Lack of operational planning leads to DP incident

  • DP Event
  • Published on 28 September 2020
  • Generated on 21 September 2026
  • DPE 03/20
  • 2 minute read

Incident

The loss of both DGNSS were due to huge superstructure of the installation interfering with satellite signals.

DPE 20.03 – Lack of operational planning leads to DP incident – Flowchart

Comments

It was concluded that the loss of both DGNSS were due to huge superstructure of the installation interfering with satellite signals. This phenomenon is called reflection meaning DGNSS picks up reflected signals from the surroundings.

Considerations

  • The vessel was not being operated as a DP Equipment Class 2, as the requirement is at least three independent position reference systems should be installed and simultaneously available to the DP control system.  Reference Guidance on Position Reference Systems and Sensors for DP Vessels (IMCA M252).
  • Loss of more than one DGNSS position reference system is a well-known issue due to external common cause failures, for example shielding of reference satellites and/or differential corrections.
  • Operational planning and decision support tools, such as Activity Specific Operating Guidelines (ASOG), were clearly not in use or were inadequate.  Reference Guidance on Operational Activity Planning (IMCA M220).
  • It appears that the DP Alert system was not used.
  • It is mentioned in the report that at 08:09, master takes control of the vessel by the IJS.  It is unclear from the report why the vessel then made contact with the installation.  Reference: The Training and experience of Key DP personnel (IMCA M117). 
  • .This event clearly demonstrates the benefit that can be gained from regular DP exercises and drills.

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The case studies and observations above have been compiled from information received by IMCA. All vessel, client, and operational data has been removed from the narrative to ensure anonymity. Case studies are not intended as guidance on the safe conduct of operations, but rather to assist vessel managers, DP operators, and technical crew.

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