This paper reports on a project in the area of simulation based decision support (SBDS) at the operational level of the manufacturing system. The purpose of the project was to explore and describe the possibilities to use a standard discrete event simulation package for capacity planning purpose in a situation where labor was a primary and scarce production resource. This has been done through a case study at a Radio Base Station (RBS) assembly line at Ericsson Radio System, Gavle. Results from the study are a conceptual structure for a SBDS system and a prototype simulation system tailored for the RBS-2OOO assembly line. The system has been tested in a simulated environment and results indicate a delivery precision improvement of eleven percent. Conclusions from the study are that this kind of tool for operational decision support offers a flexible decision support environment and that the need for high quality information and information collecting systems are crucial for the success of such tools.