The active identification of ships, the improved tracking and the
back-up of (all danger related) radar information will give a dramatic increase in the
safety of shipping.
4. Status of "Transponder" Applications
As a consequence of serious shipping accidents and due to national
needs and the technical "Transponder" development, the installation of
"Transponders" has been promoted. The applications reach from obligatory use to
trials on maritime applications.
4.1 Prince William Sound ADS (VTS)
The wake of the grounding of the supertanker "EXXON VALDEZ"
in 1989 in the Prince William Sound has initiated the improvement of the regional VTS
system by applying "Transponders". The main information about the development of
the new "Automated Dependence Surveillance" system (ADS) is given in Table 1.
Table 1: Relevant data of the Prince William Sound ADS
Origin / Event
Grounding of 300m tanker "EXXON VALDEZ" in 1989
Consequences
Oil Pollution Act '90
Improvement of the VTS system (ADS)
Use of DGPS, radar, modified DSC transponder (!)
Operation
1.Ship reports entrance into ADS (Channel 70)
2.VTC polls automatically ship's data (Channel 11)
3.Ship is monitored on VTC display
4.If needed, VTC gives "information" to ship
Vessles
Tanker > 20.000dw (mandatory)
Passenger ship (non-mandatory)
Coverage
5000nm2 (previously 400nm2 using radar tracking
only)
