NLR developed enhanced Virtual Block Control for Milan Malpensa Airport during low visibility conditions. Instead of working with traditional physical stop bars, the virtual block control concept makes use of virtual stop bars, which enables multiple aircraft to be within one block during low visibility conditions, enhancing capacity. Safety nets are added to the concept in the form of Runway Incursion Alerting, Virtual Stop Bar violations and route deviation alerts. The system works with digital clearances or instructions for push-back/start-up and taxi (D-Taxi). NARSIM Tower was used for the concept development, prototyping and validation of the system by air traffic controllers from ENAV. Also NARSIM Tower was connected with the Alenia cockpit simulator for integration of the Virtual Stop Bars on the pilot navigation display.