This paper describes progress on an ICAO tasking to the FAA and Eurocontrol to lead an effort to harmonize wake turbulence separation standards for existing and new aircraft and to safely increase capacity. The first phase of the re-categorization effort looked at placing the existing traffic mix of both the U.S. and Europe into 6 categories. The second phase of the effort will determine static pair-wise spacing that will work for all atmospheric conditions. The final phase of re-categorization will provide dynamic pair-wise spacing that will vary with atmospheric conditions and aircraft performance. This paper provides the methodology of the first phase of re-categorization and gives examples of new aircraft categories that show capacity increases over today’s U.S. and ICAO categories.