I posted some updates on ATC this morning.
http://www.boatered.com/forum/topic.asp?TOPIC_ID=109388
http://www.boatered.com/forum/topic.asp?TOPIC_ID=109388
quote:
The primary function of VTS San Francisco is to facilitate good order and predictability on a waterway by coordinating vessel movements through the collection, verification, organization, and dissemination of information. To accomplish this, VTS San Francisco uses the concept of a "continuum of traffic management". This continuum consists of the following levels of control: Monitor, Inform, Recommend, and Direct.
(1) Monitor: Using AIS, radar, CCTV, and radiotelephone equipment, VTS monitors vessel traffic in the VTS Area. VTS also receives information from various sources on predicted vessel movements, hazards to navigation, aids to navigation discrepancies, and other information of interest to VTS users. Monitoring vessel traffic allows us to ensure that vessels are navigating safely and efficiently in accordance with applicable regulations and Navigation rules.
(2) Inform: VTS analyses the information gathered then informs participants as applicable. This is done at the user's request, when it appears necessary to VTS personnel, or at regular intervals. The purpose of informing participants is to give them timely information to allow them to make decisions concerning the navigation of their vessels.
(3) Recommend: Almost all of VTS San Francisco operations are conducted at the monitor and inform levels. However, at certain times the VTS will recommend action be taken by a participant to prevent a potentially dangerous situation. Such recommendations are offered to assist the participant in avoiding hazardous situations early on. Recommendations are made on the pretence that there is information available to VTS of which the participant may not be aware.
(4) Direct: On rare occasions (and during heightened security conditions) VTS will direct movement or actions of a participant. Direction would be given in cases when the VTC observes obvious violations of regulations or an obvious and immediately dangerous condition of which the participant is not or does not seem to be aware. Directions will normally be in the form of a general objective such as staying out of a certain area or coming no closer than a certain distance from a vessel or facility.