Definition

Transonic refers to the condition of flight in which a range of airflow velocities exist. The air surrounding and flowing past an aircraft or an airfoil which is in transonic flight will be concurrently below, at, and above the speed of sound. This speed of this condition can vary with an aircraft's critical Mach number, but it is generally considered to be approximately 0.8 Mach to 1.2 Mach.