As a former de-icer in STL, I will be the first to tell you it gets really, freakin' cold doing that job..... Suspended up about 40 feet in the air with the cold air whipping around your body, the sweet taste of the glycol in your mouth....YUCK!!!!!!!!! I've also had one catch on fire while I was fully extended in the boom......NOT FUN!!!!!!!

--- --- --- --- --- --- --- --- ---

Replying to:

How does De Icing work?



Spraying down the surfaces of a jet to remove the ice is just one step in a complex de-icing process.

Step two is anti-icing, to keep the frozen stuff they just washed off from building back up as the plane sits in the snow/sleet/freezing rain/freezing fog, waiting to take off.



Both steps use fluids that contain glycols, chemicals that have a lower freezing point than water.

De-icers use either ethylene glycol or propylene glycol in a 50-50 mix with water, heated to 180 degrees Fahrenheit, and sprayed from a power hose onto the plane. The heat and powerful spray do some of the de-icing work. But the key is glycols, which reduce freezing points to as low as 60 degrees below zero Fahrenheit.



After spraying the de-icing fluid on the plane,the “holdover time” during which the plane stays clean is only 6 to 15 minutes, depending on weather conditions. So sometimes a second step, called anti-icing, in which they spray the plane with a mix of glycol and other substances called non-Newtonian fluids. Which is a fancy name for fluids too thick to run by themselves. Ketchup and honey, for example, are non-Newtonian fluids.

The thicker fluid stays on the plane longer and lets the glycols keep things from refreezing while the plane is waiting. Holdover time after a step-two anti-ice “treatment” can be as much as 80 minutes, depending on the specific fluid used and the weather conditions.



Usually the thicker anti icer is sprayed only on the critical control surfaces of the plane: the wings — which are colder because they have the fuel tanks inside — and the tail.

Non-Newtonian fluids designed for anti-icing have special advantages. They have the unique ability to change viscosity when confronted with aerodynamic forces acting on the fluid. When the plane speeds up for takeoff, the force of the wind on the fluid makes it get thinner, and it drips right off the plane. By the time the plane passes 130 knots, the fluid is gone, the plane’s surface is clean, and takeoff — at speeds of 150 to 180 knots for your average jetliner — is completely safe.



By the way, you can tell the de-icers and the anti-icers apart by their color. The step-one fluids are pinkish. The step-two fluids are greenish.



Perhaps you’ve heard questions raised about the environmental impact of airplane de-icing and anti-icing fluids. It’s true that glycols consume oxygen when they get into aquatic ecosystems — oxygen required by the critters living in the water. But these fluids biodegrade quickly. In five days, they’re 70 percent gone. After 20 days, they’re 96 percent gone.



In-flight ice

is removed with engine heat or by inflating rubber bladders, called pneumatic boots, installed along the wings

The SmartBoot developed by BF Goodrich Aerospace in Uniontown, Ohio, has a magnetostrictive system that determines when the pneumatic boot should be activated. A coil inside a probe vibrates ultrasonically; as ice builds up, the probe’s vibrational frequency decreases. The SmartBoot is the primary ice-detection system in all Boeing aircraft.

Jenny