This used to be something I encountered an awful lot flying old piston twins around the UK year round. In winter it was pretty common that we would be in solid IMC the whole flight, and you could start to pick up excessive ice at any given moment really, so not possible to avoid it in such scenarios. We did have some basic de-icing capability (boots and hot props) but it was uncommon for these to get overwhelmed and for us to require descent. ATC never had any issues with this, we were never kicked out of ‘the system’ and would be provided with all the support needed for the flight.
Generally speaking, UK ATCOs are excellent, some of the best in Europe. It is the infrastructure and system they are given to deal with that let’s the whole thing down. If everything is working as planned, they are forced to follow the system and it’s a mess, but if you genuinely need support you will get it.
I don’t think the limitation is solely aircraft, capability is all relative, many people died in equipped FIKI aircraft by staying 1h on same heading & altitude in ice with +3000fpm +600hp aircraft which is waste, they could have been out of the icing band in less than 2min if PIC/ATC are sharp and take the topic seriously
Cumulus you can avoid laterally, convective bits you just don’t go in, you keep turning 30deg until turbulence stops, not sure if it’s a good idea to climb inside in a FIKI you could win the lottery going into a CB?
Stratus you should fly above in the sun or under in IMC (never an issue in UK), land when you are tired in one of the familiar airfields or turn back when you hit the MSA
Crossing cold front in winter bellow zero is doable, you time it with an airport before as backup if you have a gap go in otherwise land and watch it passing by, it may take 3 hours to clear up
Crossing warm front in winter bellow zero, is a bad idea, the 0C/-10C is a vertical wall and no point climb/descend and even if you safely divert you need to take 3 days of hotel and the train/car would be faster
There is no such thing as “FIKI certified” in a SEP sooner or later you have to do something climb/descend or left/right, just how long it takes to make that call 2min, 5min or 30min? if you have non-FIKI turbo & hot prop & oxygen you are in far better position than NA FIKI with no oxygen
Also there is some benefit in OCAS IFR when things are tights, you can position like you wish, getting vectored by ATC for 10NM final or sent to Hold/Arrival at -7C is not funny, where on your own you can hit a quick 3NM final from MSA with barely 5min of descent in IMC…
In reality you request a heading or level change well before entering cloud, especially cumulus cloud.
@arj1 effectively not launch into icing conditions that exceed the capability of the average puddle jumper.
It is a judgment call, thin stratus go on top, nimbostratus through the cold sector of a warm occluded front or convective widespread perhaps take the train.
In the old days where pilots paid their dues in Navajos and Beech 18s they would develop a healthy respect to icing.
RobertL18C wrote:
Am pretty sure that if you flew airways regularly, and had to regularly request a descent due to encounter with forecast icing (Low and High level SigWx chart) in a non FIKI aircraft you might attract an MOR.
“He dares to fly airways in a plane WE think is not suitable” :))
On a serious note, what would be the right way to do it?
I mean if you encounter visible moisture in the icing temps, what else could you do in non-deiced plane?
it would block more or less all winter IFR in non-deiced planes
That is why commercial IR training and AoC are FIKI (technically, as a piston MEP is FIKI for regulatory purposes, or INO). Am pretty sure that if you flew airways regularly, and had to regularly request a descent due to encounter with forecast icing (Low and High level SigWx chart) in a non FIKI aircraft you might attract an MOR.
I believe the FAA treats PIREPs as known icing, and USA pilots are more diligent in filing PIREPs. ATC will, and should advise you of icing from a PIREP on your route. In effect establishing on the tape you are proceeding into known icing. The correct response is to request a route or level change if you are not FIKI.
Alpha_Floor wrote:
What about temporary descents below an airway’s MEA (and therefore also below CAS presumably) due to, for instance, icing?
Not specifically for the UK situation – but I’ve always understood the MEA as an administrative (planning) limit. There should be nothing beside coordination issues that prevent you from tactically getting a clearance below the MEA. (Subject to terrain clearance etc.) Of course, you may drop out of CAS which may or may not be an issue.
Don’t both Scottish Control & Information have Radar mandate
Yes, but the funding mechanism blocks them from providing a service. Scottish tend to do it well, but London generally doesn’t.
If you are flying non-FIKI in UK SE
I don’t think that line of argument is productive because it would block more or less all winter IFR in non-deiced planes. The FAA tried this many years ago in its working definition of when “FIKI” (which is a US legal term mapped onto US wx services) is legally required, and dropped it pretty fast. I recall reading about this years ago; maybe @ncyankee recalls the detail.
Don’t both Scottish Control & Information have Radar mandate, so things are easy up there, you would get TS all over the place easily?
If you stay en-route to say Cardiff and just descending bellow 0C deg you you’ll stay with London Control, they will give you DS/TS OCAS or may hand you to Southend
It’s only when going to some OCAS destination by descent where you tend to get kicked out early and you hear “Radar services terminated”, there are zillions of unknown traffic and zones down there and you are probably going IFR to what they consider a “VFR airfield” like Stapleford or non-Radar airports, so it’s understood you are not getting a terminal service, but I am sure they would keep you up to DET at 4kft coming from Amesterdam before they say au revoir, you should be able to find your way from DET like you did many times 
If you are flying non-FIKI in UK SE and requesting unpleasant descents/climbs due to icing you would be disappointed by CAS structure and compromise your safety waiting for things to be coordinated between units, you should plan to make your destination IFR not talking to anyone after all there is load of Class G and many airfields where you can land divert in weather….
I would be fairly sure that London Control would not kick you out of their “system” if you had to descend due to icing.
Quite likely they will say something like “Basic Service on leaving CAS” and pass you traffic info. That is what I tend to get when returning back to Shoreham.
