A method for monitoring operating states, line structure, line safety and for determining outage probabilities of overhead power line systems from the air using a manned aircraft, characterized in that a) the aircraft is at least equipped with a sensor system for acquiring data representing physical properties of the overhead power line systems, at least with a high-resolution digital camera for image data of the and around the overhead power line systems, and with a high-resolution laser scanning system for acquiring data on environmental conditions, the structure of the terrain, and the conductor structure of the overhead power line systems, which has an accuracy of up to 0.7 cm/pixel; b) the sensor system, the digital camera, and the laser scanning system are coupled to one another and to satellite navigation systems, distinct from GPS, and use the same data of a single measurement antenna; c) the acquired data are assigned to one another with respect to position and time and are correlated with one another; d) the aircraft determines all data including its current fluctuations at one selected, uniform flight speed on the basis of a predetermined flight profile at the height of the overhead power line and laterally to its course direction in only one single overflight of the overhead power line system; and e) the determined data with respect to damage or defects on the overhead power line systems and/or beginning worsening and/or influences by environmental conditions of the line structure are also determined preventively and are supplied to a processing unit, in which required repairs and/or maintenance recommendations and outage probabilities for individual elements, sections, or areas of the line structure with incorporation of growth models of the vegetation are determined in terms of a self-learning system on the basis of a comparison to states contained in a database stored therein and are output at an output unit. a) the aircraft is at least equipped with a sensor system for acquiring data representing physical properties of the overhead power line systems, at least with a high-resolution digital camera for image data of the and around the overhead power line systems, and with a high-resolution laser scanning system for acquiring data on environmental conditions, the structure of the terrain, and the conductor structure of the overhead power line systems, which has an accuracy of up to 0.7 cm/pixel; b) the sensor system, the digital camera, and the laser scanning system are coupled to one another and to satellite navigation systems, distinct from GPS, and use the same data of a single measurement antenna; c) the acquired data are assigned to one another with respect to position and time and are correlated with one another; d) the aircraft determines all data including its current fluctuations at one selected, uniform flight speed on the basis of a predetermined flight profile at the height of the overhead power line and laterally to its course direction in only one single overflight of the overhead power line system; and e) the determined data with respect to damage or defects on the overhead power line systems and/or beginning worsening and/or influences by environmental conditions of the line structure are also determined preventively and are supplied to a processing unit, in which required repairs and/or maintenance recommendations and outage probabilities for individual elements, sections, or areas of the line structure with incorporation of growth models of the vegetation are determined in terms of a self-learning system on the basis of a comparison to states contained in a database stored therein and are output at an output unit.