Delta Air Lines reported a 12% decline in full-year 2017 operating profit to $6.11 billion, as costs grew faster than revenue.
Revenue rose 4% to $41.3 billion in the year, and expenses were up 7% to $35.1 billion.
The Atlanta-based airline reported an 18% decline in full-year net profit to almost $3.58 billion.
"Delta people rose to the challenges of 2017 to produce solid financial results, industry leading operational reliability and strong improvements in customer satisfaction," says Delta chief executive Ed Bastian.
In the fourth quarter of 2017, Delta reported a 17% growth in operating profit to $1.19 billion despite a $60 million impact from a power outage at Atlanta airport and winter storm Benji in December.
Fourth-quarter revenue was up 8% to $10.2 billion and expenses rose 7% to $9.05 billion.
The SkyTeam carrier's net profit in the period declined 8% to $572 million, after accounting for higher non-operating expenses and income tax provisions.
In 2017, the airline posted a 2.1% increase to passenger unit revenue to 13.69 cents. Unit cost excluding fuel grew 4.3% to 10.57 cents.
Fourth-quarter passenger unit revenue rose 4.2% to 14.15 cents and unit cost excluding fuel fell 0.4% to 11.2 cents. Delta points out that the decline in fourth-quarter unit cost was driven by the impact of Delta's pilot agreement ratified in the fourth quarter of 2016, which resulted in $475 million of expenses in that period. When adjusted to discount this impact, unit cost excluding fuel in the fourth quarter of 2017 actually rose 5.6% to 11.2 cents, says the airline.