If there is a chance of Ice and a certainty of IMC, I would need some ice protection or not depart.
As I have ice protection, I only depart if the ice forecast appears to be sketchy and unconclusive, leaning toward only a couple of areas.
Plus I will treat the boots with Icex for extra help.
On that basis my main focus then becomes the exit plan.
If I ice up because all the predictions were wrong and it overwhelms the boots, can I descend to a better temperature? (may only need to be at +1 ‘c)
Or climb harder to less ice or VMC? I have some excess power so climbing is an option.
Earlier this year I made 3 flights that I wouldn’t have attempted without ice protection, all 3 had some ice predicted. Only an amount of ice that would have been acceptable without protection occured, but I was comfortable to take the flight and find out.
I’m quite happy with my process and although it was only 3 flights they were important to me, and did constitute lots of organising so cancelling would have been a real shame.
One point of note, the worst ice I’ve seen was on returning to base, passing through controlled airspace, almost home.
We were given a descent, (we were and had been IMC for 20mins.) Then held at a level slightly above the original clearance as an amendment, due to other IFR traffic (CAT) on the procedure.
We started collecting ice quite quickly. The boots were coping well but we definitely needed them. At that point it occurred to me if we didn’t have boots, we’d be making a real mess for everyone by declaring ‘unable to maintain’ and requesting immediate descent.
Obviously needs must, but I was glad to not need to make that call. On that day in that situation our choices would have affected others not just us.
I am very happy to fly through icing in my TB20+TKS. Just don’t do it for longer enroute sections because of limited fluid duration of under an hour.
Without TKS I would climb or descend through layers but would make sure there is enough warm air underneath.
Let me remind everyone again that “known icing” is a US term which maps onto US wx services, etc. Done here. In Europe, the legality of “flight into known ice” is meaningless because there are no official wx services here for GA.
Icing is not usefully forecast. In IMC, 0C to -20C or so, you need to assume there will be ice, and 90% of the time there will be. I know about the top secret (unless you pay €60) German DWD icing layer but I’ve had access for years (until the said well known individual pulled his wx site) and it never said anything other than blindingly obvious from a 1 second look at the MSLP chart.
Have I had severe icing? Maybe. One flight here maybe, but TKS would have coped OK.
Before TKS, I saw plenty of ice too but always did it with a thin layer only and with warm air underneath. But normally I fly VMC on top.
Lots already written here and here iow “Threads possibly related to this one” below.
Amazing charts posted by Antonio above. I wonder how on earth that data was collected. There is no obvious way to simulate some sort of standard icing.
Some moderate (airline category, so arguably severe for piston GA) icing encounters are pretty obvious. In some instances a mixture of SCLD and freezing rain creates lumps of jam like ice which will overwhelm GA anti/de icing systems. Alternatively, you get mixed ice formation which cannot be cleared despite using boots or TKS continuously. A five year old can figure out this is an emergency like encounter requiring an immediate exit from the conditions.
The more insidious nature is poor strategic weather planning where light GA with so called FIKi systems ploughs on, probably paralleling an occluded warm front with nimbostratus at IFR altitudes. The icing systems seem to cope with clearing the leading edges, but ice is forming elsewhere. No SOP for either exiting the situation or understanding that at a certain IAS, not far removed from normal cruise, the aircraft is near a stall which will not be benign. Ice doesn’t form symmetrically or neatly, and when the aircraft departs it is likely to be a yaw aggravated departure, ie spin.
Bertrand Russell’s quote on his chapter on universals comes to mind for those who plough on in light GA in icing conditions.
The man who has fed the chicken every day throughout its life at last wrings its neck instead, showing that more refined views as to the uniformity of nature would have been useful to the chicken :)
Peter wrote:
I wonder how on earth that data was collected.
Ice tankers and then a painful search for actual natural ice too!
This is from the report
And this from some military aircraft tests
There is some science behind it to get the SLD size to conform to FAR25…the little buggers don’t seem to oblige easily to regs!
And the best part: you need to have a working windshield anti-ice whether intended for its actual certification or not…care to guess why? (The report does mention some makeshift windshield anti-ice rigs for flight testing…)
Here (the US) the best icing info comes from PIREPs, which can be viewerd in ForeFlight or queried from FSS. ATC also put out warnings, although, IME, unless severe you have to ask.
