As airline seats belong to perishable assets, empty seats would become wastes as the flight takes off. Late-stage alternative sales channel not only helps utilize the capacity, also, due to the properties of airline industry that serving additional passenger cost little, most part of ticket revenue would become profit thus lead to revenue increase. In this research, we use second sales channel to offer the late-stage deals, and our objective is to maximize the revenue, also to determine the appropriate time to allocate the seats to the second channel and the amount to offer. We considered one-leg, single class in economy with fixed priced fare classes scenario. By customers’ choice behaviors, we use dynamic programming to find out the maximum expected revenue. The experiment results indicate that the time of opening additional channel, seat allocation will influence the revenue. We also found that it’s a stable sales mechanism with better performance on numerical simulation. In addition, different demand compositions will have different effects when providing alternative sales mechanism, same finding can be found when comparing different demand scenarios.