Due to high spectrum efficiency and flexibility in bandwidth allocation, elastic optical networks receive extensive research interest in recent years. Availability is one of the most important Service Level Agreement (SLA) metrics in telecommunication networks. In the paper, we apply the sub-band Virtual Concatenation (VCAT) technique to enhance the availability of elastic optical networks. Our study shows that the VCAT technique can greatly enhance the availability of the elastic optical networks, different spectrum distributions of sub-bands (i.e., numbers of frequency slots (FSs)) on multiple paths of a VCAT light path service can greatly impact the network availability, and a higher availability can be expected for a smaller VCAT sub-band granularity.