base reported when you set off could actually be 800ft, and 600ft 10 mins later...

The safest way is to go down a nearby ILS and continue visually, and if you can't continue visually then climb to the MSA and go somewhere else.

[DFC]

For anyone considering making a descent into an airfield with no instrument procedures please considder the following;

The legal requirment is that when IFR the aircraft must at all times be 1000ft above all obstacles within 5nm of the aircraft. The only exceptions to this are when following a published approach procedure or when visual and below 3000ft.

This means that if for example you decide to orbit your destination and descend as low as possible you are going to have to use the offical tolerances for VOR/NDB/DME which can cause a circle of error of some 2 to 5nm depending on how far you are away from the beacon(s) but let's say you are relatively close and the 2nm error applies..........Then you are going to have a turn radius of about 1nm around the airfield so that is now a circle of 3nm (6nm if a distance from the beacon). To this add the required 5nm for obstacle clearance bringing the circle to 8nm (11nm if a distant beacon).........Then allow for how acurate you fly so add on another 1nm for a proficient IR holder using a VOR/DME or another 3nm to 5nm for an IMC holder using crosscuts...........this brings the circle out to some 11 to 14nm.

A circle of 11 to 14nm around the destination could describe the area within which you must check for any obstacles and remain 1000ft above those obstacles to remain safe and legal.

Sounds a lot yes? But noe of that allows for wind drift while you fiddlw with the cross cuts or make sow's ear of the orientation!

Of course with say an NDB on the airfield then that circle could shrink to about 7 to 8nm for a slow aircraft.

However, when looking at the 1:500000 for obstacles remember that no terrain below 500ft is shown and no onstacles below 300ft AGL are shown. Thus you can have an unmarked 499ft hill with a 299ft mast on top. Most people understand that but remember that a place betwen the 500ft contour and the 1000ft countour could be 999ft tall with a 299 ft mast and right next to the 500ft contour cause it is a cliff!!!!!!!!

Airfields with instrument procedures spend thousands on accurate surveys...........even the 1:25000 Ordnance survey maps do not provide enough info for making a descent as low as 900ft AGL!

If you intend to fly IFR IMC at any stage and the destination does not have an IAP then the destination must have a ceiling above the MSA for -1 hr to +3 hours of ETA and you must have an alternate planned which has an IAP and is at the appropriate alternate minima!.

The most dangerous use of an IMC rating to ad-hoc IMC flying (not planned pre-flight).

Regards,

DFC

[2Donkeys]

DFC,

I agree with the sentiments behind your posting. However, on a point of detail, when you write:


The legal requirment is that when IFR the aircraft must at all times be 1000ft above all obstacles within 5nm of the aircraft. The only exceptions to this are when following a published approach procedure or when visual and below 3000ft.

That does not accord with the rules of the air.

There is no exception relating to a "published approach procedure", rather, it is a more generic exception, the aircraft can descend below the minimum height specified in the IFR rules "when it is necessary for the aircraft to do so in order to take off or land".

2D

[waldopepper42]

Going back to the original question, I found that the only time I really used the rating was taking the Chippy up through cloud for a few aerobatics in clear blue skies!

Had to be careful to give time for the gyros to untopple before the letdown, though.

[FullyFlapped]

If you're asking the question because you're trying to decide whether it's a good idea to go get the rating, then unless you're willing to seriously restrict your flying activities - don't waste any more time wondering, go get one.

I'd be amazed if anyone who has one - and who has used it for real - doesn't agree !

FF :ok:

[Keef]

Yes, got one, use it often, wouldn't be without it.

Only thing better would be an aeroplane with an N on the side, so that I can use the FAA IR that I added later on, and using mostly the training and hours from the IMC.

[waldopepper42]

Keef - the other way round is better. I did the FAA IR and, on my return to Blighty, the CAA graciously provided the IMC by return of post!

[Charlie Zulu]

Yup I've got one and wouldn't be without it.

The only better thing would be an aircraft with an N on the side, preferably a de-iced twin, so I could use my FAA IR to its full potential. ;)

[DRJAD]

Yes, also got one and am very glad to have it.

Two main reasons, I think:

i. As stated, it gives you options, and,

ii. the training gives one a feel for more accurate flying than is necessarily taught for vanilla PPL - and there is nothing, of course, to stop one at any stage from applying IR standards of accuracy - just that, have trained for an IMCR one has started to have a feeling for that desired accuracy.

Well worth the effort.

[error_401]

Anyone can enlighten me (dumb JAR ATPL SEP MEP MET IR holder) on what an IMC rating is?

From the posts sounds like something fly in below VMC but not yet an IR?

[FlyingForFun]

Error - you are correct.

It is a UK rating, which is only valid inside the UK. It allows a pilot to fly in IMC, but only in Class D or lower airspace (thereby denying access to the airways, which are all Class A in the UK, and restricting you to flying in Class G airspace for most of your flight). It also has much higher minima for approaches than an IR. On the plus side, though, it only requires 15 hours of training, and, more importantly, you don't have to go through the nightmare of the IR exams first, which is why it is far more popular amongst British PPLs than an IR.

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

[IO540]

FFF

You omitted to mention that while the IFR privileges are UK only, the IMC Rating also removes the restrictions which the UK CAA added to the ICAO PPL, most importantly the need to be in sight of the surface, and this change is not limited to the UK. The CAA have confirmed this in writing.

This is very useful is most places south of the UK, where one can then fly VMC on top en-route. Depart the UK "IFR", climb on top by mid-channel, and land in some nice weather in S France. Same when returning. Very handy.

Perhaps more arguably, the increased IAP minima aren't legally binding. They are mere recommendations. They aren't in the ANO so they aren't law. The bit which is in the ANO is a minimum vis of 1800m for takeoff or landing.

The CAA license issue website suggests that since JAA, the number of IRs issued to noncommercial pilots is very close to zero... a really great safety improvement!!! (not)

[DRJAD]

Interesting points IO540 - thanks for the information. I had not appreciated the full implications of the issue ref. the CAA restrictions over the JAA PPL rules. However, I was aware of the advisory nature of the approach limitations.

In reference to your point about IR issue for non-commercial pilots, I must say I would go for an IR like a shot, if I could afford it. The examinations are not an issue. Until such time as affordability also becomes a non-issue I am very glad to have an IMCR.

[IO540]

Arguably there is little point in an IR unless one wants to do European touring or business flying.

One can get adequately around the UK on the IMCR and I wouldn't go to the trouble of a JAA IR or an FAA IR unless I was going outside the UK, IFR.

[Croqueteer]

Firstly, I would like to say that good IF training is invaluable, and will improve the accuracy of your visual flying no end. I would like to add, however, that in my opinion if you are going to plan to fly in IMC in the UK, you need a full IR, and a de-iced fully equiped twin. Anythig less and you are taking a real risk.

[Chilli Monster]

in my opinion if you are going to plan to fly in IMC in the UK, you need a full IR, and a de-iced fully equiped twin. Anythig less and you are taking a real risk.


That's rather a sweeping statement for what actually encompasses a multitude of conditions. Some of these do require what you say, but others, in all honesty, don't. Flying is all about risk management and reduction. I would take issue that all these conditions constitute a "real risk".

[DRJAD]

Exactly: not having a fully de-iced twin, and not having a full IR, amount to a restriction in planning a flight which one applies to oneself.

The IMCR still allows more options than vanilla PPL in the UK - and the decision about whether to attempt any particular flight is, of course, informed by one's legal privileges, one's actual skill, one's currency, and the actual conditions pertaining.

Equally, more options would be available abroad with a full IR, but the IMCR is still valuable in the UK: less so if not kept current, more so with good currency.

[IO540]

In a legal sense, not having a known-ice aircraft is going to impose far more restrictions on flight planning than not having a full IR.

In a plane not certified for known ice: if one is willing to risk climbing through freezing layers (which is generally fair enough if it is stratiform, one has a deiced prop, and the layer is evidently 1000-3000ft thick) then a full IR would help to get on top in much of UK's airspace.

Personally I find that I cancel flights if the 0C level is below the MSA, and flying a non-deiced plane in those conditions is something I wouldn't do. A full IR would still cause me to cancel.

I absolutely do not accept sweeping statements like "if you are going to plan to fly in IMC in the UK, you need a full IR". Trained to the privileges, and equally current, there isn't going to be much difference. Most noncommercial IRs you bump into are long lapsed, and you can be sure their currency went a long time before that :O And what plane is the man with the gold-plated ATPL going to fly in IMC? Let's say it's a rented wreckage of a C172 with knackered avionics and no autopilot. That why sweeping statements are misleading.

[DRJAD]

Personally I find that I cancel flights if the 0C level is below the MSA, and flying a non-deiced plane in those conditions is something I wouldn't do. A full IR would still cause me to cancel.

Absolutely: that's the sort of point I, in my long-winded way, meant.

[Croqueteer]

I was talking about serious IMC flying. Climbing into cloud that is above safety altitude and below icing level for realistic training is one thing, but to say that you are going to fly from say Bristol to Newcastle next Thursday relying on your IMC rating if needs be is a different ball game. Note the often narrow gap between min safe and regulated airspace and you get the picture. I started commercial flying in Aztec days when bosses did their best to stop you using airways, and can vouch for being scared fartless on several occasions, and I was not the only one. If you are talking about serious IMC flying in the UK, I stand by my original statement.

[IO540]

Croqueteer

What is the problem with Bristol to Newcastle? If you are aware of an IMCR pilot who cannot plan that trivial route and fly it, I strongly suggest you report his instructor to the CAA.

The problem with the IMCR isn't the rating; it is those schools that see it as a way to shaft the student for another few k before he finally disappears for good like most of them do. Most of the instructors teaching it shouldn't be teaching instrument flight at all.

The route you describe is indeed trivial.

One needs currency (i.e. time and money), a suitably equipped aircraft (i.e. money, and since they are very hard to rent one pretty well needs to be an owner or a syndicate member, and few syndicates will agree on the degree of maintenance that's needed). The entry level for a "serious IFR plane" is probably £100k+. Nothing to do with the IMCR though!

One of the problems here is that most people look at things from the flying school spamcan point of view. Those planes are next to useless for IFR. But consider an aircraft owner who has bought something decent, and the time and money and a good instructor.

The IMCR is a fantastic privilege. Don't criticise it; instead have a go at the reasons why most people who paid for it can't make more than an occassional use of it.

[Croqueteer]

IO540, my last point. If you are flying IFR because the cloudbase is on or near the ground on your route, and the engine stops, you are deep in the poo. All flying should be organised so that you have get-out clauses, and if you regularly plan IMC flying in the average UK Wx in a single, you have straight away cut your options. I am not knocking the IMC rating, just trying to save lives. See the accident reports.

[Fuji Abound]

"and can vouch for being scared fartless on several occasions" (Croqueteer)

It would be interesting to know the circumstances.
In my opinion the average newly qualified IMC holder is poorly equipped to fly a hard IFR sector. The average newly qualified IR holder should be better equipped. In my view this is because most IMC training is based on the premise that the rating will be used to “get the holder out of trouble” whereas it is assumed an IR holder is likely to want to operate hard IFR. I have been particularly careful to use the word “average”. There are IMC instructors who approach the training like an IR.

That said, there are IMC holders who go on to use the rating in earnest. The “trick” is to realise your limitations in the early days so that you gradually increase your expertise hopefully with some more training on the way. I believe that if you take this course you will be as capable as the aircraft at flying any IFR sector.

I agree with IO540 that given the afore the critical component then becomes your assessment of the capability of your aircraft and the level of risk you are prepared to accept.

I recently started a thread about the minimum cloud base you would be prepared to accept flying in IMC. I can recall a flight from Leicester down south which was solid IMC pretty much all the way in a club Warrior. The aircraft had no autopilot, I hadn’t flown that particular aircraft before other than the trip up in good VMC, and the equipment only met the minimum legal requirements for IFR flight. I don’t want to recall the cloud base en route. In fact I was very current both in terms of flying very regularly and on instruments and despite hand flying single pilot operations (there was no one else with me to help!) the whole flight was pleasant and a complete non event.

In reality the problem was the aircraft had no reserve capacity. Had things started to go wrong there could have been a serious problem and now I would consider that flight in that aircraft was an unacceptable level of risk for me. Another person’s assessment of course might well be different.

The reason I come to that conclusion is this.

Cloud base. As the other thread suggests the chances of a successful forced landing with a low cloud base aren’t good. How low is a matter for each individual but I reckon 1,000 feet is about my limit. Of course on a SEP the assumption could be made that the chances of the donkey quitting on any aircraft are pretty remote and I would accept that again is a matter of personal decision. It may well be over cautious but I wouldn’t be happy flying an aircraft in challenging IMC unless I knew a bit about the service history of the engine and whilst the statistics I am sure don’t support this argument I would feel more comfortable in an aircraft that I knew had a reasonably low hours engine that was serviced and maintained by a reputable organisation.

Equipment level. However current you are the real problems start when systems start to go wrong and the workload accelerates. Of course you should be able to fly the approach with a failed AI but it is still a real emergency. So on your picking list you might well like a second AI, one electric one vacuum maybe, an injected engine so you aren’t worrying about carb. ice the whole time is not a bad idea, a really reliable radio kit rather than maybe just a good box 1 and the often slightly dodgy box 2, so when box 1 fails you have got a decent backup, for my money two GPS receivers etc.
Yes, of course, we would all like two engines (or maybe 5 would be better), weather radar, de-ice, cat 3 capability, etc., but I reckon IO540 has got it spot on, it all boils down to having an aircraft that is reasonably equipped for the mission which in my opinion whilst the typical IFR club trainer might meet the minimum legal requirements it will have little left in reserve if anything goes wrong, and is therefore not an adequate tool for the job – it is best kept for foguled training!

[IO540]

Gentlemen, the points you make (e.g. not flying SE in IMC when the cloudbase is somewhere below the ground :O ) are equally valid whether the pilot has an IMC Rating, a full IR, or an ATPL with 25k hours.