A package conveyor (10) operating control system comprised of a continuous conveying belt (11) supported on separate plates (23), air pressure responsive pads (27) supporting the plates (23) to effect lifting and lowering of the plates (23), photocells (48, 64, 77) associated with each plate to detect the presence of accumulated packages, groups of air pressure flow valves (44, 59, 75) to control the lifting and lowering of the plate (23) to permit accumulation of the packages when a leading photocell (48) signals accumulated packages to initiate the lowering of the trailing support plate after a time delay and when both a leading and trailing photocell signals accumulation of packages to initiate the lowering of the trailing support plates after a shortened time delay to avoid impact damage to the accumulated packages.