JasonC wrote:
the aircraft manufacturers
Ahhh yes of course, hadn’t thought of that.
bookworm wrote:
2.a.5 is no more. The equivalent in the new BR now says(e) appropriate mitigation measures or contingency plans must be in place to deal with potentially hazardous atmospheric conditions expected to be encountered in flight;
How do you think NOO.OP.170(a) should be revised?
One solution is to delete it completely, since BR Annex V section 2.(e) already says it all. If we really must have more precise rules, I’d like to remove the reference to certification for icing, and focusing on the aircraft’s actual capabilities, not its certification. Something like:
(a) The pilot-in-command shall only commence a flight or intentionally fly into expected or actual icing conditions having considered the aircraft’s equipment and ability to cope with these conditions, and having taken appropriate mitigation measures or made contingency plans in line with the aircraft’s ability;
(b) If icing exceeds the intensity of icing which the aircraft is able to cope with, the pilot-in-command shall exit the icing conditions without delay, by a change of level and/or route, and if necessary by declaring an emergency to ATC.
lionel wrote:
One solution is to delete it completely, since BR Annex V section 2.(e) already says it all.
I think there must be “implementing rules” for everything in the BR. And would you really want to also have to check the BR?
The key thing is to not go up the road which the FAA briefly went up, which is any suggestion that one cannot depart unless equipped to fly in IMC below 0C.
Doing so opens a whole can of worms, one of which is Europe’s spectacularly crappy weather services. Nearly everybody flying in GA is using 3D data from… America 
I think it cannot be put into the BR alone. The Basic Regulation basically lays down the scope that will be regulated. The underlying cover regulations and their implementing rules finally implement the rules within the given scope of the BR.
I support this structure because I want to look in as few regulations as possible. If a change were desired, I’d amend the implementing rule in the NCO operating procedures. IMHO.
Some good points here.
There needs to be an implementing rule, the BR is not sufficient in itself. It could be transposed word for word, but it’s normal to unpack it a bit, e.g. by breaking out “potentially hazardous atmospheric conditions” into specific hazards. In the drafting of Part-NCO, ERs were explicitly cited, as in NCO.OP.170(a). This is a bad rulemaking strategy for a number of reasons, one of them now evident — a “dangling link”.
On the “certification” element, there’s a balance to strike. The operating rule cannot overrule a certification limitation, though a reminder of the definition is useful in avoiding some of the legal issues we’ve seen in FAA-land which Peter alludes to. NCO.OP.170(b) (originally drafted as AMC) was designed to make it clear that icing is unpredictable and that it shouldn’t be illegal merely to experience icing provided you exit it immediately.
I like lionel’s approach, though I’m concerned that the regulatory mindset is that it must be assumed that an aircraft cannot cope with conditions that it was not certified for. Things have changed a bit in GA regulation since 2010 when the rule was drafted, but I don’t think we are yet at a point where we can simply replace the NCO implementing rules with “The pilot must use his best judgement to avoid crashing” — even though I’m tempted. :)
One small addition. The 10 degrees for jets below 10C mostly because the jet engine. Significant term drop may happen in the engine inlet and it may cause engiine icing. Boeing says visible moisture below below 10C TAT and the OAT is higher than minus 45 C for climb, cruise. For descent we disregard the OAT limit, all the time when visible moisture exists and TAT is belov 10C the ENG AI comes on descent.
Same applies for taxi. When it is below 10 and rains or wet, Antiice is on. On TB, when I pass though IMC below 10 I adjust my seat tilt from relaxed to near “vertical” 
and when approaching 5 degrees C, getting more alerted with prop device on/. For me the ADL is a great unit to modify my route or altitude operationaly.
Zsoszu wrote:
Significant term drop may happen in the engine inlet and it may cause engine icing. Boeing says
The misty winter Shanghai effect.
On the new „super efficient“ Boeings the engine is considered free of ice only when the Engineer has inspected it according Boeing‘s Maintenance Manual. Taxi-in times need to be recorded in the Techlog and different runup procedures are required for different temps (7 deg, 3 deg) and within certain timeframes before take off. It actually is too complicated for normal ATPLs . And we’re not even at ice crystal icing yet.
Back to topic:
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!
JasonC wrote:
That is typically the aircraft manufacturers. The CJ is the same. Engine antiice comes on in visible moisture at +10C and below.
And we all know that is really just to keep the sensor perfectly clear so the FADEC doesn’t go mental!
Zsoszu wrote:
The 10 degrees for jets below 10C mostly because the jet engine.
That may be true. I did a calculation once to work out what the difference between the TAT and the lowest temperature on the lifting surfaces. It’s proportional to the wing loading, so while 10 degrees is possible for a big jet (wing loading typically 600 kg/m2), it’s rarely more than 1 degree for a light GA aircraft (typically 60 kg/m2).
