SE IR during winter time and icing conditons
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SE IR during winter time and icing conditons
Hi,
As some of you may have noticed... we are aproaching winter time and winter conditions. I was wondering if anyone have any stories or experience with flying se/ir IMC ( to try get on top) in winter conditions? Which days/conditions would you fly in and which would you not. Would you fly on a cloudy day with temperatures close to 0 etc.. If you do fly on these days.. how do you prepare with regards to icing.
Kind regards
As some of you may have noticed... we are aproaching winter time and winter conditions. I was wondering if anyone have any stories or experience with flying se/ir IMC ( to try get on top) in winter conditions? Which days/conditions would you fly in and which would you not. Would you fly on a cloudy day with temperatures close to 0 etc.. If you do fly on these days.. how do you prepare with regards to icing.
Kind regards
Last edited by Fladbrokeandbusted; 8th Nov 2007 at 08:46.
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Ice the aircraft killer!
The performance of a light SE aircraft decreases very quickly when it picks up ice so the simple rule is don't get into icing conditions that you can't get out of.
First Never fly IMC when the freezing level is below the MSA, what ever happens you must be able to decend into walmer air to de ice the airframe.
It is sometimes best to climb though a thin layer of cloud to get VMC on top even if this will result in a small amount of ice but it must be remembered that aircraft performance will be effected by any ice and a light SE will only have a marginal ability to "out climb" the icing layer.
Prelonged flight in icing conditions will result in the aircrafts ability to fly being so reduced that it is likely to become very hard if not imposable to control.
It is most likely that the newer "glass" aircraft will suffer greater performance degridation than the older "fat wing" types.
First Never fly IMC when the freezing level is below the MSA, what ever happens you must be able to decend into walmer air to de ice the airframe.
It is sometimes best to climb though a thin layer of cloud to get VMC on top even if this will result in a small amount of ice but it must be remembered that aircraft performance will be effected by any ice and a light SE will only have a marginal ability to "out climb" the icing layer.
Prelonged flight in icing conditions will result in the aircrafts ability to fly being so reduced that it is likely to become very hard if not imposable to control.
It is most likely that the newer "glass" aircraft will suffer greater performance degridation than the older "fat wing" types.
A and C makes excellent points. Here are some additional thoughts.
* Avoid CU like the plague. You may be able to climb through a stratiform layer with trace or no ice, but convective cloud is a completely different matter.
* Don't forget that if you pick up ice on your climb through the cloud, your fuel burn for the rest of the trip will increase. Sublimation is distinctly overrated as a deicing technique.
* Keep climb speed high. That offers two advantages: a higher total temperature (even a degree can help) and a lower AoA (exposing less of the wing).
* Avoid CU like the plague. You may be able to climb through a stratiform layer with trace or no ice, but convective cloud is a completely different matter.
* Don't forget that if you pick up ice on your climb through the cloud, your fuel burn for the rest of the trip will increase. Sublimation is distinctly overrated as a deicing technique.
* Keep climb speed high. That offers two advantages: a higher total temperature (even a degree can help) and a lower AoA (exposing less of the wing).
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Too much generic comment above!
In flying one should always have an escape route.
Over water, carry a raft.
Over land, a forced landing.
Electrical failure, carry a handheld GPS & radio.
Etc.
Flying IFR/airways, the name of the game is to climb to VMC on top and stay there for the whole route.
So, how thick are the clouds? You can have -3C on the ground, base of 1000ft, stratus tops of 3000ft, and perfect sunshine above that. There isn't going to be enough water in 2000ft of stratus to bring down any normal plane, in the time one can climb up through it (2-3 minutes).
Paradoxically, "UK style IFR" flight (on the IMC Rating, in Class G) is harder in those conditions because it is only in some parts of the UK (Wales, Norfolk) where one can reasonably reliably climb to VMC on top. This causes me to scrap a lot of winter flights - I would have to file them airways which is OK but hardly worth the bother for a 100nm flight.
The business of cloud top data is wrapped up in the whole subject of IFR flight planning.
Winter stratus is generally thinner than in the summer. Summer tops might average 15k; winter tops might average 10k. Often one can see blue sky through holes; that is a giveaway of a thin layer, 2000-3000ft max.
If one took a strict approach (no flight if there is subzero IMC about) there would be no GA IFR flight for half the year, and none at all (deiced planes excepted) on Eurocontrol routes in N Europe because these potentially take you into subzero temps anytime of the year.
Some people won't fly over water.
Some people won't fly over mountains.
Some people won't fly over mountains covered in cloud - I do, and I have a GPS running a topo chart so one could glide into a deep valley, which from FL180 should be possible in most places.
One just has to be a bit clever about it.
The performance drop varies according to type. I have failed to measure an IAS drop with ~ 6mm of rime. Others find a big speed loss. But then I have a TKS prop; I am sure a lot of performance loss blamed on wing icing is actually power loss due to prop ice.
In flying one should always have an escape route.
Over water, carry a raft.
Over land, a forced landing.
Electrical failure, carry a handheld GPS & radio.
Etc.
Flying IFR/airways, the name of the game is to climb to VMC on top and stay there for the whole route.
So, how thick are the clouds? You can have -3C on the ground, base of 1000ft, stratus tops of 3000ft, and perfect sunshine above that. There isn't going to be enough water in 2000ft of stratus to bring down any normal plane, in the time one can climb up through it (2-3 minutes).
Paradoxically, "UK style IFR" flight (on the IMC Rating, in Class G) is harder in those conditions because it is only in some parts of the UK (Wales, Norfolk) where one can reasonably reliably climb to VMC on top. This causes me to scrap a lot of winter flights - I would have to file them airways which is OK but hardly worth the bother for a 100nm flight.
The business of cloud top data is wrapped up in the whole subject of IFR flight planning.
Winter stratus is generally thinner than in the summer. Summer tops might average 15k; winter tops might average 10k. Often one can see blue sky through holes; that is a giveaway of a thin layer, 2000-3000ft max.
If one took a strict approach (no flight if there is subzero IMC about) there would be no GA IFR flight for half the year, and none at all (deiced planes excepted) on Eurocontrol routes in N Europe because these potentially take you into subzero temps anytime of the year.
Some people won't fly over water.
Some people won't fly over mountains.
Some people won't fly over mountains covered in cloud - I do, and I have a GPS running a topo chart so one could glide into a deep valley, which from FL180 should be possible in most places.
One just has to be a bit clever about it.
The performance drop varies according to type. I have failed to measure an IAS drop with ~ 6mm of rime. Others find a big speed loss. But then I have a TKS prop; I am sure a lot of performance loss blamed on wing icing is actually power loss due to prop ice.
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IO540
I think that you have a point with the prop ice, I once had to do an engine ground test in freezing fog and the size of the ice layer that built very quickly was impressive an would no doubt have had a grave effect on prop performance.
I think that your TB20 has rather a "fat" wing by the standards of the glass aircraft that are now flying, I think that this by be the reason that your aircraft performs reasoably well in ice.
I wish that I had the internet skills to post a photo that I took in the DANYE hold south of Manchester at FL80 there is a lump of ice as big as my fist on the windscreen wiper arm!
I think that your TB20 has rather a "fat" wing by the standards of the glass aircraft that are now flying, I think that this by be the reason that your aircraft performs reasoably well in ice.
I wish that I had the internet skills to post a photo that I took in the DANYE hold south of Manchester at FL80 there is a lump of ice as big as my fist on the windscreen wiper arm!
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The TB20 probably does have a fatter wing but somehow doesn't deliver a worse "MPG" than the glass types. Maybe because the glass types are mostly fixed gear so they chuck away the advantage into that.
But the point I was hoping to make is that there are often ways to work around the problem. It's wrong to say one needs a twin - 2 engines are nothing to do with ice resistance and most twins have poor SE climb anyway and most likely sub zero if they carry ice as well.
In the end, there are times when one simply cannot fly. For example I would not depart into forecast tops of FL150 with the 0C level low down - it would take me maybe 30 mins to climb up there and in that time I would expect to pick up too much ice. Rightly or wrongly I would scrap such a flight. Some missions are just not possible in some types - that's why people buy turboprops and jets
But the point I was hoping to make is that there are often ways to work around the problem. It's wrong to say one needs a twin - 2 engines are nothing to do with ice resistance and most twins have poor SE climb anyway and most likely sub zero if they carry ice as well.
In the end, there are times when one simply cannot fly. For example I would not depart into forecast tops of FL150 with the 0C level low down - it would take me maybe 30 mins to climb up there and in that time I would expect to pick up too much ice. Rightly or wrongly I would scrap such a flight. Some missions are just not possible in some types - that's why people buy turboprops and jets
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I am with IO and A&C here generally.
I will climb on top in known icing as long as I can get into the sun. Once i am there the ice comes off very quickly. I have an excess of HP so I can carry quite a bit of ice on the climb without to much hassle. I will not fly when I know I have to pass through the CU all the time as the ice build is amazingly quick and if there is not enough clear sky time it won't come back off.
Unlike IO I will fly airways even on a short distance if it means I am above the clouds.
I won't fly when the freezing layer is below the MSA as it does not give me any room to get ice off that I picked up on the descent before flying the procedure.
I will climb on top in known icing as long as I can get into the sun. Once i am there the ice comes off very quickly. I have an excess of HP so I can carry quite a bit of ice on the climb without to much hassle. I will not fly when I know I have to pass through the CU all the time as the ice build is amazingly quick and if there is not enough clear sky time it won't come back off.
Unlike IO I will fly airways even on a short distance if it means I am above the clouds.
I won't fly when the freezing layer is below the MSA as it does not give me any room to get ice off that I picked up on the descent before flying the procedure.
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"If there's any likelihood of icing conditions forget it unless you're de-iced, which means you don't go in a single." This is true CJBoy...
...unless of course you are in a TKS equiped FIKI approved Mooney.
Although ice is still best avoided and exited as soon as possible this is the time of year when my TKS system pays for itself.
SB (hoping for a new (TKS equiped) Mooney Acclaim-S from Santa)
...unless of course you are in a TKS equiped FIKI approved Mooney.
Although ice is still best avoided and exited as soon as possible this is the time of year when my TKS system pays for itself.
SB (hoping for a new (TKS equiped) Mooney Acclaim-S from Santa)
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Well I don't have any de-ice!
I have been to Exeter and back this morning to collect a part for an aircraft. Airways via SAM, got on top at around FL70 picked up ice on the way as the freezing level was around 2k. Visible build up on the leading edges and struts, quite a bit on the fairing and brakes.
About 5 minutes at FL100 in the cruise and there was nothing left. I picked quite a bit up on the descent and still had some showing at the FAF, nothing by the time I started the descent.
The damn wind was another matter!!!
Flying in icing conditions in inevitable for a pilot flying in the UK in winter, you have to manage it and make sensible decisions not just avoid it like the plague.
I think a lot of the problem is that the club scene makes ice out to be an instant killer.
I have been to Exeter and back this morning to collect a part for an aircraft. Airways via SAM, got on top at around FL70 picked up ice on the way as the freezing level was around 2k. Visible build up on the leading edges and struts, quite a bit on the fairing and brakes.
About 5 minutes at FL100 in the cruise and there was nothing left. I picked quite a bit up on the descent and still had some showing at the FAF, nothing by the time I started the descent.
The damn wind was another matter!!!
Flying in icing conditions in inevitable for a pilot flying in the UK in winter, you have to manage it and make sensible decisions not just avoid it like the plague.
I think a lot of the problem is that the club scene makes ice out to be an instant killer.
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First of all thank you all for your insights. I listen and learn from you guys.
Problem is that i fly a standard C-172 with fixed pitch no turbo etc... ****ty performance in other words. Climb about 500 fpm (up to 8-9000 feet at most) and therfore I was wondering how much is acceptable. is there any rule of thumb on how long you would accept to stay imc or do you simply look out on your wings/struts and count the seconds till an impending crash??
I really would like to get some real IFR time this winter but i also really like to keep it fairly safe.
Problem is that i fly a standard C-172 with fixed pitch no turbo etc... ****ty performance in other words. Climb about 500 fpm (up to 8-9000 feet at most) and therfore I was wondering how much is acceptable. is there any rule of thumb on how long you would accept to stay imc or do you simply look out on your wings/struts and count the seconds till an impending crash??
I really would like to get some real IFR time this winter but i also really like to keep it fairly safe.
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Light aircraft that can operate in most winter conditions are pretty few on the ground. As others have said you need to make sensible decisions about the weather and the ability to climb on top.
I can think of very few in line aircraft. The Mooney of course and the Cessna Skymaster with boots are very good examples.
The vast majority of twins use boots - I can only think of the DA42 that uses TKS which in my limited experience works ok.
For a host of reasons I am not convinced these aircraft are really at home in the weather in winter which would ensure reliable capability - for that I think you probably need to step up to something like an Aztec, which whilst old, I think is a super aircraft able to provide very reliable point to point transport with comfort even in conditions that would be unpleasant in "lesser" aircraft.
In anything "lesser" the key is to ensure you are always ahead of the weather rather than being able to rely on the aircraft to "cope" with it.
I can think of very few in line aircraft. The Mooney of course and the Cessna Skymaster with boots are very good examples.
The vast majority of twins use boots - I can only think of the DA42 that uses TKS which in my limited experience works ok.
For a host of reasons I am not convinced these aircraft are really at home in the weather in winter which would ensure reliable capability - for that I think you probably need to step up to something like an Aztec, which whilst old, I think is a super aircraft able to provide very reliable point to point transport with comfort even in conditions that would be unpleasant in "lesser" aircraft.
In anything "lesser" the key is to ensure you are always ahead of the weather rather than being able to rely on the aircraft to "cope" with it.
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In your case Fladbrokeandbusted I would stick to VMC.
If potentially going into IMC I would want the 0C level to be at least 1000ft above the MSA.
But as I said thin stratus is normally fine. I've often gone into the stuff to see how much ice I can pick up (having the obvious escape route of 0C level well above the MSA) and most of the time there is so little (after say 10 mins) one has to look carefully to see it. And I am doing only 150kt; aerodynamic heating at 150kt is only about 3C so not significant. So climbing up through it should be fine.
A key point is that no plane can fly in icing indefinitely. Not even a 747. The name of the game is always to make it a transient condition, and de-ice kit will help with that.
The most effective anti-ice equipment currently available (for non-jets) is full TKS, but the fluid container will last only an hour or two.
There is a class of pilots out there who fly in virtually all conditions. They are happy to sit in an Aztec for hours, with inches of ice hanging off it. They usually don't carry oxygen so they have no choice anyway. One should not criticise these pilots because, in the right plane and with the right experience, they don't actually get killed. But it is not the way to go about things, IMHO.
Jets get around it by having good anti ice equipment, climbing and descending fast, and flying fast. At 250kt TAS, airframe heating is around 10C and given that supercooled water will exist (in stratus) only between 0C and about -15C, if your airframe is heated by 10C then the thickness of the "icing band" shrinks from 15C (say 7500ft) to 5C (say 2500ft). At 300kt+ TAS you won't get any ice at all...
Even on a piston plane, there is a noticeable difference in ice accumulation rates between climbing at 90kt and descending at 170kt.
For background, here is a good NASA icing course.
A good article on freezing rain (the ultimate hazard) is here.
If potentially going into IMC I would want the 0C level to be at least 1000ft above the MSA.
But as I said thin stratus is normally fine. I've often gone into the stuff to see how much ice I can pick up (having the obvious escape route of 0C level well above the MSA) and most of the time there is so little (after say 10 mins) one has to look carefully to see it. And I am doing only 150kt; aerodynamic heating at 150kt is only about 3C so not significant. So climbing up through it should be fine.
A key point is that no plane can fly in icing indefinitely. Not even a 747. The name of the game is always to make it a transient condition, and de-ice kit will help with that.
The most effective anti-ice equipment currently available (for non-jets) is full TKS, but the fluid container will last only an hour or two.
There is a class of pilots out there who fly in virtually all conditions. They are happy to sit in an Aztec for hours, with inches of ice hanging off it. They usually don't carry oxygen so they have no choice anyway. One should not criticise these pilots because, in the right plane and with the right experience, they don't actually get killed. But it is not the way to go about things, IMHO.
Jets get around it by having good anti ice equipment, climbing and descending fast, and flying fast. At 250kt TAS, airframe heating is around 10C and given that supercooled water will exist (in stratus) only between 0C and about -15C, if your airframe is heated by 10C then the thickness of the "icing band" shrinks from 15C (say 7500ft) to 5C (say 2500ft). At 300kt+ TAS you won't get any ice at all...
Even on a piston plane, there is a noticeable difference in ice accumulation rates between climbing at 90kt and descending at 170kt.
For background, here is a good NASA icing course.
A good article on freezing rain (the ultimate hazard) is here.
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Sorry if I spoil the party here but what the heck are you guys doing climbing through ice in non FIKI aircraft in the first place? Are you aware that it's not legal? There's no way you can say 2000 ft of cloud isn't enough to bring an aircraft down because even if that may be true for some types and in some conditions, it simply isn't legal!
And don't give me any crap about the UK weather, I spend all my time at 55-65 degrees north so I deal with winter as much as anybody. Winter IFR in non-deiced aircraft, and even some that are, is risky business. Even FIKI kit doesn't help. Do you have any idea how many accidents due to icing conditions that take place each year? And I'm talking deiced kit, like the Cessna Caravan for example. Standard procedure is to stay away from ice and if encountered by accident get the hell out asap!
You're not seriously cruising around with an inch of ice on your Pipers and Cessnas are you?
And don't give me any crap about the UK weather, I spend all my time at 55-65 degrees north so I deal with winter as much as anybody. Winter IFR in non-deiced aircraft, and even some that are, is risky business. Even FIKI kit doesn't help. Do you have any idea how many accidents due to icing conditions that take place each year? And I'm talking deiced kit, like the Cessna Caravan for example. Standard procedure is to stay away from ice and if encountered by accident get the hell out asap!
You're not seriously cruising around with an inch of ice on your Pipers and Cessnas are you?
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I think if you havent experienced ice before you can get hung up on watching the leading edge of the wing expecting to see some rim ice forming in text book fashion.
Unfortunately in icing conditions the weater does not know it should behave in accordance with the text book.
My friend operates Kingairs for a living and many years ago I told him I had never seen ice. As it turned out conditions were perfect for icing, and as we entered IMC the sceen went instantly white - not what I had expected at all. You couldnt see a thing out which obviously should not have mattered being on instruments anyway but hell - it was disconcerting at the time.
The point I am seeking to make Flad is your expectation of how icing may manifest itself is not necessarily what actually happens.
Unfortunately in icing conditions the weater does not know it should behave in accordance with the text book.
My friend operates Kingairs for a living and many years ago I told him I had never seen ice. As it turned out conditions were perfect for icing, and as we entered IMC the sceen went instantly white - not what I had expected at all. You couldnt see a thing out which obviously should not have mattered being on instruments anyway but hell - it was disconcerting at the time.
The point I am seeking to make Flad is your expectation of how icing may manifest itself is not necessarily what actually happens.
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We should get some guys from Ben-Air and Kato-Air in here to talk about ice and single engine aircraft.
Even in a de-iced turbine a/c it can go really bad, really quickly.
(I think we both know a least one Caravan incident deice!)
I really like to know what knowledge you can have 540, that makes it possible to determine that the 2000ft cloud layer you want to climb trough won't bring down your aircraft.
I've seen a jet trainer collect enough ice trough 3500ft of cloud to make it almost uncontrollable, in clouds that where supposed to be without icing.
Same clouds in even a high performance piston? Breeze block?
Even in a de-iced turbine a/c it can go really bad, really quickly.
(I think we both know a least one Caravan incident deice!)
I really like to know what knowledge you can have 540, that makes it possible to determine that the 2000ft cloud layer you want to climb trough won't bring down your aircraft.
I've seen a jet trainer collect enough ice trough 3500ft of cloud to make it almost uncontrollable, in clouds that where supposed to be without icing.
Same clouds in even a high performance piston? Breeze block?
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I'd like to see stratus 2000ft thick, flown through in 2-3 minutes, that would accumulate more than a few mm of ice. 90% of the time, there would be zero ice.
Bet let me qualify this: I have a TKS prop which also keeps the front window clear, and the TKS comes ON anything below 0C 1-2 mins before entry into IMC.
That King Air, being fairly upmarket, should have had a heated screen which should been on similarly on that flight, so I don't see why his window turned white. Was he not paying attention?
As for the jet, it might plummet with 2mm of ice for all I know - I have no idea how e.g. laminar flow wings work or don't work. But the story doesn't ring true. A standard strategy for icing is a significant change of level - ice tends to be constrained vertically by a few thousand feet - and subject to having the performance, or there being no terrain, one would either climb or descend. A jet would never be stuck in a 3500ft thick layer - what the hell was he doing? At some 10,000fpm he could have got out of it in seconds. Even under ATC direction, he would have declared a mayday and got out of it. Maybe he wasn't telling the whole story. You say "clouds that where supposed to be without icing" but there can be no such thing. Who said the clouds would have no ice?
Bet let me qualify this: I have a TKS prop which also keeps the front window clear, and the TKS comes ON anything below 0C 1-2 mins before entry into IMC.
That King Air, being fairly upmarket, should have had a heated screen which should been on similarly on that flight, so I don't see why his window turned white. Was he not paying attention?
As for the jet, it might plummet with 2mm of ice for all I know - I have no idea how e.g. laminar flow wings work or don't work. But the story doesn't ring true. A standard strategy for icing is a significant change of level - ice tends to be constrained vertically by a few thousand feet - and subject to having the performance, or there being no terrain, one would either climb or descend. A jet would never be stuck in a 3500ft thick layer - what the hell was he doing? At some 10,000fpm he could have got out of it in seconds. Even under ATC direction, he would have declared a mayday and got out of it. Maybe he wasn't telling the whole story. You say "clouds that where supposed to be without icing" but there can be no such thing. Who said the clouds would have no ice?
Last edited by IO540; 9th Nov 2007 at 08:14.
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That King Air, being fairly upmarket, should have had a heated screen which should been on similarly on that flight, so I don't see why his window turned white. Was he not paying attention?
Sorry, I did give the impression we were flying the King Air. We werent - just a very ordinary SEP. I mentioned the other fella because I would not have flown into those conditions at that time by myself.
The point I was seeking to make is you do need to have some idea of what you are doing before entering icing conditions and until you do, it is best kept for cocktails.
I am not convinced about the difference in icing characteristics between modern "laminar" flow plastic aircraft and older designs. On the one hand ice tends to form first on sharp edges and second on any "imperfections" on the skin. Once a little ice has started to accumulate on a flush rivet head behind the leading edge it will build up quickly if conditions remain favourable. Of course plastic aircraft have far fewer "imperfections" or sharp surfaces so they should accumulate ice a lot slower. On the other hand their ability to carry ice one would expect would be no where near as good.
No one surely wants to remain in icing conditions for any length of time. My point about the Aztec is with or without oxygen or pressure for all sorts of reasons it may not be possible to remain clear of icing conditions in the winter if you want to rely on flying, and in an aircraft with its proven capability you have a far greater margin available to operate in these conditions without coming to grief. I was simply suggesting that the entry level for reliable winter operations in most weather is around this level.
Sorry, I did give the impression we were flying the King Air. We werent - just a very ordinary SEP. I mentioned the other fella because I would not have flown into those conditions at that time by myself.
The point I was seeking to make is you do need to have some idea of what you are doing before entering icing conditions and until you do, it is best kept for cocktails.
I am not convinced about the difference in icing characteristics between modern "laminar" flow plastic aircraft and older designs. On the one hand ice tends to form first on sharp edges and second on any "imperfections" on the skin. Once a little ice has started to accumulate on a flush rivet head behind the leading edge it will build up quickly if conditions remain favourable. Of course plastic aircraft have far fewer "imperfections" or sharp surfaces so they should accumulate ice a lot slower. On the other hand their ability to carry ice one would expect would be no where near as good.
No one surely wants to remain in icing conditions for any length of time. My point about the Aztec is with or without oxygen or pressure for all sorts of reasons it may not be possible to remain clear of icing conditions in the winter if you want to rely on flying, and in an aircraft with its proven capability you have a far greater margin available to operate in these conditions without coming to grief. I was simply suggesting that the entry level for reliable winter operations in most weather is around this level.
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Icing can happen anytime of the year as I was reminded on a trip to Mull last year.
I've never picked up any significant ice in stratus but I got distinctly uneasy about the ice I picked up in MAY in solid IMC in the cumulus above the Scottish hills. I had an escape route out over the sea and descended from about 5000ft to 3000 and was then clear of cloud (as expected) but it was a good wake up call.
I've never picked up any significant ice in stratus but I got distinctly uneasy about the ice I picked up in MAY in solid IMC in the cumulus above the Scottish hills. I had an escape route out over the sea and descended from about 5000ft to 3000 and was then clear of cloud (as expected) but it was a good wake up call.