Closest point of approach (CPA) is a basic factor taken into consideration for risk assessment during the meeting of two ships at sea. Navigators should use radars with automatic target tracking for collision avoidance and should know the accuracy to which radar data are calculated. Basic information about these requirements can be found in IMO resolutions. The currently binding document for devices manufactured after 2008 is IMO Resolution MSC.192(79). But there are two independent requirements for relative motion. One of these refers to relative motion parameters (relative course and speed) and the other one to the value that is the result of this motion (CPA). The other important document is Standard 62388. This specifies the minimum operational and performance requirements, methods of testing and the required test results published by IEC and also refers to radar equipment. However, this standard is not so popular in different publications focusing on radar equipment, so these requirements were not analyzed in the article. The main problem described in this paper refers to the mutual consistency of IMO Resolution requirements. The results of simulations and their analysis are presented.