SE IR during winter time and icing conditons

[Fladbrokeandbusted]

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

[A and C]

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.

[bookworm]

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).

[IO540]

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.

[A and C]

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!

[IO540]

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 :)

[ab33t]

Bottom line Plan Plan and Plan again... that magical escape must exist .

[S-Works]

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.

[scooter boy]

"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)

[S-Works]

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.

[Fladbrokeandbusted]

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.

[Fuji Abound]

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.

[IO540]

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 (http://aircrafticing.grc.nasa.gov/courses.html)is a good NASA icing course.

A good article on freezing rain (the ultimate hazard) is here (http://gltrs.grc.nasa.gov/reports/2000/TM-2000-210058.pdf).

[deice]

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? :uhoh:

[IO540]

Knowledge is power.

[Fuji Abound]

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.

[M609]

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?

[IO540]

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?

[Fuji Abound]

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.

[Johnm]

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.

[S-Works]

Fuji I agree that for reliable winter operations a de-iced aircraft is the way to go. But this does not preclude an experienced pilot making safe decisions around known icing conditions.

I would bet that IO and I probably have a lot more REAL experience of flying in these conditions than the anecdotal evidence offered so far. Ice does not build up at the rate claimed in stratus and real experience over many thousands of hours has shown me in the type of conditions where I know I can get in top (yesterday for example) that the accretion rate on my aircraft is minimal. Minimal to me may be bum clenching to you, but then you don't know my aircraft.

I don't have the luxury of a TKS prop but I do have the luxury of excess horsepower and a windscreen heater that keeps a perfect hole clear!

So what if the screen whites out on the climb, I have an instrument rating and am perfectly capable of conducting the entire flight without seeing out. The crucial decision is making sure that the temp is high enough to clear the screen before starting the IAP.

[Fuji Abound]

Bose - I was in no way intending to contradict anything you said or IO.

I mentioned the matter of the window icing only becasue there are obviously those low hours pilots who have never experienced icing before and think ah well lets "punch" through that bit of cloud I will keep a good eye on the leading edges, it will not be a problem .. .. .. I suppose that is exactly what I expected when the screen turned white in an instant. As you say with an IR and experience, so what, but with much less experience the first time it happens it might not be what you are expecting.

The analogy holds good for those unfortunate pilots who get themselves in clear air on top (perhaps having found a good hole or two through which to climb). An hour later into the flight perhaps having been forced higher over a solid undercast and their shiny new IMC appears to provide a good solution for a descent until all of a sudden as they enter the undercast the screen turns white and the airframe starts to ice up at rate far greater than they had anticapted (assuming they had even anticipated it was going to happen at all). As we all know it happens, hence my comment about having a healty respect for icing conditions or the possibility of entering them particularly if the aircraft is inadequately fitted to deal with ice, because ultimately you are relying even more on the skills of the pilot to ensure a problem does not ensue.

[M609]

At some 10,000fpm he could have got out of it in seconds

Yes, but the subsequent contact with cumulus granitus would be fatal, as going up was not an option due to fuel constraints. He had to follow a PAR until below cloud, and started to loose the ice again fairly quick. (Saab 105 btw)

Stratus clouds from approx 500ft to 4000ft. Temp/humidity would suggest no ice present.
The pilot had a few words with his weather briefer afterwards. And surprise-surprise a ICE MESSAGE ticked of the AFTN printer minutes later.

Where I work now, ice is an issue in clouds pretty much all year.
When briefing visiting MIL helo pilots , the Flight Safety Officer always include "never, EVER fly into cloud".

The reason for that? The RNoAF has had a few helos over the years that tried to sneak trough some thin layers, only to find themselfs in trouble. All shed the ice on the way down and regained control, but still.

Will you collect dangerous amounts of ice each time? Certainly not. But enough times to avoid the possibility IMHO. My main concern is how you know you can climb/descend faster then the ice building. You must be fairly certain about conditions on both sides of the layer, as well as thickness.

[IO540]

An hour later into the flight perhaps having been forced higher over a solid undercast and their shiny new IMC appears to provide a good solution for a descent until all of a sudden as they enter the undercast the screen turns white and the airframe starts to ice up at rate far greater than they had anticapted (assuming they had even anticipated it was going to happen at all).

Agreed; this is another reason why flying VMC on top on the IMC Rating is rarely practical even if within the pilot's privileges.

The key issue is that you can come up against CAS, and unless on a Eurocontrol IFR routing (which is all but impossible to do in the UK without an IR and which always needs an IR overseas) you may not get the clearance into it, which is required to climb to remain VMC.

When I fly IFR/airways, I get a rough idea (which is all one can get) of the cloud tops, add a few thousand feet, and file a flight plan for that. And remain VMC. If unable to remain VMC (i.e. the tops have climbed above FL190) I would turn back - no way to fly through IMC at say -15C for 4 hours.

Yes, but the subsequent contact with cumulus granitus would be fatal,

I meant climb at +10,000fpm. Any half decent mil jet can do that, even without reheat.

as going up was not an option due to fuel constraints

I hate to sound like a smart ar*se but it was a seriously bad move to go flying at all, with the OAT barely above zero, OVC005, and with not enough fuel to climb out of a 3500ft thick layer..... I wonder what sort of conditions were expected? I would have a 2 hour reserve on any flight - enough from the UK to roughly La Rochelle.

Perhaps the pilot actually had his back against the wall due to some other previous stuff, had no fuel left, and picking up ice was just the last straw on his way down? Otherwise, I can't see the issue. At a TAS of 350kt+ (again, a mil jet on maybe 10%-20% power?) you will pick up no ice at all due to aerodynamic heating taking the whole airframe out of the region where supercooled water can exist. You can't land at 350kt TAS but you won't be iced up, and your options are limited only by fuel.

Temp/humidity would suggest no ice present.

Any temp below 0C and IMC = potential ICE. The humidity is unknown, except on the surface. In cloud, it's 100% anyway.

And surprise-surprise a ICE MESSAGE ticked of the AFTN printer minutes later

The generator of that message should apply for a job at the UK Met Office. With such amazing knowledge, he might provide a useful service to pilots :) The fact is that stuff cannot be meaningfully forecast. You can put a probability on icing in cloud but only over a huge area. E.g. here (http://ows.public.sembach.af.mil/)(look under Flight Hazards).

The RNoAF has had a few helos over the years that tried to sneak trough some thin layers

I know nothing about helicopters but understand they do suffer much worse from ice. The mach # of the main rotor is also a small fraction of that of a normal piston engine prop, whose blade tips are struggling to stay below mach 1 by design.

I don't disagree with warnings about ice but I think there is too much general "fear" stuff going around.

[deice]

What happened to regulations? Is it just me who believes flying in to known ice without FIKI equipment is against the regs? I understand it CAN be done, but it isn't allowed. I thought that should override all the "can" statements.

But you enter inadvertently no doubt...:E

[IO540]

The argument, deice, is what constitutes "known ice".

The FAA has defined it for US pilots, at various times. I am not up to date on the current definition, and in any case there is an intractable question mark over the way an FAA definition (which refers to a U.S. weather service) maps onto some European weather service. For example the UK MO Form 215 forecasts icing in all cloud irrespective of temperature which is obviously nonsense.

Private flight in icing conditions is not illegal anyway; it comes down to the PIC making the appropriate decisions to handle the situation.

[mm_flynn]

There was a brief period on the FAA side where visible moisture forecast and less than 0 C was deemed as Known Ice. After AOPA and others howled that this was an impractical definition, the FAA seem to have moved to a complex and vague position that if a reasonably prudent pilot with the PIREPS, weather data, route plan would concluded that ice is likely to form and stick then this is Known Ice.

See this (http://www.thefederalregister.com/d.p/2007-04-03-07-1620)

[M609]

I would have a 2 hour reserve on any flight - enough from the UK to roughly La Rochelle.


I got to list all facts i see.

1. SB05 on 450nm-ish IFR nav ex ending at another aerodrome, but had to divert due weather (TEMPO did kick in)
2. Alternate was departure AD 80-ish nm away from dest.
3. Temp was not fcst below zero at alt in that area, but temp was colder at alttitude than fcst. (It happens as I'm sure you know well)
4. Did 2 attempts and climbed out to VMC on top due to ice, but with only 15 min of fuel left, was committed to land. (Had it been one with 2 bang seats, and not a 4 seat one, he might have done a MB letdown.)
5. 2hrs is closer to the 105s total endurance than reserves.....

My point is that you can get youself on the wrong side of a cloud containing substaitial and dangerous amounts of ice. If you allways have a surefire way of flying to an alternate without any clouds with ice, and you are sure if it (and have plenty of fuel to do it), perhaps its fine.


At a TAS of 350kt+ (again, a mil jet on maybe 10%-20% power?)

Or at close to 80-90% as the case with the 105...... :ugh:
This is not an F-16....the 105 on the old engines was asmatic at best.
Belive me a run with gear up all the way down the PAR was considered, but he decided not to. Had the celing been a bit better he probably would have.
250kts would do to protect against the ice. You do howver need to bleed of quite a lot of speed.

The fact is that stuff cannot be meaningfully forecast. You can put a probability on icing in cloud but only over a huge area

Correct, and alltough I don't remember, the ICE MESSAGE probably covered the better part of South Sweden with mod or severe ice.
You might consider it a bit inaccurate, but I'v seen to many cases of flights encountering eighter ice or tubulence that they did not expect, so I prefer them to err on the side of caution.

But all pilots are free to do as they feel I guess as long as they know the consequenses of getting caught bending the rules! :)

[S-Works]

M609, So what you are actually quoting is a completely screwed up situation and trying to blame it on icing?

What a load of pap, you should let this one die before you make yourself look any stupider.

[bookworm]

concluded that ice is likely to form and stick then this is Known Ice

The choice of words is critical.

If the composite information indicates to a reasonable and prudent pilot that he or she will encounter visible moisture at freezing or near freezing temperatures and that ice will adhere to the aircraft along the proposed route and altitude of flight, then known icing conditions likely exist.

Does this actually define anything? :confused:

[deice]

Moisture in clouds at sub zero temperatures should provide a cue to icing conditions, which would be known to an experienced pilot. Regardless if you have a thin layer which only results in slight ice this is still in validation with regs as far as I see it. What section of the TB20/21 AFM states that 6mm ice is ok (if that's what you're flying)? I fail to see the logic, do you spin your aircraft too even if it says prohibited?
You can argue for decades about experience this way and that, but launching into an overcast with temps below zero and no gear sounds like a violation to me. But, I shall rest my case, it's your decision after all.
I'm glad I've got TKS on the DA42.:ok:

[M609]

you should let this one die

Sure, if you say so! :oh:

[IO540]

I'm glad I've got TKS on the DA42

Most likely, your full-TKS DA42 will hang on in icing for longer than my prop-only-TKS TB20.

However, neither of us can fly significant enroute sections in freezing IMC. Even if TKS protects you, it will last only, what, 1-2 hours?

So while you may have a adequate solution for short exposures, the bottom line is that both you and I have to plan for the flight to be VMC on top (talking airways now) and scrap it otherwise. Your endurance is something like 10 hours and the TKS won't go for that long.

And, like oxygen, you can't get your TKS tank refilled at the vast majority of European airports. So these things remain a go/no-go flight planning issue. The stuff is also awfully expensive; I've recently bought a drum of about 20 litres and it was about 200 quid - the full system would get through that on one flight.

One could also argue that the DA42 aerofoil will suffer from ice a lot more than a TB20. I have never seen other than anecdotal evidence for this. One experienced Lancair 400 pilot I know says it is really affected by water (rain) on the wings, which is pretty serious...

[mm_flynn]

.
Does this actually define anything? :confused:Not really - Which confirms my view the FAA have moved to a 'vague' position!!

[Fuji Abound]

One could also argue that the DA42 aerofoil will suffer from ice a lot more than a TB20.

Why?

Even if TKS protects you, it will last only, what, 1-2 hours?

Two and a half hours will a full tank.


It is not a de-icing system as the manual makes clear any more than on the Mooney - its purpose is to prevent the accretion of ice. If you allow the ice to build before use you will have a problem. The reverse is true of boots and hot air bleed.

[IO540]

Because the DA42 is a more aerodynamically efficient aerofoil, Fuji :)

I could be wrong of course. It could be that a "blunter" aerofoil picks up more ice. OTOH a thicker aerofoil might be able to carry more ice, for a given % increase in drag.

2.5hrs is more than I thought but still not enough to be able to file a 4hr Eurocontrol IFR flight plan at FL100 if the tops are forecast at FL140 all the way.

[A and C]

A thin object will (all other factors being the same) pick up ice faster than a thicker object.

This is largley because the thicker object has a greater effect on the air ahead and starts to "push" the air aside at a greater range than a thin object.

This fact is used to the pilots advantage in detecting ice, most light aircraft are fitted with a thermomiter that has a long hex probe in the veiw of the pilot and being a thin object that is usualy the first thing to pick up ice.
It is wise if you suspect that you may be entering icing conditions that you monitor the temp probe for ice build up.

As the wings of the "glass" aircraft usualy present a much thiner leading edge to the airflow it follows that this type of wing will pick up more ice than a thicker wing.

It also follows that being thinner the tailplane (Stab for the Americans) will have a greater ice buildup and therefore the first problems that you might encounter might be ones of control, either aerodynamic from the shape of the ice or if you have a "flying" tailplane problems resulting from the change in mass balance.

A year or so back I had a DVD on the subject of icing and GA aircraft that was made by NASA, it was required veiwing for my IMC students untill it went "walkabout", perhaps one of you who is much better at this internet thing could find a way for us all to veiw this online, I'm sure that it would bring some clarity to this debate.

[Fuji Abound]

Yes, but doesnt ice start to form far more quickly on imperfections in the surface - so the build up will start around joints between the aluminium sheet, flat rivet heards etc.

[DFC]

Before more rubbish is spoken here perhaps everyone should complete the following course from NASA.

http://aircrafticing.grc.nasa.gov/courses.html

After that then there may be a bit more informed comment.

Regards,

DFC

[A and C]

Normaly the ice starts to form just above and below the airflow stagnation point on the leading edge and then as the airflow is altered by the ice formation the gaps get "filled in".

A most leading edges are smooth rivet heads and joints have little effect, I have no doubt that the imperfections do pick up ice but this is trivia when leading edge ice is considered however if your aircraft has deicing on the wings and can fly for some time in icing conditions the buildup of ice on unprotected areas will become a problem.

DFC thank you for the link, I will see if it is the DVD that I used.

[deice]

IO540, as you say, we're not planning on loafing around in icing conditions, nobody does that with their head stuck on, and I'm rather sure the DA42 will pull through clouds with equal enthusiasm as the TB. The key point is you shouldn't launch into a known icing condition if you don't have gear for it, and the aircraft is approved. I believe the AFM details that, but as you most certainly know FIKI does not mean you're immune to ice, and yes the TKS system is anti-ice. Regardless, it works if you use it sensibly whereas if you have nothing you also have no options. And, you're still not legal. But then, breaking the regs seems to be standard procedure on many occasions..:ugh:

[soay]

A thin object will (all other factors being the same) pick up ice faster than a thicker object.and Yes, but doesn't ice start to form far more quickly on imperfections in the surface - so the build up will start around joints between the aluminium sheet, flat rivet heards etc.
Because composite wings have smooth surfaces, they can be designed to take advantage of the effects of laminar flow. Rivetted metal wings generally don't, so have a thicker chord to compensate.

This (http://ntrs.nasa.gov/search.jsp?R=753433&id=6&qs=Ntt%3Dlaminar%252Bflow%252Bairfoil%252Bice%252Baccretion% 26Ntk%3Dall%26Ntx%3Dmode%2520matchall%26N%3D0%26Ns%3DArchive Name%257C0) NASA publication concludes that "In the laminar region of an airfoil, roughness [due to heavy rain, ice, and frost accretion] interferes with smooth flow and tends to encourage transition from laminar to turbulent flow upstream of its normal point of occurrence. In the airfoil's turbulent region, roughness considerably worsens the turbulent friction coefficient, thereby increasing the drag coefficient. Consequent dramatic decreases of maximum lift coefficient at high angles of attack lead to premature stall. Such decreases in stall angle destroy the safety margin of an aircraft approaching stall."

Even an accumulation of dead flies can slow down an SR22 or a DA40, because of the need to increase the angle of attack to compensate for the loss of lift.

[DFC]

deice,

I can see your point.

However, fly in level flight at FL70 in stratus with OAT-5 on a certain day and you don't get ice. Do it again the next day (or even a few hours later) and you pick up ice.

Ice is so unpredictable that unless the previous pilot has reported ice at your level recently then there is very little to go on. Most icing forecasts are based on the probability of icing being in any cloud at sub zero temperatures and the fact that icing in convective situations is more serious i.e. cu family and over rising terrain.

So in your aircraft that is not approved for flight in icing conditions, you can indeed stay on the ground or limit yourself to VMC below cloud flying. However, you will find that you will cancel many flights that could have been safely completed.

If you are flying in visible moisture and you start picking up ice, the only answer is to exit icing straight away. The question is do you go up or go down. Icing is normally found in 3000ft bands so if you are 1000ft into the band when you see ice forming, is it quicker to climb above or descend below the icing layer?

You would only be illegal if you had to descend below MSA to clear the ice or you remained in icing conditions i.e. you continue to pick up ice.

Most IR candidates will be familiar with the pre-takeoff brief that they give the examminer. It goes along the lines of;

..........If we encounter icing conditions I will climb above or descend below icing but not below MSA and then decide to continue or divert............

The IR test is asumed to be in icing conditions and many people manage to pass in aircraft with no approval for icing conditions because they will comply with the above statement.

As soon as IMC is simulated on the test i.e. at 300ft the first thing the candidate is expected to say is "icing check".

Unfortunately, airframe icing is often glossed over on the IMC course and thus there is a widespread misunderstanding.

Complete the NASA course I gave the link to above and while it is designed for people who fly aircraft which are approved for flight in icing conditions, it is useful for everyone.

Finally note that most light twins are only approved for flight in light icing conditions. Light icing is defined as;

“Light — The rate of accumulation may create a problem
if flight is prolonged in this environment (over one hour).
Occasional use of deicing/anti-icing equipment removes/
prevents accumulation. It does not present a problem if
the deicing/anti-icing equipment is used;

Regards,

DFC

[whitehorse]

Complete the NASA course I gave the link to above and while it is designed for people who fly aircraft which are approved for flight in icing conditions, it is useful for everyone.

Couldn't agree more with DFC:ok:

[S-Works]

And for once even I agree with him.

[deice]

Me too! All good points here I think.

My personal issue with ice and flying aircraft without equipment stems from the fact that it is so unpredictable, as we all attest to. I've heard countless statements of how much ice a PA28 or C172 can handle yet we see deiced aircraft tumble out of the sky from time to time. It isn't to be taken lightly and as an instructor I don't want to give newbies the wrong idea.
I know people who do all kinds of weird things in aviation and survive, but it's not so intelligent to sanction these actions - they are dangerous, and flying in ice is too.

So, as a last word from my part, please consider what you do, and consider who you tell about it.

[IO540]

we see deiced aircraft tumble out of the sky from time to time
Do you have references for accidents where icing resulted in loss of control, in any aircraft whether KI or not?

I know there are some where the pilot said so but out of the vast piles of NTSB AAIB etc reports there are very very few.

[S-Works]

deice, and as an Instructor I disagree with you, we have a duty to present the facts not old wives tales.

[bookworm]

I've heard countless statements of how much ice a PA28 or C172 can handle yet we see deiced aircraft tumble out of the sky from time to time.

Can you give any examples of this? The SHK website has its reports online, so perhaps we can learn something. I've struggled to find many reports of accidents involving airframe icing in the UK. There was N8174V (http://www.aaib.dft.gov.uk/publications/bulletins/august_2005/cessna_150m__n8174v.cfm) a couple of years ago, which I think it would be fair to say was not the pilot's smartest flight. Any others?

[deice]

There was one a couple years ago wih a Caravan in Finland, although it was probably a combination of ice and bad loading.
You should check the Caravan pilots website, there are a number of accounts there as I recall. The problem may be that if you come down due to ice, and temps are above zero on the ground the evidence is gone... An SR22 went down in the US after accumulating ice and didn't get the chute out, last year or year before that I believe.
I know I've read these reports, but I don't have any links to them that I can add, but the US NTSB and Swedish accident board (www.havkom.se) present some facts. I'll go digging again. :)
What's this about old wives tales? You haven't met some of the pilots I have!:eek: I know of a number (VFR only pilots) that climb through cloud without IFR clearance in uncontrolled airspace and fail to see the hazards as in IFR traffic heading the opposite direction. They seem to think that if ATC doesn't know they're there and breaking the regs then they're ok.
These same persons would gladly take off into an overcast to see how much ice they might pick up. Stupid. Why would I want to tell them how much ice a PA28 can handle? I have no idea, and I'm pretty sure you don't either. If you do, please contact NASA and have them employ you as their expert. :E
Yes I've had an inch of ice on a warrior, and I feel stupid for doing it. :ooh:
I've had the same on the Seneca knowing what I was up against. It's different. Knowing how to handle ice with de-ice or anti-ice equipment is part of the trade, knowing when not to fly in non-equipped aircraft is the same, as I point out to my students. But that's just me.
Please keep up with your work and train them as you like.

[Fuji Abound]

Can you give any examples of this?

I think if you look at the NTSB reports you might find more than a few.

You know how few private pilots are qualified in Europe to fly IFR. Given the small numbers doing it, and their experience levels, I would guess that is one reason for less icing accident here rather than there.

[S-Works]

What's this about old wives tales? You haven't met some of the pilots I have! I know of a number (VFR only pilots) that climb through cloud without IFR clearance in uncontrolled airspace and fail to see the hazards as in IFR traffic heading the opposite direction. They seem to think that if ATC doesn't know they're there and breaking the regs then they're ok.

Which just proves my point.......


You have presented NO evidence that a properly prepared pilot is capable of safe flight through icing conditions. You have just proved that those who are stupid are capable of getting themselves into trouble.

[bookworm]

I think if you look at the NTSB reports you might find more than a few.


You're right. The first one I found was an SR20 that flew (or tried to fly) across the Rockies with scattered embedded TS. It's fairly typical. Interestingly, most of the accidents occurred above 10,000 ft over mountains.

I was a bit amused by the second (http://www.ntsb.gov/ntsb/brief.asp?ev_id=20051014X01652&key=1). It starts

"The flight crew, an airline transport certificated captain, and a commercial certificated co-pilot, were flying a restricted category, icing research equipped airplane in instrument meteorological icing conditions under Title 14, CFR Part 91. The purpose of the flight was to locate icing conditions for a prototype helicopter's in-flight icing tests. While in cruise flight, the airplane encountered icing conditions, and had accumulated about 1" of ice on the leading edges of the wings. The captain reported that he activated the wing deicing pneumatic boots, and the ice was shed from both wings. About 4 minutes after activating the deice boots, both engines simultaneously lost all power. The crew attempted several engine restarts, but were unsuccessful, and made a forced landing on frozen, snow-covered terrain."

[IO540]

Well now that we are trawling the internet looking for the biggest possible mugs who somehow managed to get a PPL :) I could tell you some stories I've read in certain places. They got deleted very quickly afterwards when somebody pointed out that (to give one example) the FAA mandates oxygen above 12500ft but this man was flying at 14000+ for much longer than the 30 mins max while obviously suffering hypoxia because he had totally lost it mentally and he stuck his arm out of the little LH ventilation window and tried to scrape the ice off his wing with his bare fingers until they were bleeding. That one (a non deiced SEP of a type I know quite well) actually landed OK, with several inches of ice still remaining. I believe the pilot (a public performer in the music business) gave up aviation after that.

There is no shortage of total mugs, and some are bound to get into a plane eventually. This must not be confused with a dispassionate discussion of risk factors etc.

although it was probably a combination of ice and bad loading

well there you go... bad loading! I wouldn't like to guess how much ice a Caravan can carry but it's a helluva lot more than even an Aztec.

The thing which concerns me more is fuel icing. This does happen on some types at OAT below about -25C. I have never found any report of it happening on a TB20/TB21 though. This would be a disaster because the engine stops and absolutely will not restart until you are back in warm air. I recently met a twin (KI) pilot who lost both engines over the N Sea at FL250, and didn't restart until down to 2000ft. He sold the plane immediately and bought something a bit bigger but more importantly something that burns avtur. One can get additives for avgas for this but there isn't much data on how different types are affected.

[Fuji Abound]

The airplane was substantially damaged during an in-flight collision with terrain following an inadvertent stall on short final. The pilot reported that the instrument flight rules (IFR) flight had initially been operating above a broken to overcast cloud layer. However, about the mid-point of the trip the flight encountered instrument meteorological conditions (IMC) and light rime ice. The pilot stated that he requested a higher altitude in an attempt to avoid the icing conditions, but air traffic control cleared him to a lower altitude due to the flight's proximity to its intended destination. The flight remained in IMC as it was vectored for an instrument approach. At the missed approach point, the pilot did not have the airport in sight due ground snow cover and his unfamiliarity with the area. He executed a missed approach. While being provided with radar vectors for another approach, the pilot obtained visual contact with the airport. When he entered visual flight rules (VFR) conditions, he cancelled the IFR flight plan and entered a traffic pattern for runway 36. The pilot reported that on short final the airplane drifted left of the runway centerline. He applied a little power in an attempt to get re-aligned. The pilot stated: "The aircraft started rolling left. I applied full power and attempted to abort my landing. The aircraft engine responded but we completely rolled until inverted and subsequently made contact with the ground." In a follow-up interview, the pilot stated that the aircraft had accumulated rime ice along the leading edges of the wings. An AIRMET for occasional moderate rime or mixed icing below 10,000 feet mean sea level was in effect at the time of the flight. A certified re-recording of the weather briefing was provided to the NTSB. During the briefing, the pilot was informed of the AIRMET and of a pilot report of light rime ice along his route of flight. The pilot had received his instrument rating seven weeks prior to the accident. He reported 2.5 hours of actual instrument flight time and minimal experience with in-flight icing conditions. Federal Aviation Administration publications state that ice formation on an aircraft's flight surfaces may adversely affect performance and control. They note that with ice accretion an "aerodynamic stall may occur with little or none of the usual cues in advance of the stall or at the occurrence of stall."

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

The pilot's continued flight into icing conditions resulting in ice accretion on the wing and his failure to maintain airspeed resulting in a stall.

Since we are all trawling that one took 5 minutes to find.

I suppose the problem with any encounter with ice that goes horribly wrong is the pilot will be considered negligent.

For those who fly regularly in the winter in IMC may by the grace of God or by the level of their skill none of us make such a mis judgement.

[deice]

You have presented NO evidence that a properly prepared pilot is capable of safe flight through icing conditions. You have just proved that those who are stupid are capable of getting themselves into trouble.


OK? Bose-X, I'm not following you. I never said a properly prepared pilot could do that. I was trying to say we shouldn't and especially not without the gear for it. I think there are others here who say they can and do because they know how to. But it seems I am the only one who believes limitations in an AFM are meant to be followed, as well as regulations.
I'm not sure I understand what you mean. What old wives tales are you referring to and are you suggesting that I should tell my students that they can climb through an ice condition with their PA28 provided they're not stupid enough to do it?:confused:

[IO540]

I don't know what plane type that was Fuji but I bet that IF icing had anything whatsoever to do with it (for which there is actually zero evidence - apart from the pilot's belief - in that quote) it would have needed more than "light rime ice" to cause the behaviour described, ending in inverted flight.

[deice]

What's your suggestion to the cause then IO540? It seems ice is not on your plate of plausible accident causes, regardless what anyone says.

[DFC]

Ever heard of asymetrical ice shedding?

There is one simple issue. If you know that icing conditions exist ahead (ice adhering to and remaining on the airframe). Then unless the aircraft is approved you avoid those conditions in advance.

There will be few occasions that one knows about ising conditions ahead. There may be posibilities or probabilities but that is different.

If you are ever flying a non approved aircraft (regardless of equipment) in icing conditions that you knew where there then please put on your stupid hat.

There are plenty of icing incidents.

Try searching for the UK ATP crew that suffered tail stall due ice.

Most icing incidents happen to commercial pilots. Just do a google search on "light icing" to get a few good ones.

Regards,

DFC

[Fuji Abound]

I always wondered why they called them Turkeys in the Sates until some one in Florida told me they are as commom as .. .. .. never been sure whether that was the correct explantion

any way it was a Turkey - or to us a PA28.

[IO540]

It seems ice is not on your plate of plausible accident causes, regardless what anyone says

Come on deice. Let's keep this discussion technical and avoid personal attacks, A lot of smart people have b*uggered off from this place because of this kind of thing. Unfortunately it still goes on.

Not light rime.

Anyway, it doesn't ring true. He says it started rolling left, so he applied full power. One would assume he also did something with the ailerons, like turning the yoke fully to the right.... In a traditional SE full power will make things worse due to the torque reaction - this is a known thing in more powerful turboprop types some of which do not have enough aileron authority at Vs to counter full torque and rudder has to be used at the same time to prevent the left roll.

IMHO this isn't caused by "light rime". Much more likely, he stalled it after the MAP because he didn't reapply power for the MA.

And

The pilot reported that on short final the airplane drifted left of the runway centerline. He applied a little power in an attempt to get re-aligned

doesn't make any sense at all. You don't apply power to correct left drift. Maybe there was wind from the right?

Could be all sorts of things. Most PPLs are taught to fly approaches quite slowly. That isn't a good idea for several reasons, but if you have a bit of ice you don't want to be flying slowly anyway.

I am not doubting there have been accidents caused by serious icing; of course there have been. But it takes more than "light rime" on a PA28 to make it roll to the left and crash upside down.

[Fuji Abound]

Slightly different circumstances and an early impact of icing for TB20 drivers from the French AAIB a few years back.

Air traffic control had routed a Socata TB20 further west than the pilot had planned for because of military
activity. This re-routeing brought the aircraft to the area of extensive frontal cloud, which was well away from
the original route. The pilot climbed to Flight Level 100 then FL 110 in an attempt to stay above the cloud
layer. However he was eventually forced into the cloud where he reported that the aircraft experienced light
airframe icing in an outside temperature of –7 degrees C.
Suddenly the engine stopped and manifold pressure dropped rapidly towards zero. The pilot
selected fully rich mixture, switched on the fuel pump and selected a different tank, but to
no avail. He put the aircraft into a descent which settled at a rate of about 1000 feet per
minute.
Approximately one minute after the engine had stopped, the pilot selected “alternate air”.
The engine coughed back into life and the pilot continued on his route, rather lower than he had abandoned it.
After landing, the aircraft was inspected, but there was no apparent reason for the engine stopping.
The BEA concluded that the most probable cause of the engine failure was a blockage of the air filter by ice,
which reduced the airflow into the engine. Selecting “alternate air” by-passed the filter and allowed a free flow
of air to the inlet valves. The Flight Manual for this aircraft recognises the hazard, and recommends that the
pilot select alternate air when flying in icing conditions, which are defined as “in precipitation or in cloud with
an outside air temperature of less than or equal to +5 degrees C”.


and an interesting actual account:

This story began as an attempt to get some actual
IMC for an aspiring instrument pilot. He would fly; I
would file IFR and instruct. We had a well-equipped
C-172 with the 180-horsepower conversion avail-
able. The weather and our schedules matched on
Saturday, November 8. Conditions seemed ideal.
There was warm, moist air over most of Minnesota,
with a southerly flow and widespread low-overcast
conditions. A slow-moving cold front lay across
northwestern Minnesota and was forecast to reach
the St. Cloud area that evening.

We departed at 10 a.m. on a flight from St. Cloud to
Duluth, planning to complete the return leg before 3
p.m. That Saturday morning, St. Cloud, Duluth, and
all en route reporting stations had surface temperatures
of 35 to 38 degrees Fahrenheit. Sky conditions
were overcast at 600 to 1,000 feet. Visibility
below the overcast was four to six miles in mist and
haze. Winds aloft were out of the southwest, and
forecast freezing levels were 6,000 feet. We had
two pireps that indicated the cloud deck along our
route was about 2,000 feet thick with no mention of
icing. The only icing forecast was along the cold
front in northwestern Minnesota.

We picked up an IFR clearance to 4,000 feet and
departed. The instrument student climbed through
the overcast at St. Cloud. Because we were IMC,
we had the pitot heat on. I watched the outside
temperature; it held at 35 degrees through the
climb. There was moisture in the clouds; water
beads were forming and rolling back off the Skyhawk's
wing strut. Leveling at 4,000 put us 200 feet
above the tops in brilliant sunshine. The temperature
read 38 degrees.

Our clearance was St. Cloud-Mora-Duluth, and we
planned to do an en route NDB approach at Mora.
The NDB is on the field. The distance from St.
Cloud to Mora is less than 40 nautical miles. After
enjoying the sunshine for a few minutes, we
requested the NDB at Mora from Center. The controller
gave us 3,000 feet. As we leveled at 3,000,
15 nm southwest of Mora, we were cleared for the
approach. Mora's ASOS was reporting 800 overcast,
five miles in haze, and 36 degrees. Our loran
was giving us distance information to the NDB.
A couple of minutes after leveling at 3,000, I noticed
a trace of rime ice forming on the leading edges. I
was surprised because this was not forecast, and we
had climbed through the overcast 20 miles back
with no problems. I was a little complacent.
Though the temperature here was 32 degrees, I
knew this deck was just 2,000 feet thick, and there
was warmer air above and below. I was still hoping
to complete the practice approach. As we neared
the NDB, still at 3,000, I realized the ice was building
and that we had to leave that air mass. I told Center
we were going missed approach and requested
5,000 feet direct Duluth. As soon as Center
answered with the clearance, we started climbing
and pulled the control for alternate static air. During
this time, the rate of ice buildup increased significantly.
Ice ridges formed on the windshield, and
the protrusions on the leading edges grew rapidly.
Then, I realized the aircraft had leveled at 3,500
feet.

The aircraft had full power, was flying at 70 knots,
and was unable to climb. Incredulous, I said I would
take the airplane and climb the last 300 feet to clear
air. As I took the airplane, I increased the angle of
attack slightly. Shortly thereafter, I began having
trouble with roll control. Still IMC, the attitude indicator
showed a constant left bank of 20 to 25
degrees. The rudder yawed the airplane, but would
not lift the wing. Ailerons did not lift the wing. I
suspected an attitude indicator failure. Then I realized
the heading indicator was rotating in a constant
left turn. The turn coordinator also showed a left
bank. It had to be true. We were indeed flying 65 to
70 knots in a constant left bank, level at 3,500 feet,
too iced up to control the bank at that airspeed. It
was clear we could not climb out.

I lowered the nose and headed for the NDB. Unsure
of our instruments, I asked the other pilot to continuously
read out the aircraft heading from the compass
while I turned to the bearings shown on the ADF and
loran. I told Center we had encountered some ice and
were flying the NDB 35 at Mora to a full stop. We
crossed the NDB at 2,800 feet. In descending flight,
we had control and the instruments worked fine.
However, ice was still forming. I flew outbound for the
procedure turn and let the aircraft continue to settle.
When the other pilot called one minute south of the
NDB, we were at 2,500 feet (300 feet below the published
altitude for the procedure turn), and I noticed
water streaming up the windshield. I added power,
held altitude, flew a tight procedure turn, and
descended to the NDB.

We broke out at 800 feet agl as expected. I gave
the airplane to the other pilot, who circled the field
and landed smoothly without flaps at 80 knots.
While he circled, I noticed the chunks of ice being
carried away by the slipstream. On the ground, we
saw horn-shaped ice formations on all the leading
edges. Ice covered the center of the leading edges,
then ballooned into an ice ridge three times the
thickness of the attached section. To me, it looked
like a large, three-sided engineering ruler attached
to the leading edge of the wing at one of the three
points. We called Flight Service to close our flight
plan and give them our icing pirep.

Over a cup of coffee, we discussed the lessons
learned. The time from the first trace to the decision
to climb out was about five minutes. From
that decision to the point where the aircraft stopped
climbing was, perhaps, another four minutes. The
rate of buildup was many times higher during the
last minutes of the encounter. We reflected on the
danger incurred when the aircraft went into an
uncontrolled left bank during the attempted
climbout. At that point, we both suspected instrument
failure. Being IMC, it took all our combined
skill to interpret the situation and realize that we
had to increase airspeed, which required a descent.
Without pitot heat, we would not have had the airspeed
indicator. Could we have maintained control
without airspeed? How close to the stall did we
get? The actual stall speed was anybody's guess.
We decided the aircraft went into a bank because
the ailerons lost effectiveness. With ice masking
the ailerons and substantially increased drag on the
wings, those control surfaces would no longer overcome
the aircraft's left-turning tendencies at slow
speed. The rudder was effective throughout this
scenario. From practicing slow flight, we knew that
at minimum controllable airspeeds, the rudder is
more effective than ailerons.

It would have been a very dangerous approach if
the icing conditions had continued to the surface.
Throughout the scenario, it was reassuring to have
the current ASOS and know we would break out in
warmer air. The landing was not difficult, as we
had forward visibility and a long runway to accommodate
the required high-speed touchdown.
I will never again doubt that ice can form very
quickly. I also know that a moderate amount of ice
will prevent a small airplane from climbing and will
impact slow-speed flight characteristics. I was
reminded, again, that complacency is a dangerous
flight mate—thinking about the warmer air above
and below made me complacent enough to stay in
the icing conditions until getting out required
unnecessary and dangerous risks.

[deice]

Ok IO540, and I wasn't intending an attack, sorry if it came out too blunt. I was however interested in your alternative suggstion, of which I had one in mind myself. Basically the pilot lost control, but there is a chance that ice added to the effect. You can't predict the behaviour of an aircraft with ice on it. And yes, you can probably climb through thin layers with little ice acretion and cruise on top but that doesn't make it legal.
My intention wasn't to argue whether our little aircraft CAN or CAN'T fly in ice, but rather that you aren't allowed to, as I said in my first post.
I found an article that may shed some light on the FAA's definition of known ice here:
http://www.ifr-magazine.com/defining_known_ice_certification_faa_ifr.html
If it is to be believed then you can't fly in clouds at sub-zero temps unless you have FIKI equipped aircraft. I don't know the EASA/JAA definition, but it shall be sought out.

[Fuji Abound]

Ice accretion may be asymetric between the two wings or ice loss may be asymetric. The roll effect is similiar to asymetric flaps.

A tail stall is a very likely outcome of applying landing flaps carrying ice.

Good reasons for most icing accidents occurring during the approach with what would otherwise appear an "ordinary" stall or otherwise loss of control.

Of course the ice is gone by the time the AAIB turn up.

[DFC]

All this talk of light icing etc is meaningless when in an aircraft that is not approved for flight in icing conditions.

Please remember that any icing encountered in an unequipped aircraft is by definition Severe for that aircraft.

Icing is severe whenever the rate of ice accumulation is such that de-icing or anti-icing equipment cannot control or reduce the hazard. Typically an immediate heading and/or altitude change is necessary

Regards,

DFC

[Pilot DAR]

I agree with DFC.

Icing is just so scary in inadequately equipped aircraft, no matter how many engines. I've had a fully deiced Cessna 303, and a non-deiced DHC-6 Twin Otter no longer able to maintain safe level flight due to un forecast ice. It was only the profound luck of warm air below that saved me in each occasion.

Asking for ice is asking for increased danger, even in some deiced aircraft, let along your average single.

My Opinion.

Pilot DAR

[IO540]

Thank you Fuji for those two cases.

The TB20 one:

Suddenly the engine stopped and manifold pressure dropped rapidly towards zero. The pilot selected fully rich mixture, switched on the fuel pump and selected a different tank, but to no avail

As he discovered, he missed out the most important step in the conditions: alternate air.

The Cessna one:

What isn't clear (without retracing the possible route) is how long they were sitting in the cloud.

If you fly a 747 in freezing IMC for long enough, it will eventually plummet due to carrying too much ice. From his description he picked up several inches and with the extremely draggy "horn" formations one is going to get on the leading edges when it gets to that thickness that is enough to get almost any plane into trouble. I don't think he picked up several inches in say a few minutes.

The strategy, as I have mentioned before, is to avoid continued flight in IMC. If one was VMC on top, the strategy is to remain there until a continuous descent is possible to destination.

The pilot's comment that ice was not forecast is just another symptom of the myths that go round this business. There is no such thing as an icing forecast (that can be relied on).

Deice

I disagree that what you offer is the current FAA definition of KI. There was a time, IIRC, when a flight into forecast freezing IMC would be KI but they have moved away from that. And the impact of this for Europe is complicated by the factors I mentioned (continuous ice forecast in all cloud, and the absence of PIREPs outside the USA).

[bookworm]

Please remember that any icing encountered in an unequipped aircraft is by definition Severe for that aircraft.

Nonsense.

Light ice is the rate of accumulation that may create a problem if flight is prolonged in this environment (over 1 hour). Occasional use of deicing/anti-icing equipment removes/prevents accumulation. Light icing does not present a problem if the deicing/anti-icing equipment is used.

This clearly envisages that a non-deiced/anti-iced aircraft could in principle remain in light icing for up to an hour without adverse effects.

The definitions are almost useless, as most authorities have recognised over the years.

[DFC]

This clearly envisages that a non-deiced/anti-iced aircraft could in principle remain in light icing for up to an hour without adverse effects.

Only if the aircraft is certified for flight in known icing conditions and it has been demonstrated safe without any de/anti-icing.

For example the B737-800 has no anti or de-icing on the outer portion of the wings. Not a problem because the effect of carrying ice was checked during the flight test programme.

An aircraft not certified for ice in icing conditions should not have ice n the airframe at any time. If you read the definition of severe icing again;

Icing is severe whenever the rate of ice accumulation is such that de-icing or anti-icing equipment cannot control or reduce the hazard. Typically an immediate heading and/or altitude change is necessary

and compare that to the pre brief you give the examminer on your IR test;

..........If we encounter icing conditions I will climb above or descend below icing but not below MSA and then decide to continue or divert............

The briefing clearly shows that you will treat any ice as severe and will take the appropriate actions i.e exit icing asap.

Regards,

DFC

[IO540]

Nonsense, DFC. The brief which your CAA IR examiner expects is nothing to do with any legal or practically safe position on the matter.

If one adopts the totally ignorant position on ice which seems prevalent in UK training (if you see any ice you immediately install a fresh pair of trousers) that is one thing, but we are trying to get beyond that.

[Fuji Abound]

I think, however this thread started, the issue that is being discussed is:

The wisdom of climbing or descending through ice for short periods to achieve VMC on top or below or to exit icing conditions in aircraft not fitted with de/anti icing.

I dont think anyone is advocating remaining in icing conditions for any longer than necessary however the aircraft is fitted.

It seems to me the question is can you react sufficiently quickly to the early signs of icing to prevent it becoming a problem.

I0 mentioned the scenario of a climb through an overcast of 2,000 feet to achieve VMC on top with perhaps a small accumulation of ice during the transition.

I thought the reports mentioned were interesting because they illustrate cases were pilots thought they could avoid the more severe reprecussions of icing but failed to do so.

Surely as is so often the case it all depends where you draw your own boundaries?

If you can guarantee the overcast is 2,000 feet with VMC on top, light icing through the overcast and a good margin between the base and MSA and positive temperatures below I dont suppose anyone would really consider the transition a risk.

On the other hand if the sector requires a lengthy flight on top with reliance on the TAFs about conditions at the destination but the possibility of a longer descent through icing, uncertainty about the degree of icing and the possibility of being held in IMC it might not be such a good idea.

[IO540]

If you can guarantee the overcast is 2,000 feet with VMC on top, light icing through the overcast and a good margin between the base and MSA and positive temperatures below I dont suppose anyone would really consider the transition a risk.

On the other hand if the sector requires a lengthy flight on top with reliance on the TAFs about conditions at the destination but the possibility of a longer descent through icing, uncertainty about the degree of icing and the possibility of being held in IMC it might not be such a good idea.

Agreed.

I would add that one can accept more potential icing on a descent than on the climb because of obvious performance issues. Plus the aerodynamic heating (SAT v. TAT) can make a significant contribution.

Fortunately it's not hard to establish whether the cloud tops are say 2000ft versus 15000ft. What is much harder is establishing whether they are 15000ft versus 18000ft - impossible IMHO. I would scrap a climb into anything like the latter scenario. A TBM700 would be OK; you pays your money and....

[DFC]

Don't forget that if you are basking in the sunshine on top it is going to be warmer than just inside the cloud tops. Something I find that many pilots forget......especially when it comes time to descend.

Regards,

DFC

[Pilot DAR]

No too long ago there was a vigorous debate on doing something which is stated as "not approved" on the limitation placard of a Cessna. The majority of contributors asserted that it was unacceptable to do something which was not approved, even though it was not prohibited either.

So now we come to flight into known icing in a (presumably) non-deiced aircraft (number of engines not relevant). My Cessna's limitations placard is clear on that: "flight into known icing to be avoided". So if you encounter icing, or reasonably know that it could be found ahead, you are to avoid it.

Continuing into icing (which you know to be there, 'cause you're in it!) is a violation of the limitations placard (in my Cessna anyway). There is no time period associated with the "don't fly into known icing" warning, so immediate retreat would be the only compliant action. And, if you could have known the ice might be there, you have been told not to even try.

People have railed against unusual attitude flying in non-aerobatic aircraft in previous posts. To me, venturing into any ice in a non-deiced aircraft is very much worse. The deliberately flown unusual attitude can be recovered whenever you want, and does not change the way the aircraft flies and what it weighs. Ice changes everything, and all at the same time! Add to that, the surprise unusual attitude you're about to have to recover will have be done (or not) on instruments only, with an aircraft which now flies differently that it did when you took off!

I speak from experience!

(which I carefully plan to never repeat)

Pilot DAR

[IO540]

You are mixing up legal and practical issues.

The reason for a "cannot do this" placard might be an engineering / structural one, or it could be a liability / lack of certification one. I have loads of placards, like my GPS can be used for enroute and BRNAV but not for SIDs/STARs :)

I would much rather fly along in a bit of stratus collecting a few mm of rime ice than try to do an inverted spin, because the latter might break the plane right there and then. Not to mention not having an inverted fuel / oil system so the engine will stop, etc etc.

I did some tests the other day, sitting at -4C flying dead straight and level, monitoring the IAS. Got to about 4mm of rime on the leading edges and could not see any drop, then the cloud ended... The 0C level was about 2000ft above the MSA, BTW.

Cloud internals are indeed colder than outside. I bank of an immediate 3C to 5C drop upon entry, so if about to enter IMC and the OAT is below +5C, on comes the prop de-ice, and it is always on MAX, never on the lower standby setting.

[Pilot DAR]

Each to their own I guess. I've got hundreds of hours or aerobatics and unusual attitude flying including all sorts of evaluation flying outside the "approved" operations. I've also got hundreds of hours flying in actual icing.

It's the flying in icing which has created the most fearful moments in my flying career, not the unusual attitudes in VMC, in an aircraft flying the way the manufacturer said it would.

You really need to be falling helpless, laden with ice, and with only marginal control to get the real meaning of what I'm trying to say. I've been in that situation four times, in two, the huge margin of safety built into Cessnas saved me. In the other two it was warm air below. The latter two events were a C303 (fully deice equipped) and a Twin Otter over the south of France in late August (I never expected ice in those cloud tops!).

The reference to icing being avoided on the limitation placard is because the applicant for approval, and regulator, have agreed that the characteristics of the aircraft in such an environment are not completely understood, therefore have not shown design compliance with the requirements, and thus cannot be approved that way.

I have written prohibition of flight into known or forecast icing as a limitation to the operation of deiced aircraft, to which I have approved external modifications. I have done this because I had not tested the aircraft in that configuration, and could not show design compliance with ANY ice on the airframe.

There's lots of chatter about pilots suddenly becoming test pilots in different situations. Flying a non-deiced aircraft into icing conditions is near the top of this list of dangerous things to attempt. A very experienced qualified test pilot friend of mine nearly killed himself in a PA28 doing this. He did spend the night trapped in the wreck during a northern Canadian winter.

Pilot DAR

[Fuji Abound]

I think what is confusing this issue is the belief that the route out of icing will always be sufficiently quick to avoid it becoming a problem.

We talk about a few mm of rime ice and I suspect no one believes that would cause a problem in most cases. The perception is that if the ice starts to accumulate quickly a rapid exit can be made.

However I suspect problems occur because icing conditions are encountered where the rate of accumulation is far greater or the exit strategy is flawed.
For example, AT place you in a hold in IMC, you become overloaded flying an "unexpected" holding pattern and "manage" to accumulate a significant amount of ice before realising. Alternatively, you set up for a climb believing the tops to be at say FL120 and start accumulating ice in the climb. As we know the ice will accumulate far more rapidly underneath the wing as the angle of incident presents more of the lower wing surface to the airstream. Of course you dont find the expected tops and performance or oxygen limitations prevent the climb continuing. It is now a long way down carrying an awful lot of ice, with more to accumulate on the way down. Perhaps a section breaks free on one wing and immediately all sorts of asy considerations come into play.

I recall a recent flight form Ireland. I wasnt expecting icing in August and nor did I expect the tops to be as high as 10.5. They were and there was a lot of ice in the last 1,000 feet. The aircraft was approved for flight in icing so it wasnt an issue, nor I guess would it have been even if it wasnt anti iced becasue the ice was only in the last 1,000 feet with no restrictions on a descent, but it could have been different. Fact was I was surprised to find that amount of ice there in August - I should have listened to what DFC had to say.

[deice]

Thanks for enlightening us Pilot DAR. At least I feel I'm not on the wrong path entirely, and I still believe that if the AFM says not approved it means just that.
Isn't it the same thing with spinning really? An AFM usually states not approved for intentional spins and I presume either the aircraft wasn't tested so the manufacturer does not know how it will behave or it behaved in a manner that makes it unsuitable because it may kill you.

If ice wasn't a problem, then wouldn't most manufacturers want to approve their aircraft for it? I don't know, it's just a thought...

IO540, I know you have years of experience, and perhaps you've developed an acute sense of what works and what doesn't but I'm not sure how you can teach anyone that "know-how". It seems that knowledge has to be acquired somehow by years of practice. Or do you feel there is a way of providing this kind of real-world weather fying experience in a box?

[bookworm]

So lemme see DFC... You're simulating the following scenario in your IR test:

You intend to depart knowing you will enter freezing cloud above 300 ft. By definition, the icing conditions are severe, and the aircraft is prohibited from flight in known icing conditions of any sort. The MSA is at least 700 ft above the freezing level, and more likely several thousand feet above the freezing level. Remaining visual below cloud is not an option.

Nevertheless, you decide to take off, after giving your brief. And you expect the examiner to pass you?! ;)

[IO540]

You really need to be falling helpless, laden with ice, and with only marginal control to get the real meaning of what I'm trying to say
How much ice (thickness in inches please) was needed to do that, and on what aircraft type?

Deice - I don't have the years of experience you think. I just like to question blanket scare warnings which put no figures on the ice.

There is a big difference between say 5mm of rime (which you might pick up anytime climbing or descending through say 2000ft of stratus) and which doesn't usually do any harm, and 4 inches of clear ice (which is what you can get in CU/TCU/CB and which could easily kill you).

Most types can carry a few mm of ice. If they could not due to some weird aerofoil, they could not fly spattered with dead flies, or in heavy rain.

The enroute strategy for IFR is the key.

When I fly IFR, I aim decisively to be VMC on top. None of this "it will be OK for half an hour" stuff because by the time you have been in IMC for half an hour, flying blind, you have absolutely no idea how high the tops above you are and an expectation of being able to climb out of it is a bit daft. A descent isn't such a great option either; at best ATC will get cheesed off with a pilot who is flying well below the airway MEA because they have to route him well away from terminal areas etc. Due to the high Eurocontrol MEAs, this can happen in N Europe during the warmest summer. At worst there is terrain, and often the radar vectoring altitude is 3000-5000ft above the terrain so ATC will be getting very worried long before you might be.

Enroute, I will never enter a solid wall of IMC rising to say FL250, because I have no idea how long it will go on for. If I can't outclimb it, I would turn back. So far, I have never had to turn back but that is only because I look at various weird weather sources to get an idea of cloud tops and I scrap flights where the tops are likely to be above FL160 (my ceiling is 20k, or FL190 given the lack of 8.33).

Obviously one needs oxygen, but that's cheap and easy.

I would guess that 25% of my planned flights would be scrapped on a random day.

Nearly all flights through a front would be thus scrapped. This is a very conservative strategy, especially for cold fronts which often have little organised IMC, good vis, and widely scattered CBs. But one cannot get the data on weather to the required degree, and I am no weather interpretation expert.

What is needed to regularly fly through fronts is a FL200+ ceiling, a turbo, solid de-ice, and radar. This gives you a real mission capability increment, but you pay for it by hauling a few tons of metal everywhere you go :) Not to mention heavy Eurocontrol route charges (unless it is a 1999kg Seneca or a Jetprop).

All the poor people (like me) have to make do with a quick zoom up, VMC enroute, a quick descent.

Holds are extremely rare for GA traffic; I've only ever done one for real (and even that was not ATC directed, it was a different situation), and if I was actually collecting ice I wouldn't just sit there waiting for it to get worse.

[Cessna 402 Argentina]

Hello. I highly recommend you to fly with somebody experienced, just in your firsts IMC flights. It´s unvaluable waht you can learn with someone who knows about the matter sitting next tou you.
This winter I had my first Icing experience in a SE between mountains in ESQUEL, PATAGONIA ARGENTINA. I have 350 total flying hours and I flew with a retired b-747 captain with more than 20000.
And the most important, flying with someone like that in the plane, gives you that extra confidence to experience hazardous conditions.
Enjoy the winter!

[scooter boy]

Cessna 402, I couldn't agree more.
I also gained valuable experience with a retired jet captain in the right hand seat.
When the ice is building on the wings and empennage and the windscreen is iced over it is good to have a wealth of experience in the cockpit with you. (It is also good to have full airframe and windscreen TKS).

(I am not condoning this but...) I have seen the most rapid accumulations of airframe ice while crossing sleety cold fronts despite FIKI certified TKS being on in max mode. The FIKI/TKS doesn't protect one from turning into an iceblock, it just delays it a little. Add in greyout, windshear turbulence, sudden significant activity on the stormscope, jets far above you requesting track deviations to avoid "buildup", an iced windscreen and the intermittent thud of lumps of ice being shed by the prop hitting the airframe and before long you are really wishing you were not up there! Descending into warmer air can sometimes be helpful but if you are able to, climbing out of the tops is definitely the way to go. The only good thing about crossing cold fronts is that the torture is usually over fairly rapidly. So a tangential routing is the easiest, as opposed to a track right along the front.

As has previously been stated the real answer here is to fly straight over the top of the weather and avoid the drama.

SB

[Pilot DAR]

IO 540,

Cessna 303, less than a half inch thick of rime ice visible on the wing, but the problem was the tail. The aircraft was trying to swap ends either in yaw or pitch, at a 170 MPH. (roll control perfect). The problem worsened the slower I flew. This problem was discovered after several in flight break ups, and the subject of an AD prohibiting flight into known icing, even though it was a completely deiced and icing approved aircraft.

Twin Otter, Hard to judge dimension, but I'm guessing several inches thick of rime forming the outward ">" shape on the wing. The two problems were that we were already 3000 pounds over gross with ferry fuel (don't worry, DH Canada approved installation), and in a Twin Otter, seeing the leading edge is nearly impossible, as the nacelle is in the way. You don't realize that the ice is forming at all, until the plane begins to require full power just to descend slowly. I lost more than 6000 feet altitude at maximum continuous power, flying at just below blue line. Once lower, it melted off in chunks.

Other two times were as a passenger in C150's. Windsheild completely iced over, you can't see the wings (probably for the better anyway). One event involved what was probably a spin and recovery at night with very little outside attitude reference - really dumb!

While flying with a very experienced Aztec pilot, I've carried loads of ice on them, they are a fine aircraft, but they are icing approved!

I stand by my word, that any flight into icing conditions in a non deiced aircraft is very foolish, and certainly contrary to the stated limitations for a non deiced aircraft . That would be an illegal thing to do in such an aircraft, no grey zone about it! Yeah, I guess that you're right, it would be hard to get caught, because the ice will melt off the wreckage before the investigators get there!

Pilot DAR

[IO540]

There must be something seriously wrong with the design of the C303 to do that with just 1/2" of ice.

Several inches is fair game.

[deice]

Doesn't that prove the point that flying into an icing condition with an aircraft known NOT to be approved for ice is a bad idea?
If indeed the C303 exhibited those characteristics with deice equipment installed and presumably tested (?), what are the chances an aircraft that hasn't been tested at all could exhibit similar dangerous behaviour?

If I'm not completely misinformed, the TB20/21 has been fitted with TKS on later models (as an option). In my mind that would include testing it for behaviour in ice which hopefully proved it to be "safe". But I'm pretty sure most light aircraft have never been tested which means we all become test pilots if we take them out and try. Never mind ice on the wing, what probably causes most accidents is due to tail ice (a guess).

The Caravan Pilots website describes ice accidents that were caused by tail ice which subsequently led to the addition of boots on the stab.

[Droopystop]

To those of you who fly aircraft whose RFM allows them to fly in icing, isn't the definition of icing included in the RFM? (and therefore quite possibly different between types).

[scooter boy]

Droopy, (perhaps I am a meteorological luddite but...) all airframe ice I have ever seen looks very similar to me, so accurate definitions of type of icing by the FAA or in the POH are wasted on me. The only significant feature for me is how much is there? It is either light, mod or severe as far as I am concerned, if light I am monitoring it with the TKS ticking over at normal rate. If it is mod then I have the TKS on max and I am planning a way out of there, if severe (i:e freezing rain type situation quite possibly with alternate air indicator illuminated (comes on automatically when the main engine air intake is iced over in my aircraft) and large chunks of the white stuff flying off the prop) then I am already on my way out of there probably downwards looking for less sticky sleet.

TKS airframe deicing is my second favourite invention after TCAS.;)

SB

[deice]

What's the type Scooter Boy? I'm interested in hearing more about experiences with TKS, I have limited time with that equipment, got along fine with boots previously on the good 'ol Seneca.

[deice]

I think this thread may be of interest in case you haven't found it already.
http://www.pprune.org/forums/showthread.php?t=296541

[scooter boy]

Deice, I fly a TKS equiped Mooney Ovation 2 GX.
I have limited experience with pneumatic deicing boots!
SB

[deice]

Ah, Nice one SB!:ok: Do you really need 800 meters for it or is it for comfort? I thought the Mooneys handled short strips well provided you kept the speed back.

[Fuji Abound]

Holds are extremely rare for GA traffic; I've only ever done one for real (and even that was not ATC directed, it was a different situation), and if I was actually collecting ice I wouldn't just sit there waiting for it to get worse.

True but vectoring often serves AT in the same way as a hold. It is sometimes as lengthy. I suppose you could call vectoring holds for real pilots with a job to do.

I spent forever being vectored into EM the other day while they slotted me into to the other arriving traffic. I guess it was a bad time or I upset someone previosuly by asking for an immediate. Had there been icing conditions I would have wanted to get out of it somewhat quicker. I might add I would have done so as well.

[scooter boy]

Ah, Nice one SB!:ok: Do you really need 800 meters for it or is it for comfort? I thought the Mooneys handled short strips well provided you kept the speed back.

The 800m is for comfort.
I have been into 650m but prefer a bit more margin, especially in poor weather. I also like tarmac far more than grass (although some Mooniacs love the grass) as the suspension in the Mooney is so rigid you can bounce a lot even on relatively smooth grass strips.

Pegging back the approach speed is especially key with the Mooney as the large wing with flap deployed is so low-set and close to the ground you will get a long in-ground-effect float unless it wants to stop flying.

Where are you based?
SB

[deice]

Stockholm Bromma and Barkarby airports. You should visit if you have the time. The local EAA host a fly-in first weekend of June at Barkarby. Even if you don't come for that, if you do visit Stockholm then Barkarby is your choice. Non-towered so VFR only if the weather is too bad, but also no fees. 990 m tarmac and lights available for night ops. Also, Bromma is only open 08:00-16:00 UTC on sat and 09:00-19:00 on sundays. 06:00-21:00 UTC on weekdays. Barkarby is 24 hrs for the occasional arrival or departure.

[Droopystop]

Scooterboy,

I was thinking more along the lines of "visible moisture with temperature below freezing / viz less than 1000m below freezing etc" ie the definintion of known icing so that one can equate conditions to the capability of the aircraft/aircraft system at the planning stage as well as during the flight

[Pilot DAR]

The second half of the following link should be of interest:

http://arthuralanwolk.com:80/_wsn/page2.html

Item 8 caught my eye.

Pilor DAR

[IO540]

I was thinking more along the lines of "visible moisture with temperature below freezing / viz less than 1000m below freezing etc" ie the definintion of known icing

That definition (thankfully totally invalid) would be the end of all flight on Eurocontrol airway routings in most GA planes then :ugh:

Pilot-DAR - are you an FAA DAR i.e. a Designated Airworthiness Representative? Not a trick question, just curious. Incidentally a bit of your URL got translated into an emoticon...

[deice]

They won 480 million dollars off Cessna in 2001. No wonder new aircraft cost a frikkin fortune!!

[Droopystop]

That definition (thankfully totally invalid) would be the end of all flight on Eurocontrol airway routings in most GA planes then

Maybe invalid to you. Not to me. It's what my flight manual says. And since the ANO requires me to operate within the flight manual, its actually quite fundamental.

So do all your RFM state that you can/can't fly in icing conditions, can/can't fly in light/moderate/severe icing without defining what they mean by icing conditions?

[Pilot DAR]

Sorry about the website link translating in to the little yellow face, but I do not know how to undo that. I cannot figure out how to turn it into just text, as I would be able to in MS Word. Here it is again in quotations incase that changes things...

"http://arthuralanwolk.com/_wsn/page2.html"

It that does not work, I'll copy and paste in the relevent passages. It relates to Cessna Caravan icing problems, and resultant litigation and AD action.

IO-540,

I am a Transport Canada Design Approval Representative (private citizen who is authorized to sign Limited STC design approval on behalf of Transport Canada for design changes, once I have satisfactorily conducted the required evaluation and testing). This is not the same as an FAA DAR, but is very similar to the role of an FAA DER. Sorry for the confusing nomenclature, but I did not originate it! It does cause confusion with my U.S. colleagues

Cheers,

Pilot DAR

[IO540]

Thank you Pilot DAR. At GBP 500 per signature (the rate charged by a UK avionics shop for a mod to an N-reg) your job is only marginally less lucrative than being an FAA DAR (£1300 for a signature) :)

Of course an FAA DER (or I guess you for that matter) doesn't himself get 500 quid for a signature, but that is the rate it ends up by the time the various intermediaries have jacked it up.

[Pilot DAR]

Hi IO-540,

Speaking personally, clients don't really pay for my signature, but for my qualified evaluation of the compliance of the design change. My fee has, in some cases, been a quarter of the amount you state, for simple mods. Though, yes, most cost much more.

It is worthy of consideration, particularly in the environment of this forum, that pilots expect that they are always flying and aircraft that will do exactly what the book says it will, including the affect of the modifications. Pilots (particularly here) state very clearly that they do not want to be test pilots. By reading the posts here, I am constantly reminded that I must be very thorough in my evaluation and test. I must not send an aircraft out (with my signature) such that the pilot, while operating within the limits I approve, can find something about the characteristics of the plane that I did not know already, and account for.

So, when I am part way through my evaulation, I always stop and ask myself, "what will some silly pilot try with this plane, that I need to prevent?" So far 2 pilots have found things (though never anything to do with the mod) which I would not have imagined they would attempt, and I have had to explain in great detail to an accident investigator how the aircraft was still safe the moment before it hit. I don't get paid for my signature on that report!

Cheers, Pilot DAR

[IO540]

I know, my comment was tongue in cheek and not intended to criticise.

The FAA DER process at least offers a way to get mods implemented in a streamlined and timely manner. Here in Euroland, we have to get EASA approvals and the system now requires the STC holder (the manufacturer, usually) to apply to EASA. This can be difficult or impossible to organise if the mfg is not interested. The aircraft owner can no longer apply to EASA.

[Pilot DAR]

Yes, I quite appreciate the freedom to modify aircraft in Canada. We have sent modified products to Europe, and been frustrated with the EASA system. Sometimes we in North America wonder why the wonderful people in Europe and the UK allow the govenment to so discourage aviation there?!

I am just finalizing approval work on a research aircraft for a European research organization, who did not want to subject themselves to the EASA process.

Anyway, I'm probably guilty of thread drift here...

Always here to learn and help,

Pilot DAR

[deice]

Drift away, it's so interesting I'm having trouble concentrating on my work! :}

EASA, what can we say - they're full of... trouble.
As for Europe working FOR pilos!? Hahahahahahaha! That'll be the day!!
Come on, the French wanted an IR to be issued only to CPL holders and CPL only to be taught at universities where you'd have to do a full ATPL course anyway. Up here in the north we've allowed SEIFR with Caravans for several years, while the rest of europe says no. We couldn't be farther apart. And now they're deciding everything centrally! For whom?

[Pilot DAR]

European Aviation Safety Agency. It seems to me that EASA's vision of aviation safety, as it relates to the operation of aircraft, is that the best way to keep them safe, is to keep them on the ground.

[deice]

Yeah, it reminds me of "I Robot". The best way to keep humans safe is to keep them locked up and off the streets.