DP Reference System Transponder Near Miss

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Alert ID: 
Description of Task: 

Whilst on station alongside a platform and in DP control, the Second Officer witnessed a member of the installation's deck crew removing the radius transponder from its position on the rig.

When alerted by the Second Officer, the Master immediately deselected the transponder from the DP desk and contacted the installation deck foreman to have the transponder returned to its original position.

Had the Second Officer not sighted the rig crew removing the transponder and the Master not deselected the unit from the DP desk, there was a clear risk for a high potential incident.
Interfering with a transponder has the potential to cause a loss of signal, degradation of the signal quality, degradation of the position accuracy or if operating at an FPSO the system may switch from “follow target” to “fixed position” as has been seen recently in the US Gulf. Each of these poses a risk to the vessel and installation the vessel is working at.

Lessons Identified: 

A questionnaire conducted by the Marine Safety Forum in 2014 on safe operations within the 500m zone identified concerns relating to a general lack of understand of marine operations on installations. In this case there was a lack of understanding of the purpose of the transponder and the effect the moving it could have on the position of the vessel alongside the platform.


There appears to be a wider issue regarding a lack of awareness of the risk posed to fixed platforms by attendant vessels and of the guidance in place to control these risks.


All vessels utilizing transponders such as this are requested to mark them with a statement such as “do not move without prior permission of the attending vessel”, this should be done in a prominent position but not in a way that is detrimental to its effective operation as a position reference system.


A Step Change in Safety work group has recently be set up in cooperation with the Marine Safety Forum to help operators and mainre contractors better understand the risks posed to fixed installations by vessels and identify ways to better control these risks.

Information source: 
Marine Safety Forum
Contact Details: 
Specific Equipment: 

A Platform Supply Vessel was working cargo alongside a fixed installation when a high potential near miss occurred with the vessels radius transponder.

Incident consequence: 
Marine activity, shuttle offloading
Support vessel eg Supply, Standby
Cause of accident or incident: 
Moving vehicle or vessel