When in landing configuration flaps are full down. That means that Lift and Drag Coefficients are increased. If go around should be contacted, the Pilot must increase power, pull the elevator to take a climb attitude and decrease drag, so the aeroplane can increase speed and start climbing. The drag will be decreased only by retracting the flaps at the middle or take-off position.

If flaps during go-around stay at full down position, climb and an increase in speed will be difficult to reach, because of increased Drag Coefficient.

If flaps during go-around are fully retracted, it is possible for the aeroplane to stall because of lack of speed.

So, at go-around, flaps must be retracted at middle or take-off position until speed reaches the V_YSE speed, for safety reasons, which is the Best Rate of Climb Speed with a single operating engine in a light, twin-engine aircraft – the speed that provides the most altitude gain per unit of time following an engine failure, while maintaining a small bank angle that should be presented with the engine-out climb performance data.