This 2[SUP]nd[/SUP] tier status is attained with Qualifying Miles, the miles earned with THAI and Star Alliance airlines, during 2 rolling month periods, 10,000 Qualifying miles during a 12 month period, or 15,000 Qualifying miles during a 24 month period. This is a system automated process whereby on the most recent activity all eligible flights are evaluated for the past 12 and 24 month periods. With each new activity, status is again evaluated during the past 12 and 24 months, ensuring that all eligible flights are counted for attaining Silver status.