Modern turbochargers are much more reliable than the early versions which tended to pack up and shorten engine TBO. However I think their commercial mission was to help cope with density altitude take offs in the American west, the ability to fly in the high teens being a supplementary benefit.
The MEA over large built up areas is also a factor. Airways over London, if your not RV around, is typically FL120, and there may be a higher minimum for SE. As PIC on an IFR flight you are still responsible to comply with the glide clear rule over a built up area in a SE, and using a typical no wind de factored glide gradient of 9:1 you might need to plan higher than FL120 for London.
As the inventor of the ADL110B and ADL120 please be cautious navigating close to embedded thunderstorms using datalink weather.
Don’t worry. What I meant to say was that it seems to be great tool to plan a flight path well ahead of time to avoid the area where trouble may be waiting. I’m not talking about tactical decisions to navigate around cells at short distance but instead about planning a significant detour.
I also fly a N/A SR22 and, on flights with the profiles you describe, my practice is to fly high (FL160/170) on the longer flights and lower (FL60/70) on the shorter routes.
My reasoning is that, at the higher altitudes I am likely to be above clouds, will have a higher TAS and can lean the engine more. Obviously that needs to be conditioned by head/tail wind and icing considerations.
Obviously, I use O2 (Mountain High O2D2 and Oxyarm cannulas) at the higher levels and monitor O2 Sats regularly with a pulse oxymeter.
I don’t think I can recall a single flight when I have regretted not having a turbo. If you are thinking about that, I recommend reading the discussions on COPA about the differences between the older Tornado Alley TN and newer Continental T systems.
I’m not an expert myself, but several people there who are seem to think that the T system is likely to impact service life of the engine more than the later incarnations of the TN.
One other point: you don’t say which generation Cirrus you fly but, if it has the old Stec autopilot, you need to keep a careful eye on your airspeed when climbing to the higher altitudes in VS/ALT mode as there is no envelope protection and it will happily fly you into a stall.
And now I’m wondering about the need to file and fly high that I’ve read about so often.
I’ve been flying a normally aspirate twin around W Europe for about 10 years. We carry oxygen. I can count on the fingers of one hand the number of occasions I’ve needed to use the boots (though the prop de-ice, as a precaution, more), and on the fingers of the other the number of occasions I’ve needed to use the oxygen (pretty much always to get above FL90-120 CU tops). Both are useful to have in case they become useful.
While the idea of getting above the weather is nice, I find Peter’s view that flying VMC on top is the only way to do it, somewhat extreme.
A turbo must reduce the life of an engine (if one climbs to any altitude) because a NA engine starts off at max rated power on the runway (plus or minus a correction for the deviation from ISA) and immediately after takeoff it starts to lose power. At the aircraft ceiling (typ. 20000ft for the higher-end IFR tourers) it is doing about 40-45% of max rated power. Whereas a T engine is making the max rated power all the way to perhaps 15000-18000ft, so it spends way more time at max power than the NA engine. That translates to more wear but, much more significantly on the engines we fly, the combination of higher power being delivered at a high altitude (thin air = poor cylinder cooling) really hammers the engine.
As a result, very few T engines make TBO. I don’t fly a TB21 because not a single one I know about (I mean verifiably, not hearsay) has yet made TBO without replacing cracked cylinders.
The other side is that it takes me about 40 mins to reach 18000ft and another 20 to reach 20000ft, and if the conditions are ISA+10 then I will not make more than about 18k until some fuel is burnt off. Whereas a TB21 will reach 18000ft in about 20 mins and can reach 25000ft. That translates to a reduced (but not eliminated) exposure to icing conditions, and better options for climbing above convective wx in the vicinity of the airport of departure (though in practice that one is less of an issue because one can usually zig-zag to climb high if really necessary, and I have never yet had to do that).
So it is a personal preference. My preference is having an engine which doesn’t give me any trouble.
Just seen bookworm’s post above. I seem to collect ice a good 50% of the time in IMC between 0C and -10C, with -5C being the worst point. Also I use oxygen anytime above about 8000ft because it stops me getting tired. I would never fly at 12000ft without oxygen, although I am sure I would be conscious and functioning, due to the extreme tiredness upon arrival. Just my view 
I don’t think I ever said VMC on top is the only way to fly, but it gives you the best safety options, the best scenery, the most comfortable flight, etc.
I would never do IMC enroute long-distance… one is sitting there with no options.
Being in IMC doesn’t mean one doesn’t have any options. I have no problem with IMC over a longer period of time, of course not the convective type.
the turbo scenario is that it doesn’t make a lot of sense unless one also has de-ice – because a turbo gives you ~FL240-250 which you will be using only to get above convective wx (due to the oxygen usage being high at those levels, and borderline-practical with certain types of passengers) and if you are going to be climbing up through stuff like that, the icing risk is just too great.
Spoken by somebody without a turbo Most pilots that have both gear confirm that the turbo is the most effective ice avoidance tool. If you have a climb rate of say 800fpm, then you can avoid most types of icing. Icing is usually found at a narrow temperature range. If you’re NA and your remaining climb power is something like 100fpm, then you don’t have a lot of options above you.
And yes this means no oxygen = no IFR, for me.
I have to disagree on that, too. Oxygen is a hassle for most passengers. Hardly a possibility for small kids. On 80% of my IFR flights, I do not use oxygen even though I have a built in system and the bottle lasts forever with the O2D2 system installed.
Being in IMC doesn’t mean one doesn’t have any options
A always, it depends on the detail. If you are in IMC, 100ft below the tops, and you start to collect ice, you can quickly climb up. If you are 10000ft below the tops and the temperature is -2C and you are collecting ice, you are unlikely to solve it by climbing up (in a non deiced aircraft). Your only options are
In practice one might try climbing up but if there is say 10mm of ice, one’s climb perf is going to be gone already.
If you descend into warm air (OK if there is no terrain down there) then you are not in a better position unless, magically, you find yourself in VMC and can have another go at climbing up. Say you are going UK to Croatia (terminal areas are clear but there is thick IMC enroute) and are forced to descend over Germany. You will then be trapped and forced to land somewhere until the IMC clears up. I would call that a very inconvenient outcome, at best.
If you’re NA and your remaining climb power is something like 100fpm, then you don’t have a lot of options above you.
At 100fpm you are at the official ceiling so, correct, you have zero options above you
I have no problem with IMC over a longer period of time, of course not the convective type
But, how do you know what is ahead if you are in IMC?
My personal record is 30mm of ice in 5 minutes, at 4000ft over SE UK Stall speed rose from 75kt to about 110kt. Very smooth stratus cloud, base 1500ft, tops 4500ft or so. Temp -5C. It was only because I have a de-iced (TKS) prop that I was able to maintain flight (with a slow descent). You take the risk at your peril.
I think deicing equipment is very good for the comfort it provides. I have only used the boots once every 20-30 flights but tend only to be in the relevant temp range briefly on way up and for longer during descent into terminal areas.. Personally in a single I would opt for a turbo if I could and accept there is probably reduced TBO. The climb rate gives you more options and of course makes for faster trips given more time in cruise. But you do need to watch your temps.
I went to Berlin a couple of weeks ago for a short weekend trip with my girlfriend.
We departed in CAVOK and I didn’t bother installing the oxygen system.
Two days later on the way back the weather had changed and there was a weak occluded front on our path.
There was CB activity, so entering IMC was not an option.
Limited to FL100 I had to make a major detour to stay clear of convective clouds.
The cloud tops weren’t that high; it was obvious that if I would be able to climb another 6K feet or so, I could have continued the flight without any issue. Now I had to find my way through a field of TCU, bothering ATC with a lot of heading changes, etc.
Could be a personal thing; but I find flying on FL100 without O2 for a prolonged time tiring and I have a noticeable higher heart rate.
From now on I will not depart abroad anymore without O2 on board. Having O2 gives you much more options, both for IFR routing and for weather avoidance.
There is another factor, which is passenger comfort. My GF simply does not like flying in IMC, so I will try to avoid it during the enroute phase…
Enroute EDAZ – EHLE at FL100 no oxygen, avoiding weather visually:
and I have a noticeable higher heart rate.
Another very good point.
Around 2005 I participated in a group test of about a dozen pilots, where we climbed to FL120 or so, while the heart rate and blood o2 figures were measured by a doctor.
The results were very illuminating. The ground heart rate, say 65 for a healthy individual, would be 100-110 at FL120. There was a huge individual variation too. I was pleased that I was the least affected of the group (about 85/min) but I still get very tired flying without oxygen at say FL100. I have flown with an instructor who could not read the altimeter at FL120.
Oxygen is cheap. It’s one of the cheapest things in flying.
