Describe globalization as it applies to the airline industry

Describe globalization as it applies to the airline industry. Why is it so difficult for U.S. carriers to establish hubs outside the United States? Why are bilateral agreements between the United States and many foreign countries to the disadvantage of U.S. carriers? How would an open-sky agreement improve this situation? Describe how code-sharing agreements operate. What is the impact on competition? How does the airline industry differ from other industries with regard to globalization?