Computational fluid dynamics (CFD) has become a valuable tool for predicting the aerodynamics of finite wings. However, wings with ice accretion require an incredible amount of resolution to capture the intricate details of the ice shape. This can lead to an overwhelming amount of grid points and CFD analysis can become impractical or even impossible for such problems. Therefore, two fast and accurate methods have been developed for predicting the aerodynamics of clean and iced wings. The present methods combine known viscous airfoil data with a modern lifting-line or lifting-surface method. Validation against experimental and computational results shows both methods to provide accurate predictions of the aerodynamics for clean and iced wings. The present methods experienced non-unique solutions at high angles of attack, a phenomenon noted by other researchers but never thoroughly explained. The present work provides an explanation for these multiple solutions.