What is Mach 0.8, 0.9?

Mach 0.8 and Mach 0.9 are speeds that planes fly at, almost as fast as sound.

Imagine you're on a playground swing. When you go swinging high, you feel like you’re flying, that’s how it feels to be near the speed of sound!

Mach 1 is the speed of sound, about 768 miles (1,235 kilometers) per hour. So:

• Mach 0.8 means the plane is going at 80% of that speed, like you're swinging pretty high but not quite all the way to the top.
• Mach 0.9 means it's flying at 90% of sound’s speed, almost there, just a little bit away from reaching the top.

Think about your favorite toy car. If Mach 1 is like zooming down the hallway as fast as you can, then Mach 0.8 and 0.9 are like going really fast, but not quite as fast as you could go if you were trying your hardest!

These speeds are special because they help planes travel quickly across the sky, almost like they’re racing with sound!