A proceduralized form of Crew Resource Management (CRM), Advanced CRM (ACRM) was developed and evaluated in a regional airline. Crews in two different fleets were either trained and used ACRM as standard operating procedure (SOP) or were not trained and did not use ACRM as SOP. Jump seat evaluations of ACRM were executed in both fleets on line flights. Fifty line flights were observed by a separate cadre of 5 air pilot observers. Results showed that the performance of the ACRM trained crews was significantly superior to that of the non-ACRM trained crews on 13 of the 20 items evaluated.