Des Moines International Airport narrowly missed setting a monthly passenger traffic record in August, gaining 12.1 percent over the same month last year. The total came in at 250,046, just short of June’s record of 251,265. The July total was close to the all-time high, too, at 249,944. For the year, traffic is up 6.3 percent, well above the growth rate officials hoped to see to support a proposed new terminal. The biggest gainer in August among the largest carriers was Delta Air Lines at 13.6 percent.