Cruising Alt & Freezing Level.
 

hi all

Just trying to find some information on crusining altitudes in regards to freezing level. Ive search for a while and cant seem to find anything. :ouch:

Any advice or references would be much appreciated :ok:

Not in cloud above freezing level without de-icing gear...? :}

Or, if u got da white stuff building up on wings, props etc... go lower! If you cant go lower due lsalts etc you better hope theres a nearby airport with instrument approaches to land at or that whatever your flying has the nuts to get above the cloud!! :}:E

Hope ive helped... lol :ok:

Turbz :E

Just information of pre-flight planning of altiutudes and the freezing level is a few thousand feet above the LSALT. So in cloud and no de-icing equip.

Thanks for your help, ill remeber to take a plan with nuts when flying in cloud :}

The area forecast is a good place to look!

J:ok:

I guess if you cant get above the cloud ie. it extends above A100 and you cant get a hemispherical cruising level between LSALT and FZL you just have to plan non standard levels... or just cruise at LSALT if its that tight...
You just have to be careful of freezing rain etc, coz u can still freeze up a couple of thousand feet below FZL, one day i had about 2-3 inches of ice on my wings from only 5 or so mins popping in and out of cloud 4000' below the declared FZL so keep an eye on your OAT too if its close...

Turbz :E

Ummm, was the question how to work out Freezing levels in pre-flight planning ? or how to figure if you have ice build up? or what to do if you find yourself inadvertantly cruising in it ?

Having spent 90% of my flying career in the sub-tropics/tropics, I know all about flying in icing conditions! Yeah right!

I aversion to ice is right up there with my aversion to CBs.

Here's my approach for a GA aircraft not approved for flight into know icing conditions.

1) No flight in sustained cloud at or above the forcast freezing level.

2) If flying in IMC and icing occurs - immediate 180o turn and bug outta there. There was no icing in the air you just flew through so there should be no icing when you go back there.

3) Descend into warmer air if LSA allows, before returning to the desired course.

4) Take a different course that has a lower LSA - well below the freezing level

5) If in doubt - head for the nearest instrument approach behind your present position, with the lowest LSAs and land.

Nothing is so important that you should risk smacking in!

Dr :8

PS: I suspect that people who operate in southern Australia are considerably less averse than I am!

Icing
 

below -40 SAT we switch anti ice off..... :}

Yeah, what FTDK said... i should have stated that i didnt just keep going with that ice on either, i descended and it eventually broke up and allowed me to return to normal cruise IAS again...

Sometimes (especially around Tassie) you will have FZL much lower than your LSALTs... ive heard of the troubles other pilots have had but never had to plan around a situation like that before fortunately...

My experience is that young pilots starting out are weary of ice for a few hundred hours, and then once they have had trace ice build up and do very little to the performance of the aircraft a few times they get a bit bold and tend not to do that 180 turn straight away. Then one day the trace ice turns to three inches of rime in about 40 seconds and the airspeed indicators don't match and the airspeed drops way back .....then they rethink the 180 turn thing for their next flight. Human nature I suppose. It's like they (me included) have to see it for themselves before they'll believe that it can be scary stuff.
At the end of the day, if you have no anti or de ice and you can see ice building, get out of it.

I had a question in my IREX exam about pre-flight planning said something along the lines of the freezing level is 9000ft along route WXXX. What altitude should you plan your flight at: (LSALT was about 6100ft)
The track was a westerly heading
a) flight can not proceed,
b) fly above LSALT at 8000ft
and i can remeber the other two (im sure it would help a lot if i could :8)

Cloud should perhaps include any "VISIBLE MOISTURE"

You don't always have to go lower, you can go higher - just stay out of VISIBLE MOISTURE and you won't ice up, even if "above the freezing level"

Umm... same difference Atlas, and if you read the post, i didnt say stay below the FZL... i stated "not in cloud above the FZL"... it means the same thing... :ok: I mentioned rain also...
But thanks for quoting me anyhoo...

Turbz :E

Hey,

Does anyonone know the reference for not planning above FZL in IMC ?

Can't seem to find it in AIP, CAR's or CAO's or on the web :bored:

Cheers

Have a look and see what the Canadians do in winter ops. They seem to manage ok in the winter when the temps can be as low as -35 on the ground.

As icing is only a problem down to -40 C, the Canucks can probably climb a few thousand feet ASAP and have no worries!

Investigation: AO-2007-019 - Icing event - 50 km SW Canberra, 4 July 2007, VH-VEG, Beech Aircraft Corp B58

This ATSB is a good read regarding an icing incident in a Baron a few years back near Canberra.

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?'.

Flight in known icing conditions is an aircraft certification issue and as such you will find details in the POH for your aircraft. If your aircraft is not certified for something you are not allowed to do it. That applies to other things such as aerobatics, flight at night, or in IMC.

Also worth remembering that the freezing level on the forecast is just that, a forecast. The temperature in cloud can vary and cause icing when below the forecast freezing or you could be lucky and not encounter ice at the forecast level. If your not in an aircraft certificated for flight in known icing be conservative with your planning so you can descend out of icing immediately.

Bullsh!t. :ugh: CIVIL AVIATION REGULATIONS 1988 - REG 238 Icing conditions

Basically, if your aircraft is not certified for ice (that's certified, not just "hey I've got hot props, it'll be OK") then finding yourself flying in icing conditions means you have screwed up to roughly the same extent that a VFR pilot who finds themselves flying in cloud has.


... and case law shows that is exactly how the courts view it, for those found out. (As in managing to land after some sort of distress call to ATC, not just getting killed.)

It always amazed me that when hundreds of DC3's from the war were made available to civilian operators in Australia, one of the first "modifications" these operators made was to strip off the wing and tail rubber de-icing boots. This was done to save weight and make more money. DCA looked the other way and even approved the modification.

So for years there were DC3's and Bristol Freighters and other smaller twins and singles being flown in southern Australia and across to Tasmania hauling freight and passengers in mid-winter while braving ice. Sure there was sling rings to throw de-icing fluid into the props and squirty stuff to de-ice the cockpit the windshields. But the rules designed to prevent flying in icing conditions were regularly flouted and are still flouted to this day with Chieftains and their GA ilk which are not equipped for flight into known icing. There were many frights as aircraft were covered with ice but most managed to get away with it although the number of close calls were never recorded. The good old RAAF did the safe thing and kept their Dakotas with the rubber de-icing boots installed - and still did until the last Dakota was retired.

Maybe I misunderstood but wasn't he saying that nobody will stop you from doing it at the time - ie ATC won't tell you not to - not that it isn't against the regs (which it clearly is) or that you won't be busted subsequently?

(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.

That was my understanding of the point. ATC can't/won't know of your aricraft's capabilities, so they will let you fly into known icing. ie they won't try to stop you.

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.

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 ïn flight icing"by Perkins & Rieke that I got from Sporty's.

That book by Rieke- in flight icing
 

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

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).

Thanks, Captain Nomad
 

Thanks. I appreciate it. That really was super helpful.:ok:

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)?

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 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.

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?

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!