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Sometimes you’ll see a plane getting de-iced, but sometimes you might not see it being sprayed with anything. When do planes need to be de-iced?

Ideally, planes will be de-iced and anti-iced as close to takeoff as possible to prevent more snow and ice from building up while the plane is grounded. If it’s just a buildup of frost, the process might only take 5-10 minutes to complete. During more severe weather, it can take 10-60 minutes.

There are all sorts of things about planes that many people don’t know much about, including the process of de-icing. Sometimes planes will get de-iced, sometimes they won’t. In this article, you’ll get a quick refresher on why planes need to be de-iced in the first place, what de-icing is, when planes have to be de-iced, who makes the decision on whether or not a plane needs to be de-iced, and more.

We strive to provide our readers with the most helpful content that they’ll find anywhere on the web. To make sure everything we publish is accurate, all the information in our articles is thoroughly vetted and is the culmination of research, discussion, and more. We take input from not only ourselves but others in the industry as well such as pilots and other aviation experts. This way, we are able to provide you with the full picture so you know everything there is to know about when places need to be de-iced.

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What is De-Icing & Why Do Planes Have To Do It?

Before we can get too deep into when planes have to be de-iced, it’s important that you have a better idea of what de-icing is and why planes have to do it in the first place. While we do have a full-length article written on these very topics here, I’ll give you a quick rundown here so you have an idea of what you’re reading about in this piece. But for more detailed information about airplane de-icing, make sure you check out our other article!

So let’s start with what airplane de-icing is.

As you might be able to guess from the name itself, airplane de-icing is the process of removing ice and the buildup of other types of frozen precipitation (i.e. snow, frost, slush, etc.) from the surface of the plane. This is done to ensure the aerodynamics of the aircraft and is essential for safe flight. Along the same line, another process known as anti-icing is done to prevent the buildup of ice and snow in the first place.

While there is certainly much more to the de-icing and anti-icing processes, that should give you a general idea of what you’re seeing when you catch sight of the airplane being vigorously sprayed. But why do planes have to be de-iced and anti-iced? I very briefly mentioned the aerodynamics of the aircraft above, but it’s a little bit more involved than that.

The reason that a buildup of ice and snow can have such an effect on the performance of the aircraft is because of the way that airplanes fly in the first place. In very layman’s terms, planes fly because of the lift generated by the wings. The shape of the airplane’s wings — known as the airfoil — is arguably the single most important design feature of an airplane.

Its unique shape causes air to move faster over the top and slower under the wing, creating a difference in pressure. These pressure zones enable lift to be generated and bring the plane off the ground. Without the removal of this buildup, the airflow can be significantly altered which can really affect the ability of the airplane to fly.

When Do Planes Have To De-ice?

So now that you have an understanding of what de-icing is and why it’s so necessary, let’s get into the when.

It’s important to de-ice an airplane at the proper time to make sure that the process actually does what it’s designed to do. For example, if an airplane is going to be grounded for a while before its next flight, there isn’t really any point in going through the de-icing and anti-icing processes as soon as it lands. While it’s grounded for the next few hours, the de-icing will be over with and the anti-icing chemicals will have worn off.

At that point, depending on the weather conditions at the location of the airport where the plane is grounded, it can just be covered in snow and ice again. So planes typically are not de-iced when they land, since it’s much more dependent on when the plane is going to take off. So if it’s based on the plane’s departure time, when should ground crews start the process of de-icing to make sure there is as little delay as possible.

Well, that really depends on what type of accumulation they’ll be removing from the plane and whether or not they’ll need to apply the anti-icing spray as well. If it’s just a buildup of frost and anti-icing is not needed, the process only takes around 5-10 minutes for most types of planes. So if that’s the case, the crews will usually start around 10-15 minutes before boarding begins. Although the process is safe for passengers, the crews typically prefer to de-ice before boarding when possible.

In an actual snow and winter weather event, the de-icing and anti-icing process takes much longer. Depending on how heavy the precipitation is, whether it’s just snow or also sleet and freezing rain, and also the temperature, it can take anywhere from 10 minutes up to an hour or longer. In these cases, the crews will typically de-ice and anti-ice the aircraft while the passengers are boarding or have already boarded since they don’t want more accumulation to occur during and after the boarding process.

Sometimes, especially during severe weather, the de-icing and anti-icing processes may cause the departure time to be delayed. While this may be frustrating for all the passengers (and even the crew) on board, it’s a small price to pay for the safety of everyone on board. And since the flights might be delayed, which can always potentially have a domino effect, who has the authority to make the decision on whether de-icing is even necessary or not?

Who Makes The Decision To De-ice?

In most instances, de-icing necessity is designated by guidance from the Federal Aviation Administration (FAA). In addition to following any and all guidelines outlined in the Federal Aviation Regulations (FAR), de-icing procedures are also often outlined by airlines for their specific aircraft. While FAA regulations will always trump airline procedures, airlines are able to offer additional guidance and restrictions on de-icing for their own aircraft at their discretion.

To offer more layers of security since we’re talking about the safety of the aircraft, crew, and passengers, certain people are allowed to hold departure if the aircraft either wasn’t de-iced at all or even if it wasn’t done properly. The dispatcher controlling the traffic at the airport can hold an aircraft from taking off if they believe it has not been properly de-iced. Similarly, if the pilot believes the plane needs to be de-iced, then they can also refuse to depart until it’s done.

Can Planes De-ice While Flying?

Although as passengers, you’ll typically only ever see the de-icing process happening on the ground when the airplane is being prepped for flight at your gate, that’s not the only time that ice prevention systems and processes are used. Interestingly enough, many modern aircraft actually have onboard systems that are able to be used during flight to help remove and/or prevent the buildup of ice while flying.

By far the most common type of onboard de-icing (maybe more aptly, anti-icing) is deployed by the pilot to prevent ice from building up in the first place. This type of system uses heated airplane parts, especially the leading edge of the wings, to prevent snow and ice from starting to accumulate. The leading edges of the wings are the most ideal locations for heating because if that edge stays warm and doesn’t ice up, the rest of the wing will follow suit and stay relatively ice-free.