Delta Air Lines Inc. (NYSE:DAL), the world’s largest airline, is expected to report increased third-quarter profit on reduced costs and strong trans-Atlantic traffic this summer.

The company, which reports Monday, is expected to post earnings per share of 92 cents, up 1 percent from the year-earlier level, according to an analyst survey by Thomson Reuters.

Revenue is seen rising 1.7 percent to $9.98 billion, and net income is expected to climb to $801.77 million from $765 million in the third quarter of 2011.

July and August were stronger for Delta than September. In July, it boosted passenger revenue per available seat mile (RASM), a standard industry measure, by 4.5 percent; in August it climbed 4 percent; in September it edged up a mere 0.5 percent.

The airline also was helped by capacity cuts, which result in greater efficiencies. In July it achieved a 3.1 percent capacity reduction, in August capacity fell 3.1 percent and in September capacity slipped 0.6 percent.

Efficiencies emerged in other areas. One reason for the improvement stems from grounding a fleet of all-cargo planes Delta acquired in its Oct. 29, 2008, purchase of Northwest Airlines. Rather than fly those jets, also known as “main deck cargo” aircraft, Delta has been moving freight in the baggage compartment of its passenger planes, which is less costly.

Grounding its main deck cargo fleet has cut an estimated $150 million in Delta’s operating costs, Helane Becker, an analyst with Dahlman Rose, said.

“They also had a really good quarter with respect to traffic,” she said.  “The summer months were good; they serve a lot of the European market that tends to do well in the summer.”

Further, Becker, who has a hold rating on Delta shares, said the company “is one of the more aggressive airlines in moving capacity around, based on demand, and they also did pretty well sourcing jet fuel for the quarter.”

Revenue for the Atlanta airline rose in the third quarter, partly from its expansion at New York City’s LaGuardia Airport. In July, Delta added 100 flights to 11 cities from the airport, which helped improve its operating margin by 3 percentage points on a 40 percent increase in traffic, Delta President Ed Bastian said last month at a conference.

The Northwest Airlines acquisition has made Delta more competitive, said John D. Godyn, a Morgan Stanley analyst.

“With merger and acquisition integration risk largely behind the company, Delta has been benefitting from post-merger market share gains and solid free cash flow strength vs. peers," Godyn wrote in a note.

One unknown is the effect of the company’s $150 million purchase from Phillips 66, a former ConocoPhillips unit, of a Philadelphia refinery, a bid to enhance control of its fuel costs.

As part of the April 2012 deal, Delta “entered into sourcing agreements with BP and Phillips 66 that would provide delivery of jet fuel to DAL operations throughout the northeast,” Standard & Poor’s said in a note. “In addition, the company intends to exchange non-jet fuel produced at the refinery for crude oil and jet fuel.”

Shares of Delta closed Monday up 14 cents to $10.14.