I have FIKI and just blast off and deal with what happens. If my equipment cannot cope with what I encounter, I change altitude, but in 42 years of aviation, 38 with an IFR rating, I have only had this maybe half a dozen times.
I would recommend FIKI to anyone who flies IFR extensively. And it is just as necessary in Summer as Winter.
I follow Peters recommendations on planning the flight but determine the TOPs is very difficult and PC-met is not reliable. What do you think about ?
That is why I avoid frontal weather - the tops are quite likely to be FL200+ in warm fronts (though probably rarely above FL250) and more in cold fronts, and obviously the tops of CBs could be "anything".
What I have found to be 100% reliable (in the sense I have not yet ever had to do a 180) is the satellite IR images. These are not accurate to say 1000ft but are accurate enough to tell you if the tops are going to be FL100, FL150, or FL200, and for a TB20, which can climb to FL180 easily (unless you are carrying 3 and the kitchen sink) or to FL200 at a push, this is good enough. As I say, 100% success rate, since about 2007.
But the same would not be possible in a plane whose ceiling is say FL140 or less i.e. the whole "PA28-181 and below" fleet. The IR method is just not good enough for that, unless you fly only in areas which show no more than a very light grey on the IR image (tops probably below FL080).
In fact I would say I could make the go/no-go decision perfectly well enough on the day just by using tafs, metars, and the IR images. In years past, I have played around with Meteoblue (which was a big fashion at one time) plus probably every other weather website, and had a lot of fun driving myself up the wall, and then down the wall, but in the end what really matters is what is up there on the morning of the flight and that is what the IR image gives you.
The MSLP chart (expert interpretation 
) tells you where the fronts might be some days ahead, so you can do a rough plan and get packed to go on the clear day.
However the bottom line is that I do not fly in freezing IMC enroute. Timothy's approach seems technically fine in a fully de-iced plane, and that is how commercial aviation is done, but I wonder if he does it with "sensitive" passengers? Justine (my partner of 10 years) has done most of my long trips with me and I work hard to make them smooth. She (or myself flying alone) has never had what I call an "eventful" flight but she got scared once or twice, in a little piece of IMC, and if you do that once too often you get a wife/girlfriend/whatever who will never fly with you again. On an airline it is different because the passengers can scream for all they want, and sometimes do, and if they start banging on the cockpit door they will get arrested afterwards. So the psychology, from the passenger's POV, is totally different even if the actual flight (turbulence) is the same.
OTOH some frontal weather, especially warm fronts, can be totally smooth. How can one predict that?
And still, after landing they have been interrogated by the relevant FSDO and penalized as well.
How often does this happen?
I read the US forums fairly regularly (they are quite "tech" so useful for specialised stuff) and they rarely if ever discuss that sort of thing.
Nowadays, any report of this kind, especially when slightly badly worded, will get an immense machinery going and at the very least, will get the fire crew deployed at your destination airfield, questions asked after landing, etc.
I wonder if that is a German thing, or whether there was some "personal history" to some of the pilots? Here in the UK you will certainly get the world's supply of ambulances and fire engines (and police cars) if you as much as mention something smelling funny in the cockpit but the pilot's actions are not questioned for the purposes of a prosecution. But the UK CAA does have a bit of past "form" when it comes to going after pilots repeatedly known to it...
BTW, I edited a post above to remove some unusual character codes for a apostrophe, which causes havoc with the text processor here, changing to font to a funny one 
The normal apostrophe which you have on the keyboard, probably on the same key as the @, is fine.
In reply to Achimha's question, I would climb, without question. VMC on top is nearly always the best place to be. You might just need 8.33 however
That's not an issue, I am more concerned about RVSM once I pass FL290!
But the oxygen situation at FL240 needs very careful management; much more so with passengers. You will need masks (not cannulas) for all.
I get excellent results with the O2D2 on demand regulator and cannulas at FL200+. I have never had to use a mask and the only advantage I see using a mask is that mouth breathing will be covered. Probably a good thing for passengers but I personally wouldn't use a mask even at FL240+ if my oxymeter continues to show 90%+.
Here, in Europe, the tendency seems to be the same, i.e. contollers (particularly in Germany) are becoming increasingly "investigative" as soon as anything ever so slightly out of the norm happens. I have long ago resolved to not tell ATC a single word re "icing", even if I encounter it.
I do the opposite, I use the i-word whenever I don't feel comfortable. If I ask for a level change without the i-word, I get if it's completely free and requires no effort by ATC. If I use the i-word, I will get it. I don't see how using the i-word could have any negative consequences unless you declare an emergency.
On a related subject, I would never tell ATC when I have a minor, non-critical technical problem. Nowadays, any report of this kind, especially when slightly badly worded, will get an immense machinery going and at the very least, will get the fire crew deployed at your destination airfield, questions asked after landing, etc.
Agreed. I once asked ATC for a METAR of a heliport they didn't have readily available so they asked why I wanted it. I told them that while I'm in VMC, I would like to know at which altitude the low stratus is in case of an emergency landing due to an engine failure. I shouldn't have said that, it took quite some effort to convince ATC that there is no emergency at all
I personally wouldn't use a mask even at FL240+ if my oxymeter continues to show 90%+.
A while ago I had a debate with a man claiming to be some sort of medical specialist who claimed that the percentage reading cannot be relied on at high altitudes.
Is there any evidence for that?
I once asked ATC for a METAR of a heliport they didn't have readily available so they asked why I wanted it.
That's completely wrong. It's not their job to ask.
I heard somewhere that, in Germany, ATC is a division of the national police. Is that correct?
I would recommend FIKI to anyone who flies IFR extensively. And it is just as necessary in Summer as Winter.
FIKI is what turns an expensive hobby into a very expensive hobby.
I once asked ATC for a METAR of a heliport they didn't have readily available so they asked why I wanted it.
That's completely wrong. It's not their job to ask.
The South European version of that is pretending they don't understand what you want
I heard somewhere that, in Germany, ATC is a division of the national police. Is that correct?
No, it's a privately organized corporation called Deutsche Flugsicherung GmbH (DFS). 100% of the shares are owned by the Federal Republic of Germany and it is administered through the Federal Ministry of Transport, Building and Urban Development. Some years ago this structure was put in place so that the government can sell off DFS and make some money but then the constitutional court ruled that privatizing ATC is against the constitution because the government is legally required to provide ATC. So now you have a half private institution that operates like a business (selling maps, AIPs) but is still a government branch.
The South European version of that is pretending they don't understand what you want
No; they just ignore the radio call (over and over and over) and that makes sure no evidence of their ICAO Level 1 English Language Proficiency is left on the tape
FIKI is what turns an expensive hobby into a very expensive hobby
I guess it increases the purchase cost of aircraft but are operating costs any higher ex-TKS fluid if that is your FIKI of choice?
It certainly increases your ability to launch and complete a flight safely which is especially important if it is a hobby you are using for business purposes.
You don't really have much choice if you're limited by O2 and engine power as I am.
The Skew-Ts are your friends. I operate on a principle of asking questions as below:
Is there clear air/VMC at filed cruise level?
If NO, is filed cruise level above or below 0°?
Obviously if the answer to both is no, the flight is a NOGO.
With a forecast clear cruising level, I then go through the following:
If temperature at cruise below 0°, is there space above MSA to descend to VMC/warmer conditions if icing encountered ?
Can climb be conducted in VMC?
If climb in IMC, does it involve time in icing conditions?
If so, what cloud types am I climbing through?
I am generally happy to climb in stratus below 0° if I have an exit strategy and/or know there is VMC above a short climb. When I have encountered icing in the cruise, a swift level change has always solved the problem, and I have never had to descend below airways to escape. I am fairly conservative in GO/NOGO, more so if I have passengers than when I am on my own.
If one could rely on forecast skew-ts (which are generated from the 3D computer model) then life would be easy, and sites which plot the GFS data as a "route profile" (e.g. Meteoblue) would be "perfect".
Maybe things have improved but I did not find that data reliable.
I am suprised someone considers themselves limited by oxygen, because a portable o2 kit is very cheap. Of course there are exceptions e.g. small children...
