AIS When AIS is first used to select a target this image will be seen until basic information is received. This takes about one minute. This target is displaying an AIS heading marker. This is NOT a vector and will not change with speed. This gives an instant aspect, within the accuracy of its ship’s compass. This is the image of an AIS acquired target which is turning to port. Note that this is unreliable in a seaway but very helpful in calm waters such as a river or port entrance. This image shows a target, selected on AIS but which has a CPA within preset danger limits. This target has a solid AIS heading marker and a broken ARPA vector. This vessel may be Static, heading 045oT and showing a relative vector which is the reciprocal of own ships course and speed. This target has been lost. This may be because the other vessel has just switched off her AIS transmitter.