Cruising Alt & Freezing Level.
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Luke,
There is nothing stopping you planning to fly in icing conditions, ie ATC won't ask 'confirm you want 8000 as it is above the freezing level?'.
There is nothing stopping you planning to fly in icing conditions, ie ATC won't ask 'confirm you want 8000 as it is above the freezing level?'.
(Edit to fix up the formatting)
ATC would have no idea whether your bugsmasher or any other aeroplane/helicopter is certified for flight into known icing conditions.
There's plenty of A/C that are would generally be considered a no-go for icing conditions but have subsequently been fitted with an STC'd allowing flight through said condition IAW the POH addendum.
There's plenty of A/C that are would generally be considered a no-go for icing conditions but have subsequently been fitted with an STC'd allowing flight through said condition IAW the POH addendum.
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ATC would have no idea whether your bugsmasher or any other aeroplane/helicopter is certified for flight into known icing conditions.
There's plenty of A/C that are would generally be considered a no-go for icing conditions but have subsequently been fitted with an STC'd allowing flight through said condition IAW the POH addendum.
There's plenty of A/C that are would generally be considered a no-go for icing conditions but have subsequently been fitted with an STC'd allowing flight through said condition IAW the POH addendum.
But, if you survive, and CASA figures it out, they'll throw the book at you.
Can't help but chuckle every time someone says that the guys down south must experience more icing. Started my career Sth Island NZ and slowly moved north, and the icing is definitely worse the further north I go. The air tends to simply hold less moisture due to the colder temps down south.
As far as "known or forecast icing" conditions go, I'd be interested to know what the legal take is on scattered cloud at the cruising level in sub zero temps. It certainly never caused any grief over bass straight.
As far as "known or forecast icing" conditions go, I'd be interested to know what the legal take is on scattered cloud at the cruising level in sub zero temps. It certainly never caused any grief over bass straight.
You've got to be careful not to make so many rulers that you don't go flying at all. Icing is an interesting thing. less than 500 ft can make the difference between accumulating ice and melting it.
You need to READ the forecast and make judgments based upon it. Canberra in winter is always going to be a liability. Similarly, in winter its probably better to think like a single engine VFR flight and go for longer tracks to stay on flatter ground.
In winter the cloud is usually lower and 10,000ft will get you above it most of the time (and therefore out of icing if it occurs). This still leaves the descent. But you can mitigate that by looking for holes, fast - direct descents and potentially alternates.
Interestingly, if you read William Bucks book on early airline flying, the captains in the era of the DC4 & DC6 made the same decisions.
The best advice I have been given is that as soon as any ice forms you should do something. Climb, descend, turn, something. Don't wait for ice to limit the aeroplane's performance. You can request cruise at non standard altitudes. if the LSALT is 4100 ft and you get ice, then cruising at 4100 ft is an option.
In the US where the FAA seem to have a greater concern with safety rather than bum covering rule making, there is a wealth of training material on their website. The US AOPA have this guide http://www.aopa.org/asf/publications/sa11.pdf and I have a nice little book īn flight icing"by Perkins & Rieke that I got from Sporty's.
You need to READ the forecast and make judgments based upon it. Canberra in winter is always going to be a liability. Similarly, in winter its probably better to think like a single engine VFR flight and go for longer tracks to stay on flatter ground.
In winter the cloud is usually lower and 10,000ft will get you above it most of the time (and therefore out of icing if it occurs). This still leaves the descent. But you can mitigate that by looking for holes, fast - direct descents and potentially alternates.
Interestingly, if you read William Bucks book on early airline flying, the captains in the era of the DC4 & DC6 made the same decisions.
The best advice I have been given is that as soon as any ice forms you should do something. Climb, descend, turn, something. Don't wait for ice to limit the aeroplane's performance. You can request cruise at non standard altitudes. if the LSALT is 4100 ft and you get ice, then cruising at 4100 ft is an option.
In the US where the FAA seem to have a greater concern with safety rather than bum covering rule making, there is a wealth of training material on their website. The US AOPA have this guide http://www.aopa.org/asf/publications/sa11.pdf and I have a nice little book īn flight icing"by Perkins & Rieke that I got from Sporty's.
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That book by Rieke- in flight icing
You've got to be careful not to make so many rulers that you don't go flying at all. Icing is an interesting thing. less than 500 ft can make the difference between accumulating ice and melting it.
You need to READ the forecast and make judgments based upon it. Canberra in winter is always going to be a liability. Similarly, in winter its probably better to think like a single engine VFR flight and go for longer tracks to stay on flatter ground.
In winter the cloud is usually lower and 10,000ft will get you above it most of the time (and therefore out of icing if it occurs). This still leaves the descent. But you can mitigate that by looking for holes, fast - direct descents and potentially alternates.
Interestingly, if you read William Bucks book on early airline flying, the captains in the era of the DC4 & DC6 made the same decisions.
The best advice I have been given is that as soon as any ice forms you should do something. Climb, descend, turn, something. Don't wait for ice to limit the aeroplane's performance. You can request cruise at non standard altitudes. if the LSALT is 4100 ft and you get ice, then cruising at 4100 ft is an option.
In the US where the FAA seem to have a greater concern with safety rather than bum covering rule making, there is a wealth of training material on their website. The US AOPA have this guide 404 Error - AOPA and I have a nice little book īn flight icing"by Perkins & Rieke that I got from Sporty's.
You need to READ the forecast and make judgments based upon it. Canberra in winter is always going to be a liability. Similarly, in winter its probably better to think like a single engine VFR flight and go for longer tracks to stay on flatter ground.
In winter the cloud is usually lower and 10,000ft will get you above it most of the time (and therefore out of icing if it occurs). This still leaves the descent. But you can mitigate that by looking for holes, fast - direct descents and potentially alternates.
Interestingly, if you read William Bucks book on early airline flying, the captains in the era of the DC4 & DC6 made the same decisions.
The best advice I have been given is that as soon as any ice forms you should do something. Climb, descend, turn, something. Don't wait for ice to limit the aeroplane's performance. You can request cruise at non standard altitudes. if the LSALT is 4100 ft and you get ice, then cruising at 4100 ft is an option.
In the US where the FAA seem to have a greater concern with safety rather than bum covering rule making, there is a wealth of training material on their website. The US AOPA have this guide 404 Error - AOPA and I have a nice little book īn flight icing"by Perkins & Rieke that I got from Sporty's.
Old Akro--do you still have that book? Can I buy it or borrow it or something? Looks like it is out of print in the US, can't find it anywhere.
Heard about Rieke, some said he is an expert in the field. I just got my first turbo-prop job and it is single pilot. Want to figure out this icing deal before winter.
Thanks
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Hedgehog, my tips for you if you are flying a turboprop:
- Go high and go early before you lose the performance to out-climb it (especially if it is a long flight).
- Make good use of the SIGWX and mid-level SIGWX charts and note any areas and levels of mod/sev icing. Plan a cruising level above the areas and levels noted if possible.
- Ask ATC if there have been any reports if there are SIGMETS affecting you.
- Fly in clear air whenever possible (ie. amend your cruising level to stay in the clear air between two layers of cloud when able/necessary).
- If you encounter sudden onset heavy icing, change levels. As others have mentioned you may not have to climb or descend much to get out of the worst of it.
- Even aircraft equipped to fly in icing conditions are not designed to fly in sustained heavy icing where ice can form beyond the protected areas. Always be vigilant and observe how the ice is forming.
- When iced up and running de-ice gear expect a hit on your cruise TAS which may have an effect on your fuel planning and performance
- Regarding the previous point, sometimes descending into warmer air and clearing the ice might be the best option
- Think about what you will do if one of the de-icing systems fail (actions will vary a lot based on MEL requirements, which system has failed and the known/forecast weather affecting the flight).
- Go high and go early before you lose the performance to out-climb it (especially if it is a long flight).
- Make good use of the SIGWX and mid-level SIGWX charts and note any areas and levels of mod/sev icing. Plan a cruising level above the areas and levels noted if possible.
- Ask ATC if there have been any reports if there are SIGMETS affecting you.
- Fly in clear air whenever possible (ie. amend your cruising level to stay in the clear air between two layers of cloud when able/necessary).
- If you encounter sudden onset heavy icing, change levels. As others have mentioned you may not have to climb or descend much to get out of the worst of it.
- Even aircraft equipped to fly in icing conditions are not designed to fly in sustained heavy icing where ice can form beyond the protected areas. Always be vigilant and observe how the ice is forming.
- When iced up and running de-ice gear expect a hit on your cruise TAS which may have an effect on your fuel planning and performance
- Regarding the previous point, sometimes descending into warmer air and clearing the ice might be the best option
- Think about what you will do if one of the de-icing systems fail (actions will vary a lot based on MEL requirements, which system has failed and the known/forecast weather affecting the flight).
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Thanks, Captain Nomad
Thanks. I appreciate it. That really was super helpful.
Question--when you mentioned you may not have to climb or descend a lot to get out of icing condition, I imagined a scenario and want to ask you about that. So, I have quite a bit of flying experience in Oregon and Washington State. The two are pretty notorious for icing due to the amount of moisture in the air and the Cascade mountain range that lifts the air and exacerbates it.
Winter temperatures are generally anywhere from 0-10 degrees celsius on the ground, which means freezing level is around 0 to 4000 feet MSL. Generally there are to escape to warmer temperature in this case, one has to descend pretty low and since it is mountainous it would be difficult to descend that low and maintain MEA or even be on minimum vectoring altitude. If you are not sure of your climb capability and have to descend to get the ice to melt off (I have heard of 3 inches of ice in a minute in a Super King Air so it gets really hardcore around here sometimes), then what would be the next step if you would end up below MEA and vectoring altitude at that point while on IFR plan. Does it mean scudrun to destination necessarily?
How about climbing? Generally in the Pacific Northwest you would encounter a couple layers but would break out in the clear if you could go high enough (I heard high enough is like 10000, have not verified) If you have to climb higher than that but found yourself collecting ice in a climb, is there a way to step climb (say climb some, shed ice between layers in the clear, then continue climbing?)
And how about freezing fog (we get that a lot in the winter) is that a go or no go and how do you judge?
Thanks for your advice. I am a newbie Freight pup, and appreciate it. Are you from the US too? If not, where do you live (and fly)?
Question--when you mentioned you may not have to climb or descend a lot to get out of icing condition, I imagined a scenario and want to ask you about that. So, I have quite a bit of flying experience in Oregon and Washington State. The two are pretty notorious for icing due to the amount of moisture in the air and the Cascade mountain range that lifts the air and exacerbates it.
Winter temperatures are generally anywhere from 0-10 degrees celsius on the ground, which means freezing level is around 0 to 4000 feet MSL. Generally there are to escape to warmer temperature in this case, one has to descend pretty low and since it is mountainous it would be difficult to descend that low and maintain MEA or even be on minimum vectoring altitude. If you are not sure of your climb capability and have to descend to get the ice to melt off (I have heard of 3 inches of ice in a minute in a Super King Air so it gets really hardcore around here sometimes), then what would be the next step if you would end up below MEA and vectoring altitude at that point while on IFR plan. Does it mean scudrun to destination necessarily?
How about climbing? Generally in the Pacific Northwest you would encounter a couple layers but would break out in the clear if you could go high enough (I heard high enough is like 10000, have not verified) If you have to climb higher than that but found yourself collecting ice in a climb, is there a way to step climb (say climb some, shed ice between layers in the clear, then continue climbing?)
And how about freezing fog (we get that a lot in the winter) is that a go or no go and how do you judge?
Thanks for your advice. I am a newbie Freight pup, and appreciate it. Are you from the US too? If not, where do you live (and fly)?
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Hi Hedgehog, given this forum is for 'The Pacific' region my comments were somewhat related to that context. My flying experience has only been in this region so I don't claim to offer any special insights for your scenarios.
If you are in a pressurised turboprop I would have thought quickly out climbing the ice would be the way to go in most cases. In some ways the 'climb performance' problem could be worse in 'warmer' climates with ISA + temperatures where the freezing level is a lot higher and the ice forming then also happens at higher altitudes where the aircraft's performance also reduces.
This does not sound like a situation I would want to be in. If you are IMC below MEA without the ability to climb you are in a dire situation - an accident waiting to happen. Leave the scudrunning idea for the young and the bold...
The step climb is something that can work. I have used it more in the mid to upper 'twenties' flight levels. You may be able to request a 'block' altitude also (check your alphabet airspace rules). I know of people also choosing to conduct a steep descent (as opposed to a standard 3* profile) to minimise their time in weather/icing on descent. Beware of speed considerations if expecting to encounter turbulence as well however.
Have not had to deal with freezing fog but would offer the following. Check the aircraft's pilot operating handbook as there may be specific information and instructions regarding this. For example, this is stated in the icing limitations section of one pressurised, 'all weather' de-ice equipped turboprop:
Some aircraft are better at 'carrying ice' than others. Talk to others who have done what you are doing and learn what you can about the aircraft and it's behaviours. Find out their 'local knowledge' weather tips for regions and routes that you will be flying. Sift the information and add it to your bag of knowledge.
If you are in a pressurised turboprop I would have thought quickly out climbing the ice would be the way to go in most cases. In some ways the 'climb performance' problem could be worse in 'warmer' climates with ISA + temperatures where the freezing level is a lot higher and the ice forming then also happens at higher altitudes where the aircraft's performance also reduces.
Generally there are to escape to warmer temperature in this case, one has to descend pretty low and since it is mountainous it would be difficult to descend that low and maintain MEA or even be on minimum vectoring altitude. If you are not sure of your climb capability and have to descend to get the ice to melt off (I have heard of 3 inches of ice in a minute in a Super King Air so it gets really hardcore around here sometimes), then what would be the next step if you would end up below MEA and vectoring altitude at that point while on IFR plan. Does it mean scudrun to destination necessarily?
The step climb is something that can work. I have used it more in the mid to upper 'twenties' flight levels. You may be able to request a 'block' altitude also (check your alphabet airspace rules). I know of people also choosing to conduct a steep descent (as opposed to a standard 3* profile) to minimise their time in weather/icing on descent. Beware of speed considerations if expecting to encounter turbulence as well however.
Have not had to deal with freezing fog but would offer the following. Check the aircraft's pilot operating handbook as there may be specific information and instructions regarding this. For example, this is stated in the icing limitations section of one pressurised, 'all weather' de-ice equipped turboprop:
Flight in freezing rain, freezing fog, freezing drizzle and mixed conditions causing ice
accretion beyond the protected areas of the pneumatic boots is not approved.
The aircraft must be clear of all deposits of snow, ice and frost adhering to the lifting and control surfaces immediately prior to takeoff.
accretion beyond the protected areas of the pneumatic boots is not approved.
The aircraft must be clear of all deposits of snow, ice and frost adhering to the lifting and control surfaces immediately prior to takeoff.
If you haven't done so already, check the AFM for your particular aircraft on what they state constitutes "icing conditions".
For example, Beechcraft, in the B200, state that it's visible moisture below +5 Celsius.
Reason why it isn't zero degrees is, very simply, it gets colder in places inside the engine intake and ice can form. Sometimes this sheds and can damage the first stage compressor blades.
Also look for your minimum icing speed. Staying above this helps to keep ice from accumulating on areas of the airframe that don't have protection.
If you are flying an aircraft equipped with pneumatic boots, let ice accumulate on the leading edges before popping the boots; if you pop too early it may not break off cleanly and the next layer of accumulation will be harder to remove.
When ice sheds off the prop blades and hits the fuselage it will probably scare the crap out of you the first time you hear it.
Make sure you know the difference between "de-icing" and "anti-icing" gear on your aircraft.
My icing experience is very limited so can't give much more advice sorry. It can easily and quickly kill you, so treat it with the respect that it deserves.
For example, Beechcraft, in the B200, state that it's visible moisture below +5 Celsius.
Reason why it isn't zero degrees is, very simply, it gets colder in places inside the engine intake and ice can form. Sometimes this sheds and can damage the first stage compressor blades.
Also look for your minimum icing speed. Staying above this helps to keep ice from accumulating on areas of the airframe that don't have protection.
If you are flying an aircraft equipped with pneumatic boots, let ice accumulate on the leading edges before popping the boots; if you pop too early it may not break off cleanly and the next layer of accumulation will be harder to remove.
When ice sheds off the prop blades and hits the fuselage it will probably scare the crap out of you the first time you hear it.
Make sure you know the difference between "de-icing" and "anti-icing" gear on your aircraft.
My icing experience is very limited so can't give much more advice sorry. It can easily and quickly kill you, so treat it with the respect that it deserves.
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Thanks guys. Will do some more research and give you an update.
I have also found some NASA icing training program for pilot and a few case studies. In the process I got in touch with NASA retired research scientist, who promised to send me books and research paper. I will talk to him and read up on it.
I fnd icing challenging because you can't know for sure what you'll get till you get there since accumulation is different on different aircraft type and de-ice, anti-ice capability.
Be-99 manual supplement that I found from CASA database ( could not find anything on the FAA side yet) said flight in severe icing condition is prohibited. It defines severe as freezing rain, freezing drizzle but said nothing about freezing fog. According to NASA severe= SLD ( supercooled large droplets) and anything more than 50 microns in diameter is considered large. Now freezing drizzles and freezing rain droplets are larger than 50. Fog I am not sure...is not it about the same size as moisture droplets in clouds?
I have also found some NASA icing training program for pilot and a few case studies. In the process I got in touch with NASA retired research scientist, who promised to send me books and research paper. I will talk to him and read up on it.
I fnd icing challenging because you can't know for sure what you'll get till you get there since accumulation is different on different aircraft type and de-ice, anti-ice capability.
Be-99 manual supplement that I found from CASA database ( could not find anything on the FAA side yet) said flight in severe icing condition is prohibited. It defines severe as freezing rain, freezing drizzle but said nothing about freezing fog. According to NASA severe= SLD ( supercooled large droplets) and anything more than 50 microns in diameter is considered large. Now freezing drizzles and freezing rain droplets are larger than 50. Fog I am not sure...is not it about the same size as moisture droplets in clouds?
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Oh dear, this discussion brings back memories of being stuck in an un- named field in Tasmania whilst the captain refused to taxi as a few puddles had a very thin layer of ice, we had to wait till mid morning for it to ice melt, in the mean time a local flight school flew circuits against a clear blue sky, whilst I hid in a crew room! Looking out the window right now it snowing like hell, we just landed with no problems, welcome to Canada!
