Aerodynamic heating is of the same order: 1-2C at piston GA speeds.
“It’s proportional to the wing loading”
What is the dependency on IAS? Or more appropriatly the Mach number?
Most of aerodynamic heating will happen in high compressiblity regions (high mach numbers), that results in large TAT and OAT gaps, for GA the TAT/OAT is irrelevant as does the Mach number which is far from 1. for GA speeds, as we know, one never pick ice in space shuttles and most airliners will only need ice protection at low speeds ;)
For engine/wing icing in a piston airplane, I think one has to rely OAT, IAS and Density/Pressure (or manifold pressure) while for a jet engine icing you would think OAT, TAT/Mach only? (irrespective of outside pressure), for jet wing icing same story as piston but I think it gets very ugly aerodynamics in higher mach numbers than just from wing loading but in the other you get thermal heating…
The typical GA FIKI arrangement, either boots/hot propeller or weeping wing/propeller, will struggle in a typical occluded front in Northern Europe unless you are pressurised and have good climb rate to FL250 (ie SET). Orographic lift will add excitement to the mix.
Unlike the USA, Eurocontrol/typical GA IFR range, isn’t that helpful in dealing strategically with the sort of 200nm dog leg needed to avoid a wide area of nimbostratus.
Even moderate icing in a modern turbocharged FIKI MEP can have an interesting effect on performance (20-25 knot loss of IAS), and climb performance might be very degraded in turbulence.
While piston FIKI allows better despatch, I would suggest it shouldn’t allow a risk shift on the actual capability of the typical piston aircraft.
As always YMMV :)
The US, however, gets at least as nasty wx as anywhere in Europe. The Great Lakes for example generate loads of icing conditions. The Fate is the Hunter book contains pretty good accounts…
So what is the difference?
I think from the light GA point of view, the Eurocontrol routings, being basically in CAS whose bases are pretty high in places (and where they are low you mostly cannot get a routing due to airport terminal area traffic) tend to place us where ice is very likely.
And Europe doesn’t have the good wx services which the US has. Icing forecasts here are mostly fiction – other than where the potential is blindingly obvious by looking at the MSLP chart.
Peter agree on all the points, although a NE winter ‘zipper’ on the lee of the lakes and in the Appalachians (where the occluded front deepens) will shut down most alternates. Am guessing similar conditions may be found around the Alps.
I somehow feel you can plan strategically in a more flexible fashion with ATC in the USA. The Eurocontrol computer will spit out a route, and if you need an airway major dog leg for weather while airborne, a lot of European ATC will ask you to remove your puddlejumper from controlled airspace. Some might not even ask that politely.
Taking off in a non fiki single when icing conditions are reported on the ATIS, legal or not? If there was no ice, according to above legal text it should be… I’d be amazed!
I’m wondering the same thing. My current interpretation is as follows, but who knows if that’s correct? Talking about EASA-Land here.
Even if icing is forecast in SIGWX, ATIS, etc. you can take off and fly into it, AS LONG AS you can and will leave the icing conditions asap in case there is ice buildup.
So I guess that necessitates that you already have an escape plan prepared (which is prudent anyway, but not sure if it’s needed by law). Also not sure if and how you would document such plan or if it’s enough to have it in your head…
edit: formatting
My understanding that would be legal as long as no ice was observed on the airframe or you went out of it ASAP,
Also as long as you don’t disrupt ATC flow while getting out of it no one will question the legality of your planning/flying or how you did get in/out of it? so an exit route is a must, say busting LTMA to climb above ice will get you on all sort of legal troubles (but first you need to stay alive)
The same would apply the other way around if you depart in CAVOK forcast but landed as planned at destination with airframe above MTOW full of ice, I think that would be illegal…
Ibra wrote:
“It’s proportional to the wing loading”
What is the dependency on IAS? Or more appropriatly the Mach number?
I only just saw your question from back in Feb, sorry. The TAT – OAT gap depends on speed (Mach no.). But that’s not the number I’m talking about. I’m looking at the difference in surface temperature across the aerofoil, from the stagnation point (at the TAT) to a point at which the pressure and therefore temperature is reduced. For a wing with a similar distribution of coefficient of pressure, actual pressure difference and therefore temperature difference depends on the wing loading.
bookworm wrote:
similar distribution of coefficient of pressure
Wing profiles are not the same regarding pressure distribution (chordwise). I believe that partly explains differences between aircraft regarding their inclination to pick up wing ice.
Reading this (merged) thread again, and particularly above does “FIKI” have any legal meaning whatsoever in Europe?
Compare this with the FAA situation where – depending on the definition applicable a a given time, and it has varied over the years – it could have been illegal to depart if a particular US weather service forecast says such and such.
European pilots often talk about “FIKI”, and for sure you can buy a plane which is FAA-FIKI-certified, or not, but does it mean anything?
Examples include the SR22, with two versions of the TKS system, one FAA-FIKI and the other not. Or the TB20 which is never FAA-FIKI because there is no second alternator, no heated stall warner, no backup TKS pump, etc, but it is fine to fly into icing conditions per the POH on a Euro-reg.
