IMC Uncertainties
Joined: Aug 2000
Posts: 3,648
Likes: 2
From: UK
Originally Posted by rustle
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.
Joined: Feb 2005
Posts: 697
Likes: 0
From: UK
One point that is often overlooked is why should a pilot of a 'Permit' aircraft bother with IMC?
There is actually a very good reason, a 'Permit' aircraft is allowed to fly VMC which includes above cloud out of site of ground (subject to other criteria). A PPL cannot fly out of sight of ground unless he/she has the IMC rating.
Obviously, to maintain VMC conditions you still have to get through the cloud in a situation where you can see the ground but as long as you are 1,000' clear of clound you are VMC even if you don't see the ground.
There is actually a very good reason, a 'Permit' aircraft is allowed to fly VMC which includes above cloud out of site of ground (subject to other criteria). A PPL cannot fly out of sight of ground unless he/she has the IMC rating.
Obviously, to maintain VMC conditions you still have to get through the cloud in a situation where you can see the ground but as long as you are 1,000' clear of clound you are VMC even if you don't see the ground.
Joined: Jun 2003
Posts: 13,787
Likes: 0
From: EuroGA.org
Bookworm, I thought it was the met vis (not the pilot's own assessment) that mattered for the 1800m IMCR min. I am pretty sure you wrote that somewhere previously 
Funfly, I don't get that. The holder of a UK CAA issued PPL (which includes a JAA PPL issued by the CAA) has to be within sight of the surface. It doesn't matter whether he is flying a microlight, a permit, a certified IFR spacewagon, or a 747 certified for single crew operation
If that PPL gets himself an IMCR or an IR, that requirement goes out of the window and he can now fly within the ICAO definition of VMC which is 1500m, clear of cloud, etc, and he does not have to see the surface. AFAIK that is true in any type of aeroplane.
The owner of a Permit plane has no use for the IMCR (or the IR) other than the above reason. He cannot officially fly IFR (in VMC or IMC). Of course he can fly IFR (in VMC or IMC) unofficially, it's unenforceable en route - what he cannot do is overt stuff like an IFR departure or an IFR arrival
Funfly, I don't get that. The holder of a UK CAA issued PPL (which includes a JAA PPL issued by the CAA) has to be within sight of the surface. It doesn't matter whether he is flying a microlight, a permit, a certified IFR spacewagon, or a 747 certified for single crew operation
If that PPL gets himself an IMCR or an IR, that requirement goes out of the window and he can now fly within the ICAO definition of VMC which is 1500m, clear of cloud, etc, and he does not have to see the surface. AFAIK that is true in any type of aeroplane.
The owner of a Permit plane has no use for the IMCR (or the IR) other than the above reason. He cannot officially fly IFR (in VMC or IMC). Of course he can fly IFR (in VMC or IMC) unofficially, it's unenforceable en route - what he cannot do is overt stuff like an IFR departure or an IFR arrival
Why do it if it's not fun?
Joined: Jul 2001
Posts: 4,782
Likes: 12
From: Bournemouth
Bookworm,
You are quite correct that it is the in-flight visibility and not the reported met visiblity that is referenced in the IMC rating minima (see my quote from the ANO in my earlier post).
However, I ask you this: if the cloudbase is 300', and a pilot with an IMC rating is established on an ILS but not yet visual, how is he supposed to "make an assessment of flight visibility below cloud" to decide if he can continue below 1000'?
FFF
-----------
You are quite correct that it is the in-flight visibility and not the reported met visiblity that is referenced in the IMC rating minima (see my quote from the ANO in my earlier post).
However, I ask you this: if the cloudbase is 300', and a pilot with an IMC rating is established on an ILS but not yet visual, how is he supposed to "make an assessment of flight visibility below cloud" to decide if he can continue below 1000'?
FFF
-----------
Joined: May 1999
Aviation Qualifications: ATP+Mil
Posts: 27,399
Likes: 857
From: Quite near 'An aerodrome somewhere in England'
If below 140KIAS and 3000 ft, VFR flights are permitted if in 1500m visibility as long as the aircraft is clear of cloud and in sight of the surface.
Joined: Jul 2004
Posts: 100
Likes: 0
From: Surrey
I normally find myself agreeing with IO540 on nearly everything, but I must respond to his comment re Permit aircraft.
There are at least 3 reasons why a permit a/c pilot should have an IMCR, when flying strictly legally VFR.
1. As stated, it allows VFR 'on top' - but you have got to have holes to get down.
2. SVFR for me is important as I go to the CIs a few times a year. The Jersey Zone is Class A, apart from the local flying areas and Alderney-Guernsey route, which are class D up to 2000ft. The SVFR has a min of 10Km vis for non IMCR, but 3Km for IMCR pilots, all legal in permit aircraft. It is NEEDED, as in my opinion, over the sea one should not attempt to fly in less than 10km vis except on instruments, as there is no useful horizon or other visual clues unless very low. Add to that the unpredictability of vis in their maritime environment, and I wouldn't go there without an IMCR for personal safety reasons, let alone legality.
3. More generally, vis of between 5Km and 15Km even over land can, at altitude, leave one with the need to fly and navigate as if in IMC, especially if the sun is anywhere ahead, even though fully legal VFR in Class G. I have for 15 years flown a high performance PFA type, but never planned a flight when the forecast indicates that VFR may not be available. What such vis does is to encourage lower altitudes to give a reasonable horizon, against the interests of safety and avoidance of the higher density airspace, ATZs, Danger areas, MATZ, etc. Twice in the lovely weather a few weeks ago I did a day trip to Perranporth from the London area, at quadrantal levels FL60 going and FL50 returning when clear of the London TMA. Never near a cloud, unquestionably VFR legal, but on one of those trips, at those heights, it would have been impossible to fly and navigate visually. Lovely, silky smooth flights in complete relaxation. That's flying for me!
Apart from these reasons, it personally gives me comfort that being in current training on my current aircraft, in an emergency I would cope with confidence in cloud, if unpredicted weather would otherwise tempt me into one of those 'scud running' fatals. It has not, however, happened to me yet, in 40 years PPLing.
MikeJ
There are at least 3 reasons why a permit a/c pilot should have an IMCR, when flying strictly legally VFR.
1. As stated, it allows VFR 'on top' - but you have got to have holes to get down.
2. SVFR for me is important as I go to the CIs a few times a year. The Jersey Zone is Class A, apart from the local flying areas and Alderney-Guernsey route, which are class D up to 2000ft. The SVFR has a min of 10Km vis for non IMCR, but 3Km for IMCR pilots, all legal in permit aircraft. It is NEEDED, as in my opinion, over the sea one should not attempt to fly in less than 10km vis except on instruments, as there is no useful horizon or other visual clues unless very low. Add to that the unpredictability of vis in their maritime environment, and I wouldn't go there without an IMCR for personal safety reasons, let alone legality.
3. More generally, vis of between 5Km and 15Km even over land can, at altitude, leave one with the need to fly and navigate as if in IMC, especially if the sun is anywhere ahead, even though fully legal VFR in Class G. I have for 15 years flown a high performance PFA type, but never planned a flight when the forecast indicates that VFR may not be available. What such vis does is to encourage lower altitudes to give a reasonable horizon, against the interests of safety and avoidance of the higher density airspace, ATZs, Danger areas, MATZ, etc. Twice in the lovely weather a few weeks ago I did a day trip to Perranporth from the London area, at quadrantal levels FL60 going and FL50 returning when clear of the London TMA. Never near a cloud, unquestionably VFR legal, but on one of those trips, at those heights, it would have been impossible to fly and navigate visually. Lovely, silky smooth flights in complete relaxation. That's flying for me!
Apart from these reasons, it personally gives me comfort that being in current training on my current aircraft, in an emergency I would cope with confidence in cloud, if unpredicted weather would otherwise tempt me into one of those 'scud running' fatals. It has not, however, happened to me yet, in 40 years PPLing.
MikeJ
Joined: Aug 2000
Posts: 3,648
Likes: 2
From: UK
Originally Posted by IO540
Bookworm, I thought it was the met vis (not the pilot's own assessment) that mattered for the 1800m IMCR min. I am pretty sure you wrote that somewhere previously
For the purposes of an aeroplane taking off from or approaching to land at an aerodrome within Class B, C or D airspace, the visibility, if any, communicated to the commander of an aeroplane by the appropriate air traffic control unit shall be taken to be the flight visibility for the time being.
It is part of Section V, Visual Flight Rules, and is entitled "Visual flight and reported visibility". The intention of the rule when introduced was very clear: it was to prohibit VFR arrivals and departures in visibility less than 5000 m.
An argument could be put (and I presume rustle would put it and I missed the subtlety of the class D reference
) that the rule also applies to an IMC-rated pilot flying under IFR in class D. I don't believe that that was the intention.
However, I ask you this: if the cloudbase is 300', and a pilot with an IMC rating is established on an ILS but not yet visual, how is he supposed to "make an assessment of flight visibility below cloud" to decide if he can continue below 1000'?
Official PPRuNe Chaplain
Joined: Apr 2001
Posts: 3,498
Likes: 0
From: Witnesham, Suffolk
Originally Posted by Callsign Kilo
Whilst I would never look to intentionally use my rating in anger, I never actually know when it may or could be called upon.
I would suggest there are only two ways to use the IMC rating:
A. Practice regularly - like, try to do an instrument approach (under the hood or using foggles and with a safety pilot, if there's no IMC weather around) every month. If you haven't done one in several months, find an instructor and do some revision. Use the IMC "in anger" whenever you get the chance, to keep your hand in.
B. Not at all.
Joined: Jun 2003
Posts: 13,787
Likes: 0
From: EuroGA.org
Beagle
If below 140KIAS and 3000 ft, VFR flights are permitted if in 1500m visibility as long as the aircraft is clear of cloud and in sight of the surface
The above is wrong for a bare UK issued PPL. The 1500m for VFR applies only to a UK issued PPL who also has the IMCR or IR, or to some non-JAA ICAO PPL holders (FAA being one of them).
MikeJ
I agree entirely. I avoid the SVFR stuff and to be honest can't remember the rules. I also think an instrument capability is all but necessary to fly safely to the limits of legal VFR (3000m in haze, for example) but a lot of people get jumpy when one suggests that. If I was teaching somebody (that I care about) to fly I would make sure they can fully radio navigate (GPS/VOR/DME) and can fly at least an ILS before going off anywhere - it's no rocket science. Unless one is exceedingly conservative in planning, it's only a matter of time before such an option will be the only one left.... well apart from calling up 121.50 and hoping they can get you down somewhere, which is how it's normally done.
If below 140KIAS and 3000 ft, VFR flights are permitted if in 1500m visibility as long as the aircraft is clear of cloud and in sight of the surface
The above is wrong for a bare UK issued PPL. The 1500m for VFR applies only to a UK issued PPL who also has the IMCR or IR, or to some non-JAA ICAO PPL holders (FAA being one of them).
MikeJ
I agree entirely. I avoid the SVFR stuff and to be honest can't remember the rules. I also think an instrument capability is all but necessary to fly safely to the limits of legal VFR (3000m in haze, for example) but a lot of people get jumpy when one suggests that. If I was teaching somebody (that I care about) to fly I would make sure they can fully radio navigate (GPS/VOR/DME) and can fly at least an ILS before going off anywhere - it's no rocket science. Unless one is exceedingly conservative in planning, it's only a matter of time before such an option will be the only one left.... well apart from calling up 121.50 and hoping they can get you down somewhere, which is how it's normally done.
Joined: Oct 2001
Posts: 3,832
Likes: 115
From: UK
I think it is quite important that a lot of you boys and girls out there sort out your RVRs and your visibilities. Despite the fact that several of you are using the expression vis/RVR in the same breath, THEY ARE ABSOLUTELY NOT THE SAME THING!
For example, at an airfield with decent lighting a visibility of 200m would probably result in an RVR of 400m. In fact, under the Old Queen, we were allowed to double reported visibility at night to arrive at an RVR at airfields which could not report RVRs.
What I am driving at (just in case the penny has yet to drop) is that if you land at an airfield quoting an RVR of 1800m and you only have an IMC rating then you are likely to be breaking the law for your restriction is 1800m Visibility and not 1800m RVR.
For example, at an airfield with decent lighting a visibility of 200m would probably result in an RVR of 400m. In fact, under the Old Queen, we were allowed to double reported visibility at night to arrive at an RVR at airfields which could not report RVRs.
What I am driving at (just in case the penny has yet to drop) is that if you land at an airfield quoting an RVR of 1800m and you only have an IMC rating then you are likely to be breaking the law for your restriction is 1800m Visibility and not 1800m RVR.
Joined: May 1999
Aviation Qualifications: ATP+Mil
Posts: 27,399
Likes: 857
From: Quite near 'An aerodrome somewhere in England'
IO540, the UK VFR minima for ac below 3000ft and 140KIAS has nothing to do with licences, the point being that if flying in 1500m visibility under VFR, such an aircraft must also be clear of cloud and in sight of the surface.
Licence privilege may further restrict the pilot's lawful VFR limits.
Licence privilege may further restrict the pilot's lawful VFR limits.
Joined: Jul 2004
Posts: 100
Likes: 0
From: Surrey
BEagle,
In view of the title to this thread 'IMC Uncertainties', I feel that I should add to your last post that this is another benefit of IMCR when VFR.
The ANO Schedule 8, Sect 1, Sub Sect 1 (2) (c) makes it clear that without IMCR, the absolute minimum for VFR is 3Km, and the 1500m limit is only available to IMCR holders.
This is briefly referred to in Pooley's page 5, which also gives the difference when SVFR. I believe it applies equally with permit and CofA aircraft.
MikeJ
In view of the title to this thread 'IMC Uncertainties', I feel that I should add to your last post that this is another benefit of IMCR when VFR.
The ANO Schedule 8, Sect 1, Sub Sect 1 (2) (c) makes it clear that without IMCR, the absolute minimum for VFR is 3Km, and the 1500m limit is only available to IMCR holders.
This is briefly referred to in Pooley's page 5, which also gives the difference when SVFR. I believe it applies equally with permit and CofA aircraft.
MikeJ
Joined: Aug 2000
Posts: 3,648
Likes: 2
From: UK
To be pedantic, I've got a feeling that the no descent below 1000ft if the rvr/vis is not adequate has been replaced by no descent below the final approach fix, the two not necessarily being the same.
Joined: Feb 2002
Posts: 375
Likes: 0
From: london uk
MikeJ
you should read the rules of the air, as they state quite clearly that flights at speeds of less than 140Kn may be conducted with a flight visibility of <1500m
under VFR rules.Check your Pooleys for a quick reference or the ANO Rules of the air. Its also in Trevor Thom, air law. One point on the 1000ft DH rule, a normal approach profile of 3 deg gives appx 300 feet per mile decent. So 1500m or 1800m, means you will only be at 3-400 ft when coming visual. Main point to remember, they will only look at an aftercast if anything goes wrong, so what is stated therein will be the decider!! As for getting an IMCR and not knowing these rules, well ask your school for a refund under the "not fit for purpose" sale of goods act! Because thats what your imc rating is without this knowledge!
you should read the rules of the air, as they state quite clearly that flights at speeds of less than 140Kn may be conducted with a flight visibility of <1500m
under VFR rules.Check your Pooleys for a quick reference or the ANO Rules of the air. Its also in Trevor Thom, air law. One point on the 1000ft DH rule, a normal approach profile of 3 deg gives appx 300 feet per mile decent. So 1500m or 1800m, means you will only be at 3-400 ft when coming visual. Main point to remember, they will only look at an aftercast if anything goes wrong, so what is stated therein will be the decider!! As for getting an IMCR and not knowing these rules, well ask your school for a refund under the "not fit for purpose" sale of goods act! Because thats what your imc rating is without this knowledge!
Joined: Jul 2004
Posts: 100
Likes: 0
From: Surrey
piston gone,
Yes the rules of the air do say that, but in THAT part they do not say the ratings required for this.
My previous post gives the exact reference from the ANO, schedule 8, which explicitly states that without an IR or IMCR, the minimum vis for a PPL is 3Km.
That schedule also gives the min vis. under SVFR for non IR/IMCR as 10Km, but 3Km with IR/IMCR.
Please read all of pages 2 - 5 in Pooley's, especially p5.
MikeJ
Yes the rules of the air do say that, but in THAT part they do not say the ratings required for this.
My previous post gives the exact reference from the ANO, schedule 8, which explicitly states that without an IR or IMCR, the minimum vis for a PPL is 3Km.
That schedule also gives the min vis. under SVFR for non IR/IMCR as 10Km, but 3Km with IR/IMCR.
Please read all of pages 2 - 5 in Pooley's, especially p5.
MikeJ
Joined: Feb 2002
Posts: 2,547
Likes: 0
From: Dublin
Please stop referring to Poolies guide as an authoritative source. It's not...just a guide.
MikeJ, what you are referring to are the privileges for a UK issued PPL.
By way of example, I have an Irish issued JAA PPL without an IMC rating (we don't have one), and without an instrument rating. When I am flying in the UK airspace I am bound by the UK VFR rules (and the Irish ones if more restrictive).
I am not limited to the privileges of a UK issued PPL, only those of my Irish issued PPL which restricts me to VFR. Therefore the VFR rules is the only restrictions which are relevant to me. This is the subtlety that the others are trying to point out. Lots and lots of people operate in UK airspace without a UK issued PPL.
dp
MikeJ, what you are referring to are the privileges for a UK issued PPL.
By way of example, I have an Irish issued JAA PPL without an IMC rating (we don't have one), and without an instrument rating. When I am flying in the UK airspace I am bound by the UK VFR rules (and the Irish ones if more restrictive).
I am not limited to the privileges of a UK issued PPL, only those of my Irish issued PPL which restricts me to VFR. Therefore the VFR rules is the only restrictions which are relevant to me. This is the subtlety that the others are trying to point out. Lots and lots of people operate in UK airspace without a UK issued PPL.
dp
Joined: Aug 2000
Posts: 3,648
Likes: 2
From: UK
Originally Posted by dublinpilot
MikeJ, what you are referring to are the privileges for a UK issued PPL.
Joined: Mar 2001
Posts: 195
Likes: 0
From: uk
Originally Posted by bookworm
I think you are mistaken. Arts 47, 48 and 49 all refer to 1000 ft aal. JAR-OPS1 refers to "the outer marker or equivalent position" but that obviously only applies to those operating under JAR-OPS1.
Joined: Jul 2004
Posts: 100
Likes: 0
From: Surrey
Originally Posted by bookworm
Well that's hardly surprising since the discussion is about the value of the IMC rating in changing those privileges.
To tie this up with another point made earlier on this thread, The VFRules themselves allow, in the specified circumstances,
flight out of sight of the surface,
flight down to a vis of 1500m.
It is the ANO privileges of a UK issued PPL (sched 8, sub sect 1.1) that denies these facilities unless the holder has an IR or IMCR.
Dublinpilot, I originally quoted from the current text of the ANO not Pooley's.
This I have in full, by free download of CAP393.pdf from the CAA website. I got this a little while ago for study of a different subject.
MikeJ
