Virgin america uses social media engagement to respond, listen to, and connect with fans, which is important to them because it builds loyalty, which is one aspect of the pillar of the brandassett valuator.

I believe the answer is: Esteem
The Esteem pillar of the brandassett valuator refers to the customers' perception toward the quality and the popularity of our Brand.
As this esteem goes higher, customers will become more likely to stay loyal toward our brand and willing to pay more money to obtain our brand.