To improve the practicality and effectiveness of irregular flights recovery, a slot secondary assignment problem for airline in collaborative decision making mechanism was studied. This paper presented an unbalanced slot assignment model for autonomous flight cancellation under flight bank operations. By proving theorems, the characteristics of the model were analyzed and a kind of two-phase alternating solution process was developed. First the un-balanced model was converted to the balanced one and the optimized solution was obtained; and then the depth-first algorithm was used to obtain the optimized unbalanced solution via heuristic flight cancellation. The analysis results show that this method can not only reduce passenger delay time and save time slot resources, but enhance the efficiency of performance, which satisfies the requirements for quick decision and cost-effectiveness during irregular flights recovery.