For instance, Southwest Airlines challenged the industry by flying just one kind of airplane, reducing costs and allowing it to offer better ticket deals.
And this week the International Civil Aviation Organization, the ICAO, a U.N. body, agreed on a plan to do just that—that won't take effect until 2020.
Secondly, there's the perception in the industry that the Department of Transportation which has to approve airline mergers, is more lenient than the Justice Department would be.