UPDATE 1-Alaska Air quarterly profit rises 13.8 percent

(Adds results)

July 26 (Reuters) - Alaska Air Group Inc on Wednesday reported a 13.8 percent rise in quarterly profit, helped in part by the December 2016 acquisition of former rival Virgin America.

Alaska, now the fifth-largest U.S. carrier by passenger traffic, reported a second-quarter net income of $296 million, or $2.38 cents per share, from $260 million, or $2.10 per share, a year earlier.

The Seattle-based carrier posted an adjusted earnings per share of $2.51, coming just short of analysts' consensus forecast of $2.52, according to Thomson Reuters I/B/E/S.

Quarterly passenger unit revenue, which compares sales to flight capacity, rose 1.3 percent in the period ended June 30.

Earnings from the prior year do not include Virgin America's results.

"We had a very solid quarter, driven by a growing customer base and strong revenue performance," Alaska Air Chief Executive Brad Tilden said in a statement, noting "a number of operational challenges" as the two airlines unite.

Total operating revenue rose 40.7 percent to $2.10 billion. (Reporting by Alana Wise in New York and Ankit Ajmera in Bengaluru; Editing by Anil D'Silva and W Simon)