Call Sign Masking Pilot Project Update

By Robert Luke, U.S. VOS Program Manager

For several years now, ship owners and masters have been concerned that the traditional "open exchange" of ship observation data between the different national meteorological services around the world could allow certain ship call signs and their locations to become available on public web sites. The World Meteorlogical Organization (WMO) and its members have discussed how to best assist in safeguarding the identities and locations of these ships while at the same time, collecting the critical real-time marine observations.

In response to an agreement reached at the WMO Executive Council Meeting #58 (2006), NOAA began selectively "masking" ship identifiers, or call signs, before sending observations to the Global Telecommunications System (GTS). National meteorological services around the world use the GTS to share weather observations. The purpose of call sign masking is to enhance maritime security by limiting access to information about positions and routes of selected ships that report weather observations in real-time. Weather data will still be distributed to the worldwide meteorological community in real-time, but only authorized personnel will be able to match an observation with the ship that sent it. Ships that do not request "masking" will continue to have their call signs openly distributed with the associated weather data.

Some international VOS programs have initiated their own pilot projects that just replace the true call sign with an assigned “alias”. While masking the ship’s true identity, this action does nothing for tracking ships via their newly assigned call sign. For this reason, the U.S. VOS decided to replace the true call signs with the generic “SHIP” upon receipt of the observation at the National Weather Service’s Telecommunications Gateway (NWSTG). These pilot projects are just an initial effort until a more complete and robust universal system can be established by WMO (estimated in 2012).

NOAA’s masking of call signs will be limited to ship observations that originate from NOAA into the GTS. This incorporates all observations initially received by the two U.S. Land Earth Stations, Southbury and Santa Paula. At this time, only observations processed through one of these Land Earth Stations can be controlled so, observations sent to NOAA by electronic mail, or through the USCG telecommunications system cannot be masked. Ships that request call sign masking should only transmit their observations via the AMVER/SEAS electronic logbook in binary format.

Your observation report positions will continue to be routed to the AMVER Center as their system does not have any public access to the data. The masking can be established with either of two control periodicities: 1) data can be released publically after 90 days (shared with archive centers) or 2) data can NEVER be released to the public.

Additionally, the National Centers for Environmental Prediction (NCEP), and in particular, the Ocean Prediction Center (OPC), in support of this masking effort, have removed call signs from all charts distributed by their fleet facsimile broadcast, internet, or FTP Retrieval system. OPC has recently announced that they are now able to create a “White List” of call signs that are acceptable to be displayed on the charts.

To register for the call sign masking or to add your ship to the OPC White List, please contact your local Port Meteorological Officer (PMO) or the national VOS program office at

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