Fifty one no more: US Airways now requires carryons to measure no greater than 45”. They had been the last to adhere to the old 51” standard. Will monetary considerations win out and drive the standards to be more restrictive (for more checked bag fee $) or can we expect the 45” standard to hang around for a few more years? I don’t expect much size constriction but weight and piece limits (no personal item/1 carryon) are another matter. They’re already here in some case and should propagate.