The fault detection filter(FDF) design problem for a class of networked flight control systems with multiple channels data transmission is studied. Considering the network-induced delay and packet dropouts of each channel, discretetime Markov jump linear system model with partly known transition probabilities is established. Based on the obtained model, observer-based FDF is designed. Then the addressed fault detection problem is converted into a problem of H_∞ filtering. Sufficient conditions to guarantee the existence of the FDF and solutions of this problem are simultaneity derived. Finally, a simulation experiment on a networked flight control system validates the effectiveness of the proposed method.