A method of selecting a safe landing zone for an aircraft, preferably a helicopter, comprising the steps of: receiving, from a LADAR or LIDAR system, 4 dimensional, 4D, point cloud data as sequential image frames; referencing, by a processor, each image frame to geographic coordinates; characterized in that the method further comprises the steps of: classifying a region in each image frame as either a land region or a water region based on geographic information system meta data associated with the geographical coordinates referenced to each image frame; selecting, by the processor, a region that has been classified as a land region in each image frame based on the classification of a region as land; forming a height map of the selected land region, the height map including pixel values of height over the land region; detecting edges of an object in the height map, the edges forming boundaries of the object; finding a maximum height within the boundaries of the object; classifying the object as a vertical obstruction, VO,, if the maximum height is larger than a predetermined VO threshold value; based on the VO, selecting by the processor a possible landing zone for the aircraft; and determining by the processor, that the possible landing zone is a safe landing zone for the aircraft. receiving, from a LADAR or LIDAR system, 4 dimensional, 4D, point cloud data as sequential image frames; referencing, by a processor, each image frame to geographic coordinates; characterized in that the method further comprises the steps of: classifying a region in each image frame as either a land region or a water region based on geographic information system meta data associated with the geographical coordinates referenced to each image frame; selecting, by the processor, a region that has been classified as a land region in each image frame based on the classification of a region as land; forming a height map of the selected land region, the height map including pixel values of height over the land region; detecting edges of an object in the height map, the edges forming boundaries of the object; finding a maximum height within the boundaries of the object; classifying the object as a vertical obstruction, VO,, if the maximum height is larger than a predetermined VO threshold value; based on the VO, selecting by the processor a possible landing zone for the aircraft; and determining by the processor, that the possible landing zone is a safe landing zone for the aircraft. classifying a region in each image frame as either a land region or a water region based on geographic information system meta data associated with the geographical coordinates referenced to each image frame; selecting, by the processor, a region that has been classified as a land region in each image frame based on the classification of a region as land; forming a height map of the selected land region, the height map including pixel values of height over the land region; detecting edges of an object in the height map, the edges forming boundaries of the object; finding a maximum height within the boundaries of the object; classifying the object as a vertical obstruction, VO,, if the maximum height is larger than a predetermined VO threshold value; based on the VO, selecting by the processor a possible landing zone for the aircraft; and determining by the processor, that the possible landing zone is a safe landing zone for the aircraft.