A Reederei Nord aframax hit Mississippi River shore structures for a second time in an hour because the master was distracted by making a phone call about the first allision.

The 116,000-dwt Nordbay (built 2007) ended up causing $6.4m of damage to itself, a dock and a wharf in the incident on 2 February, 2016, near New Orleans, the US National Transportation Safety Board (NTSB) found.

The German tanker, in ballast, was southbound with a pilot on board when it allided with a dock and water intakes on the left bank.

Less than an hour later, as the vessel moved through another bend in the river while heading toward an anchorage, it hit with a wharf.

Both the master and the pilot stated they were aware of the wind and high-water conditions for the downbound transit but they did not discuss the effect of these conditions on the ship, the report found.

Both considered the risk of getting under way acceptable and determined no additional measures were needed to mitigate the risk.

After the first incident, the men became occupied with communications and notifications about the accident, the report said.

When approaching the second turn, the master was on the phone with his company representative and responding to requests for information.

"It was only when the pilot notified the master that he needed more engine rpm that the master ended the phone call to attend to the pilot’s urgent request," NTSB said.

"The master, occupied with this call, had no awareness of the rapidly developing situation until the pilot alerted him to it."

NTSB said there was insufficient evidence to establish whether more rpm would have made a difference at that stage in the accident sequence.

It added that the probable cause of the two accidents was the pilot and the master not adequately assessing the risks of handling the ballasted vessel during high-river conditions with strong following currents while turning into the wind.

"Contributing was the bridge team’s poor situational awareness of the vessel’s position in the waterway. Contributing to the second allision was the master’s distraction from his duties while making a phone call," it added.

"Although it is important to provide timely notification of an accident, doing so should never interfere with the safe navigation and control of the ship," it warned.