Delta Air Lines reported its most profitable quarter ended in December in the company’s history – with quarterly profit excluding special items more than doubling from a year ago.

The Atlanta-based major carrier with a hub at Memphis International Airport reported net income excluding special items of $379 million for the last calendar quarter of 2011. The net income was $221 million better than the $158 million a year earlier.

Delta’s net income for full-year 2011 was $1.19 billion, down from $1.44 billion in full-year 2010. Delta CEO Richard Anderson said the company saw fuel expenses grow by $3 billion and the additional expense was offset by revenues and a fuel-hedging program through which Delta locked in lower fuel prices before they rose.

“We are keeping a conservative stance on capacity,” Anderson told analysts Wednesday, Jan. 25. “We will continue to pass along higher input costs in ticket prices while working to manage the volatility of our fuel prices.”

Delta attributes having the revenues to cover increased fuel expenses in part to its strategy to permanently cut capacity across its system, including a cut in regional air service into and out of Memphis International Airport.

And the company didn’t rule out further changes in capacity beyond seasonal changes.

Glen W. Hauenstein, Delta executive vice president of network planning and revenue management, spoke specifically about the Memphis hub, saying Delta has had “a lot of success in reshaping” it. But he didn’t rule out further changes.

“We are very pleased with the impact we’ve had in terms of our profit performance,” he added about Memphis. “It’s still not where it needs to be. … It’s generally in the vicinity of where it needs to be.”

The cuts in regional flights at Memphis International, which began last August with a new round this month, have not been mirrored at Delta’s flagship hub in Atlanta or at its Charlotte, N.C., hub. And analysts on the earnings call noted that neither had been part of the restructuring.

Delta executives said they had no plans to readdress capacity in the region at either of those hubs and that both had a “geographic pull.”

Delta’s philosophy has been to regard the Memphis hub as a place for overflow passenger traffic from its Atlanta hub at Jackson-Hartsfield International Airport, the world’s busiest passenger airport.

Anderson and the other executives on the call also flatly refused to speculate in any way about a possible merger with AMR Corp., the parent company of American Airlines, which filed for Chapter 11 bankruptcy protection in November.

Delta and US Airways Group are exploring a possible merger with AMR. The first questions from analysts on Wednesday’s call were about what might happen in any merger of any two airlines, and Anderson declined to speculate.

When the question shifted to “organic growth,” Anderson refused again.

The Delta front office took a similar stance on how it might handle a possible Chapter 11 bankruptcy filing by Memphis-based Pinnacle Airlines Corp., whose CEO specifically mentioned the possibility earlier this month. Pinnacle is under contract to fly some regional flights for Delta, and those contracts have been cited by Pinnacle CEO Sean Menke as a factor contributing to Pinnacle’s financial difficulties.