How is "known ice" defined in the UK?
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How is "known ice" defined in the UK?
This subject was briefly discussed recently, in connection with the "de-iced prop" thing.
It is more straightforward in the USA, where the FAA will (or won't) certify a plane for flight into a specified category of known icing conditions. Moreover, the FAA has ruled that a forecast of icing amounts to known icing.
My view is that it's pretty obvious that the FAA was referring to forecasts done by US weather services in the USA.
It is stretching things to stretch this "forecast icing = known icing" to the rest of the world (as one would do by default, if the plane is N-reg), where one gets local forecasts of widely varying quality, ranging from none at all, to UK's well known permanent (F215) forecast of icing in all cloud, which is patently ludicrous unless the Met Office has discovered something new about physics of liquids and solids
However, the CAA also will (or won't) certify a plane for flight into known icing. So, what does the CAA use to define what constitutes known ice? Or does the CAA simply use the FAA categories? Or do they simply use the FAA test results and rubber stamp them (or not)?
One example which I believe is current is a TB20 with full TKS. Under G this is OK for known ice but under N it isn't. This is a rare example of the CAA being more generous than the FAA - quite reasonably so in this case because the full TB20 TKS is reportedly exceedingly effective.
A known ice certification must involve two things
a) it must be done by reference to specified icing conditions, and
b) since the certification status is a legal thing, none of it makes sense unless there is a specified and legally referenced category of weather which one can (or can't) fly into. For example, the respective national CAA would state that a particular forecast would constitute known ice if it says so.
The b) bit is missing in the UK and AFAIK in Europe.
It is more straightforward in the USA, where the FAA will (or won't) certify a plane for flight into a specified category of known icing conditions. Moreover, the FAA has ruled that a forecast of icing amounts to known icing.
My view is that it's pretty obvious that the FAA was referring to forecasts done by US weather services in the USA.
It is stretching things to stretch this "forecast icing = known icing" to the rest of the world (as one would do by default, if the plane is N-reg), where one gets local forecasts of widely varying quality, ranging from none at all, to UK's well known permanent (F215) forecast of icing in all cloud, which is patently ludicrous unless the Met Office has discovered something new about physics of liquids and solids
However, the CAA also will (or won't) certify a plane for flight into known icing. So, what does the CAA use to define what constitutes known ice? Or does the CAA simply use the FAA categories? Or do they simply use the FAA test results and rubber stamp them (or not)?
One example which I believe is current is a TB20 with full TKS. Under G this is OK for known ice but under N it isn't. This is a rare example of the CAA being more generous than the FAA - quite reasonably so in this case because the full TB20 TKS is reportedly exceedingly effective.
A known ice certification must involve two things
a) it must be done by reference to specified icing conditions, and
b) since the certification status is a legal thing, none of it makes sense unless there is a specified and legally referenced category of weather which one can (or can't) fly into. For example, the respective national CAA would state that a particular forecast would constitute known ice if it says so.
The b) bit is missing in the UK and AFAIK in Europe.
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My understanding be that known icing = in cloud above the zero level. The question for an ice equiped aircraft whether the icing is light, moderate or severe. It seems the new 214 forms show moderate and severe areas. How risk averse they are I cannot tell.
My understanding is that the ICAO view is that forcasts are not to provide unecessary descriptions. Therefore trace and light icing isn't shown because all certified ice equiped aircraft are by default certfied for at least light so that is null information. No icing is shown for Cbs as they automatically are classified as severe icing. Moderate icing is not shown for convective cloud for the same reason. Freezing rain is also assumed to be severe. In all other areas moderate and severe icing may be shown on the Sigwx and I assume (haven't looked at them yet) the new fangled 215s.
Again, my understanding is that trace icing means it is visible but poses no risk for upto an hour without the use of deice. Light icing means that you can fly for an hour without problems with occasional use of de-ice. Moderate icing means that the use of de-icing equipment will be necessary in a short amount of time. Severe icing means that de-icing equipment fails to remove it faster than it forms.
As I have never flown in icing I can't say I have been looking at this area in detail. However, I start my IR flights in a week or two in an certified Seneca so time start thinking about it!
Other than the ICAO and ATPL notes. I'm haven't yet found the relevant UK document.
My understanding is that the ICAO view is that forcasts are not to provide unecessary descriptions. Therefore trace and light icing isn't shown because all certified ice equiped aircraft are by default certfied for at least light so that is null information. No icing is shown for Cbs as they automatically are classified as severe icing. Moderate icing is not shown for convective cloud for the same reason. Freezing rain is also assumed to be severe. In all other areas moderate and severe icing may be shown on the Sigwx and I assume (haven't looked at them yet) the new fangled 215s.
Again, my understanding is that trace icing means it is visible but poses no risk for upto an hour without the use of deice. Light icing means that you can fly for an hour without problems with occasional use of de-ice. Moderate icing means that the use of de-icing equipment will be necessary in a short amount of time. Severe icing means that de-icing equipment fails to remove it faster than it forms.
As I have never flown in icing I can't say I have been looking at this area in detail. However, I start my IR flights in a week or two in an certified Seneca so time start thinking about it!
Other than the ICAO and ATPL notes. I'm haven't yet found the relevant UK document.
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Just did this online NASA GA Icing course yesterday:
http://aircrafticing.grc.nasa.gov/courses.html
VERY good (free) course, I wouldn't have recognised a tail stall to save my life (literally), also shows that complete flight surface deice/anti-ice is NOT a guaranteed 'get out of jail free' card - ice WILL form on non-protected structures.
Have a look.
Con
http://aircrafticing.grc.nasa.gov/courses.html
VERY good (free) course, I wouldn't have recognised a tail stall to save my life (literally), also shows that complete flight surface deice/anti-ice is NOT a guaranteed 'get out of jail free' card - ice WILL form on non-protected structures.
Have a look.
Con
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Yes, the NASA stuff is good practical advice.
But, I still need a reference for a statement like
My understanding be that known icing = in cloud above the zero level
Physically speaking, it isn't known icing, because as any pilot will tell you, most of the time you won't pick up any ice at all. Today I spent nearly 2 hrs in IMC at below 0C and picked up a total of about 2mm of rime, in all that time. No measurable loss of IAS.
OTOH, looking at e.g. http://ows.public.sembach.af.mil/
(Flight Hazards -> Icing)
you get what might be a plausible map of where you might get some real ice.
But, I still need a reference for a statement like
My understanding be that known icing = in cloud above the zero level
Physically speaking, it isn't known icing, because as any pilot will tell you, most of the time you won't pick up any ice at all. Today I spent nearly 2 hrs in IMC at below 0C and picked up a total of about 2mm of rime, in all that time. No measurable loss of IAS.
OTOH, looking at e.g. http://ows.public.sembach.af.mil/
(Flight Hazards -> Icing)
you get what might be a plausible map of where you might get some real ice.
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In fact I think even in the States it is less clear than you state, IO540. While the NTSB has decided that a forecast of icing can be defined as known icing the FAA has contradictory advice. I believe that depending where you read the FAA have said that forecast does not mean known icing, and backed the NTSB therefore implying that forecast is known icing. Mmmmmmm, not overly helpful!
Originally Posted by IO540
Moreover, the FAA has ruled that a forecastof icing amounts to known icing.
How is "known ice" defined in the UK?
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No. It has done precisely the opposite, by distinguishing the definitions of the two in the AIM.
From the cases usually cited, the principle applied seems to be that a pilot departing into forecast icing who subsequently encounters ice is held to have departed into known icing conditions. Indeed, there have been a substantial number of rulings about what information a pilot may use to negate the otherwise grounding effects of such a forecast. PIREPs indicating the absence of ice for example, are not held to be substantial enough to negate a forecast of icing at the planned level on the planned route.
The effect of this is to blur the practical line between forecast and known icing despite the wise words of the AIM.
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This is the sort of info I am looking for, but in more detail.
The problem is that a lot of stuff (e.g. "forecast=known") is being regurgitated all over the place, and without references to look up it's hard to know where it comes from.
For example, I know that there are concerns in the USA about icing AIRMETs. These are certainly icing forecasts but they can cover huge areas and therefore cannot represent physical reality.
Which bit of the AIM applies?
My question about the certification position in the UK and nowadays EASA was a reasonable one, I think. AFAIK, the TB20 TKS example is real, but I don't have document references to look up.
Aren't any planes certified for known ice in Europe, or does everyone just work off FAA certification? Does anyone actually know anything about this?
The problem is that a lot of stuff (e.g. "forecast=known") is being regurgitated all over the place, and without references to look up it's hard to know where it comes from.
For example, I know that there are concerns in the USA about icing AIRMETs. These are certainly icing forecasts but they can cover huge areas and therefore cannot represent physical reality.
Which bit of the AIM applies?
My question about the certification position in the UK and nowadays EASA was a reasonable one, I think. AFAIK, the TB20 TKS example is real, but I don't have document references to look up.
Aren't any planes certified for known ice in Europe, or does everyone just work off FAA certification? Does anyone actually know anything about this?
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Aren't any planes certified for known ice in Europe, or does everyone just work off FAA certification?
On the first point, the position is crystal clear. Until recent times, the CAA (now EASA) is responsible for certificating new aircraft types and any significant modifications to those types. So far as light aircraft are concerned, the certification requirements applied by the CAA (and now by EASA) are not a million miles away from the Part 23 requirements under which the FAA certificates light aircraft. If known-icing certification is required by an applicant in the US, the aircraft must meet the requirements specified in 23.1419 (and a couple of other less important sections). Broadly similar (but not identical) standards are to be required by EASA. The CAA/EASA undoubtedly draws some comfort from a pre-existing FAA Known-Icing certification, but are certainly not in the business of simply rubber-stamping US-certified aircraft. There is a job-protection element to this, no doubt.
On the second area of what constitutes flight into known icing in the UK/Europe, the position is blurred by the blanket forecasts issued by the UK Met Office.
What this conversation lacks though is the practical dimension. The reality is that you will only end up having this conversation for real if you are involved in an accident resulting from an icing encounter. Therefore, regardless of any forecasts, you will have, de facto, flown in icing conditions. Should you survive to have the conversation, it will be framed in terms of whether it was reasonable for you to have predicted the ice that you encountered. That is a very different question from the one being asked repeatedly around here.
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The reason I "wandered" the discussion was because of bookworm's apparent suggestion that there is no "known ice" certification category in the UK. Like any good lawyer, he's asking a question to which he probably knows the answer I don't know the answer, and it would interest me.
Perhaps I am missing something obvious but clearly if there is to be a meaningful icing certification then it must be by reference to a specified weather forecast. Otherwise, it doesn't make a lot of sense. One could certify an aircraft for flight into specified conditions (and that deals with that) but how is the pilot supposed to apply that, when faced with nonsense like a permanent icing forecast for all cloud?
Perhaps, like so many things in aviation, this has never been addressed, and thus keeps pprune busy
Obviously I know that one isn't likely to get into trouble unless there is an incident serious enough to draw attention. However, is there any European case body on this? Let's say you are flying a non-cert airframe and you encounter serious icing, and declare an emergency, and ask for a 180, a descent below the published airway MEA (but still above the MSA/MOCA), has this ever resulted in action being taken?
I don't know the answer, and it would interest me.Perhaps I am missing something obvious but clearly if there is to be a meaningful icing certification then it must be by reference to a specified weather forecast. Otherwise, it doesn't make a lot of sense. One could certify an aircraft for flight into specified conditions (and that deals with that) but how is the pilot supposed to apply that, when faced with nonsense like a permanent icing forecast for all cloud?
Perhaps, like so many things in aviation, this has never been addressed, and thus keeps pprune busy
Obviously I know that one isn't likely to get into trouble unless there is an incident serious enough to draw attention. However, is there any European case body on this? Let's say you are flying a non-cert airframe and you encounter serious icing, and declare an emergency, and ask for a 180, a descent below the published airway MEA (but still above the MSA/MOCA), has this ever resulted in action being taken?
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Bookworm is playing with you. The word "known" does not feature in CAA icing certifications. This undermines the basis of your original question, and was at the root of my suggestion of a more practical approach.
A pilot is in contravention if he flies an aircraft into ice which is "not approved for flight in icing conditions".
Should he suffer an accident as a result of an icing encounter, then he has de facto flown contrary to the aircraft's placarded limitations. The question of whether or not ice was "forecast" and might reasonably have been expected has value only in terms of mitigating any enforcement action that might be taken.
On that subject, I am unaware (in the UK at least) of anybody having been zapped for reporting the need to leave a level because of ice accretions. ATC take no responsibility for policing whether or not aircraft are operated in accordance with their limitations, nor will they know whether or not any particular aircraft is in contravention. Because of this, the mechanism for initiating enforcement action is normally missing, absent an accident.
PS: As a footnote, you might find EASA's attempt at FAR 23 useful. In particular, you'll note the magically numbered 23.1419 (wonder where they got that from?) which gives a hint of what EASA has in mind
A pilot is in contravention if he flies an aircraft into ice which is "not approved for flight in icing conditions".
Should he suffer an accident as a result of an icing encounter, then he has de facto flown contrary to the aircraft's placarded limitations. The question of whether or not ice was "forecast" and might reasonably have been expected has value only in terms of mitigating any enforcement action that might be taken.
On that subject, I am unaware (in the UK at least) of anybody having been zapped for reporting the need to leave a level because of ice accretions. ATC take no responsibility for policing whether or not aircraft are operated in accordance with their limitations, nor will they know whether or not any particular aircraft is in contravention. Because of this, the mechanism for initiating enforcement action is normally missing, absent an accident.
PS: As a footnote, you might find EASA's attempt at FAR 23 useful. In particular, you'll note the magically numbered 23.1419 (wonder where they got that from?) which gives a hint of what EASA has in mind
Last edited by 2Donkeys; 24th Mar 2006 at 10:15.
Originally Posted by 2Donkeys
Bookworm is playing with you.
The reality is that you will only end up having this conversation for real if you are involved in an accident resulting from an icing encounter. Therefore, regardless of any forecasts, you will have, de facto, flown in icing conditions. Should you survive to have the conversation, it will be framed in terms of whether it was reasonable for you to have predicted the ice that you encountered.
In the EASA Ops consultation I tried to make that very point, but got fobbed off. There is at least an opportunity to champion that view when it comes to the implementing rules.
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I would like to believe that -- indeed that is exactly the sort of holistic risk management that I would like to see promoted by aviation safety regulation. While I don't have any reason to doubt that that is policy, it would be reassuring to have confirmation in black-and-white that the authorities' attitude mirrors yours.
The bigger question, which nobody here can answer, is whether as a matter of policy, our regulator is inclined to push enforcement action in cases of accidents induced by icing encounters. I am unaware of any high-profile examples, so I am inclined to conclude either:
a) That most accidents following icing encounters are fatal; or
b) That the CAA tends not to pursue action in such cases.
We agree though, that clarity would be a good thing. The same applies to much of the CAA's enforcement strategy. The problem is that such clarity might encourage those who seem to actively seek ways of arbitraging the rules. We see plenty of them on Pprune.
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There have also been some accident reports I've read where:
(c) by the time the investigators reached the bent aircraft any ice that might have been on it had melted
so there was no guarantee that there was "beyond reasonable doubt" evidence that would stand up in court.
(c) by the time the investigators reached the bent aircraft any ice that might have been on it had melted
so there was no guarantee that there was "beyond reasonable doubt" evidence that would stand up in court.
Originally Posted by 2Donkeys
The problem is that such clarity might encourage those who seem to actively seek ways of arbitraging the rules.
"The question raised by the complaint is respondent's judgment in taking off." (Administrator vs Groszer)
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I don't believe that "most" icing encounters are fatal, because if one has the obvious escape route (0C level being well above the MSA) one can descend. The other option might be to plan the en route section above the likely tops, which needs oxygen and a capable aircraft. To do otherwise is stupidity, IMHO.
The other thing is that the group of pilots routinely flying European airways at nonpressurised levels is a tiny fraction of what there is in the USA - perhaps only a few hundred in the whole of Europe, and this is another possible reason why this subject has not been clarified: no pressing need to.
In either case, the pilot probably knows what he's doing.
But, I still don't get how one is supposed to conduct oneself, given the absence of meaningful "official" icing data.
As for the case of ice melting after the crash, unless the pilot has been on the radio saying he is covered in ice and is going down, I don't see how anybody can tell it wasn't a heart attack, for example. An awful lot of AAIB reports on GA fatal accidents are just pure speculation, no matter how they dress it up. And this would not need proof BRD because everybody is dead and you can't do a criminal prosecution against a dead person; more likely it would be a civil action defended by the insurance company, but then insurance does cover negligence... and this takes us back to how should the pilot know he is launching into conditions which the aircraft was not certified for?
The other thing is that the group of pilots routinely flying European airways at nonpressurised levels is a tiny fraction of what there is in the USA - perhaps only a few hundred in the whole of Europe, and this is another possible reason why this subject has not been clarified: no pressing need to.
In either case, the pilot probably knows what he's doing.
But, I still don't get how one is supposed to conduct oneself, given the absence of meaningful "official" icing data.
As for the case of ice melting after the crash, unless the pilot has been on the radio saying he is covered in ice and is going down, I don't see how anybody can tell it wasn't a heart attack, for example. An awful lot of AAIB reports on GA fatal accidents are just pure speculation, no matter how they dress it up. And this would not need proof BRD because everybody is dead and you can't do a criminal prosecution against a dead person; more likely it would be a civil action defended by the insurance company, but then insurance does cover negligence... and this takes us back to how should the pilot know he is launching into conditions which the aircraft was not certified for?
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The aircraft I fly is "cleared for flight in light icing conditions". Attached to this are various items of equipment that must be fitted and working. Included in this list of items is an ice detector. The definition of light icing is based on the rate at which ice accretes on the detector. In other words the icing clearance is type specific and is no doubt determined after extensive trials. Moreover, there are operational procedures that are applied during flight planning that allow one to escape from icing conditions beyond the capability of the aircraft.
Very practical.
Icing conditions are assumed when there is a) Freezing rain (get another cuppa, remain earthbound), b)OAT less than 0 deg C with visible moisture/flight viz less than 1000m (in effect IMC).
I assume the 215 has a permanent warning of ice simply because the met in the UK changes so quickly, can be very localised and is effected by our very varied topography. The 215 is simply too generalised to be more specific about icing. I suspect it is more aimed at the VFR GA community.
Very practical.
Icing conditions are assumed when there is a) Freezing rain (get another cuppa, remain earthbound), b)OAT less than 0 deg C with visible moisture/flight viz less than 1000m (in effect IMC).
I assume the 215 has a permanent warning of ice simply because the met in the UK changes so quickly, can be very localised and is effected by our very varied topography. The 215 is simply too generalised to be more specific about icing. I suspect it is more aimed at the VFR GA community.
Last edited by Droopystop; 25th Mar 2006 at 08:45.
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Originally Posted by IO540
I don't believe that "most" icing encounters are fatal
Originally Posted by IO540
But, I still don't get how one is supposed to conduct oneself, given the absence of meaningful "official" icing data.
The fact that all 215s contain an ice warning is not going to be of particular help to the case of a regulator in nailing you down. The fact that you actually encountered ice despite your planning, will not help your case.
I think that you may be trying to extract more mileage from this than is available to extracted. If your real point is that you don't like the blanket warnings on 215s, then join the club. The Met office has dumbed-down and generalised many aspects of its forecasts in recent years.
2D
Originally Posted by Droopystop
The aircraft I fly is "cleared for flight in light icing conditions". Attached to this are various items of equipment that must be fitted and working. Included in this list of items is an ice detector. The definition of light icing is based on the rate at which ice accretes on the detector. In other words the icing clearance is type specific and is no doubt determined after extensive trials. Moreover, there are operational procedures that are applied during flight planning that allow one to escape from icing conditions beyond the capability of the aircraft.