As stated in Newton's first law of motion, an aeroplanes natural tendency is to fly in a straight line, if the pilot wants to turn the aeroplane, a horizontal force towards the centre of the turn must be generated. To keep the aeroplane turning this horizontal force must continually act on the airplanes body, this force is called centripetal force, but as there are no fancy magnets in the sky, the airplane must generate its own centripetal force and this is how it works.

In straight and level flight, the lift force generated by the wings acts perpendicular to the relative airflow and opposite to the weight force. when the aeroplane banks to the side the lift force tilts to the side with the airplane, the lift force can now be broken down into two components, the vertical lift component that opposes weight and the horizontal lift component that pulls the aeroplane into the turn. The horizontal component of the lift force is the airplane's centripetal force but what about the vertical lift component? it's much smaller now when compared to weight, the aeroplane will begin to descend if the vertical lift component is not increased, the most practical way of increasing the vertical lift component is to increase the lift force, the pilot can achieve this by pulling back on the control column to increase the aeroplanes angle of attack, when turning the airplanes load factor and stall speed will increase.