Mach Number Explained: What It Is and Why Pilots Use It
Pilot Institute
JULY 11, 2025
Key Takeaways Mach number is a dimensionless ratio of true airspeed to local speed of sound. Mach number is simply a ratio of your true airspeed to the local speed of sound. Air density drops with altitude, so for a given true speed, dynamic pressure (and thus IAS) will be lower at high altitudes. Here’s why.
52 
Let's personalize your content