on flying with polished ice on your wing
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I don't recall reading any reference to the possible affect of engine failure during TO when carry ice and snow on the wing and fuselage. A lot of people get away with TO carrying unacceptable amounts of contamination because they don't suffer an engine failure.
The slightest amount of contamination, eg. frost on a wing similar to a very fine grade sandpaper, results in up to a 30% reduction in lift and a 40% increase in drag. Add to that a failed engine and the bravest out there might start to sweat just a little.
So many companies, especially operators of freighters believe it is good enough to determine go or no go re the wing/fuselage at least, by looking from the top of the stairs. I have proved that to be woefully inadequate, by actually getting up and inspecting the wing up close.
I agree with comments re the total folly of accepting snow blowing off the a/c during TO. SAS have extensive material on the subject and they advise that you should never presume contamination will clear during TO.
Sound advice and worth heeding I believe.
The problem is that crew allow themselves to be pressure into not de-icing as it costs money and can delay the flight. Remember that companies write all sorts of stuff in their manuals to cover their back sides re cold weather operations and then often expect you to ignore it to keep the show on the road.
If you are caught breaking these rules for expediency, the company lawyers will burn you to save the company from litigation. You are only doing yourself a disservice by pushing the envelope.
Just my opinion.
The slightest amount of contamination, eg. frost on a wing similar to a very fine grade sandpaper, results in up to a 30% reduction in lift and a 40% increase in drag. Add to that a failed engine and the bravest out there might start to sweat just a little.
So many companies, especially operators of freighters believe it is good enough to determine go or no go re the wing/fuselage at least, by looking from the top of the stairs. I have proved that to be woefully inadequate, by actually getting up and inspecting the wing up close.
I agree with comments re the total folly of accepting snow blowing off the a/c during TO. SAS have extensive material on the subject and they advise that you should never presume contamination will clear during TO.
Sound advice and worth heeding I believe.
The problem is that crew allow themselves to be pressure into not de-icing as it costs money and can delay the flight. Remember that companies write all sorts of stuff in their manuals to cover their back sides re cold weather operations and then often expect you to ignore it to keep the show on the road.
If you are caught breaking these rules for expediency, the company lawyers will burn you to save the company from litigation. You are only doing yourself a disservice by pushing the envelope.
Just my opinion.
Last edited by Roadrunner; 8th Nov 2006 at 04:53.
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The slightest amount of contamination, eg. frost on a wing similar to a very fine grade sandpaper, results in up to a 30% reduction in lift and a 40% increase in drag. Add to that a failed engine and the bravest out there might start to sweat just a little.
And so I agree with punkalouver. You have to know your aircraft. We've all seen the NASA videos from the Twotter tests - but those were ridiculous amounts of ice, and I cannot believe that anyone would be foolish enough to attempt a take-off with that **** stuck to the wings/tail. I still think there's a huge difference between, say, the F28-4000 accident at La Guardia, where the wings were FULL of ice and snow (and they rotated too early), and a turbo prop with low wing loading and a little residual ice or frost.
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We do lots of winter OPS here in Iceland and our policy states No T/o with contaminated wings, we always do a very good pre-flt walk around and in winter pay even more attention to ENG intakes , Fan blades and ctrl surfaces.We' ll perform de- ice when required and respect HOT (hold over time)if HOT is over then we'll de-ice again .I think if you take off with a clean wing you' ll be always on the safe side. Of course we 'll use Eng AI on TO and if conditions are really bad
(i.e. freezing rain)
we ' ll also use wing AI after TO.
Keep it Clean ,Keep it safe.
(i.e. freezing rain)we ' ll also use wing AI after TO.
Keep it Clean ,Keep it safe.
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Here, here.
To clarify, my previous post was referring to your average commercial jet.
Just doing some more reading via google search into the subject and they suggest that the tail plane will more readily ice up than the wing. Interesting that commercial jetliners don't have any tail anti-icing.
Do any aircraft have tail anti-icing or de-icing?
To clarify, my previous post was referring to your average commercial jet.
Just doing some more reading via google search into the subject and they suggest that the tail plane will more readily ice up than the wing. Interesting that commercial jetliners don't have any tail anti-icing.
Do any aircraft have tail anti-icing or de-icing?
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Anti-icing/de-icing sys on modern jets are generally eng bleed air hot air systems.
In systems of this type the leading edge sections of wings including leading edge slats but not leading edge flaps,and tail units are usually provided with a second, inner skin positioned to form a small gap between it and the inside layer of the leading edge section.The hot air is ducted into the gap and provides sufficient heat(controlled by a shutter or butterfly VLV SYS) in the outer skin.The air is then exhausted through outlets in the skin surface or also ,in some cases, trough wing tips and tail units.The use of wing Anti Ice is not recomended on the ground ,cause it may damage the wing structure.
Electrical resistance heating sys or peneumatical operated de- icing boots are usually choosen for turboprops.
In systems of this type the leading edge sections of wings including leading edge slats but not leading edge flaps,and tail units are usually provided with a second, inner skin positioned to form a small gap between it and the inside layer of the leading edge section.The hot air is ducted into the gap and provides sufficient heat(controlled by a shutter or butterfly VLV SYS) in the outer skin.The air is then exhausted through outlets in the skin surface or also ,in some cases, trough wing tips and tail units.The use of wing Anti Ice is not recomended on the ground ,cause it may damage the wing structure.
Electrical resistance heating sys or peneumatical operated de- icing boots are usually choosen for turboprops.
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ICEMAN,
You are right for the commercial jets but consider the possiblity of using the anti-icing on RJs or large turboprops at the airports without appropriate facilities (Canada is coming into mind, just from personal experience).
Also, some jets are designed to use the l/e anti-icing system on the ground. Good examples are Challengers (600 series, 300 series), Gulfstream as well as Bombardier's RJs (200, 700, 900).
They are all capable of using the stuff on the ground. During design of these models it was assumed that there will be no facilities for spraying available all the time.
The biggest problem was that too much bleed air would damage the l/e ribs plus too much heat just in front of you fuel tank would be a big no-no
I've seen ribs from test Challengers being black completely around the anti-icing going trough the leading edge
However one can assume the problem was more on the side of design i.e. improperly designed anti-icing system or better too much bleed air removed from the engine.
Amway, using bleed air on the ground is a considerable possiblity, especially on remote airfields.
Cheers
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I believe that after the Washington crash in 1982 Boeing modified the wing TAI system on 737 aircraft, to allow it to be used on the ground. However, while the L/E may be the most critical part of the wing, the entire upper surface must be free of frozen contamination at takeoff.
In the unlikely event that the only part of the aircraft with frost or ice on it was the L/E, selecting wing anti-ice would certainly remove it but the potential then exists for melting frost or ice to run back and re-freeze behind the L/E. To imply that this system can be used on the ground, in lieu of a standard de-/anti-icing operation, is in my opinion highly dangerous.
There would also an issue with selecting wing anti-ice on the ground, immediately following de-icing or anti-icing with Type II or IV fluid. The fluid remaining on the heated L/E would evaporate fairly quickly, leaving behind deposits of dried out thickening agent. Add moisture at some stage in the future and the water soluble thickener will swell to form a gel like substance on the L/E.
In the unlikely event that the only part of the aircraft with frost or ice on it was the L/E, selecting wing anti-ice would certainly remove it but the potential then exists for melting frost or ice to run back and re-freeze behind the L/E. To imply that this system can be used on the ground, in lieu of a standard de-/anti-icing operation, is in my opinion highly dangerous.
There would also an issue with selecting wing anti-ice on the ground, immediately following de-icing or anti-icing with Type II or IV fluid. The fluid remaining on the heated L/E would evaporate fairly quickly, leaving behind deposits of dried out thickening agent. Add moisture at some stage in the future and the water soluble thickener will swell to form a gel like substance on the L/E.
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Grunft your are probably right on using anti-Ice on the ground 
it varies between acft , on the 757 it is automatically inihibited on the ground.Good to know we always learning something new.
it varies between acft , on the 757 it is automatically inihibited on the ground.Good to know we always learning something new.
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Well, my job was more on the structural side (issues with too much bleed air going through the tube).
I have no procedural knowledge of what way they were using it but I am quite sure they have tested it in Iqaluit (north of Canada, province of Nunavut).
You have to check with someone flying these smaller jets a little bit "up north" to see what's their procedure.
Cheers
I have no procedural knowledge of what way they were using it but I am quite sure they have tested it in Iqaluit (north of Canada, province of Nunavut).
You have to check with someone flying these smaller jets a little bit "up north" to see what's their procedure.
Cheers
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I find it interesting to read recently that the CAA have issued a warning with regards to the use of Type II/III/IV fluids and the number of applications. The residues left over from the fluids can dry out and when re-hydrated swell up to form a thick paste. After a number of aplications the amounts of residue can cause flight control problems! Yet more things to think about on these cold mornings!
Still though, if in doubt DEICE the thing!
By the way, with regards to the use of AI. 737's are not permitted to use wing AI whilst on the ground or on the TO roll.
Still though, if in doubt DEICE the thing!
By the way, with regards to the use of AI. 737's are not permitted to use wing AI whilst on the ground or on the TO roll.
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Would agree that it can't be used during takeoff as the wing TAI switches will automatically move to the OFF position. This reduces engine bleed loads and conserves thrust for climb.
Are you suggesting that Boeing do not permit use of this system on the ground or that your company do not allow it ?
Of course we 'll use Eng AI on TO and if conditions are really bad (i.e. freezing rain)
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From SP.16 ,737 FCOM :
Use wing AI ,during all ground operations between engine start and take off when icing conditions exist or are anticipated,unless the airplane is,or will be protected by use of type 2 or type 4 fluid in complance with an approved ground de-iceing program.
Warning: do not use wing anti-ice as an alternative for ground de-iceing/anti-icing.Close inspection is still needed to insure that no frost,snow or ice is adhering to the wing,LE devices,stabilizer,control surfaces or any other critical aircraft components at take-off.
I very much doubt that any company will,for some reason decide not to follow this.
One big problem with taking off with 'some' ice on the wings is the chance of not symetrical icing of both wings,and you'll be amased how fast you'll do a barrel roll,even with a heavier airplane.It's just aerodinamics.
And ,unfortunately ,it happened already,so you better learn from their death.
Use wing AI ,during all ground operations between engine start and take off when icing conditions exist or are anticipated,unless the airplane is,or will be protected by use of type 2 or type 4 fluid in complance with an approved ground de-iceing program.
Warning: do not use wing anti-ice as an alternative for ground de-iceing/anti-icing.Close inspection is still needed to insure that no frost,snow or ice is adhering to the wing,LE devices,stabilizer,control surfaces or any other critical aircraft components at take-off.
I very much doubt that any company will,for some reason decide not to follow this.
One big problem with taking off with 'some' ice on the wings is the chance of not symetrical icing of both wings,and you'll be amased how fast you'll do a barrel roll,even with a heavier airplane.It's just aerodinamics.
And ,unfortunately ,it happened already,so you better learn from their death.
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You should know that (rather long) sentence... It's your aircraft it's refering to...
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NTSB gives more requests to FAA on icing
hell all.
Talking 'bout the Devil: here is an excerpt from the latest Most Wanted List from NTSB on icing:
November 14, 2006 SB-06-61
"...Aircraft Icing -- The consequences of operating an airplane in icing conditions without first having thoroughly demonstrated adequate handling/controllability in those conditions are sufficiently severe that they warrant a thorough certification test program.
The FAA has not adopted a systematic and proactive approach to the certification and operational issues of airplane icing. Recommendation: Complete research on aircraft structural icing and continue efforts to revise icing certification criteria, testing requirements, and restrictions on operations in icing conditions.
Evaluate all aircraft certified for flight in icing conditions using the new criteria and standards. Timeliness Classification: Unacceptable ...."
So, watch out, please.
Cheers
Talking 'bout the Devil: here is an excerpt from the latest Most Wanted List from NTSB on icing:
November 14, 2006 SB-06-61
"...Aircraft Icing -- The consequences of operating an airplane in icing conditions without first having thoroughly demonstrated adequate handling/controllability in those conditions are sufficiently severe that they warrant a thorough certification test program.
The FAA has not adopted a systematic and proactive approach to the certification and operational issues of airplane icing. Recommendation: Complete research on aircraft structural icing and continue efforts to revise icing certification criteria, testing requirements, and restrictions on operations in icing conditions.
Evaluate all aircraft certified for flight in icing conditions using the new criteria and standards. Timeliness Classification: Unacceptable
...."So, watch out, please.
Cheers
