In recent years, Boeing has investigated the effectiveness of virtual technologies for aircraft maintainer training. In these studies, we collected data comparing transfer performance following various types of virtual maintenance training to that achieved with more traditional hardware-based training. These data revealed that performance following virtual environment (VE)-based training was marked by significant inter-subject variability. In addition, our results indicated that this transfer performance was mediated by the spatial visualization aptitude. Individuals with higher spatial visualization aptitudes learned effectively from VE-based training, while those with lower visualization aptitude did not. Results for mockup training showed no similar pattern -- mockup trainees performed equally well on the training transfer task regardless of their spatial visualization aptitude. The current study further investigates the role of spatial visualization with regard to the effectiveness of an immersive VE-based trainer. Does the same spatial visualization relationship exist within an immersive virtual training environment? And, if so, are there additional factors that could help to minimize the impact of spatial visualization, therefore making VE-based training more effective for individuals with a broader range of aptitudes? Results indicate that training transfer for the immersive VE-based training was similar to that of other VE-based training conditions. Performance in the training transfer task was highly variable and was mediated by spatial visualization aptitude. Additional experience factors of general maintenance/tool familiarity and 3-D video game exposure did not significantly reduce the effect of spatial visualization aptitude on training transfer performance. Although additional practice within the immersive VE prior to maintenance training suggests a trend towards minimizing the association between visualization and post-training performance, the relationship between visualization and post-training performance was still statistically significant. Implications for future research and training are discussed.