Provide a Five Forces Analysis of the structure of the U.S airline industry

1-) Read Delta Airlines (A) case 2-) In the case analysis , discuss the following :

1-) Provide a Five Forces Analysis of the structure of the U.S airline industry.

2-) During the 1990s none of the five largest US carriers earned their cost of capital. Why have such low rates of return persisted in the airline industry?

3-) Despite the challenging industry environment airlines like Southwest and JetBlue earn enviable returns.