News: Understand the plan

The ATSB is highlighting the need for a shared understanding or ‘shared mental model’ of a ship’s passage plan by bridge crew and harbour pilots to ensure a safe voyage.

Bulk carrier, Aquadiva

The ATSB’s investigation into the near grounding of the bulk carrier Aquadiva in Newcastle Harbour on 12 February 2017 also underlines the importance of a ship’s bridge crew and harbour pilot engaging in effective communication and information exchange to develop this shared understanding or mental model of a ship’s passage plan.

During the investigation, the ATSB found that Aquadiva’s bridge crew had not received the harbour pilot’s passage plan before he boarded. This meant the harbour pilot and the bridge crew were operating with a different set of assumptions for what constituted a safe passage.  

This misunderstanding restricted the ability of the crew to monitor the ship’s progress properly and identify or correct any errors in the ship’s progress.

A shared understanding or mental model of a ship’s passage lets the harbour pilot and bridge crew work together to identify errors and take steps to correct them quickly.

As a result, when insufficient rudder was applied during the ship’s passage through a section of the harbour known as The Horse Show, the bridge crew did not identify the issue or alert the harbour pilot. The ship then slewed, or moved sideways, toward the southern edge of the channel, and went over the limits of the marked navigation channel.

Once the issue was identified, additional tugs were required to arrest the ship’s movement and return it to the channel to complete its safe passage out to sea.

ATSB Executive Director, Transport Safety, Mr Nat Nagy, said a shared understanding or mental model of a ship’s passage lets the harbour pilot and bridge crew work together to identify errors and take steps to correct them quickly.

“This shared understanding can be enhanced through tools such as a portable pilotage unit,” Mr Nagy said.

“In this case it could have helped with the communication between the pilot and bridge crew to point out and clarify the differences between each passage plan.”

Read the investigation report, MO-2017-002: Near grounding of Aquadiva, Newcastle Harbour, NSW, on 12 February 2017

Last update 16 November 2018