A `coupled mode' analysis is useful in predicting the unsteady aerodynamic response of vibrating multistage turbomachine blades. Using this approach, the coupling between the blade rows is modeled using a subset of spinning modes. The blade rows are represented by reflection and transmission coefficients which describe how spinning modes interact with and are scattered by, a given blade row. These coefficients are calculated using a linearized full potential flow model together with rapid distortion theory to account for incident vortical gusts.