Compound aircraft, merging the advantages of two or more aircraft, is now a promising concept for designing modern aircraft. How to achieve successful docking of two aircraft in flight is an important issue for the applications of vertical compound aircraft. In order to resolve such an issue, this paper proposes a new visual based navigation docking scheme, which is different from rendezvous and docking operations in space applications. The present scheme uses a monocular camera mounted on the chaser aircraft with a certain installation angle to collect the visual features of the target aircraft, then the position and attitude of the landing gear of the target aircraft can be determined. Moreover, a six degrees of freedom docking mechanism mounted on the chaser aircraft is designed to catch hold of the landing gear tires of the target aircraft. In order to avoid undesired collision during the docking process, Z-direction position of the target landing gear is predicted and the proposed Z-direction speed control algorithm is applied to the chaser platform. The robustness of the present scheme has been validated numerically and experimentally by means of a chaser platform and a target platform on the ground testbed. Successful docking of the chaser platform and the target landing gear has been achieved, respectively, when the target platform performs a Z-direction movement and a compound movement.