Rigid and strictly defined business models do not support changes required to meet today's competitive business needs and demands. The business model must be adaptable and should have the agility needed to remain in such an environment. This implies that systems on which companies rely must therefore also be flexible and agile. However, in the case of Online Airline Reservation Systems (OARS), flexibility is undeterminable without accounting for traveler's flexible travelling behavior. In this paper we investigate and explore the concept of users' perception on factors influencing flexible traveling behavior and flexible OARS. A qualitative approach using grounded theory was conducted. Our findings show that users travelling behavior is molded by a number of important personality relevant determinants, both internal and external in characteristics. We conclude that flexibility of users and system are independent but still very much dependent on one another. © 2011 Springer-Verlag.