Poor navigation and poor “bridge resource management” were the cause of the Maersk container ship, the Leda Maersk, running aground in a New Zealand harbor channel during fair weather.
New Zealand’s Transport Accident Investigation Commission (TAIC), the official state transport accident investigator, has concluded in its final report that the pilot and crew of the Leda Maersk did not look at the navigation instrumentation on the bridge of the ship, which is the immediate cause of why it ran aground.
TAIC noted that a harbor pilot of the Port of Otago, along with the crew on the bridge, were “primarily navigating using visual cues outside the ship,” i.e. they were looking out of the window rather than using the ship’s navigation equipment. Those navigation aids “clearly showed the ship deviating from the center of the channel.”
TAIC also found that the standard of bridge resource management aboard the Leda Maersk “fell short of industry good practice” and that the bridge crew were not fully following the policies and procedures of the company.
Port Otago’s policies, procedures and compliance monitoring during pilot operations “fell short of meeting good industry standards,” according to TAIC.
Another key finding was that a variety of human factors – a lack of teamwork and communication, complacency and issues with safety culture, contributed to the accident.
Factors that led-up to the accident
Leda Maersk, a box ship with just over 4,000 TEU capacity, is deployed on Maersk’s “Southern Star” service between Singapore, Malaysia, Australia and New Zealand.
The vessel arrived at the Port of Otago, near the southernmost city of Dunedin, New Zealand, in June 2018. Port Otago is built within a natural harbor that is the drowned and highly-eroded remnants of the crater of an ancient volcano last active about 10 million years ago. Because of its origin, the twisting waterway that forms the harbor is bounded on all sides by cliffs.
It was at 4:59 p.m. when the sun set on the day of the accident. The harbor pilot arrived, set up his equipment, briefed the crew and took control of the ship’s speed and direction. It was 5:54 p.m. when the ship began to enter the harbor. It was dark outside.
The Port Otago passage plan required the ship to stay near the center of the narrow shipping channel but, by 6:10 p.m., the pilot’s electronic equipment indicated that the ship was off-center.
A check by the pilot revealed that there was an 18-meter (59-feet) offset to starboard (the right-hand side of the ship with reference to the forward direction of the vessel) “to allow for the position of the [equipment] aerial in relation to the ship’s centerline.” That offset caused the equipment to show that the ship was 18 meters (59 feet) further to port (to the ship’s left) than it actually was.
Critical decisions made
“The pilot was unable to remove the offset so decided to discontinue using [that piece of equipment] for monitoring the ship’s progress,” the TAIC stated.
The pilot navigated the ship visually and by using the ship’s radar. He did not tell everyone else on the bridge that he had stopped using the equipment.
At just after 6:24 p.m. the ship was moving at about six knots (about 6.9 miles per hour). The channel was curving to the left around a headland. The Leda Maersk needed to follow the center of the channel.
But the ship was moving off track to the left. It was no longer in the center of the channel. The pilot gave a series of orders to move left.
The ship’s installed navigation equipment, ECDIS, squawked out an alarm. Although a member of the crew acknowledged the alarm, it was then ignored. The crew member did not tell anyone else that the alarm had sounded.
Then, at 6:28 p.m., the ship began to heel to the right. The ship’s master asked the pilot why the ship was going so slowly, so the pilot ordered an increase in speed.
And by 6:29 p.m. they had run it aground.
The ship had to be rescued by tugboats, which pulled the vessel back into the center of the channel so that it could continue to the container terminal. Fortunately, the ship received only superficial damage.
Physical factors in the accident
Ships displace water as they sail. When a ship nears an underwater bank of earth, the water in the rapidly narrowing space between the hull and the underwater embankment will be displaced at speed. This creates a suction effect that draws the ship toward the underwater embankment. This is likely what caused the Leda Maersk to heel toward the right and the pilot “unknowingly” would have had to overcome these forces.
Meanwhile, the pilot and the crew lost sight of both the cliffs and the channel’s navigation lights because it was dark and the containers on the ship were stacked-six high. The containers blocked out the sight of the navigation lights from the viewpoint of the ship’s bridge.
“The grounding is an example of why it is not appropriate to use visual navigation alone (often referred to as line-of-sight navigation) when maneuvering large ships in narrow channels, and in the dark,” the TAIC said.
There were five main human factors that led to the grounding of the Leda Maersk, the TAIC said. These were a lack of teamwork, complacency (the bridge team “put too much faith in the pilot getting it right”), a lack of situational awareness, a failure to communicate or act on alerts, and there were issues with safety culture (specifically, the crew did not follow bridge and navigation aspects of the safety management system; secondly, the port operator’s safety management system had not been fully developed).
TAIC also identified four key lessons.
There must be an “absolute agreement and shared understanding” between the bridge team and the pilot about the passage plan and the monitoring of that plan.
Bridge teams must “actively promote and use the concept of bridge resource management” to manage voyages.
A ship’s ECDIS system is important for monitoring the progress of the vessel and for warning the bridge team if navigation is going awry.
Portable pilot units are useful aids to navigation but pilots should be “fully trained” and proficient in their use.
TAIC recommended to Maersk that the company should review the implementation of its safety management system across its fleet in respect of navigation and pilotage. Maersk responded that navigators must undergo mandatory ECDIS (starting 2019) and Bridge Team Enhancement Programme Training (to be completed by 2025).
Port Otago received the recommendation that it should note in TAIC’s report were pilotage operations can be improved and take necessary actions to ensure pilotage operations “fully meet” good industry practice.
The port responded that all pilots have been given refresher training on the use of their pilotage equipment and Maersk has been instructed to change stowage plans to improve visibility on ships visiting Port Otago.
The Leda Maersk
According to VesselTracking.net, the Leda Maersk (IMO 9190755) is a 265.84-meter long by 37.4-meter wide (872.12 feet by 122.7 feet) fully cellular container ship with a draught (the underwater part of the hull) of 14.02 meters (46 feet). It has a container capacity of 4,045 twenty foot equivalent units (TEU), of which 1,109 are refrigerated. The Denmark-flagged Leda Maersk is owned by Maersk Line and it was built in 2001.