Westwind

[goingnowherefast]

Except ice will change the physical shape and texture of the airfoil. Every single situation will be different based on speed, AoA, temperature, droplet size, super-cooled, etc. Even freezing rain on a parked plane. How far do the droplets run before freezing? There's absolutely no way to accurately predict the performance of this "mystery" wing that's been modified by ice. I suppose you could put the plane in a wind tunnel and test the modified lift characteristics before every departure, but that seems more expensive than just cleaning it off.

[Diadem]

What thousands of different types of contamination?

Type, let's narrow it down to: Frost, clear ice, rime ice.
Location: full fueslage, leading edge, full wing, full tail, randomly divided 50% coverage of the wing, randmoly divided 20% coverage of the wings, or whatever seems significant from the simulations
Thickness: you'll have to estimate that yes. Would be easy to fix with a marking somewhere on the wing, I'm sure you could find a small bolt or hook popping out of the wing and put a scale on there if you want. Or measure it with a piece of paper, no big deal

Environmental condition: I wasn't even thinking about freezing precip, but it should be easy to add as well. Freezing precip will most likely create a constant weight increase over the whole plane, so that can be added as an extra factor.

It might take a few weeks of running simulations, but in the end you'll have a rough idea of how screwed you would be if you tried to take off.

Not sure if it is frost or clear ice? Doesn't matter, you can read the table "if this was clear ice we have an equivalent of an additional 4000 lbs on board, if it is frost, we have an additional 2000 lbs on board". Either way, you're not allowed to go anyway, but the danger becomes much more tangible.

You're grossly over-simplifying things. For types of contamination you have: frost, snow on frost, snow pellets on frost, ice pellets on frost, snow, snow on a wet wing, snow pellets on a wet wing, ice pellets on a wet wing, frost with residual impact ice, snow with residual impact ice... Etc... That's before you even begin accounting for thicknesses, and there's certainly no allowance for uneven contamination.
And after all your huff about telling pilots exactly how much is safe, you want them to estimate the thickness? And you're only going to give them a "rough idea"? Well, those pilots who are taking off contaminated now are just going to underestimate the thickness, because they figure it worked before. They're going to look at 1/4 inch of rime ice and figure it's probably closer to 1/8, and really, what difference does it make? The plane has always down before!

[pelmet]

There should be research to show pilots and ground crew how much is too much.

There are too many variables for the regulator to be able to do this. It would be endless so it ain't gonna happen.

I disagree. How does ice affect the airplanes? There is weight, change of shape of the aerofoils and a different texture/friction indexes. Every airplane of the caravan/pc12 generation and newer is exists digitally. Every part is simulated somewhere. Any manufacturer of modern airplanes can tell you exactly how ice would affect the performance.

I am not intimately familiar with certification, but if I remember correctly, at some point you'll have to proof that your data matches reality and a whole bunch of flight tests need to happen. That is not necessary for what I'm asking. I am not asking for certified data to allow pilots to fly with ice on the wings. No, I merely want relatively accurate data to show them what a stupid idea it is to go flying with frost/ice/wet snow/.... on the wings. That can be calculated with the current models that already exist to a great level of accuracy. It will be an eye opener and way more accurate than the one "30% / 40%" number we have now.

What would be easier: forcing 20 manufacturers to simulate data in let's say 20 example scenarios, or get decent deicing equipment installed in every little northern community?

It ain't gonna happen.

Thanks for the outside the box idea.

Back to the thread subject.

[digits_]

You're grossly over-simplifying things. For types of contamination you have: frost, snow on frost, snow pellets on frost, ice pellets on frost, snow, snow on a wet wing, snow pellets on a wet wing, ice pellets on a wet wing, frost with residual impact ice, snow with residual impact ice... Etc... That's before you even begin accounting for thicknesses, and there's certainly no allowance for uneven contamination.
And after all your huff about telling pilots exactly how much is safe, you want them to estimate the thickness? And you're only going to give them a "rough idea"? Well, those pilots who are taking off contaminated now are just going to underestimate the thickness, because they figure it worked before. They're going to look at 1/4 inch of rime ice and figure it's probably closer to 1/8, and really, what difference does it make? The plane has always down before!

It will be a lot more accurate than the 30%/40% number we have now, I can guarantee you that.

I hope that they will see that -for example, as there are no accurate numbers- an increase from 1/8 to 1/4 will mean a weight penalty increase from 500 lbs to 3000 lbs, so they better be damn sure that it is only 1/8 if they want to be stupid enough to take off illegally.

People take off with ice because they think they can get away with it. Convince them that they can't, and they will not attempt a take off with ice on the wings.

[Diadem]

It will be a lot more accurate than the 30%/40% now, I can guarantee you that.

I hope that they will see that -for example, as there are no accurate numbers- an increase from 1/8 to 1/4 will mean a weight penalty increase from 500 lbs to 3000 lbs, so they better be damn sure that it is only 1/8 if they want to be stupid enough to take off illegally.

People take off with ice because they think they can get away with it. Convince them that they can't, and they will not attempt a take off with ice on the wings.

What does it matter if it's more accurate if it's still just an estimate? There are far too many variables to ever be certain that it's safe unless the manufacturer has dedicated the time and resources to testing. Boeing did it for the Max, for only frost, and that's for a variant of the most common commercial airliner in the world. They probably spent millions of dollars testing a single type of aircraft, and a single type of contamination, and you want to do it with every model of every aircraft in Canada? A lot of those aircraft were made by companies that are out of business, so are taxpayers going to pay for it? You want the government to spend potentially billions of dollars so a few pilots can eyeball the contamination on their aircraft and estimate a weight penalty? Like someone else said, why not calculate by how much each aircraft can exceed MTOW while we're at it?
Honestly, I don't even know what you're advocating anymore. You want to spend huge amounts of money researching exactly how much contamination can be left on a plane and still allow it to fly, but you admit that pilots won't actually be able to measure that contamination in the wild. You've flip-flopped between this being an actual system that will be able to be applied in the real world and stating that you just want to show pilots how dangerous it actually is.
The research exists, and if pilots are ignoring it because the testing wasn't done on the specific aircraft that they fly, then they aren't likely to be swayed by data anyway; they're going to fly regardless. The 30%/40% stat that you're so fixated on isn't the most accurate data out there, it's a generalization, and there are numerous articles with very precise measurements, including one that I already linked. If pilots aren't reading those and taking the info to heart, why do you think they would accept the findings of your system? The whole mentality behind flying contaminated is that the rules are stupid and the pilots know better than the experts.

[C.W.E.]

You've flip-flopped between this being an actual system that will be able to be applied in the real world and stating that you just want to show pilots how dangerous it actually is.

He has been trying to teach me about the subject so I won't fly with to much wing contamination but alas he is to late because I no longer fly even for pleasure.

[digits_]

Like someone else said, why not calculate by how much each aircraft can exceed MTOW while we're at it?

I'm pretty sure manufacturers know exactly what the consequences are of flying weights that are exceeding MTOW. It could be damage in turbulence, damage to the gear, metal fatigue etc. Main reason to not worry too much about this, is that the number of accidents where overweight flying resulted in death or crashed airplanes, is smaller than the number of icing related deaths.

Honestly, I don't even know what you're advocating anymore. You want to spend huge amounts of money researching exactly how much contamination can be left on a plane and still allow it to fly, but you admit that pilots won't actually be able to measure that contamination in the wild. You've flip-flopped between this being an actual system that will be able to be applied in the real world and stating that you just want to show pilots how dangerous it actually is.

The calculation/simulation of "XX ice on plane YY results in a performance penalty of ZZ" can be accurately calculated. Planes already need to show that they can fly into known icing if they are to be certified like that. For modern airplanes, that guarantees there are computer models available of icing during flight. Use those models and make an accurate and educated guess on how it will affect take off performance.

The regulator can define XX amount of cases, with predefined parameters as mentioned before. Frost, clear ice, mixed ice, whatever. Those limited amount of cases can be precisely and accurately calculated. Pilots then have information on their specific airplane type (excluding mods) how the plane would be affected in those circumstances. They can pick/average the most accurately described situation and be convinced that the plane can not fly safely.

The research exists, and if pilots are ignoring it because the testing wasn't done on the specific aircraft that they fly, then they aren't likely to be swayed by data anyway; they're going to fly regardless. The 30%/40% stat that you're so fixated on isn't the most accurate data out there, it's a generalization, and there are numerous articles with very precise measurements, including one that I already linked. If pilots aren't reading those and taking the info to heart, why do you think they would accept the findings of your system? The whole mentality behind flying contaminated is that the rules are stupid and the pilots know better than the experts.

I could only read the first page of the article that was linked to. It sounded promising, but was specifically dealing with droplets encountered during flight, not with taking off with a contaminated wing on a clear day for example.


Let me ask you this:

Why do pilots not take off in a plane with one wing missing? Why do they not take off (most of us anyway) in a twin engine plane with a failed engine? Because they know and are convinced that the plane wouldn't fly.

Convince them that an iced up plane will not fly, and they will not attempt it. If you have other suggestions on how to accomplish this, by all means, please share. I do not think the current policy/TC video is sufficient.

[Diadem]

I'm pretty sure manufacturers know exactly what the consequences are of flying weights that are exceeding MTOW. It could be damage in turbulence, damage to the gear, metal fatigue etc. Main reason to not worry too much about this, is that the number of accidents where overweight flying resulted in death or crashed airplanes, is smaller than the number of icing related deaths.

No, it's very much a similar discussion to the one we're having: an airplane won't bend as soon as the MTOW is exceeded by one pound, the maximum weight limit is set at some point that the manufacturer thinks the performance of the aircraft will be adequate, usually factoring in engine-out performance. The performance is highly unlikely to be degraded significantly one pound over, it probably won't happen a hundred pounds over, it might not even happen a thousand pounds over; the point is that you don't know because the manufacturer didn't test it. By your logic, we should have every aircraft tested to find out at exactly what weight and atmospheric conditions the performance will no longer be acceptable, just to show those pilots who are inclined to fly overweight how bad it would be.

The calculation/simulation of "XX ice on plane YY results in a performance penalty of ZZ" can be accurately calculated. Planes already need to show that they can fly into known icing if they are to be certified like that. For modern airplanes, that guarantees there are computer models available of icing during flight. Use those models and make an accurate and educated guess on how it will affect take off performance.

For modern airplanes, you might be able to approach the manufacturer and have them provide complex computer models, but do you not realize that those models don't exist for things like Navajos and Otters that have been out of production for thirty or forty years? The Q400s and 737s aren't the ones taking off contaminated, so it doesn't even matter if you can get models for them. You're going to have to get 206s, Conquests, Beech 99s, and all the other outdated pieces of crap from up north that are the ones being flown contaminated, collect every single tiny little piece of data on every version of those aircraft with every engine, every propellor, every STC, in every configuration, for every phase of flight, and then figure out how icing affects them.
Who the hell is going to pay for that?

The regulator can define XX amount of cases, with predefined parameters as mentioned before. Frost, clear ice, mixed ice, whatever. Those limited amount of cases can be precisely and accurately calculated. Pilots then have information on their specific airplane type (excluding mods) how the plane would be affected in those circumstances. They can pick/average the most accurately described situation and be convinced that the plane can not fly safely.

I don't think you've read a single thing that's been written here. You can't boil down icing to "frost", "clear ice", "mixed ice", and "whatever". You're oversimplifying things to the point that any models you make will be utterly pointless. You have to have data for every single combination of types of icing, that accumulates both on the ground and in the air, and you have to be able to accurately measure the thickness. Otherwise it's no better than eyeballing the conditions, and that's what people are doing already.

I could only read the first page of the article that was linked to. It sounded promising, but was specifically dealing with droplets encountered during flight, not with taking off with a contaminated wing on a clear day for example.

There isn't much data on the effects of ice on top of a wing on take off, because even NASA test pilots don't want to go blasting off with a sheet of ice on the wings. That should tell you something. Anyway, most of the studies I've found discuss in-flight icing, which apparently isn't relevant to you, or are behind a paywall, so here's a publication from TC that has some very detailed information, including wind-tunnel data: http://publications.gc.ca/collections/c ... -2008E.pdf
Residual impact ice is also a concern, and arguably more complex to classify, as you need to measure not only the thickness, but how far back along the wing it spread; if the boots broke some of the ice off, you have to calculate the performance degradation for the remaining amount. How do you do that?

Let me ask you this:

Why do pilots not take off in a plane with one wing missing? Why do they not take off (most of us anyway) in a twin engine plane with a failed engine? Because they know and are convinced that the plane wouldn't fly.

Convince them that an iced up plane will not fly, and they will not attempt it. If you have other suggestions on how to accomplish this, by all means, please share. I do not think the current policy/TC video is sufficient.

Your analogy is stupid, because we're talking about incremental deteriorations in performance, not a loss of a component. It's not binary. Like I said, and I'm certain you didn't read, there's no point in presenting data to someone who is convinced the data is stupid and the experts are just living in ivory towers. It doesn't matter if you show them data that is slightly more forgiving than what they're expecting, because they don't care about the numbers; they "know" the aircraft will fly, and they'll keep pushing limits until they don't get away with it anymore.
Anyway, I don't think there's much point in wasting further breath on someone who thinks an aircraft will suffer gear damage or metal fatigue if the fuel gauges are slightly off or one of the people onboard had a big lunch.

[pelmet]

Diadem....you are being trolled. Look how much time you spent on the your last post.

Minimize time wasted with obviously ridiculous stuff by simply saying.....

Ain't Gonna Happen.

[C.W.E.]

Diadem....you are being trolled.

And by someone who is not even a pilot or if he/she is he/she should not be.

[shimmydampner]

No, I merely want relatively accurate data to show them what a stupid idea it is to go flying with frost/ice/wet snow/.... on the wings.

That already exists. It's called accident reports.
I hope you're trolling because if not this might be the most poorly thought out idea ever to grace the pages of this site.

[Donald]

Instant death with a contaminated wing?

Not in Russia:

https://youtu.be/5GIU94dg1ek

[goingnowherefast]

Raise the temperature 1 degree, and I bet it wouldn't have mostly blown off before Vr.

Warm fuel melting and refreezing the snow into a gravel texture on top of a supercritical wing.

Luck saved them from repeating the Dryden crash.

The only time "it will blow off" is acceptable is a thin layer of fluffy cold snow. Even then, sweep it first so you can actually tell if any of it is sticking. If I can't see the wing skin, and it won't blow off by waving my hand above the snow, then look for another solution.

[pelmet]

Instant death with a contaminated wing?

Not in Russia:

https://youtu.be/5GIU94dg1ek

It is well known that many aircraft can fly with some contamination on their wings. We do it on a regular basis on approach with residual ice on the leading edge after encountering icing conditions. Some aircraft can handle contamination much better than others and certain techniques can be implemented to reduce the risks. Other aircraft can be extremely unforgiving of contamination. Contamination on the leading edge can be much different than on top of the wing as we can see with one posters experience on the DC-3 with a bit of frost yet I am sure thousands of DC-3's have landed with ice on the leading edge. Then again, maybe some aircraft can handle frost better than ice on the leading edge while others are extremely sensitive to both. Who knows and the regulator isn't interested in legally allowing endless new pilots to figure things out on their own. The Air Ontario pilots Convair experience versus Fokker jet experience is a good example of how it can end up.

But the idea that the TC is going to do anything other than perhaps what has been done with the example given with the Boeing 737 is ridiculous. I am sure that Airbus or Bombardier or some other manufacturer could approach the regulator and try the same as Boeing has done if a bunch of other factors aligned in terms of economics and safety but TC is not going to be spending a biunch of money testing dozens of types of aircraft to show us the risks of flying with contaminated wings on a case by case basis. Same with flying overweight, or the increased risks of flying at higher than allowed speeds, etc.

There are enough accidents to prove that sometimes, flying with frozen contamination on the critical surfaces can cause a serious incident that the regulator has decided that the only way to cover all the risks is to have a blanket ban unless an outside entity can prove that it is safe.

[iflyforpie]

Instant death with a contaminated wing?

Not in Russia:

https://youtu.be/5GIU94dg1ek

Aside from a few places in aerodynamically quiet areas, that wasn’t a contaminated wing. Remember, the operative word is adhering.

Cold soaked plane below zero? As long as the snow isn’t thick enough to compress into ice and it isn’t sticking to the surfaces... no problem.

It’s a decorum thing in this case, not a safety thing.

[digits_]

No, it's very much a similar discussion to the one we're having: an airplane won't bend as soon as the MTOW is exceeded by one pound, the maximum weight limit is set at some point that the manufacturer thinks the performance of the aircraft will be adequate, usually factoring in engine-out performance. The performance is highly unlikely to be degraded significantly one pound over, it probably won't happen a hundred pounds over, it might not even happen a thousand pounds over; the point is that you don't know because the manufacturer didn't test it. By your logic, we should have every aircraft tested to find out at exactly what weight and atmospheric conditions the performance will no longer be acceptable, just to show those pilots who are inclined to fly overweight how bad it would be.

Similar, yes, but the data already exists.
With the exception of the 12500 lbs limit, that is already calculated in to detail. Once you exceed MTOW your safety margins in other areas -damage from turbulence, hard landings, structural fatigue, take off distance, single engine performance, ...- will decrease. I don't think we can know how many pilots take off overweight, but we do know that the amount crashes where being overweight is a major factor are -luckily- very rare. More research in this area is, for me, therefore not necessary. Every question that you have about that, could already be answered by the manufactureres, if their lawyers would let them.

For modern airplanes, you might be able to approach the manufacturer and have them provide complex computer models, but do you not realize that those models don't exist for things like Navajos and Otters that have been out of production for thirty or forty years? The Q400s and 737s aren't the ones taking off contaminated, so it doesn't even matter if you can get models for them. You're going to have to get 206s, Conquests, Beech 99s, and all the other outdated pieces of crap from up north that are the ones being flown contaminated, collect every single tiny little piece of data on every version of those aircraft with every engine, every propellor, every STC, in every configuration, for every phase of flight, and then figure out how icing affects them.
Who the hell is going to pay for that?

That is why I specifically mentioned planes of the Caravan / PC12 generation and newer, which, I assume, exist digitally. Maybe even the recent model king airs. If you start with that today, a big part of the fleet will be covered, and the percentage of airplanes that have the numbers will only increase. It would probably be cost prohibiting to develop a full 3 D model for something like a DC3. Although, maybe the basler conversion already has a model like that, I do not know.

I don't think you've read a single thing that's been written here. You can't boil down icing to "frost", "clear ice", "mixed ice", and "whatever". You're oversimplifying things to the point that any models you make will be utterly pointless. You have to have data for every single combination of types of icing, that accumulates both on the ground and in the air, and you have to be able to accurately measure the thickness. Otherwise it's no better than eyeballing the conditions, and that's what people are doing already.

You can accurately calculate/simulate the effects for certain predefined cases. And you know it is just frost or clear ice, because that is what the predefined case is. Where the uncertainty will arise, is when you show up to a plane and you don't know exactly what standard configuration matches with the plane. If any. Ok. Let's say you look in the provided data, and you find 3 possible options that you think match the situation. That gives the pilot 4 options: don't go, or go with possibly a 4000 lbs penalty over MTOW, or a possible 2000 lbs penalty or a 3000 lbs penalty, based on the estimated condition of the airplane, I hope at least a significant amount of pilots will choose for the no go option.

Regarding your remark about the multiple layers: that probably indicates there is a huge amount of ice on the plane. So much, that even today, I doubt any pilots would dare to take off. But even if they are using the data and contemplating a take off, any possible contamination they will try in the chart, will show that you are taking off with severe weight penalties.

Another reason why research would be interesting, would be to determine how 2 layers of different ice would interact. Intuitively, I would say the friction index on the top layer is important, and the weight of both layers would be a factor, but yes, there could be unexpected effects. One more reason to learn and investigate.

There isn't much data on the effects of ice on top of a wing on take off, because even NASA test pilots don't want to go blasting off with a sheet of ice on the wings. That should tell you something. Anyway, most of the studies I've found discuss in-flight icing, which apparently isn't relevant to you, or are behind a paywall, so here's a publication from TC that has some very detailed information, including wind-tunnel data: http://publications.gc.ca/collections/c ... -2008E.pdf

I'm not asking anyone to go blasting off with ice on the wings. Use the models, simulate the ice build up, and publish the results. The document you linked to mentions the wind tunnel experiments, but only for the effect on the fluid as far as I can tell.

there's no point in presenting data to someone who is convinced the data is stupid and the experts are just living in ivory towers. It doesn't matter if you show them data that is slightly more forgiving than what they're expecting, because they don't care about the numbers; they "know" the aircraft will fly, and they'll keep pushing limits until they don't get away with it anymore.

The pilots don't claim they know better than the experts, because the experts don't say what the problem will be. How can you trust the experts if they claim a 1 inch wide strip of thin frost just behind the leading edge is as deadly as a plane covered in 1 inch thick sheet of solid ice? There is no distinction at the moment to show the difference between those situations. Is the 30/40 rule applicable to 1 inch line of frost, or to the 1 inch of solid ice?

While I do not condone it, I can understand that a fatigued pressured pilot without any deicing equipment flying with an empty turboprop could be tempted in the middle of the night to illegally take off with a bit of frost behind the leading edge. On the other hand, if you told him this would put him 2000 lbs over the MTOW, then I hope that pilot would not even think about attempting a take off like that.

That is what I would like to achieve.

[digits_]

There are enough accidents to prove that sometimes, flying with frozen contamination on the critical surfaces can cause a serious incident that the regulator has decided that the only way to cover all the risks is to have a blanket ban unless an outside entity can prove that it is safe.

And if, after 30 years, it turns out that a big part of the pilots are not following that rule, wouldn't it be wise that the regulator took action? Even if that rule is perfectly safe if you do follow it, you have to look at the big picture. A rule that is safe when followed, will be unsafe if the majority of people do not follow it. At that point it just becomes window dressing.

There are few options in that case:
- change the rule, which in this case would mean certified data of allowing flight with contamination. I think that is unrealistic for aguments mentioned by other people before. Lots of uncontrollable factors. Risky
- enforce the rule more aggressively. Could work, but I find it highly unlikely TC inspectors are going to set up camp in reserves, let alone at night or in crappy weather
- make sure the rule can be followed. That is the TSB suggestion: make sure there is plenty of deice fluid where needed. A noble cause but I don't think it is realistic to expect deicing stations at every northern airport.
- educate people: explain the rule objectively. This seems the way to go to me. Trustworthy, operation specific data that tells you why taking off contaminated is a bad idea.

[pelmet]

There are enough accidents to prove that sometimes, flying with frozen contamination on the critical surfaces can cause a serious incident that the regulator has decided that the only way to cover all the risks is to have a blanket ban unless an outside entity can prove that it is safe.

And if, after 30 years, it turns out that a big part of the pilots are not following that rule, wouldn't it be wise that the regulator took action? Even if that rule is perfectly safe if you do follow it, you have to look at the big picture. A rule that is safe when followed, will be unsafe if the majority of people do not follow it. At that point it just becomes window dressing.

There are few options in that case:
- change the rule, which in this case would mean certified data of allowing flight with contamination. I think that is unrealistic for aguments mentioned by other people before. Lots of uncontrollable factors. Risky
- enforce the rule more aggressively. Could work, but I find it highly unlikely TC inspectors are going to set up camp in reserves, let alone at night or in crappy weather
- make sure the rule can be followed. That is the TSB suggestion: make sure there is plenty of deice fluid where needed. A noble cause but I don't think it is realistic to expect deicing stations at every northern airport.
- educate people: explain the rule objectively. This seems the way to go to me. Trustworthy, operation specific data that tells you why taking off contaminated is a bad idea.

The 737 is the example for certified data...can already be done. Too expensive for inspectors at each station....They are not even out there checking flights out of YYZ so don't expect them is remote sites. The rule can be followed, if de-ice fliud is insufficient as can happen even in YYZ under certain weather conditions, don't go. People are educated. They just don't follow the rules.

[Guilden]

This accident was not caused by contaminated wings. TC will also use contamination as a cause but it was not the primary issue...

[pelmet]

This accident was not caused by contaminated wings. TC will also use contamination as a cause but it was not the primary issue...

I have to admit thAt I have been under the impression that contamination was a primary cause or central to it. Perhaps that is not the case.