this `` priority reservation '' system would in theory apply only to the rush hour periods of 7 a.m. to 9 a.m. and 4 p.m. to 6 p.m. but as mr. davis noted in a recent speech , `` any hour when scheduled operations exceed '' the optimal aircraft flow `` would be classified as a peak hour , '' raising the prospect of far-reaching access restrictions if logan traffic continues to grow .