How And Why Planes Are De-Iced Before Takeoff

by SharonKurheg

If you have winter where you’re traveling from, de-icing a plane can become a frequent part of the air travel journey.

There are some experts out there who probably know about every aspect of de-icing. To those of you reading this, I tip my hat. However, for those who are just regular flyers and know about as much as me about de-icing a plane (‘something something gets the ice off the wings of the plane so it doesn’t crash something something’), this might be a good lesson. 😉

The basic knowledge that us “non-experts” have is pretty much what I said – if there’s ice (freezing rain, or even snow, which can turn to ice) on the wings, it can disrupt airflow, which will affect the plane’s lift. And before you ask, from NASA:

Lift is the force that directly opposes the weight of an airplane and holds the airplane in the air. Lift is generated by every part of the airplane, but most of the lift on a normal airliner is generated by the wings. Lift is a mechanical aerodynamic force produced by the motion of the airplane through the air.

So in the simplest terms, ice will mess up the lift, which is the aerodynamic force that helps keep the plane in the air. Ergo, having ice on the plane (especially on the wing) is bad and it needs to be removed before take-off.

De-icing (or deicing, although de-icing appears to be the preferred spelling, according to Professor Google) is the process of removing ice from the plane. There’s also another step, called anti-icing, which may also be required to, you guessed it, stop ice from reforming once it’s been removed. I’ll get to that in a minute.

De-icing agents vary based on weather conditions, but whatever the case, they always include glycol and water. Know what else uses glycol and water? Antifreeze in your car. Surprise!

Anyway, the pilot is the one who makes the decision if the plane should be de-iced or not. After making the call, (s)he’ll usually bring the plan to the area of the airport where de-icing occurs (no sense in leaving the gate occupied). (S)he will then also oversee the process, which has to be done exactly as the FAA says (the FAA rule book has a whole chapter, 30+ pages long, just about de-icing a plane. It goes into what it’s made of, how to handle it [I bet there’s stuff about OSHA in there], how fast it has to be applied, and the documentation that has to be done after a plane has been de-iced).

The wings are the most important part of the plane to be de-iced, but the de-icing agent often also has to be applied to the tail, fuselage, engine inlets and fan blades, control surfaces and gaps, landing hear (and landing gear door), antennas and sensors, and/or propellers. The ground crew and flight crew work together to decide which surfaces need to be de-iced, and, based on weather conditions and temperature, the best procedure to do it.

Here’s what de-icing looks like:

De-icing generally only works on the ice that’s on the plane at the moment. If it’s suspected that ice will re-form (i.e. if it’s snowing, sleeting or there’s freezing rain while the plane is being de-iced), the decision may be made to anti-ice the plane after it’s de-iced. Anti-icing agents are also made of glycol and water, but usually has more glycol in it than de-icing agents do. They also usually have a thickener incorporated to help the stuff adhere to the plane.

The FAA recommends that anti-icing agents be applied within three minutes of de-icing. Anti-icing agents shouldn’t be applied at all if the deicing fluid has frozen or if frost has reformed on the plane. If either of those happens, the plane has to be de-iced again before it can be anti-iced.

A single round of de-icing or anti-icing can last from 10 to 30 minutes, depending on weather conditions. Tell that to your connection in Atlanta. 😉

When applied, most of the de-icing fluid doesn’t adhere to the aircraft surfaces; it falls to the ground. Airports typically use containment systems to capture the used liquid, so it doesn’t get a chance to seep into the ground and watercourses (even though the materials they use in de-icing agents are classified as non-toxic, it pollutes waterways since it consumes large amounts of oxygen as it decomposes. This, in turn, cause aquatic life to suffocate. So they try to not get it into the waterways or groundwater).

Anyway, once the plane is in the air, it has its own systems to keep ice from forming on it. Even in the summer, the temperature at 35,000 to 40,000 feet is below freezing, so commercial planes always have systems to keep the wings warm via hot air generated by the engines. It just doesn’t work while the plane is on the ground.

References: CNN, Delta, the FAA, Jalopnik, NASA, Southwest, Wikipedia

Feature Photo (cropped): Nicholas Hartmann / Wikimedia

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This post first appeared on Your Mileage May Vary

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