In this paper, the problem of guidance formulation for autonomous landing of unmanned aerial vehicles on stationary or moving or maneuvering ground vehicles at desired approach angles is considered. Nonlinear engagement kinematics have been used. While integrated nonlinear controllers have been developed in the literature for this purpose, the controller inputs often need modification of the existing autopilot structure, which is challenging. In order to avoid that, a higher-level guidance algorithm is designed in this paper leveraging a sliding mode control-based approach. In the presented guidance formulation, target-state-dependent singularity can be avoided in the guidance command. The effectiveness of the presented guidance law is verified with numerical simulation studies. © 2020, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.