Potential points of collision (PPC) and predicted areas of danger (PAD) are used in marine radars for assessment of risk of collision and of action to avoid collision. Both are useful concepts for automatic radar plotting aids (ARPA) which lead to a better understanding of collision avoidance. The PAD display, developed by Sperry Ltd, is a graphic form3 alternative to the vector display. More information can be obtained from the PAD display than from the vector display but additional knowledge is necessary for the mariner to correctly interpret and use the information. The IMO Resolution on ARPA Performance Standards emphasizes the need for deck officers to understand the basic principles involved in the use of the equipment. In this paper consideration will be given to the information obtained from the PAD display and a suggestion will be made for possible improvement of the shape of the PAD.