Would you buy a twin without anti-ice?

[fltcom]

There seems to be mixed opinions on this subject, and a fair number of twins only have hot props and not much else.

Comments pls....1

Flt

[IO540]

Depends on the climb rate i.e. power versus weight, and operating ceiling.

If it can climb at 3000fpm, and has TKS props, and can climb at that rate all the way to say 20k feet, it won't get a chance to pick up much ice. You just need to avoid doing this in CBs etc :O

For most practical planes that would tend to imply turboprop engines though and most of those are pressurised for marketing reasons.

[flyboyike]

Given the choice, I'd prefer anti-ice, but there are many other factors when buying a twin, or buying any airplane really.

[Croqueteer]

:= IO540. So wrong. You can pick up heavy icing at any level regardless of rate of climb. I did my initial commercial work on Aztecs in the early 70s and if you want to fly regular IMC in UK you need 2 engines, an IR and ice protection airframe and prop, and most de-iced twins are certified for light icing only. You must take icing seriously.

[IO540]

Croqueteer

You should not pick up "heavy ice" in stratus clouds. If you do then you have wondered into something a lot stronger. One has to look at the weather before flying.

I've climbed through 5000ft or so of stratus many times and have usually picked up a few mm of rime, occassionally nothing at all. I have a TKS prop which maintains power regardless of ice but that doesn't help with the airframe.

I suppose you would say the only proper way to fly is a jet with weather radar, and that nobody should venture into IMC below 0C with anything less, and totally pedantically you would be right. But that doesn't exactly broaden somebody's understanding of these issues as they affect flight planning.

Your comment about needing 2 engines for flight in IMC is interesting. Can you please explain the physics involved? I am always willing to learn something new.

If you make a "serious" post you ought to explain the reasoning. Brief posts like this help nobody to learn anything.

[FlyingForFun]

Surely the answer to your question depends on what you're going to use your new twin for? If you're planning on doing serious touring around the UK, then I would say de-icing is pretty much essential.

On the other hand, if you're thinking about basing your aircraft in Africa, or only flying in VMC (but maybe you want a second engine for more peace of mind over water or at night), or you are buying the aircraft for a flying school which will do initial multi-engine ratings predominantly in VMC, then de-icing is overkill.

There are probably in infinite number of situations in between, too. I know of pilots with PPL/IRs or very current PPL/IMCs who have de-iced twins, but are sufficiently wary of ice to want to drive rather than fly if icing is forecast. It's not a view I subscribe to, as long as the aircraft is suitably equipped, but it's their right to have this point of view. For these people, de-icing is probably overkill, but maybe they prefer to spend the money for peace of mind in case they find themselves in a situation where they need it.

More information needed!

FFF
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[Croqueteer]

Bit of a clever answer, IO540. Watch you don't become a statistic.

[Ni Thomas]

:=.....and if you want to fly regular IMC in UK you need 2 engines, an IR and ice protection airframe and prop,...... You must take icing seriously.
I fly IMC in the UK, very regularly. Have done for the last 22 years - With only one engine and no deicing - I take icing seriously and I'm not a statistic..... so please, no generalities :ugh:

[Croqueteer]

You have accepted the risk that if the clag is on the ground, in the event of your one engine failing you have little chance of survival. You certainly can have heavy icing including freezing rain below 10000ft in the UK. I am only interested in cutting the casualty count. I will say no more on the subject. (Good, do I hear you say?)

[S-Works]

yep.......:cool:

[IO540]

Croqueteer

You have accepted the risk that if the clag is on the ground

Who mentioned flight when IMC is all the way to ground? That's a flight planning issue, which works against a single engine plane, but it's very rare.

can have heavy icing including freezing rain below 10000ft in the UK

Possible, in stratus cloud which is what I said, but not very likely?

Freezing rain occurs when snow falls through a warmer layer and melts.

No aircraft is certified for flight in freezing rain, AFAIK.

The standard escape route for all icing conditions is a descent into warmer air below - another flight planning issue: make sure 0C is above the MSA. A good escape route from freezing rain would be an immediate 180.

You are automatically assuming that every pilot is an idiot.

[S-Works]

Actually IO I think it is more like he is assuming that the "lesser mortal" private pilot is an idiot.

Holding a CPL automatically makes you a better pilot......... At least that's what I have been told all the way through the exams.....

Mind you how about the Instructor at a large airfield who recently cancelled a lesson on a perfect VFR day because the AI was US and she did not know how to gauge steep turns...........

[foxmoth]

Mind you how about the Instructor at a large airfield who recently cancelled a lesson on a perfect VFR day because the AI was US and she did not know how to gauge steep turns...........

Might be a reason not to do the steep turn exercise (not in my book - but some might consider the demo to the stude requires it!) but given wx conditions in the UK an instructor should be capable of some flexability and gone on to another lesson - eg. PFLs, or even start the Nav.:rolleyes:

[S-Works]

anyone who cant do a steep turn ny looking out the window should not be flying an aircraft. An instructor who cant do it is just a lost cause.

[High Wing Drifter]

anyone who cant do a steep turn ny looking out the window should not be flying an aircraft. An instructor who cant do it is just a lost cause.
I suspect this has more to do with the impracticality of teaching steep turns without an AI.

[S-Works]

good god, what are you on about? How do you think pilots of aircraft without AI's manage to learn?

There is no requirement to have an AI to learn a steep turn, thats what the window is there for!

I am the first to campaign for the use of gadets but attitude with reference to the outside world is fundamental to basic flying skills.

[Sleeve Wing]

Freezing rain occurs when snow falls through a warmer layer and melts.


Actually not quite right,IO540.
Freezing rain, causing translucent rime icing (the dangerous one), occurs when supercooled water droplets fall from a warm sector of a depression through the warm front into the cold sector. In winter, the temperature of the cold sector could well be below zero.
Thus aforesaid supercooled droplets impinge on freezing airframe, freeze on impact (the proportion flowing back and freezing dependent on the actual temp. below zero) and the aircraft is now heavier with a wing displaying much-adjusted lift characteristics.

[IO540]

Not quite what the NASA airframe icing courses say but I won't argue with your JAA ATPL met theory; my IR came on the back of a fag packet :O

I think you are describing more conventional icing.

Here's some light reading:

http://aircrafticing.grc.nasa.gov/courses.html

http://gltrs.grc.nasa.gov/reports/2000/TM-2000-210058.pdf

and finally, put q23g763mxxn3knp8.pdf into google (sorry the URL looks a bit weird)

[Irish Steve]

I remember leaving Dublin in relatively clear weather, heading for EXT in a very nice little PA39 that was my regular transport around the place. After nearly an hour at 6000 Ft above a layer, it was time to head down for the landing at EXT. Snag was, as I was coming down into the layer, it was rising big time under the influence of the granite of Devon, with a freezing layer at 2400 Ft. I'd been cleared to 2900 Ft due to terrain, and discovered very rapidly that 2900 Ft with a nice cold airframe and a layer that was rising rapidly due to the terrain was not a nice place to be.

In the space of less than 5 minutes, I'd lost about 15 Kts, and it was clear that there was more than a light layer of ice around the place, and that was with the de ice boots running, and the prop anti ice alcohol running.

A short conversation with ATC resolved the problem, in less than another 2 minutes, I was able to descend below the freezing level, and dropped out of the bottom of the layer into clear air, so the icing stopped. My alternative, and the decision would not have waited much longer, was to attempt to get back above the worst of the icing, and do a quick and dirty duck down from above much later in the approach.

There was still ice on the airframe some 10 minutes later when I landed.

That was with anti icing on the aircraft, and it was operational, and shedding ice, but it was building up faster than the anti ice was getting rid of it, on a day when it was just above freezing on the ground, and not particularly bad as such.

So, if you can get an aircraft with anti ice, and it's working, then I reckon that you might find one day that it's been worth having it there and keeping it servicable, if you're planning to fly IMC in the winter months over terrain that can encourage rapid lift of the cloud. If you're not planning IMC, and not doing a lot of winter flying, then it might not be as important. I wanted to be able to travel regularly, and so the anti ice was a useful comfort factor. I probably only used it in anger on 3 or 4 flights over a 2 year period, but on those 3 or 4 occasions, I was happy it was there.

[IO540]

Assuming we are talking unpressurised here, much depends on your attitude to oxygen.

Many pilots don't use it, despite flying at FL100-120 which is practically necessary if flying IFR (airways) routes around Europe.

Unfortunately, the 0C level can easily be at FL100 at any time of the year, in northern Europe. So the season doesn't really come into it. Additionally, winter cloud tops are likely to be lower than summer ones, so the risk of being stuck in IMC at FL100-120 is greater in the summer than in the winter.

But if you carry oxygen and enough of it (most planes with fitted oxygen, or with portable kits) have oxygen duration much shorter than their fuel endurance, especially with 3-4 people aboard) then FL140-FL160 becomes easily feasible in any half-decent tourer, even if not turbocharged (standard low-end Cessna/Piper types excepted).

Then, the idea is to climb into VMC and sit there. The question then becomes how fast one can make the transition, and how much data one can find on the cloud conditions before going.

Personally, I have no experience of flying types with rubber boots but have always found my TKS prop to be perfectly sufficient for the above strategy. However, I qualify that by saying I would not fly in IMC through a front, and would not consider flight with actual or forecast CBs unless VMC conditions were guaranteed (either by being below the cloudbase but above MSA, or by being VMC on top) during the entire route section.

I think, if you want a plane which can go anywhere without having to worry too much, which can climb through 15000ft of known or probable ice, you need to buy a big jet. A 747 would do nicely, I am sure, and you can pick up old ones for under £1M. But even then there are potential issues with de-ice. Anywhere below that, one has to look at the whole picture and there will be missions which have to be scrapped.

A turboprop with all-over TKS should be very capable with regard to icing but that isn't anywhere near the original question which was, I assume, how usable is a cheap old twin without de-ice.

[fltcom]

Now were back on thread - these are the answers I am looking for

Flt