In addition, international traffic climbed 3.2%, while domestic traffic increased 9.5%, while the load factor (the ratio between revenue and available seats) improved by 3.5 points to 84.4%.
But for the September quarter, Delta said it now expected passenger unit revenue growth of between 2% and 3%, compared with guidance of 2.5% to 4.5% growth provided in July, as a recovery in domestic yields has been slower than anticipated.
The airline now expects third-quarter operating margin of 16.5% to 17.5%.
That compares with previous guidance of 18% to 20%, due to in part higher fuel prices.
Delta shares flew 2% lower to $46.57.