A parachutist flying in an aeroplane jumps when it is at a height of 3km above ground. He opens his parachute when he is about 1km above ground. Describe his motion ?

Motion before opening the parachute: A parachutist jumped from an aeroplane flying at a height of 3km above the ground. Assume the aero plane is flying horizontally. Now he falls down like a freely falling body (initial velocity is zero) in vertically downward direction and with uniform velocity equal to plane velocity in horizontal direction till he opens parachute at a height 1km above the ground.
Motion after opening the parachute: After parachute is opened, we should consider air resistance (viscous drag) air buoyancy also acting on him along with gravitational force. In the presence of these forces the acceleration will become zero after falling through certain height, there he attains constant velocity called terminal velocity. Further he falls downwards with the same terminal velocity till he reaches the ground.