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GPS antenna problems

A member has reported a serious failure of a vessel’s GPS positioning equipment. When approaching the work area, which was close to the shore, the vessel experienced a complete failure of all its GPS receivers (eight receivers from four different manufacturers/suppliers).

Following extensive fault-finding which isolated the problem to the area of the vessel bridge, it was discovered that one GPS unit was causing the failure of all the other units. The receiving antenna for the unit had failed and had become a transmitter, the signal from which subsequently blocked all the other GPS receivers mounted nearby. The close proximity (<1m) of this damaged antenna unit to two other GPS antenna units may also have caused damage to the internal electronics of these units.

Members are warned to be aware of the potential hazard posed by a faulty GPS antenna and that all GPS antennae be separated by at least two metres where possible. It is recommended that when selecting the mounting location and installing global navigation satellite system (GNSS) antennae, guidance is taken from the system manufacturer with regard to safe operating distance from other equipment and with special attention given to transmit/receive devices. Care should also be taken in the selection of appropriate cabling and antennae and to the shielding and grounding required for these systems. A regular inspection and maintenance schedule is also recommended, with periodic replacement of cables.

IMCA Safety Flashes summarise key safety matters and incidents, allowing lessons to be more easily learnt for the benefit of all. The effectiveness of the IMCA Safety Flash system depends on Members sharing information and so avoiding repeat incidents. Please consider adding [email protected] to your internal distribution list for safety alerts or manually submitting information on incidents you consider may be relevant. All information is anonymised or sanitised, as appropriate.

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IMCA makes every effort to ensure the accuracy and reliability of the data contained in the documents it publishes, but IMCA shall not be liable for any guidance and/or recommendation and/or statement herein contained. The information contained in this document does not fulfil or replace any individual’s or Member's legal, regulatory or other duties or obligations in respect of their operations. Individuals and Members remain solely responsible for the safe, lawful and proper conduct of their operations.