An upgraded vessel tracking system, which can track 4,000 moving vessels plus 1,000 stationary targets in real time, has been in operation since early 2002. It provides the latest technology such as AIS, ECDIS, CCTV, new VHF-direction finders and modern communications systems to further improve navigation safety and operation efficiency. Marine Department patrol launches maintain a watch on shipping, traffic separation schemes, fairways, navigational channels, typhoon shelter and cargo-working areas. They provide on-scene support to the VTC, and are in continuous radio contact with the VTC and local marine traffic control stations located at Ma Wan and Kwai Chung Container Port. The VTC is thus able to promptly initiate and co-ordinate actions required to facilitate safe navigation in the port. The Hydrographic Office of the Marine Department surveys Hong Kong waters and produces nautical charts to facilitate safe navigation within the port. It functions with reference to the standards laid down by the International Hydrographic Organisation (IHO). Notices to Mariners are promulgated fortnightly to update bilingual nautical charts. A Differential Global Positioning System correction signal is broadcast continuously on 289 kHz to assist mariners using GPS navigation to position-fix their vessels more accurately. Tidal height predictions and real-time tidal information are provided on the department's website. Pilotage is compulsory for ships of 3,000 gross tons and above and gas carriers of any tonnage. Quarantine and immigration facilities are available on a 24-hour basis. Advance immigration clearance and radio pratique may be obtained by certain vessels on application. Dangerous goods Dangerous goods are moved in the waters of Hong Kong strictly in accordance with the International Maritime Dangerous Goods Code. Their movements must be recorded in Marine Department's Dangerous Goods Information System. Fire-fighting vessels operated by the Fire Services Department are kept in a state of readiness at all times. The Marine Department's pollution control vessels are on 24-hour standby to deal with oil spills. Other working facilities To facilitate transfer of cargo between vessels and the shore, and cargo to and from Pearl River ports, the Marine Department provides and manages 7,756 metres of public cargo-working sea frontage in various parts of Hong Kong. Bulk handling facilities for coal and oil are provided at the power generating stations at Tap Shek Kok in Castle Peak and at Po Lo Tsui on Lamma Island. Hong Kong Shipping Register Hong Kong is a major centre of ship ownership and management. Ships owned