Isn’t “what you can expect” directly related to the cloud tops? If you have light icing in FL110 inside cloud and you know that the tops are in 120, isn’t that a better reason to keep on climbing than if you have to climb to FL200 in icing conditions?
What I’m looking for is something like “if you see X, get out while you can” or “if you see X and you are climbing fast enough, you can continue but expect Y for the next minute or two”
It depends firstly on the temperature.
Warmer than 0C, your main issue is whether there is nasty stuff in there. The only way to be sure of that is to get wx radar imagery, and sferics, and the IR image. I normally get these before the flight and that has always worked for me. I won’t fly in IMC if there is convective wx around.
If you are colder than 0C then you will get ice sooner or later, and there is no way of knowing when and how much. -5C is the worst place to be for ice accretion. Colder than about -10C it is a lot less likely. I have had it down to -17C but it was just a fine white coating.
If you are near the tops e.g. you can almost see the sun coming through, that is very hazardous because the wettest IMC is near the cloud tops. You can get rapid ace accretion there. I once got ~3cm in 5 minutes. Vs was about 110kt and the plane was only just controllable at 120kt on full power (TKS prop) and in a slow descent (I allowed that situation to develop to see what the limit is, and had an escape route into warm air below).
Also, if you are in VMC, and are about to enter IMC, you can expect a 3C temp drop.
I understand that ice will destroy lift at a certain point. I have a counter measure to get out of that condition either my going up to find very cold air or down to warmer air. I understand that other things (fuel) may also be affected by the cold. But the loss of lift is a more likely and direct adverse effect.
It depends to some extent on the plane. Some types are very sensitive to contamination. I see no speed loss with 5mm of rime, maybe 10kt with 10mm of mixed ice, and beyond that I would be executing Plan B pretty fast. From many reports, the Cirrus and the DA40/42 are able to carry much less and need TKS a lot more to be usable for IFR.
Climbing is almost never an option unless the ice is only just starting to build – because you need loads of spare power to climb. Especially at altitude – unless you have a turbo. This is where one gets into the TKS or Turbo debate… 
On the ADL point, I think it’s not just the colour but also the gradient. If upwind of the cell it goes straight yellow without gradient colour (green then yellow), I think it’s a more exciting cell. Perhaps somebody else could verify if gradient and not just colour matters greatly?
Actually, Peter, since a lot of us are now flying with ADLs, it might be worth a dedicated topic to decode what people experience with different scenarios as they are painted on the device.
it might be worth a dedicated topic
Feel free to start one I don’t have the ADL so all I can do is ask questions.
DMEarc wrote:
since a lot of us are now flying with ADLs, it might be worth a dedicated topic to decode what people experience with different scenarios as they are painted on the device.
I would love some reports of experience about that. “It was yellow reaching up to FLxxx and I experienced that and that …” would be helpful.
Flyer59 wrote:
Isn’t “what you can expect” directly related to the cloud tops? If you have light icing in FL110 inside cloud and you know that the tops are in 120, isn’t that a better reason to keep on climbing than if you have to climb to FL200 in icing conditions?
Yes. That is true. But then I’m looking for more information about what to expect while you are in it.
So far I’ve passed through rain, snow, the light hail with and without turbulence. I’ve been beaten around with no icing as well.
One way is to make all the experiences myself, and probably get into an emergency one day, or draw from the experiences of others. Hence my question about early signs of danger or discomfort to bail out or hang in there.
Stephan_Schwab wrote:
One way is to make all the experiences myself, and probably get into an emergency one day, or draw from the experiences of others. Hence my question about early signs of danger or discomfort to bail out or hang in there.
I fear that there are’nt going to be many more tales to tell other then what’s been said since not many survive icing emergencies.
The book by Robert Buck, Weather Flying, suggests ‘anything over 40dbz is considered something we need to avoid’. Weather radar scale which I believe ADL subscribe to, use yellow upto 41dbz. Interestingly yellow on the Radar scale paints still as green on NEXRAD. So without sufficient experience, I think green=ok, yellow=rocky, all others=let us know!
http://m.aviationweek.com/bca/how-use-nexrad-and-airborne-weather-radar-together
Ps I’m definitely not qualified to give an opinion on this so perhaps a more experienced radar navigating pilot would comment on the above texts.
@DMEarc
That’s actually how I handle my flights with the ADL – by intuition. I always try to avoid the yellow areas. So far (1 year) my experience was that green was always normal rain while the two times I flew (one time I had to on an approach) through the yellow the rain was very intense and there was some light turbulence. It might be a coincedence but on my flights the information was very precise.
The ADL delivers temperatures at various altitudes aswell (FL59, 80, 120, 140) and I always compare that with the OAT displayed on my PFD.
My worst ever icing incident was with absolutely nothing showing on radar…
I do not have oxygen (or a turbo) so restricted for safety to 10000 feet. The only time in the last 30 years I have had any ice that really concerned me was here in UK. Flying in the winter at around 4000 feet and good vis. when really suddenly it snowed heavily and accumulated quite quickly. As i say the vis. was good so a quick exit to clear air again was not an issue. I honestly thought that snow would just melt and slide off but definitely not.
