Airlines measure how much money they collect for each seat flown one mile. Delta's increases have consistently been stronger than most competitors.
On Monday it said that January traffic was flat, as measured by paying passengers flown one mile.
But Delta reduced the amount of flying it did by 2.4 percent. The result was planes that were fuller. Its occupancy rose 1.9 percentage points to 79.4 percent.
Delta and its European flying partner Air France-KLM have been struggling to avoid offering too many seats across the Atlantic. Delta cut Atlantic flying by 10.4 percent in January. Traffic across the Atlantic fell 6.4 percent, so planes on those routes saw occupancy rise 3.3 percentage points, to 77.5 percent. Delta cited "improved Transatlantic performance" as one reason for its revenue gains last month.
Dahlman Rose analyst Helane Becker wrote on Monday that airlines in general have taken flights off of low-demand days and added them on higher-demand days and times. "Most of the airlines have done a great job matching capacity with demand," she wrote.
Delta shares rose 13 cents to $13.95 in morning trading. They have traded in a 52-week range of $8.42 to $14.20.