NAB executives should be obsessed with working for customers, interim chief executive Phil Chronican said as he promised change at the scandal-hit lender.
Mr Chronican started in his post on Friday following the abrupt resignation of his predecessor Andrew Thorburn, who was last month criticised in the financial services royal commission's final report.
In an internal email sent to the bank's 100 most senior executives on Thursday, Mr Chronican said he agreed with the Royal Commission's finding that NAB was not meeting the expectations of its key stakeholders.
"We are the bank's most senior leaders: we need to run the bank - and we need to change it," wrote Chronican, who was a non-executive director on the NAB board when tapped for the interim role.
"We need to bring the same obsession to customer outcomes that airline companies do to safety."
His first day in the top job coincided with the arrest of a former supplier accused of defrauding NAB of millions of dollars.
NAB said it was cooperating with police, with the alleged fraud involving a former staff member.
"If the alleged fraud is proven, it represents a most serious breach of trust by a former employee," the bank said in a statement on its website.
During the royal commission, the bank admitted its subsidiaries wrongly charged fees to thousands of customers without providing them with services.
In his email to executives, Chronican also said the bank was focused on ensuring fair compensation to customers for its wrongdoing.
"I am focused on making sure we compensate customers as quickly as possible; and on fixing the issues that caused the failure."