Paper Submitted 02/08/06, Accepted 03/13/06. Author for Correspondence:

Recently most maritime countries in the world have fitted auto-matic identification system (AIS) in vessel traffic services (VTS) in compliance with regulations of International Convention in order to identify ship name and collect ship information. Traditionally VTS operators use automatic radar plotting aids (ARPA) to get ship maneu-vering information for preventing ships from navigational faults. Although the two equipments can provide similar functions for VTS, the operational theory of them is quite different. In this study an experimental observation was carried out by means of ARPA radar and AIS fitted in the building of Merchant Marine Department, NTOU. The detected information was analyzed for comparison of their difference on characteristics. Results reveal that AIS can detect target ships with wider area coverage, larger quantity and more voyage information than ARPA radar. The latter can provide an active monitor to detect small ships that can not be done by AIS. Consequently for navigation safety VTS operators must concentrate on ARPA radar in priority and use AIS as supplementary installation for identification of ships