3. Describe the role of the major and national carriers. Identify some of the carriers in each category. How did the regional carriers get started? Describe a typical regional carrier in terms of its role in the air transportation system, type of aircraft flown, and route structure. What is meant by hub-and-spoke network? Why has the number of regional carriers declined since deregulation? Describe some of the changes that have taken place in this segment of the industry. What is code sharing?