Nowadays, research has been developed in order to increase the autonomy of Unmanned Aerial Vehicles (UAVs). The procedure of autonomy increase consists of transferring part of the decision-making process of the human UAV operators for the vehicle itself. This work approaches the autonomous landing of UAV of the type Vertical Takeoff and Landing (VTOL). The VTOL UAV autonomous landing is a complex problem due to the existence of a significant error between the real helipad's position and the helipad's position estimated by the UAV navigation system, when this system is based on the fusion of data from a Global Positioning System (GPS) receptor and measurements from an Inertial Navigation System (INS). Thus, the objective of this work is the development of a computer vision system for tracking helipads in digital images obtained in outdoor environments, with nadir direction. Through information of the tracked helipad, the system estimates a set of flight data and generates commands to the UAV's autopilot, in order to reduce the error between the helipad's central position and the UAV's position.