Method for safely landing an unmanned aircraft, comprising the steps of: determining whether all of the communication links of a multiplicity of communication links between the aircraft and a ground control station, set up for controlling and/or monitoring the aircraft, are interrupted; and on determining an irreversible interruption of the communication link between the aircraft and the ground control station, landing the aircraft as quickly as possible at a suitable landing site on the basis of data stored in a navigation system of the unmanned aircraft concerning the current flying conditions and nearby landing sites; characterized in that the stored data comprise at least the nearby landing sites and the current wind and weather data relating to the immediate surroundings of the aircraft and the nearby landing sites, wherein during the flight the stored data are successively reloaded via a communication link with the ground control station for at least part of the stage of the flight; wherein, on the basis of the stored wind and weather data of the nearby landing sites at an expected time of arrival at the landing site, the suitable landing site is selected according to defined rules; and wherein the method further comprises the step of: determining by the ground control station whether all of the communication links of the multiplicity of communication links between the aircraft and the ground control station are interrupted and transmitting information concerning the interruption to an air traffic control centre; wherein the defined rules are known to the unmanned aircraft and the air traffic control, so that, if there is an interruption in the communication links, the identical landing site is selected as a suitable landing site; and wherein the air traffic control centre closes at least part of an available airspace and the suitable landing site for safe landing of the aircraft. determining whether all of the communication links of a multiplicity of communication links between the aircraft and a ground control station, set up for controlling and/or monitoring the aircraft, are interrupted; and on determining an irreversible interruption of the communication link between the aircraft and the ground control station, landing the aircraft as quickly as possible at a suitable landing site on the basis of data stored in a navigation system of the unmanned aircraft concerning the current flying conditions and nearby landing sites; characterized in that the stored data comprise at least the nearby landing sites and the current wind and weather data relating to the immediate surroundings of the aircraft and the nearby landing sites, wherein during the flight the stored data are successively reloaded via a communication link with the ground control station for at least part of the stage of the flight; wherein, on the basis of the stored wind and weather data of the nearby landing sites at an expected time of arrival at the landing site, the suitable landing site is selected according to defined rules; and wherein the method further comprises the step of: determining by the ground control station whether all of the communication links of the multiplicity of communication links between the aircraft and the ground control station are interrupted and transmitting information concerning the interruption to an air traffic control centre; wherein the defined rules are known to the unmanned aircraft and the air traffic control, so that, if there is an interruption in the communication links, the identical landing site is selected as a suitable landing site; and wherein the air traffic control centre closes at least part of an available airspace and the suitable landing site for safe landing of the aircraft. determining by the ground control station whether all of the communication links of the multiplicity of communication links between the aircraft and the ground control station are interrupted and transmitting information concerning the interruption to an air traffic control centre; wherein the defined rules are known to the unmanned aircraft and the air traffic control, so that, if there is an interruption in the communication links, the identical landing site is selected as a suitable landing site; and wherein the air traffic control centre closes at least part of an available airspace and the suitable landing site for safe landing of the aircraft.