…but it was unpredictable for a pilot with medium experience, like me.
Now it is 
I think we’ve had that topic before: The teperature drop from outside a cloud to inside can be 2-5 degrees Celsius, so “slightly above” freezing outside may well be “slightly below” inside. But in cases like this there is hardly a problem because as soon as you exit the cloud, you will be above freezing again and the ice will start to melt.
The best advice I have is to always have an option out, whenever icing can be expected. Ice itself is not harmful for an aeroplane, only ice that keeps growing and won’t get away before landing. So the safest option (and the only one that I accept for myself) is a freezing level above MSA. This will always allow to safely exit the icing conditions by simply descending. Outclimbing the icing layer may be possible on some occasions, but is much less safe, because the ice can rapidly degrade the performance of the aeroplane. Further climbing may not be possible.
I would like to start to compile a list of examples to come up with some good guidelines for dealing with ice during climb and descent. It’s clear that one doesn’t want to cruise in icing conditions.
This is what I do:
I would depart into IMC which is to be expected to be below 0C if the 0C level is well above the MSA, say 2000ft above.
Of course the execution of the Plan B (a descent into warm air) will result in the likely abandonment of the trip, because you will end up trapped under the clouds, with no way back up – because if you could not climb up through it originally you sure as hell are not going to climb up through it later.
So, without full TKS in my case, I would not depart into such conditions unless I can see the layer is obviously broken up or just very thin (say < 2000ft thick) OR the surface temperature combined with the cloudbase is such that structural icing is unlikely (example: surface temp -7C and cloudbase 5000ft).
Thus far, with IFR capability back to 2002, I have never had to descend (on an actual planned IFR flight to somewhere), so the above Plan B has never happened. But that is just a result of being cautious (that’s a word you never use in your internet dating profile ) with the departure wx assessment.
I have done plenty of departures into broken or thin cloud, and a few into very cold cloud.
As regards descent, again you need to make sure, before departure, that the surface will be at least a few degrees C above zero, otherwise any ice you pick up in the descent you will be landing with, and that needs a longer runway, because you need to fly at a higher speed.
The problem is that you don’t know much much extra speed you need for any given amount of ice… A TB20 has a Vs of 59kt and can be flown down to that for landing (short final at say 70kt) but with a few cm of ice (which is a massive amount of ice for any aircraft!) you may need to land at 100-120kt which is a dramatically longer runway, say 2000m.
Otherwise, icing in the descent is not normally a big deal, because you don’t need a lot of power. If you are iced up then you must tell ATC and request a continuous descent, in case they want you to hold or give you extended vectoring for spacing or whatever. I have done that once or twice, but have never ended up landing with a load of ice.
Other considerations for the descent is that if there is terrain around, you may not have the option of just flying around (at say +1C) for half an hour (yes it can take that long) waiting for the ice to melt off. So if flying into say Innsbruck, that’s not a good idea…
The above factors put an obvious damper on IFR flight in the winter, in non-deiced aircraft. In reality, if flying for pleasure, it is not normally a big deal, because one rarely bothers to fly somewhere where the wx is going to be crap. And there are ample CAVOK or near-CAVOK opportunities in the winter. I have done about 50-60 hours already this year, with trips in Jan Feb and March.
The other issue is whether you have a de-iced propeller only. A lot of people have a TKS prop but no other de-icing. This is especially true of aircraft delivered in the early 2000s (TB20GTs for example) when this was a popular factory option costing a few k. Today, it is expensive to retrofit because CAV (the monopoly vendor) are taking the p1ss on pricing and run restrictive practices on who can install it (i.e. who they will ship the equipment to).
I have a TKS prop and it is brilliant. It ensures full available power under practically all icing conditions, and the front window has never ever iced up, due to the mist coming off the prop. If I didn’t have a TKS prop I would be much more cautious on the departure conditions.
As regards enroute, it is VMC on top for me 
I have done IMC at times, for say 30-60 mins, but even at temps too low to get airframe ice (say -15C) one can get fuel servo icing. I believe the use of prop TKS protects one from that (because it has happened only when TKS was not used) but that is likely to be engine installation dependent. I am now quite reluctant to do IMC enroute again at these temperatures – at least not until somebody has done some temperature measurements with a suitably instrumented aircraft and established what is really going on.
What_next’s post above is spot on. If you are sitting at say FL100, -5C, collecting ice, and above is just solid uniform grey IMC, you are unlikely to make it on top unless you have a turbo engine.
This not going to be very helpful but since my ID can be traced I have to use the legal approach. That is, if it is 0 C or below on the ground and there are clouds at the Departure point, enroute, or at the destination it is next to impossible not to pick up ice. Flying in Central Europe it pretty much means you can hangar you plane if you intend to do anything more than local flying. My experiences flying between Budapest and Munich. The winter of 2013 was particularly bad. 2014 not too bad there were breaks of 3 days with good VFR. But to use it as practical transportation tool without encountering ice is very difficult. This past winter even better.
Inspite of the legal mumbo jumbo a few tips Ive heard from reckless pilots of years past.
A tip if you are going to fly make sure the temps are above freezing below the base layer. Make sure the cloud bases are high enough and temps warm enough below the bases to allow time for the ice to melt if you ice up and have to descend. Thin wings pick up ice easier and there is more degradation of performance with such a wing. Dont use flaps when iced up so a longer field is required.
In the US I used the area forecasts for tops and layer reports through a WX specialist. Guys who really knew the weather and what light aircraft can handle. In Europe I use Achim’s Gramet to give me an idea where the tops are and what I will be flying through.
Thats a start maybe some others can chime in.
In my experience, the icing charts of Jeppesen Mobile Flight Deck are quite accurate.
And regarding landing with an iced-up airframe: In some aircraft manuals (unfortunately not in all) there are recommendations about the procedure to use when landing with resdual ice: Speed additionals and whether or not to use flaps.
I have a TKS prop and it is brilliant. It ensures full available power under practically all icing conditions, and the front window has never ever iced up, due to the mist coming off the prop. If I didn’t have a TKS prop I would be much more cautious on the departure conditions.
If you are sitting at say FL100, -5C, collecting ice, and above is just solid uniform grey IMC, you are unlikely to make it on top unless you have a turbo engine.
Where does this put me with a C182 that has a turbo charged engine and a hot prop (i.e. heated, not TKS)?
I’m not flying IFR, but if I were to do that in the future, that is going to be my most likely touring aircraft for IFR flights.
In my experience, the icing charts of Jeppesen Mobile Flight Deck are quite accurate.
My experience is as different from yours as it can be, what_next
Well, with the caveat that if Jepp forecast icing here
then you will get some, but that’s a case of no sh1t Sherlock
I’d say that a lack of an icing forecast is worth very little, unless of course the conditions are VMC!
The Jepp wx data is straight from GFS, AFAIK.
So the safest option (and the only one that I accept for myself) is a freezing level above MSA.
True, and this obviously works in many countries, but not in Germany, as you know. They will not allow you to go below the MVA, which is often 1500 feet or so higher than the MSA. And these 1500 feet can be crucial, at least in spring and autumn.
So, in Germany, with the above guideline, you would have to be ready to cancel IFR at the MVA (and say you are VMC…) in order to get to the MSA. Not nice. And you wouldn’t be able to get back into the IFR system once IFR has been cancelled…
So, in Germany, with the above guideline, you would have to be ready to cancel IFR at the MVA (and say you are VMC…) in order to get to the MSA. Not nice.
This is why I call it an “option out” or contingency plan or whatever. To be used in an ice-related emergency. Not for normal everyday operation…
As said before: Nomal everyday operation with a non-deiced aeroplane is: Stay out of icing. Period.
Thank you Peter for breaking the ice with your long post.
On a recent flight I departed into blue skies with a FEW cloud. After 100 NM I was flying at FL100 over a BKN layer that had tops at FL090. The METAR for the destination was CAVOK, but that only means no cloud up to 5000’, and after a while it was time to get onto the STAR and into the BKN layer. The IAF was at 4000’. The outside temperature within the BKN layer was slightly below 0C and while I descended through the layer at 1000 ft/min the ice appeared and went as soon as the temperature went slightly above 0C. It got washed away by the warmer water from the clouds.
So that’s a clear and simple case similar as to what Peter was saying about descending.
But then… Ice can apparently be encountered at any time of the year whenever the OAT is between 0C and maybe -20C and there are clouds. If it happens depends on the moisture content of those clouds. With my limited experience I’m challenged to predict when a cloud is sufficiently wet to pose a greater danger than others. Data from the ADL weather radar is probably helpful as well.
What is it with the fear of saying something about the subject in public? Have people been prosecuted anywhere for talking about how get OUT of ice? I’m aware of the US discussion about the FAA opinion about visible moisture at below 0C, which has been taken back. I believe many people viewed is fear mongering and not helpful.
It is a bit similar to the flight instructor always telling PPL (VFR) students to never ever touch a cloud out of fear that knowing how to get out of the cloud alive might seduce someone to fly deliberately into one. As soon as the same person goes for the IR right after the PPL the very first thing to happen is precisely that. I think fear is a bad guide. Knowledge is better.
However, I’m not looking for confessions. My intent is to learn about useful tactics to deal with the issue. Questions like judging the moisture content of clouds when in flight or when to go up in a high-power aircraft. I would love to compile the information into a document so that it can serve others.
Have people been prosecuted anywhere for talking about how get OUT of ice?
Certainly not. But this is a public forum that is read by at least ten times as many people as the number of contributors may suggest (Peter has the numbers). For me, it is more about my conscience than about the legal aspect. If I would tell in public what I got away with over the years (not only ice related), and only one of these many anonymous readers takes this as professional advice (I instruct IFR among other things) and fails, my Karma will suffer – so to say. Come flying with me and I’ll show you what’s possible and what isn’t. But not here in public. Just as I won’t tell you here how to import counterfeit Nike trainers without them getting confiscated by customs
