Over the last quarter of 2011, the airline earned a net profit of $425 million, or 50 cents a share, compared with the $19 million - or 2 cents per share - the airline earned over the same period a year ago. This equates to a 95.5% increase.

Excluding one-off items, such as gains on the sale of airport landing slots, net income more than doubled to $379 million during the fourth quarter.

The airline said its revenue rose 8% to $8.4 billion in the final three months of 2011, countering a 5% rise in fuel expenses for its mainline operations.

For the year as a whole, Delta reported a 2011 profit of $854 million, 44% higher than in 2010, while revenue rose 11% during the year to $35 billion.

The Atlanta-based airline has now turned a profit two years in a row.

Delta's operating revenue grew $610 million, or 8%, in the final quarter compared with a year earlier. Load factor increased to 81.7%, with traffic down 3% on a 3.5% decrease in capacity. 

Passenger revenue increased 8%, or $555 million, compared with the last quarter of 2010, while cargo revenue increased 8%, or $20 million.

Ed Bastian, president of Delta, said: “With the December quarter's strong revenue performance, Delta produced a revenue premium to the industry and fully covered our fuel cost increase with higher revenues. 

“Our revenue momentum has continued into 2012, and we are currently seeing our January consolidated passenger unit revenues up 15% year over year.”

Elsewhere, US Airways also posted its fourth quarter results yesterday revealing a drop in profits to $18 million, or 11 cents a share, from $28 million in 2010, on record revenue of $3.2 billion.

Although the airline’s profit declined 36% from a year earlier, unit revenue, the amount taken in for each passenger flown a mile, increased 11%.

Doug Parker, CEO of US Airways Group, said: “We are very pleased to report a profit for both the fourth quarter and full year of 2011, particularly given the extraordinarily high cost of jet fuel.

“Passenger revenue, total revenue, and passenger revenue per available seat mile all set new company records for both the fourth quarter and the full year.”