Acceleration is the rate of change in velocity. The average acceleration over a time t of a body that starts with a velocity u and has a velocity v after t seconds is equal to a = (v - u)/t
The fighter pilot can reach a speed of Mach 2 in 8 seconds starting from rest. Mach represents the speed of sound and Mach 2 is equivalent to a speed of 680.58 m/s.
Substituting u = 0, v = 680.58 and t = 8 gives an acceleration of (680.58)/8 = 85.0725 m^2/s.
This acceleration is approximately 9 times that due to gravity, as a result of which the weight of the pilot is approximately increased to 9 times the weight at rest. This exerts a very large stress on the organs of the pilot and for the pilot to be able to survive this requires extensive preparation.