the reason to de-ice
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OK Feherto, since you asked, here's a brand new thing for you to know: de-icing fluid that is not also rated as an anti-icing fluid is not only very common, but it is what we use 99% of the time.
There's a technical reason, as well as practical and commercial considerations - the thickened fluids that are intended to shear away during the takeoff roll cannot be used on aircraft that get airborne at lower speeds (like piston, turboprop, or light jet aircraft) because they don't break away before rotate speed.
Instead we use a de-icing fluid - Kilfrost RDF brand if you want to get some - which removes any deposits very succesfully, but does not adhere to the airframe, and therefore has NO hold-over anti-icing capabilities.
The practical effect is that if is is actually snowing at any non-trivial rate, we need to wait for it to stop before we can depart. It's not as restriciting as you might think, especially if the airport allows us to hold near the departure point for de-icing - we only need it to stop snowing for about 90 seconds to jump in and go.
There's a technical reason, as well as practical and commercial considerations - the thickened fluids that are intended to shear away during the takeoff roll cannot be used on aircraft that get airborne at lower speeds (like piston, turboprop, or light jet aircraft) because they don't break away before rotate speed.
Instead we use a de-icing fluid - Kilfrost RDF brand if you want to get some - which removes any deposits very succesfully, but does not adhere to the airframe, and therefore has NO hold-over anti-icing capabilities.
The practical effect is that if is is actually snowing at any non-trivial rate, we need to wait for it to stop before we can depart. It's not as restriciting as you might think, especially if the airport allows us to hold near the departure point for de-icing - we only need it to stop snowing for about 90 seconds to jump in and go.
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Just to add some further information for CJ Driver and others. It is important to check with the airframe manufacturer which fluids are approved for use on each particular a/c type. Most manufacturers approve the use of Type I, II, III or IV fluids. All are de-icing and anti-icing fluids depending on mixture strength used and OAT / wing temperature.
It might be intesting to see if your brand Kilfrost RDF is approved for use as Type I, II, III, IV fluid or if it is approved for use on your airframe. You would then see if it is a de-icing or anti-icing fluid.
It might be intesting to see if your brand Kilfrost RDF is approved for use as Type I, II, III, IV fluid or if it is approved for use on your airframe. You would then see if it is a de-icing or anti-icing fluid.
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Kilfrost RDF (Rapid De-icing Fluid) is a cold de-icing fluid, often used on GA aircraft. It doesn't meet SAE AMS 1424 (Type I fluid) or SAE AMS 1428 (Type II, III and IV fluid), so wouldn't be approved for use on most commercial aircraft.
Technically it would only be considered as being a de-icing fluid, as it offers no anti-icing protection.
Technically it would only be considered as being a de-icing fluid, as it offers no anti-icing protection.
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Its now the season for de-cing and I have been reading with interest all the good stuff that reminds pilots how icing on wings on the ground can ruin your day.
From a ground up perspective, there are plenty of problems that you should also be aware of even before the fluid exits the gun.
Fluid exit temperature should be 85deg C at the gun.
You loose about 10 degrees /metre as the fluid travels from gun to surface.
Ideal spaying distance based on a 45 degreee gun angle of attack is about 1.1m. Double that you loose more temperature and use a 33% more fluid to do the same job.
In some de-icers sytems, the supply pump can 'shear' the fluid ( render it chemically useless)
Its worth paying attention to the de-icer vehicle, system and the operator to minimise the risk of not getting getting what it says on the side of the vehicle.
From a ground up perspective, there are plenty of problems that you should also be aware of even before the fluid exits the gun.
Fluid exit temperature should be 85deg C at the gun.
You loose about 10 degrees /metre as the fluid travels from gun to surface.
Ideal spaying distance based on a 45 degreee gun angle of attack is about 1.1m. Double that you loose more temperature and use a 33% more fluid to do the same job.
In some de-icers sytems, the supply pump can 'shear' the fluid ( render it chemically useless)
Its worth paying attention to the de-icer vehicle, system and the operator to minimise the risk of not getting getting what it says on the side of the vehicle.
Last edited by falcon12; 19th Oct 2009 at 13:55. Reason: missed an important word
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Get it off!!
Excrab - Excellent post regarding experience v vulnerability.
For the rest of us, think about this...
How many aircraft have departed uneventfully following unsuccessful De/Anti icing?
Nearly got caught out by clear icing last year after our De-icing crew signed off wings that were contaminated with re-frozen De-icing fluid/water for reasons mostly associated with a typical early morning winter departure.
Thankfully we did not, therefore, add ourselves to the history books as another Birmingham swept wing icing stall event at rotation.
The usual precursors will be lurking again this winter. So if you can't see it(the aerofoil), assume its contaminated and get it off. And assure the boss you wont fly until he/she has double checked even if it's F***** bitter outside on the ramp.
Because clear ice does not advertise itself with sparkly gems atop the fuselage or a dusting of snow on the ramp. Find somewhere on the aircraft that has a cold soaked upper surface and put your HAND ON IT. You can even call out the guys on the rig and get THEM to do it. Do not be fobbed off with iffy flashlights, no access platforms, pushy despatchers.
Verify its absence.
If you do not, you might depart successfully but it is worth considering that there is little, if any, data available on near misses for aerofoil icing, nor will there be any evidence of your's.
And finally, De/anti Icing is not maintenance. It is entirely the responsibility of the operator to assure the necessary measures are in place to permit freedom from contamination before every flight. The last link in the chain here is the crew.
Happy winter
For the rest of us, think about this...
How many aircraft have departed uneventfully following unsuccessful De/Anti icing?
Nearly got caught out by clear icing last year after our De-icing crew signed off wings that were contaminated with re-frozen De-icing fluid/water for reasons mostly associated with a typical early morning winter departure.
Thankfully we did not, therefore, add ourselves to the history books as another Birmingham swept wing icing stall event at rotation.
The usual precursors will be lurking again this winter. So if you can't see it(the aerofoil), assume its contaminated and get it off. And assure the boss you wont fly until he/she has double checked even if it's F***** bitter outside on the ramp.
Because clear ice does not advertise itself with sparkly gems atop the fuselage or a dusting of snow on the ramp. Find somewhere on the aircraft that has a cold soaked upper surface and put your HAND ON IT. You can even call out the guys on the rig and get THEM to do it. Do not be fobbed off with iffy flashlights, no access platforms, pushy despatchers.
Verify its absence.
If you do not, you might depart successfully but it is worth considering that there is little, if any, data available on near misses for aerofoil icing, nor will there be any evidence of your's.
And finally, De/anti Icing is not maintenance. It is entirely the responsibility of the operator to assure the necessary measures are in place to permit freedom from contamination before every flight. The last link in the chain here is the crew.
Happy winter
Last edited by darkbarly; 25th Oct 2009 at 20:58. Reason: reference
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Darkbarley, You are correct, the responsability rests ultimatly with the commander of the aircraft. However, in many situations, the inspection is delegated to a specific trained individual who will supervise from outside after doors closed, or even in some cases, after taxi. This was the case in the situation I mentioned earlier, and that is why the said individual lost his job.
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And no not kill me for this statement, it is true: Pilots of business jet operators or corporate flight squads are the ones with the lowest knowledge
After a decade of de-icing aircrafts, i may finally have cracked the key to the Commercial Pilots Dictionary for Ground De/Anti-icing:
- Clean Aircraft Concept: Why aircrafts are washed and polished every now and then.
- Clear Ice: OhmygodOhmygodOhmygod!!
- De-icing Coordinator: Some rookie nitwit who has no clue about de-icing(even if he has as many sucessfully de-iced aircrafts in his belt as you have flighthours).
- Frost: No worries, it'll blow off...
- Holdovertime: The time it takes to have the aircraft treated, lined up, and airborne.
- Ice: No worries, it'll blow off...
- Lowest Operational Use Temperature: The fluids aren't hot enough.
- Snow: No worries, it'll blow off...
The best PIC's i know of, are those than can admit that they are no experts in Ground De/Anti-icing, and might i add that they are few and far between...
OK Feherto, since you asked, here's a brand new thing for you to know: de-icing fluid that is not also rated as an anti-icing fluid is not only very common, but it is what we use 99% of the time.
Instead we use a de-icing fluid - Kilfrost RDF brand if you want to get some - which removes any deposits very succesfully, but does not adhere to the airframe, and therefore has NO hold-over anti-icing capabilities.
For the rest of us, think about this...
How many aircraft have departed uneventfully following unsuccessful De/Anti icing?
How many aircraft have departed uneventfully following unsuccessful De/Anti icing?
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As a lowlife execetive pilot I may have not a clue, but I (my airplane that is) have been deiced by total prats with no clue and worse, with a distinct tendency to sqander high expensive fluids thus betraying us. I've seen to low a temperature set to the heater on the truck, I have seen falsified records on fluid counters. I have had clashes with a deicer crew because I stepped out of the airplane and checked it over. (for delaying the following ops). Iīve had an APU compartment filled with fluid despite distinct instructions supplied (as a drawing) not to.
I have flown with a a fellow pilot that wanted us to deice only the left side of the airplane because that is what the client sees. I have seen pilots fill their wheel wells with snow on taxi and then not understand why the gear wonīt retract completely and leave the hydraulic pressure on and thus damage the hydraulic system.
Point: the de Icer crews are as human as we pilots are. But we die if we are to stupid to understand what contamination does to our airplanes.
Thus knowing this area of operation is crucial.
What I donīt get, is that no 2 airports do have the same set of procedures, that often you canīt get any info on which fluids are used, thus leaving us with very little info. I have to make up my mind in a rush - something I hate.
I have flown with a a fellow pilot that wanted us to deice only the left side of the airplane because that is what the client sees. I have seen pilots fill their wheel wells with snow on taxi and then not understand why the gear wonīt retract completely and leave the hydraulic pressure on and thus damage the hydraulic system.
Point: the de Icer crews are as human as we pilots are. But we die if we are to stupid to understand what contamination does to our airplanes.
Thus knowing this area of operation is crucial.
What I donīt get, is that no 2 airports do have the same set of procedures, that often you canīt get any info on which fluids are used, thus leaving us with very little info. I have to make up my mind in a rush - something I hate.
I recollect at a European airport being uncertain whether the droplets on the upper surface of the wings was ice or liquid.
"Sorry, no way of getting up there to check."
Bas: "Well I've plenty of time to wait, park on your stand and have a coffee whilst we decide what we're going to do with our passengers."
"Ah, there's a set of trolley steps which will do." "What? You want to go up there yourself, captain?"
Bas: "I certainly do."
As it turned out, it was liquid. Totally irrelevant. I'd still do the same thing under the same circumstances.
As PIC you are not in a popularity contest; it's either your way or the highway. Don't be fobbed off. You are the one who will be die or be fired if it goes wrong.
"Sorry, no way of getting up there to check."
Bas: "Well I've plenty of time to wait, park on your stand and have a coffee whilst we decide what we're going to do with our passengers."
"Ah, there's a set of trolley steps which will do." "What? You want to go up there yourself, captain?"
Bas: "I certainly do."
As it turned out, it was liquid. Totally irrelevant. I'd still do the same thing under the same circumstances.
As PIC you are not in a popularity contest; it's either your way or the highway. Don't be fobbed off. You are the one who will be die or be fired if it goes wrong.
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TO CJ DRIVER:
Kilfrost RDF is not an approved de-icing/anti-icing fluid, either by FAA nor by Transport Canada. So what you are talking about ? That you let the ground crew spray a product on your wings, which is not qualified by any authority. This applies not only for commercial airliner. I suggest you contact the FAA guy in the Tech Center responsible (I can give you the contact details, he is a friend of mine for 15 years).
It is useless to discuss with you, as you believe that a private flyer has to be treated different as a big commerical airliner. Exactly this is the reason, why so many crash of you or have incidents.
I am one of the people working on the fluid specs as acknowledged by the industry (SAE AMS 1424 and AMS 1428). You shoudl have a look on them that you understand what means de-icing/anti-icing fluid, especially what a qualified one is. Also, you will not find this product in the manuals of your aeroplane type.
It is very interesting that you think you have to talk with me like a teacher. I believe that we are talking right opposite.
Kilfrost RDF is not an approved de-icing/anti-icing fluid, either by FAA nor by Transport Canada. So what you are talking about ? That you let the ground crew spray a product on your wings, which is not qualified by any authority. This applies not only for commercial airliner. I suggest you contact the FAA guy in the Tech Center responsible (I can give you the contact details, he is a friend of mine for 15 years).
It is useless to discuss with you, as you believe that a private flyer has to be treated different as a big commerical airliner. Exactly this is the reason, why so many crash of you or have incidents.
I am one of the people working on the fluid specs as acknowledged by the industry (SAE AMS 1424 and AMS 1428). You shoudl have a look on them that you understand what means de-icing/anti-icing fluid, especially what a qualified one is. Also, you will not find this product in the manuals of your aeroplane type.
It is very interesting that you think you have to talk with me like a teacher. I believe that we are talking right opposite.
