It is commonly believed that digital skills are highly perishable, yet little empirical data exist to document just how perishable these digital skills are. Skill decay for Force XXI Battle Command Brigade and Below (FBCB2) was investigated with 54 infantry captains who attended a two-day FBCB2 familiarization course. Operator knowledge and skills were measured immediately after the course and again eight weeks later. During the eight-week retention interval, none of the participants had an opportunity to practice with an FBCB2 system. At baseline, individuals did not do as well on the knowledge test (avg. score 40%) as they did on the hands-on test (avg. score 72%). After the eight-week retention interval, there was no significant overall decline in performance on the knowledge test, but this may have been due to a floor effect. On the other hand, there was a small (10%) but significant forgetting of operator skills. Decay of knowledge and skills was not uniform across individual items. On the knowledge test, forgetting was most acute for a specific fact (the packet mode message size limit in bytes - 45% decline). On the operator skill test, auto-centering the icon on the map, creating a route, and creating an address group all showed significant declines of 20% or more while creating and sending free-text messages and using the line-of-sight tool showed virtually no decay. Measures of training, experience, and knowledge were all examined as possible mediators of skill decay but were not found to have a very large impact on proficiency scores. In summary, these findings suggest that digital skills are not uniformly prone to decay and therefore training can be made more effective and efficient by targeting the most perishable skills. Different methods for improving skill retention are discussed.