AC deicing procedure ?
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
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Yes I do! Familiarity breeds contempt. However, if his family were on board, he would have insisted on full de-icing! Funny how not travelling on the aeroplane somehow made tyres 'that's OK Captain!'
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After de-icing has taken place within my company, we (ground staff), check the wing to make sure the frost or clear ice has totally gone by doing a hands-on check.
It really is the only way to make sure it's all gone.
There are some plonkers out there operating the de-icing equipment for the handling companies !
On a couple of occasions, the fluid temperature wasn't checked before applying it to the wing (it was freezing cold!
) and Mr sprayer was just adding to the problem.
The lack of steam and my hands-on check may have saved the day.
Obviously for larger aircraft (where you can't get some engineering steps to the wing), the contamination check can't really be performed, only from the window or door, but for the smaller beasts it's fine!
Those of you chaps operating in and out of LHR presently with the current fuel sittuation need to take extra care! Lots of frost and clear ice around!
Safe flying
It really is the only way to make sure it's all gone.
There are some plonkers out there operating the de-icing equipment for the handling companies !
On a couple of occasions, the fluid temperature wasn't checked before applying it to the wing (it was freezing cold!
) and Mr sprayer was just adding to the problem. The lack of steam and my hands-on check may have saved the day.
Obviously for larger aircraft (where you can't get some engineering steps to the wing), the contamination check can't really be performed, only from the window or door, but for the smaller beasts it's fine!
Those of you chaps operating in and out of LHR presently with the current fuel sittuation need to take extra care! Lots of frost and clear ice around!
Safe flying
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At LHR indeed we have been warned to take particular care due to fuel situation, when making headset walk around and after and before push back. In parts of the network it seems to be a skill that is all to often left to chance?
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Originally Posted by Rainboe
Yes I do! Familiarity breeds contempt. However, if his family were on board, he would have insisted on full de-icing! Funny how not travelling on the aeroplane somehow made tyres 'that's OK Captain!'
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It is a perfectly good practice to check the wing by your self but it's not always possible. Most places we deice the BAe-146 we do it on deicing stands with engines running, so going back and opening the back door to check is not an option! We have to trust the ground staff when they tell us that the deicing of wings and tail is completed.
And by the the way, type I fluid does give you a little bit of hold over time.
And by the the way, type I fluid does give you a little bit of hold over time.
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Originally Posted by MotorCityMadman
Incident in Bos precipated procedure. De-ice crew forgot to spray one wing. Fuel truck was in the way and they neglected to come back and spray remaining wing. Now required to visually check after every spray.
Any incident report avail ?
Do you know what happened after that, did the aircraft actually take off in that configuration ... ?
I don't know what's the deicing procedure in BOS but apparently it was done at the gate, is it a "in house" deicing procedure, or is it the usual way for BOS ?
I am still surprised AC implemented such a procedure after every spray in a place like YYZ where deicing crew has the authority to verbally certify the airplane is free from any contaminant and if necessary protected against further contaminant. Maybe the deicing crew is not in the aircraft, but I would think they're in a much better position to check these critical surfaces ...
Now, if we follow the same logic, as a passenger, should I complain the Boss didn't send the FO to visually check if the deicing crew didn't forget ... the tail ?!
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Originally Posted by Faire d'income
That would be the IAA. 
Well, they could try to pay for only one de-iceing around these parts... "Your flight has been slightly delayed.. ..until may...."
No wonder some airlines have problems with making the holdover-time, with so much paperwork to fill in and exchange with the groundcrew after de-iceing...
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Holdover time of course begins at the START of spraying.... once at BHX the holdover time had run out BEFORE the crew had finished.... then they ran out of fluid. We had a lovely breakfast on board, most of our pax did too, then wandered off home. We canx a while later...
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Captain Airclues:
There is a scary CRM video shown to us in Europe. It covers de-icing as well. It was on an F28? and sounds just like your scenario as it was in Canada. The crew were behind schedule. You guessed it, it was snowing, the APU was U/S,, the ground starter was unreliable, there was no de-icing with the engines running (SOP's). A pax, pilot I think, asked the C/A to tell the captain there was a lot of snow on the wings. She went away, returned and said it would blow off on takeoff.
Guess again! Crash!!
It is the captain's legal responsibility to ensure the surfaces are clean. He can delegate this or do it himself. Either way he makes the call. It has been well known in Scandanavia for years that a tactile test is the only 100% sure way, in nasty icing conditions, especially where ice has been present.
There was case recently where Type 1 was ordered and 100% water was used. A/C called back from taxi by the de-ice company. Could have been VERY serious. And not to mention the numerolus incidents/accidents where assymetric ice caused by cold soaked fuel has led to some 'recovery from unusual attitude' demonstrations.
Surely the pax would like to see a sound professional flight preparation. There are already too many dilutions of that on clear sunny days. Let's not allow more to happen in critical situations. Remember the lack of respect/knowledge for icing that might have led to the winter dip in the Potomac.
There is a scary CRM video shown to us in Europe. It covers de-icing as well. It was on an F28? and sounds just like your scenario as it was in Canada. The crew were behind schedule. You guessed it, it was snowing, the APU was U/S,, the ground starter was unreliable, there was no de-icing with the engines running (SOP's). A pax, pilot I think, asked the C/A to tell the captain there was a lot of snow on the wings. She went away, returned and said it would blow off on takeoff.
Guess again! Crash!!
It is the captain's legal responsibility to ensure the surfaces are clean. He can delegate this or do it himself. Either way he makes the call. It has been well known in Scandanavia for years that a tactile test is the only 100% sure way, in nasty icing conditions, especially where ice has been present.
There was case recently where Type 1 was ordered and 100% water was used. A/C called back from taxi by the de-ice company. Could have been VERY serious. And not to mention the numerolus incidents/accidents where assymetric ice caused by cold soaked fuel has led to some 'recovery from unusual attitude' demonstrations.
Surely the pax would like to see a sound professional flight preparation. There are already too many dilutions of that on clear sunny days. Let's not allow more to happen in critical situations. Remember the lack of respect/knowledge for icing that might have led to the winter dip in the Potomac.
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Generally, aircraft anti-ice (note anti-ice, not deice) systems only prevent the ice from forming, they can't remove ice that has already formed, although see the post below for B747 specific operations.
These systems (on jet aircraft) use hot air bled from the engine compressors and feed it through ducts in the leading edges of the wings and engine nacelles. This is becaues the ice tends to start to form on the leading edges and work its way aft, so by heating the leading edges it prevents the initial formation. If the wing is already covered in ice, this leading edge only system won't affect the rest of the wings surface, so the ice needs to be removed before flight. Once cleared and the aircraft is flying, the antiice system prevents new ice forming.
Edited in view of new information posted in the reply below....
These systems (on jet aircraft) use hot air bled from the engine compressors and feed it through ducts in the leading edges of the wings and engine nacelles. This is becaues the ice tends to start to form on the leading edges and work its way aft, so by heating the leading edges it prevents the initial formation. If the wing is already covered in ice, this leading edge only system won't affect the rest of the wings surface, so the ice needs to be removed before flight. Once cleared and the aircraft is flying, the antiice system prevents new ice forming.
Edited in view of new information posted in the reply below....
Last edited by ANOTHER ton?; 21st Mar 2006 at 21:57.
Just another number
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Not strictly true A t.
There is plenty of moisture at high altitudes, as anyone who has had to dodge the Cb's over Africa will confirm. Ice can be a problem at any altitude. However, when the temperature is below -40, the super-cooled ice pellets will not stick to the airframe.
The wing anti-ice system on the 747-400 is actually a de-icer. The technique is to allow an appreciable build up of ice to form and then switch it on, so that the ice breaks away in large chunks. The problem with leaving it on for too long is that the melting ice runs back over the top surface of the wing and then freezes, with no way of removing it.
The wing anti-ice system cannot be used when the flaps are extended as the hot air vents to the atmosphere with the leading edge flaps out. The wing anti-ice system only heats the leading edge, and it is the entire wing which required de-icing prior to take-off.
Airclues
There is plenty of moisture at high altitudes, as anyone who has had to dodge the Cb's over Africa will confirm. Ice can be a problem at any altitude. However, when the temperature is below -40, the super-cooled ice pellets will not stick to the airframe.
The wing anti-ice system on the 747-400 is actually a de-icer. The technique is to allow an appreciable build up of ice to form and then switch it on, so that the ice breaks away in large chunks. The problem with leaving it on for too long is that the melting ice runs back over the top surface of the wing and then freezes, with no way of removing it.
The wing anti-ice system cannot be used when the flaps are extended as the hot air vents to the atmosphere with the leading edge flaps out. The wing anti-ice system only heats the leading edge, and it is the entire wing which required de-icing prior to take-off.
Airclues
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I stand corrected....
Am I still correct in my statement that the ice starts to form at the stagnation point and works aft, or am I just really embarassing myself now??
My background is aircraft engineering based, so my knowledge of how the aircraft are used isn't as good as how they work.
Am I still correct in my statement that the ice starts to form at the stagnation point and works aft, or am I just really embarassing myself now??
My background is aircraft engineering based, so my knowledge of how the aircraft are used isn't as good as how they work.
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A t
You are correct. The ice initially forms on the leading edge and then works it's way back.
The problem with using the wing anti-ice before there is an appreciable build up is that the water freezes further back on the wing. By allowing a build up to occur and then switching it on. the ice that is in contact with the wing melts and then the ice breaks away in chunks.
http://icebox.grc.nasa.gov/ext/galle...icing_wing.jpg
You are correct. The ice initially forms on the leading edge and then works it's way back.
The problem with using the wing anti-ice before there is an appreciable build up is that the water freezes further back on the wing. By allowing a build up to occur and then switching it on. the ice that is in contact with the wing melts and then the ice breaks away in chunks.
http://icebox.grc.nasa.gov/ext/galle...icing_wing.jpg
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Water at temperatures far below freezing point, is very unstable and when disturbed by an aircraft, rapidly changes into clear ice. Air Force research has shown that this rate of ice buildup on an airfoil can be much more rapid than previously thought. In a number of cases, two to three inches of ice developed in less than five minutes. As little as one half inch (1.27cm) of ice can reduce aircraft lift by 50%. As Captain Airclues already stated, the strong convective currents of a cumulo-nimbus cloud develop the large super cooled droplets at those very low temperatures. While an icing layer in the winter may be only about 3,000 or 4,000 feet thick, in cumulo-nimbus the layers may be 20,000 feet in thickness. The freezing level of these convective clouds will be about 15,000 to 18,000 feet AGL and if the cloud top is near 40,000 feet, there is a freezing layer of 20,000 feet or greater.
From an article published in Professional Pilot by Norman Schulyer.
From an article published in Professional Pilot by Norman Schulyer.
For the laymen and amateurs out there:
It is clearly stated on our Flight Ops. Manual that after the holdover time for a given temp and precip. condition has elapsed (for one-step or two-step de-icing process), a uniformed crewmember, who is current on the same type of aircraft, can look at the top/leading edge of a wing and if clearly visible (often not enough light), he/she can try to determine whether any precip. has begun to freeze. If any surface condition is in doubt, you return for more de-icing, especially for the two-step process, which has a longer holdover time.
One-half inch of ice is far too much.
Research has proven that even particles as small as medium-grit sandpaper can increase the stall speed a significant amount.
Aircraft with no slats, such as the Fokker 28, DC-9 (-10 series) and CRJ are even more at risk from just "a little ice".
If in doubt, check the NTSB website.
The ATR-42 (American Eagle) turboprop was re-certified after a planeload of passengers and crew smashed into the ground in Roselawn, IN.
Before this tragedy, the US FAA had "allegedly" been notified of serious problems with European ATR-42 aircraft in icing conditions: these experienced 'aileron snatch'-but the FAA "allegedly" did nothing about it until body parts lay on the frozen ground in Indiana.
It is clearly stated on our Flight Ops. Manual that after the holdover time for a given temp and precip. condition has elapsed (for one-step or two-step de-icing process), a uniformed crewmember, who is current on the same type of aircraft, can look at the top/leading edge of a wing and if clearly visible (often not enough light), he/she can try to determine whether any precip. has begun to freeze. If any surface condition is in doubt, you return for more de-icing, especially for the two-step process, which has a longer holdover time.
One-half inch of ice is far too much.
Research has proven that even particles as small as medium-grit sandpaper can increase the stall speed a significant amount.
Aircraft with no slats, such as the Fokker 28, DC-9 (-10 series) and CRJ are even more at risk from just "a little ice".
If in doubt, check the NTSB website.
The ATR-42 (American Eagle) turboprop was re-certified after a planeload of passengers and crew smashed into the ground in Roselawn, IN.
Before this tragedy, the US FAA had "allegedly" been notified of serious problems with European ATR-42 aircraft in icing conditions: these experienced 'aileron snatch'-but the FAA "allegedly" did nothing about it until body parts lay on the frozen ground in Indiana.
Last edited by Ignition Override; 22nd Mar 2006 at 00:52.
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A few years ago we had an aircraft that was mistakenly de-iced with hot water. The cabin crew noticed that icicles had formed as the aircraft taxiied to the holding point, informed the captain and perhaps saved the day. Failure to confirm that the airframe was clean was one of the many error made by the crew of the 737 that hit the Potomac bridge. After a de-ice I always have the wings checked by a flight deck crew member before take-off.
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Brain, I had a small exec jet de-iced at your home base, the guys there did a great job, there was one guy under instruction and they must have used as much fluid as you would on one of your big birds. He even did under the wing, which was nice
I was stood outside watching I got covered as well as the aircraft, the pax had to walk through the stuff so the carpet inside got de-iced too.
Somone once said that no matter how much it costs to de-ice an aircraft its still cheaper than crashing.
I was stood outside watching I got covered as well as the aircraft, the pax had to walk through the stuff so the carpet inside got de-iced too.
Somone once said that no matter how much it costs to de-ice an aircraft its still cheaper than crashing.