Commercial jets are large passenger planes that carry hundreds or even thousands of passengers at a time.
They are typically larger than private jets and have a longer range. But just how fast do commercial jets travel?
It can be tricky to find this information out and leaves many of us unsure where to turn or who to trust. After all, we want to know how fast we are going to travel before we step on the plane!
Well, today we find out how fast commercial jets fly, and how pilots usually measure the speed of their aircraft.
How Fast Can Commercial Jets Fly?
Commercial jets vary widely in speed and capacity. Some are capable of cruising at speeds over 500 miles per hour, while others cruise at around 200 mph.
The fastest commercial jets can reach Mach between 0.7-0.85, which means they travel almost 85% of the speed of sound.
As a rule of thumb, the higher a jet flies, the faster it can go.
How Is The Speed Of An Aircraft Measured?
There are two main ways to measure how fast an aircraft is flying: by measuring its speed relative to the air (airspeed) or by measuring its speed relative to the ground (ground speed) (see also “How Fast Do Blue Angels Fly?“).
Another option is to measure aircraft speed relative to the speed of sound.
Let’s take a closer look at these three measurements.
Ground speed is the time a vehicle takes to travel from one place to another on the ground.
The majority of commercial jets have a ground speed between 300 to 600 nautical miles per hour.
Ground speed is measured using an instrument called a pitot tube. This device measures the difference in pressure on either side of the plane as it passes through the air.
If you were standing next to the plane when it was flying at 100 knots, the pressure difference would be 1/2 psi.
The more pressure on one side of the plane compared to the other, the faster the plane is going.
So, the wind does impact the speed of an aircraft significantly. Headwind slows down the aircraft, while tailwind helps it to accelerate.
This can also have a significant impact on the aircraft’s fuel consumption.
Airspeed is the speed of the aircraft relative to the surrounding air, so airspeed is how fast the air flows around the plane’s wings.
Airspeed works in a different way to ground speed (see also “How Does A Constant Speed Prop Work?“). For example, if an aircraft is still on the ground but the headwind is 30 mph, then the aircraft has an airspeed of 30 mph.
If the same aircraft were moving forward at 60 mph, it would have an airspeed of 90 mph.
Airspeed is a popular measurement because the speed of air over the wings does indicate how much of a lift each wing will be producing during flight.
This lift is what essentially keeps the jet in the air.
Airspeed is the main measurement for commercial jets. Pilots usually use airspeed to refer to how fast they fly.
Airspeed is measured with an instrument called an air data probe. It consists of a small sensor attached to the bottom of the fuselage near the nose of the plane.
Airspeed is not always accurate, though. If the air is turbulent, the air data probe may not pick up the correct reading.
Turbulence occurs when the air is disturbed by something like a mountain or a cloud. When this happens, the air becomes turbulent and the air data probe won’t give a reliable reading.
When that happens, pilots rely on their instruments instead of relying solely on airspeed.
Speed Of Sound
The speed of sound is the maximum speed at which sound travels through the air.
While most of the time the speed of aircraft is measured in miles per hour or knots, when a jet reaches heights of around 25,000 feet, then they reference their speed in “Mach”.
This Mach number indicates how fast in relation to the speed of sound an aircraft travels. So, when a pilot says that he travels at 0.7 Mach, then this is 70% of the speed of sound.
This speed is not set, so it can vary depending on the air temperature. The higher the air temperature, the faster the jet.
You may have heard certain shockwaves when fast jets pass. This is because when an aircraft gets close to the 100% of the speed of sound, then it starts to create shockwaves, which you can hear many miles away.
The speed of sound is just a reference speed measurement, so it’s not used very often. Commercial jets usually don’t achieve 100% speed of sound.
This means that there is usually a maximum limit of Mach that an aircraft can achieve.
What Are Supersonic Aircraft?
Supersonic aircraft are those that travel faster than the speed of sound. These planes are capable of flying at speeds above 1,000 mph.
These aircraft are rare today and used mostly for military purposes.
Today, only one type of aircraft remains as a working supersonic aircraft. That is the Concorde.
It has been retired since 2003 due to safety concerns and high maintenance costs.
The first flight of the Concorde took place in 1969. However, it wasn’t until 1976 that the first commercial flights took off.
In 1985, the last flight took place, and then the Concorde was replaced with the slower Airbus A380.
So, what will be the next generation of supersonic aircraft? Will we ever see them fly again?
As the technology and engineering of jets continually develop, we are likely to see one of these superfast jets as passenger jets in the future.
Advantages Of Supersonic Aircraft
These aircraft do have several advantages over traditional airplanes:
- They could reach supersonic speeds without using afterburners. Afterburners are engines that burn fuel to produce additional thrust.
- Their design is more aerodynamic.
- They are quieter.
Disadvantages Of Supersonic Aircraft
However, these aircraft also have some disadvantages:
- New, innovative technology has its price. They are expensive.
- They are more difficult to fly.
Commercial jets are a common sight in modern skies, and we use them regularly to travel short and long distances.
While the speed of commercial jets varies significantly with each plane, they all fall within a range between 0.6 Mach and 0.8 Mach. This is up to 80% of the speed of sound.