In the paper an efficient noniterative method for ranking line outage contingencies in an AC-DC system based on overload and voltage deviation performance indices is developed. The method is based on the calculation of complex line outage current compensations using a coupled AC-DC load flow Jacobian matrix. The proposed method is further extended for the calculation of line outage distribution factors which could be very useful for reducing the computational burden in security constrained optimisation problems. A mathematical model for handling bus-type switching resulting from reactive power limit violations is also developed. Results for a modified IEEE 14-bus system have been obtained with the proposed method and are compared with those obtained by rigorous AC-DC load flow.