Physics one question

What is the magnitude of the acceleration, in 'g' units (where 1 g = 9.8 m/s2), of a pilot whose aircraft enters a horizontal circular turn with a velocity of v0 = (400 x-direction + 500 y-direction) m/s and 24.0 s later leaves the turn with a velocity of vf = (−400 x-direction − 500 y-direction) m/s.