Icing: Mission gap between NA, TN, TC engines, HOT/COLD propellers, and CLEAN, TKS, FIKI wings?

It should help if one reads the actual regulation.

NCO.OP.170 Ice and other contaminants — flight procedures
(a) The pilot-in-command shall only commence a flight or intentionally fly into expected or actual icing conditions if the aircraft is certified and equipped to cope with such conditions as referred to in 2.a.5 of Annex IV to Regulation (EC) No 216/2008.

GM1 NCO.OP.170(b) Ice and other contaminants — flight procedures
KNOWN ICING CONDITIONS
Known icing conditions are conditions where actual ice is observed visually to be on the aircraft by the pilot or identified by on-board sensors.

This is supremely unhelpful. The GM defines a term that isn’t even used in the regulation, and it does not.

So we can all argue until the cows come home what that means – some people lean towards the “liberal” interpretation and say “well, I don’t expect it and I certainly don’t have any icing right now because I am not in the air, so I will take off” while others will say “well, there is a forecast that says there could be icing so i should expect to encounter some and will stay on the ground.”

And for those who buy aircraft with strange limitations in the POH, they have the additional burden to figure out what they mean, too.

I humbly suggest that the desire to fly safely and remain alive overrides all these legalistic criteria, and that we should only fly if we believe that we can remain out of icing conditions and, should that not work out as planned, that we have an out (descent, 180, hot prop, TKS).

IIUC EASA basically leave all decisions regarding ice to the PIC
Known icing in terms of the DA42 are:-
1/ depicted as such on a SIGMET chart
2/ PIREP
3/ When the pilot sees ice forming on the aircraft.

All the rest is there might be icing such as a cloud and freezing level combined, or under clouds when approaching a.warm front etc.
The DA42 is a TKS system and is therefore an anti ice not a deice system which is why it is worded in the AFM, the way it is. It is for the PIC to decide that there might be a risk of icing and therefore turn the TKS system on before it starts.
Boots are an deice system in that you wait for t ice to form before you turn the boots on to inflate and deflate. The good old Aztec with boots was very efficient when ice started to form but it never held FIKI status, not because the system wasn’t as good as that on a Cirrus but because the whole concept of FIKI did not exist when the Aztec and its boots were TCd.
When it comes to icing, IMO pilots should not be looking or thinking about what’s legal, only what is safe with the aircraft and equipment they have and the knowledge of how to use it. But even with anti or de icing equipment IMO the safest way to treat icing is to avoid it, if you can.

Cobalt wrote:

KNOWN ICING CONDITIONS
Known icing conditions are conditions where actual ice is observed visually to be on the aircraft by the pilot or identified by on-board sensors.

Well, it actually is a logical statement with regards to forecasts, which never ever will make any phenomenon KNOWN but only state that there is a certain amount of probability that it will be encountered at or around the forecast time. Hence, known ice can never be legally deduced from a forecast product.

Cobalt wrote:

I humbly suggest that the desire to fly safely and remain alive overrides all these legalistic criteria, and that we should only fly if we believe that we can remain out of icing conditions and, should that not work out as planned, that we have an out (descent, 180, hot prop, TKS).

Absolutely.

I think they should rewrite the rules and start with if you see feel the known icing ….my experience is not the wing but the prop that suffers first and you feel the ice in your but. :-)

UdoR wrote:

But why prohibit something that is perfectly safe?

That is a completely different question – but it would also be perfectly safe to drive 140km/h on many Swiss motorways – and still it is prohibited and expensive ;-)

Part of safety culture is also to be honest with oneself and others. And in my opinion the discussion on the legal nature of adwice (btw.: Hard to type as at least my browser thinks it has to correct me…) is part of escapism. Reality is much simpler.

Take last Sunday as an example:
We had a 5/8-6/8 cloud layer with about 4000ft base and an OAT at ground of about 3°C. You don’t need any forecast for this (although it was exactly as forecast) but see all of this when you stand on the field and look into the sky. You KNOW in these conditions that there is icing in the clouds. Completely independent of any legal discussion. Flying around every cloud is practically impossible.

We did an IFR flight and encountered exactly what was to be expected: We spent no more than 90 sec in the cloud layer and did pic up some ice (obviously in that time more like some rime.

Flying through these clouds with an airplane that has the operational limitation not to fly through known and forecast ice is illegal. It might still be perfectly safe but is illegal. Therefore last Sunday you could not do any IFR in IMC flight legally with an airplane that has this operational limitation.

Cobalt wrote:

intentionally fly into expected or actual icing conditions

That is even takes out the discussion on what the criteria for “forecast” actually are. “Expected” is a much broader term – and you learn in meteorology 101 that (at least) in visible moisture and OATs between 0 and -20 you have to expect ice.

gallois wrote:

When it comes to icing, IMO pilots should not be looking or thinking about what’s legal, only what is safe with the aircraft and equipment they have and the knowledge of how to use it.

It’s not an or, but an and. Obviously pilots should not do something that is illegal – but that doesn’t imply that they should do everything which is. Amongst all the things that are legal we should obviously only do those that are inside the capabilities of oruselfs and our equipment.

@Malibuflyer I love living, and I think most here do. The question was not whether anyone here was searching the risk, or willing to accept such a risk as ice accumulation in a non-deiced plane. I would not, of course. With my (small) experience, and my plane, I avoid any possibility of ice accumulation. But this is not due to law binding any such operation to ground, but due to reasonable decision making.

If we look at an official publication of EASA “in flight icing for general aviation” ( here ) you may read starting on page 14:

It is often impractical to plan a flight in a way that leaves no possibility for icing conditions to be encountered, in the same way that it is impractical to plan a flight on a convective day in a way that leaves no possibility for an encounter with cumulonimbus, because it is never possible to be certain exactly where such a cloud would form. But, just as a crew must always have a plan which allows them to avoid flying into a thunderstorm that appears on their intended route, so they must have a plan to avoid icing conditions more severe than the aircraft’s systems, if any, can cope with, and to escape from any such icing that is actually encountered.

Vibration: No effect may depend on the quality build of the airframe like with cars…

UdoR wrote:

It is often impractical to plan a flight in a way that leaves no possibility for icing conditions to be encountered,

I fully agree to this EASA publication. And I hope that we also agree that there is a huge difference between “no possibility for icing conditions to be encountered” and “well, you know, there is this overcast stratus layer in -5 OAT but you really can’t know for sure that there is ice in it before you actually go there”.

UdoR wrote:

in the same way that it is impractical to plan a flight on a convective day in a way that leaves no possibility for an encounter with cumulonimbus,

I very much like this comparison. If we would take the same effort to avoid potential icing conditions as we take to avoid Cb, everybody would stay legal in 99% of the times. But let’s be honest: How many pilots act like “I know this is likely a Cb but let’s fly in it to see how bad it really is…” vs. “I know it is likely some ice but let’s fly in it to see…”?

UdoR wrote:

The question was not whether anyone here was searching the risk,

Exactly! The question has been what the advantage of “Fiki” (in the sense of a plane that by AFM is not limited to stay outside known or forecast icing) vs. non FIKI TKS is. My answer to that was, that with such a FIKI plane it is legal to fly in many situations where it is illegal to fly in non FIKI planes.
I did not mention risk at all!