Abstract: Method and arrangment in the automatic landing of an aircraft (1), comprising a unit (4) arranged on the aircraft (1) and designed to form an image of a group of radiation sources (3) located next to a runway (2), and a calculation device connected to the imaging unit (4) and designed to continuously calculate the position and orientation of the aircraft (1) in relation to the runway (2) using the image formed by the imaging unit (4), in which the radiation sources (3) are deployed at precisely plotted co-ordinates, which are stored in a memory situated in the calculation device, and in which the said co-ordinates are used in calculating the position and orientation of the aircraft (1) when landing.

Abstract: PCT No. PCT/SE78/00067 Sec. 371 Date July 2, 1979 Sec. 102(e) Date June 29, 1979 PCT Filed July 2, 1979 PCT Pub. No. W079/00260 PCT Pub. Date May 17, 1979A correlation follower comprising an image sensor (1) adjustable sideways and in height with a limited field of view, which is cyclically scanned by the sensor the output signal of which reflects the image content within the field of view and a video correlator (3) for controlling the alignment of the sensor in dependance of the output signal of the image sensor.The video correlator (3) has two addressable memories (12, 14) the one of which is a real time memory (12), i.e. in this memory a section of the field of view is stored for each cycle. The other memory is a reference image memory (14) and is updated with the content of the real time memory (12).