Follow APA style and format, and will be 5-7 pages (not including title page and references page) Describe and define the role of major and national carriers. Identify some of the carriers in each category. How did the national carriers get started? Describe a typical national carrier in terms of its role in the air transportation system, type aircraft, and route structure. What is a “hub and spoke” network, and why do some airlines use it while others do not? Describe the origination and role of regional carriers in terms of their role in the air transportation system. Describe some major changes that have taken place in the US air transportation system in recent years.