de-anti icing

[it.pilot737]

In the winter...we found frost on the wing...... we make full wing fuel so the frost will melt.....what do you think about doing the de/anti icng procedures in sub-zero condition?

I was thinking that the frost melting is still on the wing (water) and con be re-freeze.... what do you think?

[Intruder]

NO frost on the upper wing surface is allowed by US FAA rules! Only 1/8" on the lower surface under the fuel tanks is allowed.

If there is frost on preflight, get it de-iced.

[Notso Fantastic]

If there are frost, snow or ice deposits on the upper wing surface, you must de-ice before take-off, and take notice of Holdover Times according to the level of snow falling or blowing in the wind. You are allowed up to 3 mm of frost under the wing where the fuel tanks are. In addition, the aeroplane can have thin Hoar Frost over the fuselage as long as writing and surface detail can be seen underneath. This is the same as the frost that forms on cars overnight.

It is quite valid to put warm fuel into the wing tanks to melt the ice on the upper wing surface. It will remain wet, but it will not refreeze on the ground for a long time. Once you get airborne, it doesn't matter- you will quickly get up to high speed- remember you can take off into supercooled rain. All that matters is getting airborne and the first minute or so of flight. As long as when you start your take-off roll, you have no ice or snow deposits on the upper surface of the wing.

[flt_lt_w_mitty]

Just to correct 'not-so' and 'intruder' - Boeing have 'approved' upper-wing frost caused by cold fuel on their newer thin wings, as long as the 'frost' is within the marked area and the whole thing is approved by the regulatory authority.

BTW I don't think the UK has agreed to it - so there, you Limeys.:) Better talk to your 'Tony' about it.:p

[safetypee]

For European / all operators see AEA Icing Recommendations and Training (www.aea.be/AEAWebsite/Presentation_Tier/Pr_GroupMenuItem.aspx?NodeID=rootMenu398)
and
refer to JAR-OPS 1.345, particularly AMJ 1.345

For those less well informed US contributors, see NTSB Safety Alert - Aircraft Ground Icing (www.ntsb.gov/alerts/alerts.htm)

[Intruder]

Boeing have 'approved' upper-wing frost caused by cold fuel on their newer thin wings, as long as the 'frost' is within the marked area and the whole thing is approved by the regulatory authority.
So, has the FAA approved it? I have not seen any such bulletins...

BTW, which are the "newer thin wings" to which this applies? Do you have the Boeing document or doc number?

[flt_lt_w_mitty]

From Boeing 'Cold Soak' publication, May 2004

Boeing will incorporate CSFF permissable area in production starting with line number 1538 in July 2004, as a standard feature

- Lines on wing upper surface

- Manual updates to support operations will include Airplane Flight Manual, Airplane Maintenance Manual, and Flight Crew Operations Manual

Retrofit will be available as per Boeing Service Bulletin 737-11-1125

If you ain't got it, ask about it. I don't know how far it has got with 'approval', but the tests have been done and it is ok - and we need it!

[I-2021]

it.pilot737,

Try to have a look in your Company Operation's Manual, section "Cold Weather Operations" and you will find a lot of interesting stuff about Ice.

[lomapaseo]

Well we have a regulation in the operation section and now we have a manufacturer claiming that maybe it shouldn't apply to their Type certificate product, what with tests and all.

I really don't believe that things like this are that easily accomodated. A petition needs to be made for exemption, against the rule and such petition needs to be examined by the public interests (published in the Federal Register) for all coments for and against.

So who actually is filing such a petition, Boeing or the operators?

I shall be glad to place in the record my opinions on the matter after I see the petition.

[Md-driver]

We operate B-737NG:s in JAA environement.
We operate with frost on the top of the wings however only inside the markings on the wing and only in temperaures above 0C to prevent runback icing and also no precipitation is alowed.

Hope this answers your question.

[Smudger]

Here we go again. Get rid of it all. De-ice it, have the damn thing dripping with fluid immediately before departure. If you are the captain, and you are lined up for takeoff, and you are not 100% sure that your aircraft is clean, you must NOT depart. I'm talking generically, non-type specific, but please guys, don't mess with ice, GET RID OF IT. If you can't, then DON'T GO!! I know that some types are allowed to depart with a thin layer of frost on the underside of the wings within certain areas, fair enough, but for heaven's sake, if there is ice on your airframe and/or control surfaces then for all you know you are getting airborne in the aerodynamic equivalent of one of Fred Dibnah's steam rollers and you will die. Please, don't do it.

[The Bartender]

if there is ice on your airframe and/or control surfaces then for all you know you are getting airborne in the aerodynamic equivalent of one of Fred Dibnah's steam rollers


Quite common in some airlines i know, unfortunately... "It'll blow off..." :rolleyes:

[safetypee]

If you are the captain, and you are lined up for takeoff, and you are not 100% sure that your aircraft is clean, you must NOT depart.Well said Smudger, this advice needs repeating every year, even every flight.

For those unfamiliar with Fred Dibnah; he was the archetype ‘back yard mechanic’ (with university degrees in the subject). There are many good lessons to be taken from his biography; as a steeple-jack ‘one false step and you are saying hello to St Peter’. Another, ‘of all the accidents I had, they occurred when I was distracted’.

In aviation, there are three types of ice.
Good Ice, Bad Ice and Hazardous Ice.
Good Ice is found in the galley.

One of the objectives of flight is to keep the aircraft from shaking.
If it shakes, it is either too fast or too slow.
Or covered in ICE !

annon

[Notso Fantastic]

Chaps, here we have the classic pprune 'x' answers and 'x+1' different opinions! I tried to condense in reply #3 what my flying manual said for the 747 and 737. Thin frost on the fuselage is allowed. I know nothing about allowing frost on the upper wing surface. I guess everyone is right in their own way, but the only 'right' answer for <it.pilot737> is what's written in his flying manual, and a healthy dose of respect for the problem.

So many aeroplanes have piled in because of ice, and still do, that I find it strange how the rules change and if frost is now allowed on the upper wing surface. But I always believe in asking the people who know. What we need is a combined rule setting meeting of Air Canada, Air Alaska, SAS and Aeroflot to set the guidelines, and keep the politicians and office flyers out of it!

[RatherBeFlying]

Back in '89 I was SLF in a Wardair A310 out of YYC on a fine day. Taxiing out I noticed frost over the wing tanks from cold soaked fuel and considered if I should make a fuss, but in relation to the total wing area and being well back from the leading edge, I decided it was acceptable.

Back at YYZ, I sent a note to ops and received a reply from the CP that the A310 certification allowed frost over the wing tank.

After the Dryden report came out, I believe Transport Canada made regs requiring an absolutely clean upper surface irrespective of manufacturer data.

If the manufacturer has done the test flights with frost over the tanks (as well as under) and has properly accounted for an engine failure, a thin frost over the tanks can be acceptable in operation.

[BOAC]

Been following this with some interest and I see the Boeing 737-800 FCOM allows it subject to 'regulatory approval', so your airline Ops Manual should say yeay or nay.So many aeroplanes have piled in because of ice, and still do, that I find it strange how the rules change and if frost is now allowed on the upper wing surface. - I'm not sure, but I suspect there was more than a small amount of thin frost in an approved area of the wings on most of the 'departed'? The 'no ice' rule is possibly just a (sensible) blanket restriction which can now be reviewed after satisfactory investigation/testing? Things do move on, and sometimes for the better.:)

The Boeing 'limitations' on it are quite specific.

[airvanman]

In the real world keep it simple…

For simple pilots and de-icers. Yes they are in the real world! Frost on the uppers is a no go, no matter what the thickness or area it is in. I am sure many of you like myself have seen Ice/frost spread like cancer across the wing after inspecting aircraft on arrival, and just before departure. The fresh/warmer fuel temp did not melt it that time!
A lot depends on the temp (of course), the wind direction, parking location, and the way the apu hot air is blowing - is another e.g.

Many a time the crew do not look at the wings from the steps or windows with this in mind. What about that one time the aircraft is delayed that little bit longer, and they go with the attitude of - nah we will be ok? and it aint!

Boeing says they allow it in some in areas…blah…blah! :mad: off ! You get on the wing and measure it with a ruler matey! You can do a tactile test for most of the wing (without risking some damage with a basket, etc). Always cop a feel if you have any doubts. Shinny metal can look ok. But it could be covered in a thin layer of ice.
If in doubt de-ice it!

Procedures - Airlines all have their own. You would need a book the size of War and Peace on you for reference going airside.

Again keep it simple and the same rule for all types of aircraft.

[TURIN]

Completely agree airvanman.

It's bad enough already when you get some airline station managers (and pilots) insisting that "it's only a bit of ice and it's only on one side....blah blah...it'll delay us...blah blah...but de-icing will screw our bonus this month....":mad:

If they get wind of a get out claus that may apply under certain conditions they'll be leaning on the certifyer to pen it off all the bl00dy time.

At little knowledge is dangerous!

(I should know:O )

Get it de-iced. :ok:

[J.O.]

That Boeing language is a can of worms, IMHO. I wonder what it would be like to be a Captain for a company that has received approval to fly their NGs with frost on the designated areas of the wing upper surface. What do you do when a "knowledgeable" passenger makes a fuss in the cabin because they know the rule which says that the wing has to be clean? I think I'll stick to my Airbus and the clean wing concept.

[PantLoad]

Gentlemen (and Ladies, as applicable),

In my humble opinion (:) :) :) ), it's not a good idea to takeoff without a completely clean wing. My company's SOP is, very succinctly stated, "Make It Clean; Keep It Clean". There are too many pitfalls if you opt otherwise.

For example, years ago, an airplane crashed on takeoff due to icing on the wings. It was a cold, cold morning, and light snow had fallen during the night. When the crew arrived at the aircraft, the flight engineer (Yes, it was a long time ago! :) ) actually got a ladder and, with his hand, was able to brush the very dry snow off a section of the wing. It easily blew off into a fine powder. No problem...they all concluded it was safe to takeoff without being sprayed.

But, right after the snow-brushing analysis, they got their fuel. And, the fuel came from an underground tank...which, yes, you guessed it...was at a temperature well above freezing.

So, now, the warm fuel went into the wings, apparently partially melted the snow...which refroze...and, well, the rest is history.

A good, reliable rule to live by is to make it clean and keep it clean. That's the only sure way to know you're safe for takeoff. How you accomplish this is by following your company's SOPs. And, when in doubt, "DON'T" (is a good rule, too).

I've never had an engineer mind doing a tactile inspection of the wing to ensure the de-anti-icing fluid was still working. Yes, it's cold, snowing, etc., and the work conditions for these engineers are miserable. But, the consequences are simply too grave to do otherwise.


PantLoad

[Ice-bore]

Interesting thread with some positive feedback to it.pilot737.

To answer the original question I believe that the procedure is floored, in that potential would still exist for the melted frost to refreeze prior to take-off. While the uplifted fuel may raise the temperature of the upper wing skin to above the FP, other areas, e.g. where the L/G and engine(s) are attached to the wing, contain large amounts of metal which may have remained below 0 deg. C since the previous flight, or have dropped below that level due to the sub-zero conditions reported. Also if the frost was originally present on the L/E or T/E surfaces, it is unlikely to have been removed by the uplifted fuel. As suggested in the majority of posts, the only safe option would be to have the upper surface of the wings de-iced prior to take-off.

With regard to the Boeing ‘upper wing frost’ alleviation on their 737 NG aircraft, it is my understanding that this only comes into play under very closely defined conditions. For example, when ‘normal’ de-icing conditions exist at an Airport, i.e. when surfaces of all/the majority of departing aircraft have been contaminated by frost, ice slush and snow and require de-icing, standard procedures will apply and the upper wing surfaces of all aircraft, including the 737 NG, will receive a full de-ice.

However, due to the design of the 737 NG it is not uncommon for frost to be found on specific areas on the upper wing surface, even though the OAT may be above 0 deg. C and the majority of other aircraft types do not require de-icing. Don’t have any details but assume it’s associated with the design of the wing. I believe the alleviation allows for take-off with frost in these relatively small areas, provided it is within the painted lines. Must say that I have also seen similar small areas of frost on the wings of A320 series aircraft under the same conditions but presumably Airbus have not been pressurised by customer airlines into introducing a similar alleviation for these aircraft.

A significant number of the above posts quite rightly question the advisability of allowing take-off with frost patches, albeit small ones, on the upper surfaces of the wings. However, one aspect that hasn’t been discussed is the aerodynamic effect of the de-/anti-icing fluid residues that remain on the wings following treatment.

Following work they carried out during the late 80’s Boeing stated, “Flight tests show that both Type I and Type II (Type III and Type IV fluid did not exist at that time) de-icing/anti-icing fluids do flow off the wings of a treated aircraft in significant amounts during initial take-off ground run. However, the residual fluid is sufficient to cause a temporary decrease in lift and increase in drag during rotation and initial climbout....” They subsequently confirmed that sufficient performance margins were available on their aircraft to offset the effects of the fluids but there was still a detrimental effect on performance.

It’s possible that the aerodynamic effect of the small frost patches on 737 NG aircraft was found to be less than that of the de-/anti-icing fluid flowing off a fully de-iced wing, so there would appear to be some justification for introducing the alleviation.

[BOAC]

To add to 'it.pilot's' query and to explain a little more of the 'problem' to 'Ice-bore', with reference to the 737 NG the 'frost' occurs due to fuel cold soak during prolonged cruise in cold upper temperatures. The 'thin wing' then allows the cold fuel to cool the wing surface, and cause condensation (obviously humidity related). If the fuel temperature in the wing is below zero, this dew can/will then freeze to produce a thin 'frost'. The thermal capacity of the cold fuel prevents the wing from warming up in line with the rest of the aircraft, even in OATs of 14-15 degrees C or more. I have had the problem at 20 deg C.

It affects ONLY the wing - the rest of the structure (no fuel contained therein - eg other areas, e.g. where the L/G and engine(s) are attached to the wing, contain large amounts of metal which may have remained below 0 deg. C ) is not affected. They normally 'warm-up' on a t/round. If I elect to de-ice in these conditions I will de-ice only the wing upper surface. The addition of 'warm' fuel in an uplift [beware it is 'warm' - I have like a previous poster, seen sub-zero fuel loaded (in Krakow)] will, providing there is sufficient uplift, raise the tank fuel temperature to above zero. The 'frost' will melt, leaving 'dew'. In the OATs we are looking at (10 deg C plus), there is NO WAY the 'dew' will refreeze and it will obviously disappear during take-off and flight.

The upper surface is the problem - lower surface ice is allowed in controlled conditions. If you have arrived in Egypt in summer and ask to be de-iced, it proves a little difficult.:) This is, IMO, a reasonable attempt (with testing) to review the age-old philosophy of a 'clean upper wing.

I have not looked in detail at the Boeing lnk above, but I'm pretty sure there is no 'condition' that de-icing is not available? I cannot see why people are getting so 'heated':) about this - if Boeing have tested it, the 'frost' is withing the defined area and is the 'correct' type PLUS it does not affect the handling/performance any more than a coating of de-icer, what is the issue?

[TURIN]

The issue BOAC is that not all airport personnel are as educated as yourself.

Pressure will be applied by those in positions of authority (IE the ones holding the purse strings) to accomodate the B737NG philosophy on all aircraft types, irrespective of safety procedures. It happens now even with a simple 'no ice on upper surface rule'. Station managers and the like insist that they know better. I have witnessed an uninformed station manager tell a captain that his aircraft didn't need de-icing when clearly it did (that one got an MOR).

Keep it simple. :ok:

[airvanman]

BOAC
As mentioned by Turin keep it simple.
Regarding training for winter operations we work off our company procedures (keeping it simple) based on AEA etc and the many customer requirements. Our annual training includes aerodynamics and videos with examples like the BHX crash a couple of years ago included in it.
In my experience it is shocking how many pilots (unlike you) are worryingly under trained on this subject. It. pilot737 or any other pilot should have this basic knowledge.
How many of you de-icers reading this have had to explain to crews why they must turn of the air-con when we de-ice?
The worse e.g. I have is pleading with a skipper to get out of the flight deck and look at the inch long ice stalactites under just one side of his wing. After a heated debate he gave us the go ahead to clear it. I am sure if he had gone that would have been a disaster.
Us idiots, who take responsibility and freeze our tits off de-icing aircraft, take onboard a moral responsibility after our experience and training. Some say we just push for company profits. This could be true but I bet it is rare?
There are people also who de-ice who are sadly chucked in the deep end with very little training.
The whole subject should be better regulated and improved or the luck one-day will run out?
BOAC that is the heated issue I think!
I probably have de-iced you i/b from Gambia?

[The Bartender]

airvanman:
Very well put! :D
It is all too familiar!:ooh:

[falcon12]

Have just got to read the threads on this subject having been away in warmer climates.

Its no surprise that there exists a great deal of ignorance on both the aviators side as to when to de ice and on the ground side as to what deicing means.

Many years ago I lost a lot of fellow aviators when a Britannia crashed in the USA and which deicing, or the lack of it, played a part. Therefore, now building and selling aircraft de icers as well as being involved in training on their use, the subject is somewhat 'personal' for me.

The KISS principle revails. Make clean and keep it clean, a statement from a previous thread. If its ice or looks like ice, get it off.

On the ground side, and this is a proven area of the cause of possible invertion after take off due incorrect deicing, an airport in the UK who wanted to introduce deicing for its customers this season laboured under the impression that you just ordered the vehicle, sat a short course and then went deicing!! No consideration of the regulations, fluids, training and so on. It even got to the point of enquiring one afternoon half way through a second classroom course if they would be ready to deice that night!!

Yes, training is the key for both those who fly and those who spray as the next accident is, unfortunately fast approaching the ground I fear.

[Ashling]

When Boeing introduced its alleviation allowing you to get airborne with a small amount of frost on the upper wing I was very suspicious of the whole thing and refused to do it for a time while I tried to understand what was behind it. After all if you stall after take-off low down your not coming back, unless you have a rocket seat, as has been tragicaly proven many times.

Now I'm quite happy with it as it has all been tested, is well documented and trained for and can only be done in very specific circumstances. My company have never and will never put pressure on people not to de-ice and I have never heard of a decision to de-ice queried.

At the end of the day you have to know your type and the manufacturers recommendations for how to operate it and why, you also need to be totaly familiar with winter ops and if in doubt de-ice. If you still not happy do it again until you are happy or don't go its not an area to take chances with. Keep reviewing your decisions until you take-off so you know they remain valid and all will be well.

Anyone assuming snow will simply blow away is on their way to an early grave, get it brushed off then inspect it and proceed from there. I once had to do a 2 stage de-ice in these circumstances as the bottom layer of snow had compacted into some very nasty ice and that was in sub zero conditions without a refuel.

[The Bartender]

...and yet again... Two 737's, operated by a large European LCC took off today, one with roughly 6-8 square meters of 2 mm + coarse ice on the right wing, and the other with 2 mm + coarse ice covering about 50% of the fueltanks on both wings (RASN on coldsoaked wings in both cases)...

Both crews decided that it was just water, without performing a tactile check, even though ladder was provided. When informed that there was in fact ice on the wings, they simply denied it, claiming it was water... :rolleyes:

[Linton Chilcott]

I have seen a very thin layer of frost removed completely from the top surface of the wing by filling the fuel tanks with relatively warm fuel. There was no moisture left at all on the wing - completely dry, so nothing to refreeze back on.

An unusual situation.

What about the tailplane, though? Well, the tail provides lift in the opposite direction (i.e. downward) on most aircraft. Therefore, a very light dusting of frost on the upper surface of the tailplane is the equivalent of the same dusting of frost under the main wing, and may therefore be acceptable, depending on the manufacturer's limitations.

[BOAC]

Linton - post #22?

[Linton Chilcott]

BOAC - Que?

[Linton Chilcott]

BOAC. Yes, I think I've got it.

But the very thin layer of frost I mentioned had occurred overnight (not due to a cold soaked wing in flight) with the aircraft parked outside.

The warmer fuel de-frosted the wing, and the rising sun evaporated any dew immediately.

[BOAC]

That is by no means uncommon, and often a fuel uplift is not even necessary. As the wing warms up in the morning sun................

If the tailplane is 'frosted' and there is no sign of it melting, I would guess the wings are the same and therefore = de-ice. This again is a separate issue to cold-soak frost.

[s artois]

If there's ice on my wing I either do one of two things.

[s artois]

Answers on a postcard!!:cool:

[Dutch Gold]

C'mon the suspense is killing me!! What do you do???
Personally I like to scrape the ice off and put it in my Gin & Tonic!!!:ok: