SE IR during winter time and icing conditons

[deice]

IO540, as you say, we're not planning on loafing around in icing conditions, nobody does that with their head stuck on, and I'm rather sure the DA42 will pull through clouds with equal enthusiasm as the TB. The key point is you shouldn't launch into a known icing condition if you don't have gear for it, and the aircraft is approved. I believe the AFM details that, but as you most certainly know FIKI does not mean you're immune to ice, and yes the TKS system is anti-ice. Regardless, it works if you use it sensibly whereas if you have nothing you also have no options. And, you're still not legal. But then, breaking the regs seems to be standard procedure on many occasions..

[soay]

Originally Posted by A and C

A thin object will (all other factors being the same) pick up ice faster than a thicker object.

and

Originally Posted by Fuji Abound

Yes, but doesn't ice start to form far more quickly on imperfections in the surface - so the build up will start around joints between the aluminium sheet, flat rivet heards etc.

Because composite wings have smooth surfaces, they can be designed to take advantage of the effects of laminar flow. Rivetted metal wings generally don't, so have a thicker chord to compensate.

This NASA publication concludes that "In the laminar region of an airfoil, roughness [due to heavy rain, ice, and frost accretion] interferes with smooth flow and tends to encourage transition from laminar to turbulent flow upstream of its normal point of occurrence. In the airfoil's turbulent region, roughness considerably worsens the turbulent friction coefficient, thereby increasing the drag coefficient. Consequent dramatic decreases of maximum lift coefficient at high angles of attack lead to premature stall. Such decreases in stall angle destroy the safety margin of an aircraft approaching stall."

Even an accumulation of dead flies can slow down an SR22 or a DA40, because of the need to increase the angle of attack to compensate for the loss of lift.

[DFC]

deice,

I can see your point.

However, fly in level flight at FL70 in stratus with OAT-5 on a certain day and you don't get ice. Do it again the next day (or even a few hours later) and you pick up ice.

Ice is so unpredictable that unless the previous pilot has reported ice at your level recently then there is very little to go on. Most icing forecasts are based on the probability of icing being in any cloud at sub zero temperatures and the fact that icing in convective situations is more serious i.e. cu family and over rising terrain.

So in your aircraft that is not approved for flight in icing conditions, you can indeed stay on the ground or limit yourself to VMC below cloud flying. However, you will find that you will cancel many flights that could have been safely completed.

If you are flying in visible moisture and you start picking up ice, the only answer is to exit icing straight away. The question is do you go up or go down. Icing is normally found in 3000ft bands so if you are 1000ft into the band when you see ice forming, is it quicker to climb above or descend below the icing layer?

You would only be illegal if you had to descend below MSA to clear the ice or you remained in icing conditions i.e. you continue to pick up ice.

Most IR candidates will be familiar with the pre-takeoff brief that they give the examminer. It goes along the lines of;

..........If we encounter icing conditions I will climb above or descend below icing but not below MSA and then decide to continue or divert............

The IR test is asumed to be in icing conditions and many people manage to pass in aircraft with no approval for icing conditions because they will comply with the above statement.

As soon as IMC is simulated on the test i.e. at 300ft the first thing the candidate is expected to say is "icing check".

Unfortunately, airframe icing is often glossed over on the IMC course and thus there is a widespread misunderstanding.

Complete the NASA course I gave the link to above and while it is designed for people who fly aircraft which are approved for flight in icing conditions, it is useful for everyone.

Finally note that most light twins are only approved for flight in light icing conditions. Light icing is defined as;

“Light — The rate of accumulation may create a problem
if flight is prolonged in this environment (over one hour).
Occasional use of deicing/anti-icing equipment removes/
prevents accumulation. It does not present a problem if
the deicing/anti-icing equipment is used;

Regards,

DFC

[whitehorse]

Complete the NASA course I gave the link to above and while it is designed for people who fly aircraft which are approved for flight in icing conditions, it is useful for everyone.

Couldn't agree more with DFC

[S-Works]

And for once even I agree with him.

[deice]

Me too! All good points here I think.

My personal issue with ice and flying aircraft without equipment stems from the fact that it is so unpredictable, as we all attest to. I've heard countless statements of how much ice a PA28 or C172 can handle yet we see deiced aircraft tumble out of the sky from time to time. It isn't to be taken lightly and as an instructor I don't want to give newbies the wrong idea.
I know people who do all kinds of weird things in aviation and survive, but it's not so intelligent to sanction these actions - they are dangerous, and flying in ice is too.

So, as a last word from my part, please consider what you do, and consider who you tell about it.

[IO540]

we see deiced aircraft tumble out of the sky from time to time
Do you have references for accidents where icing resulted in loss of control, in any aircraft whether KI or not?

I know there are some where the pilot said so but out of the vast piles of NTSB AAIB etc reports there are very very few.

[S-Works]

deice, and as an Instructor I disagree with you, we have a duty to present the facts not old wives tales.

[bookworm]

I've heard countless statements of how much ice a PA28 or C172 can handle yet we see deiced aircraft tumble out of the sky from time to time.

Can you give any examples of this? The SHK website has its reports online, so perhaps we can learn something. I've struggled to find many reports of accidents involving airframe icing in the UK. There was N8174V a couple of years ago, which I think it would be fair to say was not the pilot's smartest flight. Any others?

[deice]

There was one a couple years ago wih a Caravan in Finland, although it was probably a combination of ice and bad loading.
You should check the Caravan pilots website, there are a number of accounts there as I recall. The problem may be that if you come down due to ice, and temps are above zero on the ground the evidence is gone... An SR22 went down in the US after accumulating ice and didn't get the chute out, last year or year before that I believe.
I know I've read these reports, but I don't have any links to them that I can add, but the US NTSB and Swedish accident board (www.havkom.se) present some facts. I'll go digging again.
What's this about old wives tales? You haven't met some of the pilots I have! I know of a number (VFR only pilots) that climb through cloud without IFR clearance in uncontrolled airspace and fail to see the hazards as in IFR traffic heading the opposite direction. They seem to think that if ATC doesn't know they're there and breaking the regs then they're ok.
These same persons would gladly take off into an overcast to see how much ice they might pick up. Stupid. Why would I want to tell them how much ice a PA28 can handle? I have no idea, and I'm pretty sure you don't either. If you do, please contact NASA and have them employ you as their expert.
Yes I've had an inch of ice on a warrior, and I feel stupid for doing it.
I've had the same on the Seneca knowing what I was up against. It's different. Knowing how to handle ice with de-ice or anti-ice equipment is part of the trade, knowing when not to fly in non-equipped aircraft is the same, as I point out to my students. But that's just me.
Please keep up with your work and train them as you like.

[Fuji Abound]

Can you give any examples of this?

I think if you look at the NTSB reports you might find more than a few.

You know how few private pilots are qualified in Europe to fly IFR. Given the small numbers doing it, and their experience levels, I would guess that is one reason for less icing accident here rather than there.

[S-Works]

What's this about old wives tales? You haven't met some of the pilots I have! I know of a number (VFR only pilots) that climb through cloud without IFR clearance in uncontrolled airspace and fail to see the hazards as in IFR traffic heading the opposite direction. They seem to think that if ATC doesn't know they're there and breaking the regs then they're ok.

Which just proves my point.......


You have presented NO evidence that a properly prepared pilot is capable of safe flight through icing conditions. You have just proved that those who are stupid are capable of getting themselves into trouble.

[bookworm]

I think if you look at the NTSB reports you might find more than a few.

You're right. The first one I found was an SR20 that flew (or tried to fly) across the Rockies with scattered embedded TS. It's fairly typical. Interestingly, most of the accidents occurred above 10,000 ft over mountains.

I was a bit amused by the second. It starts

"The flight crew, an airline transport certificated captain, and a commercial certificated co-pilot, were flying a restricted category, icing research equipped airplane in instrument meteorological icing conditions under Title 14, CFR Part 91. The purpose of the flight was to locate icing conditions for a prototype helicopter's in-flight icing tests. While in cruise flight, the airplane encountered icing conditions, and had accumulated about 1" of ice on the leading edges of the wings. The captain reported that he activated the wing deicing pneumatic boots, and the ice was shed from both wings. About 4 minutes after activating the deice boots, both engines simultaneously lost all power. The crew attempted several engine restarts, but were unsuccessful, and made a forced landing on frozen, snow-covered terrain."

[IO540]

Well now that we are trawling the internet looking for the biggest possible mugs who somehow managed to get a PPL I could tell you some stories I've read in certain places. They got deleted very quickly afterwards when somebody pointed out that (to give one example) the FAA mandates oxygen above 12500ft but this man was flying at 14000+ for much longer than the 30 mins max while obviously suffering hypoxia because he had totally lost it mentally and he stuck his arm out of the little LH ventilation window and tried to scrape the ice off his wing with his bare fingers until they were bleeding. That one (a non deiced SEP of a type I know quite well) actually landed OK, with several inches of ice still remaining. I believe the pilot (a public performer in the music business) gave up aviation after that.

There is no shortage of total mugs, and some are bound to get into a plane eventually. This must not be confused with a dispassionate discussion of risk factors etc.

although it was probably a combination of ice and bad loading

well there you go... bad loading! I wouldn't like to guess how much ice a Caravan can carry but it's a helluva lot more than even an Aztec.

The thing which concerns me more is fuel icing. This does happen on some types at OAT below about -25C. I have never found any report of it happening on a TB20/TB21 though. This would be a disaster because the engine stops and absolutely will not restart until you are back in warm air. I recently met a twin (KI) pilot who lost both engines over the N Sea at FL250, and didn't restart until down to 2000ft. He sold the plane immediately and bought something a bit bigger but more importantly something that burns avtur. One can get additives for avgas for this but there isn't much data on how different types are affected.

[Fuji Abound]

The airplane was substantially damaged during an in-flight collision with terrain following an inadvertent stall on short final. The pilot reported that the instrument flight rules (IFR) flight had initially been operating above a broken to overcast cloud layer. However, about the mid-point of the trip the flight encountered instrument meteorological conditions (IMC) and light rime ice. The pilot stated that he requested a higher altitude in an attempt to avoid the icing conditions, but air traffic control cleared him to a lower altitude due to the flight's proximity to its intended destination. The flight remained in IMC as it was vectored for an instrument approach. At the missed approach point, the pilot did not have the airport in sight due ground snow cover and his unfamiliarity with the area. He executed a missed approach. While being provided with radar vectors for another approach, the pilot obtained visual contact with the airport. When he entered visual flight rules (VFR) conditions, he cancelled the IFR flight plan and entered a traffic pattern for runway 36. The pilot reported that on short final the airplane drifted left of the runway centerline. He applied a little power in an attempt to get re-aligned. The pilot stated: "The aircraft started rolling left. I applied full power and attempted to abort my landing. The aircraft engine responded but we completely rolled until inverted and subsequently made contact with the ground." In a follow-up interview, the pilot stated that the aircraft had accumulated rime ice along the leading edges of the wings. An AIRMET for occasional moderate rime or mixed icing below 10,000 feet mean sea level was in effect at the time of the flight. A certified re-recording of the weather briefing was provided to the NTSB. During the briefing, the pilot was informed of the AIRMET and of a pilot report of light rime ice along his route of flight. The pilot had received his instrument rating seven weeks prior to the accident. He reported 2.5 hours of actual instrument flight time and minimal experience with in-flight icing conditions. Federal Aviation Administration publications state that ice formation on an aircraft's flight surfaces may adversely affect performance and control. They note that with ice accretion an "aerodynamic stall may occur with little or none of the usual cues in advance of the stall or at the occurrence of stall."

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

The pilot's continued flight into icing conditions resulting in ice accretion on the wing and his failure to maintain airspeed resulting in a stall.

Since we are all trawling that one took 5 minutes to find.

I suppose the problem with any encounter with ice that goes horribly wrong is the pilot will be considered negligent.

For those who fly regularly in the winter in IMC may by the grace of God or by the level of their skill none of us make such a mis judgement.

[deice]

You have presented NO evidence that a properly prepared pilot is capable of safe flight through icing conditions. You have just proved that those who are stupid are capable of getting themselves into trouble.


OK? Bose-X, I'm not following you. I never said a properly prepared pilot could do that. I was trying to say we shouldn't and especially not without the gear for it. I think there are others here who say they can and do because they know how to. But it seems I am the only one who believes limitations in an AFM are meant to be followed, as well as regulations.
I'm not sure I understand what you mean. What old wives tales are you referring to and are you suggesting that I should tell my students that they can climb through an ice condition with their PA28 provided they're not stupid enough to do it?

[IO540]

I don't know what plane type that was Fuji but I bet that IF icing had anything whatsoever to do with it (for which there is actually zero evidence - apart from the pilot's belief - in that quote) it would have needed more than "light rime ice" to cause the behaviour described, ending in inverted flight.

[deice]

What's your suggestion to the cause then IO540? It seems ice is not on your plate of plausible accident causes, regardless what anyone says.

[DFC]

Ever heard of asymetrical ice shedding?

There is one simple issue. If you know that icing conditions exist ahead (ice adhering to and remaining on the airframe). Then unless the aircraft is approved you avoid those conditions in advance.

There will be few occasions that one knows about ising conditions ahead. There may be posibilities or probabilities but that is different.

If you are ever flying a non approved aircraft (regardless of equipment) in icing conditions that you knew where there then please put on your stupid hat.

There are plenty of icing incidents.

Try searching for the UK ATP crew that suffered tail stall due ice.

Most icing incidents happen to commercial pilots. Just do a google search on "light icing" to get a few good ones.

Regards,

DFC

[Fuji Abound]

I always wondered why they called them Turkeys in the Sates until some one in Florida told me they are as commom as .. .. .. never been sure whether that was the correct explantion

any way it was a Turkey - or to us a PA28.