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Ice Bridging-Myth or Reality?

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Well-known member
Jul 1, 2004
I was flipping through the new AOPA mag. and noticed an aritcle on icing which stated "researchers have learned that ice bridging is a myth." Maybe the researchers weren't ever able to produce bridging in a controlled enviornment, but I've seen and experienced it first hand on the E-120. The wings were OK, but after landing I noticed the whole tail had a "Bubble" of ice where the boots had been inflating & deflating. I wish I'd had a camera for that one. I don't care what the FAA says, I've seen it and wonder if any of you have similar stories?
Its true -FAA says its rare or not worth worrying about. Supposed to turn on the boots at first sign of ice.
Bullsh!t.... I've seen it happen.
I've seen it as well in the Beech 1900. Blowing the boots at the first sign of ice is about the worst possible thing to do in this airplane. Maybe it varies from model to model, but as blanket advice, that's dangerous.
Yea, when I was at Commutair... many of the captains would bug the airspeed at cruise! Once you started seeing the speed drop 10-20kts you would slap the boots on... and watch the speed increase again. It was pretty cool to watch. I still use that techn. at PDT in cruise with moderate icing, even with everthing done automatic in the Dash, it nice to keep an eye on that speed in cruise.
I think ice bridge depends on factors of type of ice, accumulation time,... But I think with most of the newer boots its not a real factor anymore! Atleast not in the Dash 8. Beside the 1900D (Which is a man child in ice... Its boots are great, and the plane has some powerful engines. I have landed with that thing looking like a glazed doughnut) the dash handles ice really well.
Pneumatic boots are not an anti ice measure, they are a de-ice method. Engines, props and windshields are supposed to be on continuously. Unless you have mass quantities of bleed air or TKS fluid, wings and tails off untill you have a build up. Thats what the manufacturer recommends. The people that built it have precedence over what the feds say.
The two post that precede the one am writing now pretty much sum it up. Also, keep in mind the FAA icing tests used SLD of a much smaller size than we typically see in real life.
On the Brasilia the FAA and Embraer require the boots to be on while in icing conditions. Many tests were done on the EMB-120 after various crashes and incidents because people were doing this exact thing, waiting to let the ice buid up. That is what killed them. The test determined that as soon as you enter icing conditions you turn the boots on and leave them on as they automatically cycle. There have been hours and hours of testing done on this type of thing by trained test pilots and professionals. Don't let some anecdotal evidence convince you otherwise. Any residual ice that remains is either insignificant or will shed itself soon. Ice bridgeing originates in the DC-3 era airplanes where the boots took a long time to inflate and did so under low pressure. Modern transport category aircraft have quick inflating boots at high pressure so ice bridgeing isn't an issue. If you are in severe icing conditions and still losing airspeed and performance with the boots on you are in SLD (supercooled large droplets) and you need to exit immediatly. Don't confuse that with ice bridgeing.

This exact thing contributed to the ATR 72 crash in Roselawn. I have pictures from the NTSB that showed ice bridging on the defective system that the ATR's use to use. Additionally, the ATR accident was also caused by formations of ice behind the effective area of the boots. The ice eventually built up to a point that the boots couldn't clear the ice on the leading edge and bridging occurred. So you guys are correct, it can and does accrue!

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