Concerning the incident on the last page of this report....
http://www.bea.aero/ita/pdf/ita.005.en.pdf
Why is it better to select an airspeed than a mach number.
Conduct of flight in turbulent atmosphere The pilot selected a Mach number, and not
a speed, in accordance with the instructions
in moderate turbulence, which led to speeds
above the recommended speed (308 kt
maximum) without, however, approaching
VMO(15). These actions were not sufficient in
face of the strength of the turbulence that was
in fact encountered.