Transonic is an aeronautics term referring to the condition in which a range of velocities of airflow exist surrounding and flowing past an air vehicle or an airfoil. Air flow velocities are concurrently below, at, and above the speed of sound at the pressure and temperature of the airflow of the air vehicle's local environment (about mach 0.8–1.2, i.e. 600-900 mph). It is formally defined as the range of speeds between the critical Mach number, when some parts of the airflow over an air vehicle or air foil are supersonic, and a higher speed, typically near Mach 1.2, when all of the airflow is supersonic.
