A drop in the number of flights at Atlanta's Hartsfield airport in the first three months of the year was responsible, officials said.
Hartsfield had edged O'Hare in the rankings for the first time in 1987, when Hartsfield handled an estimated 797,037 flights to O'Hare's 794,921, according to figures kept by controllers at the Atlanta airport.
With 192,211 flights in January, February and March, Hartsfield fell into the No. 2 position behind Chicago, which logged 196,589 flights in the quarter, according to the FAA.
That represents a 3% decrease in overall traffic at Hartsfield, compared to the same period last year when the airport recorded 197,657 flights, according to the FAA.
O'Hare also had the highest delay rate with 55 delays per 1,000 flights, while Hartsfield had far fewer delays during the first three months of 1988, compared to last year, FAA figures showed.
Through March, Hartsfield International recorded 9,393 flight delays of 15 minutes or more, for a rate of 49 delays per 1,000 flights, compared to a rate of 84 per 1,000 last year, according to figures reported by the Atlanta Constitution today.
Much of the reduction apparently is due to Eastern Airlines' cutting back on flights to Atlanta, although Hartsfield officials pointed out that the first quarter of 1987 set records that would be hard to match.
"We've had record growth for three years in a row, but it's not going to continue forever. Even with the decrease, those are still healthy traffic figures. Maybe we've just hit a plateau," said city Aviation Department spokeswoman Marie Powers.