Airplane brakes: Everything about how an aircraft stops

Airplane brakes: Everything about how an aircraft stops

We’re all used to using brakes in our cars, motorbikes, or bikes, but have you ever wondered how a commercial airplane brakes?

Imagine a plane weighing over 70 tons landing at almost 300 kilometers per hour. Stopping this massive machine requires a highly efficient and powerful braking system, capable of reducing speed of aircraft safely and in a controlled manner.

That’s why aspiring pilots, during the process of learning how to land, need to learn how airplane brakes work, the different types used, the auxiliary systems that ensure effective braking, and the calculations pilots make before landing. And that’s exactly what we’re going to explain here. Are you in?

What kind of brakes do airplanes use?

Like cars, airplanes mainly use disc brakes, although there are other types, like drum brakes, which are more common in general aviation.

Disc brakes

They work by creating friction between two metal discs, which slows the plane down.

They’re very effective because they dissipate the heat generated during braking well, which is crucial for stopping a plane on the ground at high speeds.

Drum brakes

They work when a shoe rubs against a rotating drum.

Although they’re simpler, they’re less common in commercial aircraft because they don’t dissipate heat as well as disc brakes.

The choice depends on several factors, such as the type of aircraft and its needs.

And what types of aircraft disc brakes are there?

Within disc brakes, there are two main materials: steel and carbon. Each has its pros and cons that affect braking.

Steel brakes

They’re robust and durable, but heat up faster due to their high density.

To avoid overheating, it’s recommended to brake more often and with less intensity.

This means that during the braking phase, pilots apply pressure on the brakes several times, rather than maintaining a constant pressure, which helps to dissipate heat and prevent damage.

Carbon brakes

They’re more expensive but more thermally efficient. They withstand higher temperatures without losing effectiveness.

Therefore, pilots can brake for longer and less frequently.

This type of brake is common on larger aircraft and those operating in more demanding conditions, as its ability to dissipate heat allows for optimum performance even in extreme situations.

Brake systems in airplanes

An airplane’s braking system isn’t just the brakes themselves. There are several auxiliary systems that ensure efficient and safe braking.

Antiskid

It works like ABS in cars. It monitors the rotation speed of each wheel, preventing them from locking up when braking. If a wheel skids, it reduces the braking pressure on that wheel so it can rotate again and maintain control. It’s crucial on wet or slippery runways.

Autobrake

It activates when touching down with the power levers at idle. Pilots adjust its intensity based on the conditions. It’s useful for smooth and controlled braking, like on wet or short runways. It distributes pressure evenly among the wheels.

Brake Fan

Brakes get very hot when landing. Brake fans activate after landing to cool them down quickly. They’re essential in operations with short turnaround times. They improve safety and efficiency.

What problems can arise during aircraft braking?

Although airplane brakes are very reliable, problems can arise. Knowing them is key for pilots and mechanics.

What happens if an aircraft declares Hot brakes?

One of the most common problems related to aircraft braking is the situation known as hot brakes. This occurs when the brakes overheat due to excessive use or emergency braking. Hot brakes can cause a decrease in braking efficiency and, in extreme cases, can even cause damage to brake system components.

When an aircraft declares hot brakes, it is essential that the aircraft remains on the ground until the brakes cool to safe levels. Maintenance technicians often use external fans or even jets of cold air to speed up the cooling process. In some cases, if the brakes are extremely hot, it may be necessary to check the condition of the brake discs and pads before the aircraft can resume operation.

In addition, pilots should exercise caution when parking the aircraft after a landing where the brakes have overheated. Parking in areas with combustible materials, such as grass or hot asphalt, could increase the risk of fire. For this reason, it is recommended to park in designated areas where the risk of fire is minimal and where cooling of the brakes can be better controlled.

Braking calculations in airplanes

Before each landing, pilots must perform precise calculations to determine the required braking distance. These calculations ensure that the aircraft can stop safely within the limits of the available runway.

Several factors influence these calculations, including the weight of the aircraft, the landing speed, wind conditions, and the condition of the runway, such as whether it is wet or dry.

Braking calculations are performed using tools such as the Electronic Flight Bag (EFB), a device that provides pilots with the information needed to perform these calculations accurately. The EFB takes into account all of the above factors and calculates the estimated braking distance, allowing pilots to adjust the approach speed and select the appropriate autobrake level.

In addition to the braking calculations, pilots must also consider the possibility of ‘emergency braking’, in case something goes wrong during landing. This includes the need to calculate additional margin distance in case the brakes do not work as expected, or if the anti-skid system is inoperative.

Airplane braking: Here’s how it works

The braking procedure of an aircraft begins even before the wheels touch the runway. During the final approach, pilots must slow the aircraft to a safe landing speed. Once the aircraft touches the ground, several systems are automatically activated to ensure that the aircraft comes to a safe stop.

First, the autobrake system begins to apply brake pressure in a controlled and gradual manner. At the same time, the aircraft’s wing flaps are deployed, which help reduce lift and ensure that the weight of the aircraft is fully transferred to the wheels, thus improving braking efficiency.
As the aircraft decelerates, the antiskid system continuously adjusts the braking pressure on each wheel to prevent slippage. On aircraft with brake fans, these are activated once the aircraft’s speed has been sufficiently reduced, helping to dissipate the heat generated during braking.
Finally, when the aircraft has slowed down sufficiently, pilots can disengage the autobrake system and take manual control of the brakes to guide the aircraft towards the landing gate. This procedure ensures that the aircraft can come to a safe and controlled stop, regardless of runway or weather conditions.

The latest in airplane brakes

As everything in commercial aviation, braking technology in airplanes is constantly evolving, with new developments in software and brake systems that improve safety and operational efficiency.

Aircraft manufacturers are investing in lighter and more efficient braking systems, which not only improve performance but also reduce overall weight, which in turn reduces the plane’s fuel consumption.

Software-assisted brake systems

These systems use advanced algorithms to adjust braking pressure in real-time, taking into account factors like the plane’s speed, brake temperature, and runway conditions. This not only improves safety but also allows for smoother and more controlled braking, reducing wear and tear on the brake system components.

New friction materials

Developed for brake discs, these materials are designed to dissipate heat more efficiently. This is especially important in modern aircraft that operate on routes with frequent landings, where the brakes need to be in optimal condition at all times.

Now you know how an airplane stops!

As we’ve seen, the process of stopping an airplane is much more complex than we might imagine. From the different types of brakes and materials used to the advanced auxiliary systems like antiskid and autobrake, each component plays a crucial role in ensuring the plane can stop safely after landing.

Next time you’re on a landing plane, you’ll be able to appreciate the whole process happening behind the scenes.

If you’re curious and want to keep reading interesting facts like this, check out our aviation blog! We’ll be waiting for you!

Airplane brakes: Everything about how an aircraft stops