Winter Flying

[Johnm]

The start point is zero ice on the flying surfaces and windows before you taxi. Use a proper de-icer and don't attempt to scrape it off with credit card or similar as it won't work and will do damage. Don't simply rely on fuel drain tests to ensure no water in the fuel, 'cos the water may well be lumps of ice! Make sure that you are reasonably confident that there was no ingress into the tanks while the aircraft was standing.

While taxiing (ESPECIALLY on grass) make sure that you use carb heat extensively, but don't leave it on for take off.

As a new PPL you won't be flying through clouds but you might have to fly through visible precipitation and you may pick up a bit of ice. If you do, don't panic but be sure to add a few knots to approach speed until over the threshold if it's still there at low altitude.

Those really cold gin clear days when the air is smooth and you can see for miles and aircraft performance is at its best are a delight for pilots, enjoy!

[mm_flynn]

I know many readers already know this, but for the benefit of the OP...

It is important to understand there are two totally separate icing issues under discussion and they effect performance very differently

1 - Airframe icing collected inflight

• Usually involves only the leading edge of the airfoil and windshields
• Increases stall speed due to extra weight
• Increases/changes stall characteristics due to changing airfoil shape
• May result in an airfoil that is 'unflyable' if you make a configuration change (like extending flaps)

2 - Frost collected when parked.

• Usually involves the whole upper surface of the airfoils
• Acts by increasing friction (which contrary to an earlier post is actually true). A small degree of roughness on the wing surface can substantially slow the circulation of air above the wing.
• Has negligable effect on weight
• Can have a dramatic effect on lift due to the reduced circulation discussed above (which is the fundamental physical aspect of lift)

1 - Can be addressed with deicing/anti-icing kit, descent into warmer air.

2 - Can only be addressed with preflight clearing of ice.

The way 2 seems to kill people is, you rotate slightly above normal, climb in ground effect, stop climbing due to reduced circulation, pull pack to increase climb rate, Stall/Spin into the ground.

This does seem to be more common on modern airfoils and even two turbines pushing you sometimes results in the above.

[goldeneaglepilot]

Totally agree with the above post, a sad lesson can be learnt from reading the AAIB report for the crash of N90AG at Birmingham in 2002. Part of the report says:

During the morning, other witnesses stated that they had seen frost or ice on the wing surfaces of N90AG prior to departure.
Other aircraft, which had been parked overnight, were de-iced during the morning, with associated reports of moderate to severe ice or frost accumulations. Neither crew member requested de-icing, so N90AG was not de-iced prior to departure.

Sadly 5 people died due to the surfaces not being cleared.

[Rod1]

tomboo

There are a lot of people who will try to help you but more info would be useful! You have been given post after post on deicing but for all we know you fly an aircraft kept in a hangar. What sort of thing do you fly and from what sort of airfield?

If you want to keep the exact location secret fine, but give us a clue…

Rod1

[Francis Frogbound]

Rod1 and PilotDAR; very very good points.

I love winter flying, but it needs to be treated with great respect, after the Birmingham crash our simulator instructors came up with a demo on what it would be like on the jets we fly and it was not fun.

On my own aircraft (PA32) I use a soft brush on all surfaces and fluid on anything that won't clear by brush. A phenomenon I have seen is light ice left around the cowling/cabin area which melted in the heat from the engine/cabin and then ran back as water to the tail to create clear ice.

I have seen the anti-balance tab on a PA34 ice up and cause a nose up pitch moment. Finally I once flew a PA28 into unforecast ice in a hold (during ATPL training) the aircraft took up the charactersitics of a shot duck and came down no matter what either me, or the instructor did.

Watch how a large commercial aircraft is de-iced sometime, the flying surfaces are cleared with hot fluid and as far as possible the whole fuselage is cleared as well. Ice weighs a lot and taking off at MTOW with a couple of mil on the fuselage would put you over weight, outside of flight envelope limits with all the possible ramifications.Ice changes the shape and weight of an aircraft and means that you are flying an unknown quantity, that is the field of test pilots and best left to the likes of PilotDAR.

FF

[robin]

My aircraft is hangared so ice is not usually the worst problem. That is trying to get it started in very cold conditions like we had over the past 2 winters.

The danger is in over-priming when starting and I've seen a number of engine fires resulting from when pilots crank and pump the throttle vigorously.

[Francis Frogbound]

Robin;

When I bought my aircraft the previous owner threw in a PowerVamp external power unit. It is an absolute life saver in winter, charge it at home, keep it warm and take it to the airfield with you.

FF

[peterh337]

Finally I once flew a PA28 into unforecast ice in a hold

How do you forecast ice?

[proudprivate]

How do you forecast ice?

When there is (visible) moisture in below freezing temperatures.

Unforecast ice is when you are flying in the clouds (e.g. during a hold) and the temperature is lower than forecast; or when you fly high up in known sub-zero temperatures and you encounter an unforecasted cloud layer.

You are not allowed to fly into "forecast ice", i.e. into conditions you know will create icing, in an aircraft not equipped to deal with it as per POH.

[Fuji Abound]

Yes. This to me is one of the few, but major problems with PPRuNe. The "P" does stand for professional, does it not?

It does, but few on this forum are "professionals" in the sense they make a living from flying, and few are "professionals" in the sense that they have enough experience to stand apart from the majority who are relatively low hours PPLs. Please, that is not meant in a condescending way, it is a statement of fact.

There is not a professional who does not change his attitude to his profession with experience. That rubs both ways - some start off cavalier, get away with it, and become more restrained, others "go by the book" when they start out, but with time take a few "risks".

Ah, I hear some say, a professional should never take risks. If you are in the first group I hear your voice louder than most, beause that is what the non risk takers would say.

However, lets for one moment be realistic. There is risk taking and there is using your best judgement.

I recall the first time I "saw" ice. My mate was a BA training captain , ex RAF fast jet instructor - enough pedigree for me. I said I had never experienced ice and wondered what it was all about. A smile hovered on the edges of his lips as he said "I have control". We headed for a small (and I mean small) CB, and literally as we entered the cloud the windscreen frozen over completely. We reamined in the cloud for a short while but long enough to accumulate a reasonable amount of rim on the wings. Out we came into bright sunshine and within a very short time the windscreen cleared and the ice vanished. It was a very good lesson for a yound and very inexperienced pilot.

So whats my point.

Ice is dangerous - very dangerous, and best avoided at all cost. However, if you fly often and if you fly in more challenging IMC conditions you will encounter ice - not you might, you will. You might even encoutner ice in VMC. I recall a flight last year at night in very good VMC. It was below freezing down to the gorund and the air had been very humid during the day. As we departed en route there were half a dozen aircraft in the area - they all reported icing and not being deiced returned. I was fly a deiced twin and we also started to accumulate a surprising amount of ice.

So coming back to the "P" and the opening post - its your first winter season. Treat winter flying with the up most caution - make sure you depart with a clean airframe and dont fly IMC (I am guessing you dont have an IMCr or IR anyway). The usual rule of avoiding IMC conditions at all costs remains as sound as ever. Leaving aside the exceptional conditions I recounted earlier you will not accumulate ice in good VMC. As to the "P" when you have your IMCr or IR you will need a good understanding of icing and you will encounter icing at some time however careful you are unless you dont use your rating in earnest. You will learn what to do, when to do it and how far you can "push" the limits - or you will kill yourself. Simple really. Best you learn slowly by experience with others who have been there and done it than by yourself. Being a professional means above all else knowing how to deal with the unexpected and knowing when the right thing to do is get the hell out and when the safe thing to do is something else.

So it is easy to say never fly a non deiced aircraft in icing conditions but if you have an instrument rating and fly IFR you will unexpectedly encounter ice and you will have to deal with it.

[Fuji Abound]

Proudpilot - I think you will find IO540s question was a little tongue in cheek - if you will reflect we know that if there is visible moisture in below freezing conditions then that COULD cause icing - however that is not a forecast it is a statement of the actual conditions. In reality most area forecasts in the UK and Europe "warn" of the possibility of icing when often there is none. Forecasting icing conditions is still a very inexact science; it is true that if you never fly in conditions where the outside air temperature is below freezing and substantially true that if it is below freezing but there is no visible moisture you will not encounter icing but it is equally true that conditions below freezing and with visible moisture will not result in icing.

[peterh337]

I have never seen a forecast system for in-flight structural icing conditions, which tells you anything that is not obvious from one look at the MSLP chart.

Icing is a highly localised phenomenon, in both space and time. For 5 minutes, no ice. Next 5 mins, you get 1mm. Next 5 mins, you get 5mm. I don't see any weather model ever being any good for this.

If somebody finds a good website for this, I'd like to know.

[RTN11]

have never seen a forecast system for in-flight structural icing conditions, which tells you anything that is not obvious from one look at the MSLP chart.

Icing is a highly localised phenomenon, in both space and time. For 5 minutes, no ice. Next 5 mins, you get 1mm. Next 5 mins, you get 5mm. I don't see any weather model ever being any good for this.

If somebody finds a good website for this, I'd like to know.

F215 from metoffice.gov.uk offers a low level forcast (below 10,000') for the UK and F415 for Europe.

The symbol for moderate ice is a semi-circle (like a smile) with two vertical lines in the centre. Severe is three vertical lines.

See the key at the bottom of the page.

[Pilot.Lyons]

icing

I know someone that asked their instructor how much frost can we go up with (the wings etc were apparently whiteover) and the cfi said that will be ok just get in and go!

And that didnt end in disaster but certainly didnt fill them with knowledge

[Jumbo Driver]

There are old pilots ... and there are bold pilots ...

JD

[RTN11]

Certainly at some schools, pressure is put on Flight Instructors to get in the air early. This can sometimes mean going up in weather that isn't 100% suitable for the lesson, or pushing the boundries a bit more by flying with ice on the wings.

Deicing fluid is expensive, and is often overused (quite rightly) by people being over cautious, rather than used sparingly. From the point of view of the CFI/school owner, this is wated money, and even more wasted by the aircraft being on the ground being deiced.

[Jumbo Driver]

... and there are also cowboys ...

JD

[Sir Niall Dementia]

PeterH337/IO540,

There isn't one, and I doubt there ever will be one, the technology doesn't yet exist so we get hit with the blanket "NOT APPROVED FOR FLIGHT INTO KNOWN ICING" for almost all GA aircraft which basically leaves the pilot to decide if there is a risk of icing or not.

I spent a couple of hours in the simulator with Francis Frogbound while Verticalhold of these pages put us through a variety of icing scenarios which had been created by the training torturers. The worst case was in the middle altitudes where you would cruise a TB20, taken from FAA and CAA reports on rapid ice accretion it went from happy campers to "where the f++*! did that lot come from?" in a very short time and serious problems due to the rapid weight increase.

The day job aeroplane can even warn me of windshear, I really wish the bugger could warn of ice ahead rather than just telling me its' happening,
my playtime aeroplane only comes out when the sun is shining at this time of year and so I've never seen ice on her, but I don't think she'd do to well with it.

[Pilot DAR]

Flying with frost

The following is one of the many very relevant passages from an accident report:

Frost contamination of the wing upper surface would cause the loss of approximately 19% of maximum lift coefficient, which would result in the stall speed in the turn being approximately 67 KIAS rather than 60 KIAS. Increased drag caused by frost contamination would result in a reduced rate of climb, explaining why the aircraft reached 200 to 300 feet when calculations show the aircraft should have reached 400 to 500 feet agl. The aircraft's stall warning system, with an audio and visual warning, should have activated 5-10 knots above the normal stall speed. As the pilots apparently did not react to recover from a stall warning and impending stall, it could be surmised that the stall warning did not activate before the aircraft stalled, indicating that the aircraft stalled before its speed reduced to 65-70 KIAS. Frost on the wings would result in a higher than normal stall speed and also inhibit normal impending stall indications such as buffet. When the aircraft stalled, it entered a spin, uncharacteristic of this airplane. Frost on the wings would explain the loss of control and abnormal after-stall characteristics of the aircraft. There had been frost during the previous night, and although no one apparently saw frost on the aircraft lifting surfaces before or after the accident, there is no plausible condition other than frost contamination that would explain this accident. It is therefore concluded that there was frost on the aircraft's lifting surfaces when the aircraft took off.

The whole report is here: (It's a very good read!)

Transportation Safety Board of Canada - AVIATION Reports - 2003 - A03O0088

If that does not give you the frost willies, I don't know what would.

I flew this aircraft just before the other pilots crashed it. I can assure readers, that it has a "high lift" wing, in the sense that pilots like the ubiquitous PA-28 wing, and lots of power to maybe help yourself out of a tight spot. The crash pilot was said to be very experienced on this aircraft type, and with winter flying.





(sorry about the photo file size, Photobucket said it shrank them to 400 x 400, but I have my doubts)

Do you still want to fly with frost?

[Sir Niall Dementia]

Here's another one from Swindon of all places:

http://www.aaib.gov.uk/cms_resources...YA%2006-11.pdf