Although most blade element momentum (BEM) models yields acceptable results for high tip-speed ratios where the local angles of attack are small, no generally accepted model exists up to date that consistently predicts the loads and power in stall regime for stall-controlled turbines. Understanding of the stall delay phenomenon on wind turbines remains, to this day, incomplete. The lack of a conceptual model for the complex three-dimensional (3D) flow field on the rotor blade, where stall is begins, how it progresses and where stall is practically terminated, has hindered the finding of a unanimously accepted solution. A correct modeling of the stall phenomenon, which results from three-dimensional rotational effects, is then essential in order to make reliable wind turbine predictions. The paper aims at giving a better understanding of the delayed stall events.