Source: pinterest.com Mach number is a measurement of the aircraft’s speed relative to the speed of sound. Mach 1 would mean the aircraft is flying at the speed of sound and Mach .5 would mean it is flying at half the speed of sound. The mach number itself is generally determined by an air … Read more: https://schaeferflight.com/index.php/2018/03/22/flight-instruments-mach-indicator/