Icing (merged threads)

Right. Severe icing can be handled, for a short time, by a large passenger jet, and even those guys will leave that area as quickly as possible. FIKI in a Seneca or Cirrus cannot handle severe icing. Many paid with their lives for that misunderstanding.

@USFlyer
Forget the idea to fly into severe icing with your shiny new G5. It has a high potential of killing you. FIKI is only a toy in these conditions. I literally cringe when i hear Cirrus pilots mention FIKI in this context.

Two years ago I flew with a DA42 into severe icing – enroute from Colmar to Vienna. A lot of ice built up in approx. 2 minutes. The aircraft slowed down, felt the vibration in the controls. 1 minute later the plane felt like near stall. Had switched Anti-Icing to max position immediately, but could not get rid of ice. Could not climb although I sometimes saw glimpses of blue sky above me. My wife next to me looked at me with a horror I will never forget. Asked the controller to immediately clear me down due to severe icing. After I went below 0 degrees, the ice went off with several loud bangs. Ice spray flew into the cabin through the air inlets. Controllers realised the situation, which we had gone through. They really cared and gave us even vectors from VOR to VOR and kept us on MVA…

I learned about flying from that – and I check SIGMETs especially in winter.

There is no useful icing forecast for Europe.

Many “valiant efforts” (meant as a euphemism ) have been made but forecasting simply isn’t that precise.

IMC below 0C will do it, sooner or later, so you need a Plan B.

I’ve had 3cm+ in 5 mins… here

I have had two encounters with severe icing in the SR22T with FIKI. Turned the TKS to max and started an immediate descend into warmer air. In the 1-2 minutes of that descend, the ice buildup was about 1-2 cm on the front screen. The TKS was spraying out of the wings, still the ice was building up. Once in warmer air, the ice was off in no time. You cannot fly or continue to fly in severe ice with the SR22T, but the FIKI system might help you get out, if you can descend down to warmer air. Often the severe ice is in a layer and descending down (where possible) just a few thousand feet can be enough to get into better conditions.

I really hate severe ice and it is very hard to predict. We do provide the Sigmets in our AeroPlus Aviation Weather app as orange triangles and I do always read them. They are there for a reason. If severe ice is forecasted, I don’t fly.

I have also been flying the SR20. It doesn’t have a lot of climb performance and no protection at all. I would be not run the risks with such an aircraft.

Peter wrote:

IMC below 0C will do it, sooner or later, so you need a Plan B.

Not trying to nitpick, genuinely asking, as I have zero actual plane experience, just observations of cars parked outside (which tells me that cars do get covered with a frozen layer at temperatures well above +2C without any apparent precipitation, just from humidity, wind and possibly convection). Isn’t it relatively easy to encounter structural icing with temperatures somewhat above the freezing point as well? I recall being told that high humidity being a factor. The FAA seems to agree – clear ice starts at +2C according to this.

Granted, 2C is just 1000ft, but at the same time, it might be the 1000ft one does not have.

My experience: whenever i fly into clouds at +2 C C it will be around 0 or -1 inside the cloud. I think i have seen up to three degrees difference

Not trying to nitpick, genuinely asking, as I have zero actual plane experience, just observations of cars parked outside (which tells me that cars do get covered with a frozen layer at temperatures well above +2C without any apparent precipitation, just from humidity, wind and possibly convection). Isn’t it relatively easy to encounter structural icing with temperatures somewhat above the freezing point as well? I recall being told that high humidity being a factor. The FAA seems to agree – clear ice starts at +2C according to this.
Granted, 2C is just 1000ft, but at the same time, it might be the 1000ft one does not have.

The first Q is whether you are measuring temperature accurately. OAT probes can be a few degrees off. The OAT readout on the popular Aspen EFD1000 is notorious and has been more than 5C out. They have issued all kinds of bodge “software” fixes for it but basically the probe is in a place where it cannot possibly be accurate, due to conduction from the cockpit. They finally did a separate probe option… The OAT probe option on a GTX330 is horrible too. So applying a few degrees margin is not a bad thing, but if the plane is yours, you can check the OAT probe by borrowing an accurate thermometer.

The “car frost” situation is not the same as flying.

With ground frost, you get a temp drop due to water evaporating, so the surfaces can be colder than the air at say 2m above ground.

In flying, the airframe will be at the temperature of the ambient air, plus an increment caused by aerodynamic heating (which is of the order of 1C at 100kt or 2C at 170kt). However, the standard round OAT probe is in the same airflow and will heat up too, similarly, so if that says 0C the leading edges of the wings etc will also be close to 0C. IOW, generally in GA, SAT=TAT.

Icing absolutely cannot happen if the relevant bit of the airframe is actually at +2C. Physically impossible. The issue is with measurement errors. On jets this does not apply because at high speeds you can get big local temp variations e.g. 10C.

We have many “icing” threads here (do a search) but basically icing exists between 0C, is worst around -5C, and is very rare at -15C. I posted a photo of -15C ice and it was the only time I had ever seen it.

Back to the topic, what this Cirrus guy was doing is anybody’s guess. Yes, crap wx, but if you keep to temps above 0C then you won’t get icing, and the remaining hazard is flying into a CB or some such. You will have an unpleasant flight (I have flown in IMC and rain so hard one could barely hear ATC through the Bose headset) but it won’t kill you. He might have just lost it on entering IMC, which happens all the time anyway, and should not happen to a VFR-only pilot (because he should have been in VMC) but hey lots of VFR-only people fly in IMC… It works unless the autopilot disconnects, which it will do in serious turbulence. Maybe he did a bad job of getting wx and then pressed on into IMC when he found it. The chute is probably a factor in Cirrus preflight planning but he ought to have known that ditching in the winter isn’t a viable Plan B. That SR22 chute ditching video which is all over youtube is quite a bit scary in the way the chute (in strong wind) seems to drag the plane along and fills it with water. Or maybe something less common happened like air intake saturated by extreme rain, or some other engine failure, or running out of fuel which is really common…

My probe is on the spot, and i did sometimes get light icing entering clouds from +2 C. Immediately after entering IMC the OAT was 0 or -1, and there was light ice after a while. I think the airframe will cool down rapidly.

My probe is on the spot, and i did sometimes get light icing entering clouds from +2 C. Immediately after entering IMC the OAT was 0 or -1, and there was light ice after a while. I think the airframe will cool down rapidly.

So you were not at +2C but were at 0 to -1C

If somebody demonstrates ice accretion with the substrate at +2C, they will be heading straight for a Nobel Prize.

To get water to freeze at +2C you would need to be flying below the earth’s surface. But it appears possible (the flight would not be of course – there would be an awful lot of drag). However this suggests that you would need to be quite deep; an order of magnitude calculation there suggests about 10 megapascals which is around 100 bar which is of the order of 1000m of water or c. 300m deep underground.