The increasing customization and requirements for product flexibility bring new challenges for the aeronautical industry. This paper addresses the mid-term planning for a mixed model assembly line, where several products compete for the use of shared production stations and where operators (human resource) availability is another key constraint. The problem has been characterized as a Resource Constraint Scheduling Problem (RCPS) and solved using Constraint Programming (CP). Results have been provided within seconds and outperforming the existing previous solutions for real industry instances, providing better solutions in terms of on time delivery and inventory cost.