There is significant tactical value for cooperatively tracking a target with a passive sensor aided by airborne radar, and the models of some exist algorithms are relatively simple. In order to close to practice, an algorithm is proposed for tracking a maneuvering target in clutter by using a passive sensor aided by airborne radar. Based on ECEF(earth-centered earth-fixed) coordinates where the practice factors such as the curvature of earth and the platform attitude are accounted for, the algorithm combines IMM(interacting multiple model) and PDAF(probabilistic data association filter), and the trace of overall predictive covariance from the output of IMMPDAF is treated as control variable to manage radar opening/closing mode. The simulation results show that radiation energy savings and improved survivability are obtained while tracking performance degradation is not obvious by choosing suitable control threshold, and the proposed algorithm is effective.