Asiana Airlines Co., South Korea's No. 2 flag carrier, said Friday that it swung to the black last year with its operating profit surging more than fivefold from a year earlier, aided by low oil prices and cost-cutting efforts.

Net profit came to 54.3 billion won ($47.3 million) in 2016, a turnaround from a loss of 139.2 billion won in the previous year, the company said in a regulatory filing.

Sales gained 4.5 percent on-year to 5.79 trillion won, but operating profit spiked 444.5 percent to 257 billion won from 47.2 billion won over the cited period.

The operating profit is the highest since 2011.

"Favorable business conditions, such as low oil prices, as well as the company's restructuring efforts, helped improve its earnings," the company said in a press release.

The company noted its restructuring efforts included sales of noncore assets, such as its 50 percent stake in Kumho Asiana Plaza Saigon.

It earlier said its debt ratio came to 572.2 percent as of end-September, down more than 490 percentage points from end-2015.

In the fourth quarter, however, its net loss widened to 116.1 billion won from 51.3 billion won in the same period last year.

Its sales advanced 6.2 percent on-year to 1.48 trillion won, with operating profit coming to 40.8 billion won to mark a turnaround from a loss of 1.2 billion won in the fourth quarter of 2015. (Yonhap)