A management system for a transportation carrier such as an airline is described that provides network-based management of customer data by allowing a user to form a list comprising multiple customers associated with different sets of criteria and to process customer data corresponding to customers associated with multiple lists defined by different criteria. In one embodiment, an airline management system allows a user to append additional customers to a list comprising previously selected customers without having to re-request the list with additional search criteria and re-select the previously selected customers. The airline management system also allows a user to simultaneously display multiple lists of customers that are defined by different criteria. As a result, airline personnel using the airline management system may more effectively and efficiently access and manage customer data required to provide airline services.