IFR in VMC with new IMC

[imtaylor]

Recenty got my IMC and part of a PA28 group based in Newcastle. Planning to go down to Chester this week but just nervous now about flying IFR above the clouds. Have little experience of flying in cold conditions and after a mate of mine sent me a "You Tube" vid of the leading edges all whited out, I'm terrified of falling out of the sky or getting caught out by ice and plummeting to the earth!

So, questions are
1. I appreciate it depends on the adiabatic rate etc. but has anyone been "iced" before (and was it slow and steady or fast and terrifying) and presumably, you just declare a "pan" and get down sharpish?

2. Flying IFR this of year generally, do you just simply avoid the clouds as much as possible? If so, what do you do if you ask for vec ILS at your destination which then takes you through clouds?

3. Forecasting cloud tops - is it possible? Other than Synoptic forecast, do you just assume cloud tops are out of your reach - period?

ta v much.

[Fuji Abound]

1. Icing (or the rate of) is difficult to predict with certainty. I recall many years ago asking my mate about icing. He spotted a Cb and headed for it. Very shortly after we entered the screen went completely white and VF was impossible for a short while after we exited. Of course the very light icing melted really quickly but it was a useful demonstration I will always remember. If you have no way to deal with ice (which you dont in a PA28) expect this to happen if you enter icing conditions because while you are watching the wing edges the screen frosting over will come as more of a shock. Icing will of course almost always only occur in cloud so as long as you can get yourself out of cloud (above or below) the ice will usually stop accumulating and will more than likely dissipate (indeed quickly if the outside temperature is above freezing). Minor incurrsions with ice as long as you have an escape route are therefore no cause for a pan but for a quick exit and careful observation. Obvioulsy exposure to ice in cloud with a high mositure content for any length of time is a very dangerous game indeed and one you will rarely win. On a very few occasions conditions can catch you out. Flying last winter in good VFR we were very surprised to find we were accumulating ice quite quickly. Several others reported the same conditions and returned to base. On went the fluid and the "problem" was solved. However it demonstrates it is possible to accumulate ice on a cold airframe when the moisture content in the air is high even though the flight conditions are visual. Such circumstances are however rare.

2. IFR flying is about avoiding the clouds at any time of year . They are wet and bumpy and only really good for giving the aircraft a clean. As I indicated earlier if the temperature is below freezing expect ice - make sure you have an escape route and if you dont, avoid the clouds at all cost. Punching through ice "laden" clouds to VMC on top takes experience which, with all respect, you probably dont yet have. People like IO540 can do this very safely when the conditions suite but with many more hours experience to their credit. On an IAP if you are vectored into cloud and the temperature is below freezing of course you can expect to build up ice. Unless the conditions are extreme it is highly unlikely clouds that close to the surface will be convective or laden with moisture so the rate of accumulation is likely to be very small given the time you will be in cloud. However note my earlier comment that the screen might well frost over. If you are in any doubt for the same reasons the clouds should be avoided. Personally I wouldnt fly if there was significant IMC on the approach with low cloud and freezing conditions to the ground unless the aircraft was de-iced.

3. There is plenty on that subject on here in very recent times - use the search function.

Now do me a favour and read the threads on FCL008 - because sadly you may not have your IMCr for very long so enjoy it while you can. You might even want to express your views on that thread.

[S-Works]

Now do me a favour and read the threads on FCL008 - because sadly you may not have your IMCr for very long so enjoy it while you can. You might even want to express your views on that thread.

Ah yes, because we can see how his extensive IMC training prepared him for the job at hand........

[Radar]

Ah yes, because we can see how his extensive IMC training prepared him for the job at hand...

Ouch .... that's gotta hurt !!!

[ab33t]

Dont even think about it I fly a Malibu extensively throughout Europe and this piece of kit is FIKI certified , I avoid icing like the plaque if I can help it . Get someone with a bit of experience flying and dealing with these conditions . ppp -ppp

[tdbristol]

Some experience of icing and some suggestions:
(a) as others have said, avoid it (by of course avoiding cloud if the temp is below zero).
(b) by all means, ask ATC for a course change if you need it to avoid cloud when the temp is below zero
(c) when planning, ensure that each leg where you may have cloud you also have the ability to stay above MSA and be sure to stay a reasonable amount above zero, i.e. so you can descend from icing conditions into conditions where any ice will melt well
(d) my experience of encountering ice is the first effect is a rapid decrease in airspeed (~10kts), likely due prop icing rather than wing ice (which can be hard to differentiate from cloud moisture on the wing if the icing is light).
(e) the temp in cloud can surprise and drop by a few degrees in seconds, to go from 2C to below zero (even in benign stratus), so keep a good eye on the ASI and OAT gauge and be prepared to ask ATC for a 'descent due icing'. If you are collecting ice DON'T wait to see what happens; DON'T hesitate, get on to ATC straight away. My experience is that ATC react immediately and are entirely willing to accommodate and give you whatever lower level you need (even in busy airspace). You can't wait, but reacting quickly means that light icing doesn't need to be a 'pucker up' moment.

For cloud tops you could look at meteoblue dot com (look at 'Cross section' tab after logging in)

[Fuji Abound]

Ah yes, because we can see how his extensive IMC training prepared him for the job at hand........

Perhaps you would care to enlighten us with your actual ice encounters during your IR training particularly if you undertook this during the summer months danw south. There again maybe your training was in somewhat wilder territory where it is a great deal colder in which case I suspect we will all have something to learn.

[IO540]

1. I appreciate it depends on the adiabatic rate etc. but has anyone been "iced" before (and was it slow and steady or fast and terrifying) and presumably, you just declare a "pan" and get down sharpish?

Airframe icing (as distinct from carb icing which is a very different piece of physics) happens when you fly through supercooled water droplets (which basically requires flight in IMC). These droplets can exist between 0C and about -15C, possibly a bit lower in convective clouds.

I don't think the adiabatic rate is related to this.

The extent to which aircraft performance (wing lift, drag etc, and prop efficiency) is affected depends very much on the aircraft. Old designs tend to be less affected, whereas something like a Cirrus are reportedly strongly affected.

The existence of supercooled water is highly statistical. You could fly along for 10 mins and get not a drop. Next 10 mins, you pick up 5mm (which is usually enough to impact performance). In extremes, in convective cloud especially, you could pick up inches in minutes (freezing rain e.g.). Thin stratus cloud is normally OK for a bit...

Strategy depends on the aircraft deice equipment and varies between pilots, from "never touch IMC below 0C", through "OK to climb/descend through it, but never fly in IMC enroute (that's me; I will climb to FL200 if necessary to stay above rising tops), to pilots who always go (some of whom fly deiced planes) but only occassionally write about it...

2. Flying IFR this of year generally, do you just simply avoid the clouds as much as possible? If so, what do you do if you ask for vec ILS at your destination which then takes you through clouds?

You are descending so should be out of it pretty quick.

But yes, the winter is a problem because on cold days your primary escape route (a descent below the 0C level but without hitting the ground etc) is closed off, and whatever ice you pick up you have to land with. That's the price you pay for not having a jet

3. Forecasting cloud tops - is it possible? Other than Synoptic forecast, do you just assume cloud tops are out of your reach - period?

There are various methods but none are that great. The UK Met Office does not release its 3D model other than to commercial weather repackagers so one has to turn to the U.S. run GFS model e.g. here. You have to use data like Soundings. But tops forecasts are rarely accurate; let's say the tops are forecast for 6000ft, you should assume they could be at 10000. I will scrap flights if the tops are forecast above 16000 because my economical ceiling is 18000 and max is 20000.

Occassionally, especially in a large high pressure area, the tops are accurately forecast, and the layer is very thin e.g. base at 1500ft and top at 2500ft. But usually in those cases you can see blue sky in holes, and then it's obvious.

Generally, in warm front conditions, you can forget it because the tops will be say 25000ft and the climb in icing conditions will be too long/risky unless you have the full deice kit. In those conditions you have a fairly uniform sky colour - indicative of a great thickness. But - frontal conditions aside - most clouds can be climbed through because the layer is so obviously thin.

In practice, in the UK, due to controlled airspace bases, cloud tops are normally too high for VMC on top flight to make sense unless one has an IR.

imtaylor - I will send you an email with more stuff.

[Pace]

Imtaylor

The whole point of icing whether the aircraft is ice capable or not is to get out.

If the aircraft is ice capable you can hang in there longer if its not you cannot.

You basically have two choices in an icing layer. You either climb up where it is too cold for ice to form or you descend to where its too warm for ice to remain as ice ie an altitude below the freezing level.

If you are in a small low powered single you are not going to make a good job of climbing especially if you are carrying ice so your only alternative is to descend into warmer air where ice will melt off.

So that is your guiding rule of thumb! Dont fly in cloud in a single low powered aircraft unless you know that you can descend and melt off the ice while still above terrain.

On your climb out note where the zero degree level is! does that give you a good margin above the highest terrrain. If you know that any ice you pick up will be carried to the ground dont go!

I can remember years ago flying IFR training for the IR. we were in a PA28 having struggled in cloud up to FL80. Both me and the instructor missed the ice build up until I had full power and could not maintain altitude with 70 kts IAS. We asked for a lower level and were cleared to FL60 with the instruction "not below". FL60 came and went as we sailed on down to FL40 powerless before the ice melted off and the aircraft behaved normally.

The hills came up to 2000 feet in that area so imagine had the air been colder and the ice had not melted off

Note the 0 degree level and if its not high enough dont go!

Pace

[IO540]

I normally find the 0C levels being forecast reasonably well - plus or minus 2000ft for sure.

Forecasting tops is much harder.

[Sir Niall Dementia]

I agree with IO540 that the forecast freezing levels are normally very accurate.

From the tone of your first post I gained the impression that you do not feel confident in what you are planning, if so take an instructor with you. If he says its a no-go then take heed and learn from his experience.

Consider the potential weight gain and changes to aerodynamic profile of ice. You may find that sudden, heavy Ice accretions can take you straight over MTOW, aerodynamic surface profiles will change and suddenly your'e a test pilot flying a new type in conditions which are already worrying you.

I can echo Pace's experience, except in my case it was in a Navajo. The met men got the freezing levels wrong as well as the rest of the forecast, I was going into Zurich and ended up putting out a mayday as the aircraft went below MSA with full power and the de-icing boots unable to cope. 500' later I was in the clear with the ice shedding and an awful lot of years added to my age.

Nowadays I fly things which cruise well above icing levels but still get it on climb and descent. the build up tends to be slow and insidious, or very fast and obvious. When flying in my own time if the forecast freezing level is less than 2000' above MSA, with IFR conditions the hangar doors stay shut and the garage doors get opened.

[Johnm]

Rules of thumb are that ice can form in cumulus anytime. In summer likely to be light in winter can be severe. In stratus it's normally much less of an issue. In some cases high humidity without visible moisture on a cold day can cause ice (as mentioned above) again that's not usually too much of an issue.

I've had ice in Cu in May in South West Scotland at 5000 ft, I had ice last week over Cranfield climbing through Cu to FL 070.

The biggest risk by far is below rain cloud with an aircraft below zero. Freezing rain will really spoil your day.

BTW I'm an IMCR holder and would have been asking the same questions soon after my test, experience comes with time

[IO540]

ice can form in cumulus anytime

You still need the OAT (= airframe temp) to be below 0C.

I tend to find that if cruising in sunshine and the OAT is say +1, immediately upon entering cloud it drops by about 3 degC i.e. to -2.

So on comes the prop TKS, before entering any such IMC (I have prop only, not the full kit).

The actual flying strategy depends somewhat on whether one is flying on an IR, or (below CAS / OCAS generally) on the IMCR. The IMCR strategy is simpler - is the 0C level below the MSA? The IR implies high altitude flight and the strategy is very different.

That is the cautious approach. There are individuals who "just go". This "usually" works because most of the time there is very little ice IMHO this is not the way to do it.

The impact of various levels of caution on the despatch rate is significant. I might do 75% (with pure legal VFR it might be 25%, on a long trip of say 700nm), and with a seriously deiced plane equipped with radar one might achieve 98% or more. Once I was at Biarritz and some jets departed for Spain, and came back half an hour later saying they could not penetrate the weather...

[imtaylor]

Thanks for the (mostly) helpful comments.

My views on the IMCr are irrelevant really but sufficed to say, I have my own opinions which some won't agree with. What will be, will be and I'll decide what to do if and when changes are made. There is little that I can do to change FCL008's views or opinions and they will make whatever decision they think appropriate, even if I disagree.

When I fly, i am extremely cautious and careful and I never take any chances. Contrary to (some) IR holder's opinions, I am not some half-wit, who ventures out into IMC at the drop of a hat, thinking that i am invincible - and I never intend to.

thanks.

[IO540]

FCL008 is just a committee.

EASA committees draw up proposals. Normally each member signs an NDA so nothing gets out. They don't make law. The proposal later goes for a comment period. Then somebody higher up in EASA looks at what (if anything) to do with it.

[Fuji Abound]

Based entirely on what I have seen so far something square, made out of metal, and usually kept in a corner comes to mind for some of it.

The only trouble is they would probably want to recyle it.

Who knows it might be more useful the second time around.

imtaylor

Dont take Bose too seriously he has some issues with this stuff.

However, your views really do matter. I know, I know no one turns out to vote any more because they think it is a waste of time - they are all the same, but it matters that we try and influence policy. After all it doesnt take long to punch out a letter. Its called democracy - and unfortunately it is the best we have.

[Pace]

Imtaylor

There is a lovely saying " If you dont push the limits you will never find what lies beyond ". Dont take that literally especially with flying but there are times when you need to be at the edge of your comfort zone to gain experience.

It is only by being in icing conditions inadvertantly or otherwise that you will get to appreciate and respect icing.

I flew with an old ferry pilot who could literally smell icing. He knew where it would be and knew where to go to get out of it.

I have had many encounters with ice and have to say that it scares me.

I have placed this in the forum before but it was the most bizarre and unusual icing situation that happened to me flying a Seneca Five twin to Inverness several years ago.

I was airways and knew there was a cold front with a wall of embedded CBs running west to east across the north of Scotland.

I knew to get any chance of finding a gap through I had to eyeball the wall.

I climbed to try and stay on top of the lower stuff. Fl100, Fl120, the screen was covered, I was working the boots and had the prop anti ice on.

FL130 I struggled on top. There was a shuuder through the airframe.
Three electric cables to the left angine prop deice had sheared meaning that side wasnt clearing.

The Seneca five has counter rotating props. Next second a huge chunk of ice flew from the left prop right across the nose and struck the right prop bending the tip.

In turn the right prop threw the ice block into the side of the nose punturing a hole. The block then came back into the screen smashing into a snow storm of a million fragments.

With the speed of the aircraft the left prop must have projected the ice at one heck of an angle forward for it to come back and hit the right prop.

I found a hole through the CB wall and landed at Inverness.
Unlikely but true. The one prop was replaced and the aircraft still bears the repair job to the nose.

That is icing for you! so beware. Step into the clouds bit by bit and learn

Pace

[Brooklands]

I normally find the 0C levels being forecast reasonably well - plus or minus 2000ft for sure.

IO, did you really mean two thousand feet? It doesn't seem that accurate to me.

Brooklands

[bookworm]

Rules of thumb are that ice can form in cumulus anytime. In summer likely to be light in winter can be severe.

Not sure where that comes from. My impression is that there's a lot more ice around in summer, it's just higher up. The higher absolute humidity and greater vertical extent of cu in summer tend to create more problems. May and June tend to be worst, with greatest instability.

In stratus it's normally much less of an issue.

That's certainly true, though stratiform cloud can still catch you out. Last January I descended from clear blue into a flat layer of SC between about 2500 and 4500 ft. At 5000 ft the temperatures were positive, so I blithely assumed the SC would be ice-free. ATC stopped my descent at 4000 ft, the temp fell to -2 degC and the ice went on faster than I can remember in stratiform cloud. No emergency, particularly with boots and prop-deice, but it certainly got the attention!

[IO540]

Pace - sounds like you have been involved in some serious "boundary pushing" operations

I have come across commercial pilots; "commercial" in the sense that they got paid for flying, and would have been sacked if they refused due weather, and they had a real can-do attitude. But they also had planes with rubber boots which should cope with a reasonable amount of ice.

A lot of pilots are fools who take off without any plan, and some get themselves into real trouble. One even wrote about it on an open forum; the original posting (commented on here - not all the comments make sense but his original story is there) even includes a photo taken after he landed, showing what must have been several inches of ice on the leading edge. That was a TB20 - very similar to what I fly. I am suprised he didn't get busted by the FAA because his flight plan would have taken him above the mandatory oxygen level and he didn't have oxygen (another stupid aspect).

IMHO ice is not anything to be afraid of. One just needs a clear strategy, and an escape route e.g. if the terrain is 14k (mountains), the 0C level is forecast for 10k, then you don't go unless VMC is assured and you will have enough fuel at all times to turn back and reach an airport which can be descended to in warm air.

Brooklands - yes I reckon temps aloft are reasonably forecast - at least for the purpose of the strategy which I am suggesting. If however one accepts a flight whose long (say hours) enroute section is in IMC then one needs to be more careful, and IMHO have a de-iced plane.

Imagine yourself flying along, NON de-iced, at say FL150, terrain at FL100, 0C probably FL080, with an aircraft ceiling of say FL180 (a typical non turbocharged figure), and looming in front of you is a solid wall of IMC (a front, or clouds caused by an updraught up a mountain) rising to maybe FL250. Whether to proceed or turn back is what separates the brave from the smart, IMHO