VARTM (Vacuum Assisted Resin Transfer Moulding) processing is typically challenging for large scale aerospace grade composite components. Although VARTM processing methods are extensively utilised in the boat hull and wind blade manufacturing industries the tight tolerances and strict quality requirements of the aerospace industry often deem RTM (Resin Transfer Moulding) processing preferable over VARTM. Despite RTM being a very robust process both capital investment and processing time are increasing exponentially with the increase of the part size often making such processes not favourable over conventional prepreg Autoclave processing. On the other hand advanced Out of Autoclave VARTM processing methods such as IRIS (Intelligent Resin Infusion) offers benefits of both worlds as it offers low processing costs and low capital investments with tight tolerances and excellent interlaminar quality. This session will focus on the challenges of VBO (Vacuum Bag Only) VARTM processing methods at a large scale such as: complex flow front propagation, tolerances control, resin management at large volumes and opportunities such as: reduced material costs, reduced energy consumption (especially when coupled with close proximity heating), reduced processing time and reduced waste as realised in advanced VARTM processing methods.