The Aratere ferry is seen grounded near Picton in the Marlborough Sounds. Photo: Samantha Gee
Leaked documents about the Cook Strait ferry grounding show a crew member accidentally triggered the auto pilot into the wrong course before it crashed into the shore.
The Aratere ship ran aground shortly after departing Picton at 9.45pm on 21 June.
None of the 47 passengers and crew aboard were injured and the ship was refloated just under 24 hours later.
The Interislander documents showed after Aratere left Picton it had been switched from hand steering to autopilot.
A staff member then "inadvertently" pressed a button which caused the auto pilot to change direction sooner than it should have.
The vessel started an "alteration of course ... almost (1 nautical mile) prior to the planned waypoint", the document stated.
The ship's crew noticed the turn to starboard but were initially unable to get back control of the vessel.
About a minute passed before hand steering and reverse propulsion could be engaged and by that time it was too late to prevent the ship running aground in Titoki Bay, the document said.
The document was shared with staff late last week - as a safety briefing intended to provide guidance, raise awareness, or reinforce good practice.
It said it was based on a preliminary finding into the cause of the accident and that - although investigations into what happened were continuing - it was unlikely its explanation of the cause "will change significantly".
"The accidental and early operation of the execute button on the starboard multipilot commenced a chain of events which led to the grounding," the briefing stated.
"The reasons why recovery controls (defences) that should have corrected this unplanned deviation were unsuccessful is part of the ongoing investigation and more information about this will be shared at a later date."
The document leaked to RNZ was sent from the Interislander safety and health executive committee to master and deck officers.
Safety briefing recommends crews not use autopilot near Picton berth
The briefing went on to recommend bridge teams hold refresher training to ensure crews understood the autopilot and steering control systems and had the ability to operate emergency steering systems.
It also said the safety committee would require a review of the vessels control systems and "identify buttons that single activation of could directly control vessels movements... and could cause significant safety or operational impacts".
It recommended hand steering be used to control the boat in the area between the berth at Picton and a line that ran from "Wedge Point and the Snout" which lies beyond Titoki Bay where the boat ran aground.
Interislander executive general manager Duncan Roy told RNZ the safety bulletin issued in response to the incident was "standard maritime procedure".
"It is designed to quickly ensure crew awareness across the fleet after a serious incident, with what is known at the time. It does not replace the three full investigations (KiwiRail, Maritime NZ and TAIC) into the grounding incident that are underway. The Safety Bulletin states this," Roy said.
"Aratere's autopilot system is not new and has been operating since 2007. It is important that we understand all of the factors involved in the incident, including the underlying causes. A fair and thorough investigation process is crucial for all parties and is being followed."
The Aratere limps back to dock in Picton after being grounded. Photo: Stuff/Maia Hart
New Zealand First cast doubts on crew
On Tuesday, a New Zealand First post - on social media site X - questioned whether crew negligence had caused the ship to run aground.
"Is it true that the Aratere ran aground when someone put the autopilot on, went for a coffee, and then couldn't turn the autopilot off in time when that someone came back?" the post read.
"If so, why haven't the public been told that?"
When approached by RNZ about the leaked document, the Maritime Union declined to comment on "second hand reports, tweets etc".
Merchant Service Guild vice president Iain McLeod said Maritime NZ and the Transport Accident Investigation Commission were interviewing crew members, canvassing the ship's logs and reviewing voice recorder files that ran during the incident.
"We were very surprised to see Interislander put unconfirmed details out in a bulletin to masters and deck officers while events are still under investigation," McLeod said.
Maritime NZ director Kirstie Hewlett said their investigation would cover a much broader scope than the Interislander's safety bulletin.
"An operator's safety bulletin is not a replacement for a Maritime NZ investigation. Our investigation involves carrying out interviews, examining the vessel, reviewing documents and gathering other information as required," Hewlett said.
"It looks at all the contributing factors that may have caused the incident, including systems, processes, training, equipment and other relevant information. We then assess all the information gathered, then decide what, if any, further action should be taken."
Detention of Aratere lifted
In a separate release, Hewlett confirmed Maritime NZ had lifted the detention notice on the Aratere.
"Earlier this week, we inspected the vessel, and observed it undertake several tests while at berth involving systems, processes and equipment. Off the back of these tests we have now lifted the detention notice, but imposed conditions on the operation of the vessel," Hewlett said.
"These conditions allow the Aratere to return to service through a graduated and controlled approach that enables further assurance by KiwiRail, any corrective and preventative measures are implemented, and the vessel is operating safely.
"Initially, the conditions will allow crew and rail freight only (four return sailings), then trucks and their drivers, followed by a limited passenger service, and then full capacity sailings to be permitted."
A full return to service would happen if no further issues had been identified and once KiwiRail had "implemented its return to service plan".
The Transport Accident Investigation Commission would not comment, but said its inquiry was ongoing.