De-Icing Boots in flight
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De-Icing Boots in flight
This was taken from the BALPA Log magazine.......Quote....
USE OF De-ICING BOOTS IN FLIGHT
There has been considerable work done since the Roselawn accident in 1994 to understand better the nature of in flight icing. Whilst further efforts continues to be made in accord with the joint US Department of Transportation and the FAA in flight icing plan this work is not yet complete . However reports continue to occur of in flight icing incidents that suggest that crews of turbo prop aircraft might not be aware of the dangers of allowing even small Ice deposits to build up in flight. It now appears to be becoming generally accepted that the practice of not activating the boots untill a good measure of ice has built up is discredited and furthermore has not been valid for very many years. The unfound myth of Ice-Bridging should not be allowed to inhibit crews of turboprop aircraft and other aircraft with boots from ensuring that their ice protection systems are activated as soon as any ice deposits are observered on their aircraft in flight.The tecnical committee dose not intend that this advice should replace conflicting instructions in aircraft or operator manuals, although representations will be made to the CAA to promote the necessary changes in training, procedures and documentation........ un quote
So when do you switch the boots on ?
I was told that if you wait for a loss of airsped of 10 kts the boots might work if you wait for a loss of airspeed of 15 kts they will probabley work but if you wait for a loss of 20 kts they will definitley work. I have always applied this method and have never had problems with ice and whats more have never suffered from premature inflation.
I would be interested to hear other views on boot operations particually with reference to early selection.
USE OF De-ICING BOOTS IN FLIGHT
There has been considerable work done since the Roselawn accident in 1994 to understand better the nature of in flight icing. Whilst further efforts continues to be made in accord with the joint US Department of Transportation and the FAA in flight icing plan this work is not yet complete . However reports continue to occur of in flight icing incidents that suggest that crews of turbo prop aircraft might not be aware of the dangers of allowing even small Ice deposits to build up in flight. It now appears to be becoming generally accepted that the practice of not activating the boots untill a good measure of ice has built up is discredited and furthermore has not been valid for very many years. The unfound myth of Ice-Bridging should not be allowed to inhibit crews of turboprop aircraft and other aircraft with boots from ensuring that their ice protection systems are activated as soon as any ice deposits are observered on their aircraft in flight.The tecnical committee dose not intend that this advice should replace conflicting instructions in aircraft or operator manuals, although representations will be made to the CAA to promote the necessary changes in training, procedures and documentation........ un quote
So when do you switch the boots on ?
I was told that if you wait for a loss of airsped of 10 kts the boots might work if you wait for a loss of airspeed of 15 kts they will probabley work but if you wait for a loss of 20 kts they will definitley work. I have always applied this method and have never had problems with ice and whats more have never suffered from premature inflation.
I would be interested to hear other views on boot operations particually with reference to early selection.
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A very quick word of warning to the above posters: the modern glass cockpit turboprop has a vastly different deicing boot design to the older types.
The older type's design meant that it was essential that a build up of ice was allowed before operation to prevent 'bridging' which most certainly does occur and can render boots totally ineffective. The modern design has interlapped elements in the inflation cycle which breaks ice off irrespective of build up. It is this latter design that is best switched on as soon as ice is detected.
Beware of confusing the two designs and techniques. It can be, indeed has been, fatal.
The older type's design meant that it was essential that a build up of ice was allowed before operation to prevent 'bridging' which most certainly does occur and can render boots totally ineffective. The modern design has interlapped elements in the inflation cycle which breaks ice off irrespective of build up. It is this latter design that is best switched on as soon as ice is detected.
Beware of confusing the two designs and techniques. It can be, indeed has been, fatal.
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Boeing Boy
Spoken like a true ... well, Boeing Boy.
I do agree that it's nice to flog around above it all as much as possible, but I have not forgotten the days when I had no choice but to sit with an ice accumulation far above zero and to pay very careful attention to deicing and anti-icing procedure.
Just trying to be helpful to the young turboprop lads, is all
Spoken like a true ... well, Boeing Boy.
I do agree that it's nice to flog around above it all as much as possible, but I have not forgotten the days when I had no choice but to sit with an ice accumulation far above zero and to pay very careful attention to deicing and anti-icing procedure.
Just trying to be helpful to the young turboprop lads, is all
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tilii
I fly Dash-7's and would be interested in finding out more about this. We have been told to activate the boots as soon as any ice build up is noticed.
Any ideas where I could find out some more info along the lines of your discussion about age and type of boots.
Any info appreciated! Email or on the thread so long as we aren't boring anyone!
[email protected]
Keep the shinny side up!
I fly Dash-7's and would be interested in finding out more about this. We have been told to activate the boots as soon as any ice build up is noticed.
Any ideas where I could find out some more info along the lines of your discussion about age and type of boots.
Any info appreciated! Email or on the thread so long as we aren't boring anyone!
[email protected]
Keep the shinny side up!
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tilii
Thanks for your input I fly The HS 748 and am therefore forced to sit in the Ice layer for longish periods of time and was unaware that there were some boot systems that you could switch on at the first sign of ice. I guess it is these aircraft that the article refers to.
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When the weight of the paper equals the weight of the airplane, only then you can go flying.
[This message has been edited by Night Freight 1 (edited 25 February 2001).]
Thanks for your input I fly The HS 748 and am therefore forced to sit in the Ice layer for longish periods of time and was unaware that there were some boot systems that you could switch on at the first sign of ice. I guess it is these aircraft that the article refers to.
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When the weight of the paper equals the weight of the airplane, only then you can go flying.
[This message has been edited by Night Freight 1 (edited 25 February 2001).]
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tilii
Please quote a definitive source for your assertion that 'bridging' does indeed occur. All the post-Roselawn work that has been done suggests otherwise and that 'bridging' is a myth that has not been true for very many years, if it was ever true at any time. Studies indicate it was probably even a myth in the 'Fate is the Hunter' era.
Please quote a definitive source for your assertion that 'bridging' does indeed occur. All the post-Roselawn work that has been done suggests otherwise and that 'bridging' is a myth that has not been true for very many years, if it was ever true at any time. Studies indicate it was probably even a myth in the 'Fate is the Hunter' era.
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Night Freight
Happy if I helped. I flew that type many long moons ago. Definitely the old technology but never had any problem with ice while flying it.
Rat Catcher
Can't help re the Dash 7. Judging by your training advice, I guess it has the newer technology deicing boot. Suggest you discuss this further with your TRI if you need better understanding.
Sorry Hew
Our posts crossed, wasn't ignoring you. Can't provide what you ask. Can state quite categorically that I have actually seen ice accretion where the boot has been inflating underneath a bridged layer without separation from the leading edge (saw it on the ground after landing when we broke it off) and found the bridged area in the ice which was consistent with the inflated boot shape and not the leading edge.
[This message has been edited by tilii (edited 25 February 2001).]
Happy if I helped. I flew that type many long moons ago. Definitely the old technology but never had any problem with ice while flying it.
Rat Catcher
Can't help re the Dash 7. Judging by your training advice, I guess it has the newer technology deicing boot. Suggest you discuss this further with your TRI if you need better understanding.
Sorry Hew
Our posts crossed, wasn't ignoring you. Can't provide what you ask. Can state quite categorically that I have actually seen ice accretion where the boot has been inflating underneath a bridged layer without separation from the leading edge (saw it on the ground after landing when we broke it off) and found the bridged area in the ice which was consistent with the inflated boot shape and not the leading edge.
[This message has been edited by tilii (edited 25 February 2001).]
