Clearcase Airlines is run by one of the largest megacorps in the world and usually only have business executives flying in them. They are a pretty old airline whose ownership has changed hands many times over the years, each owner adding a new carpeting and furnishing layer without removing the old one.

This resulted in a lot of customers complaining about the speed of the journey but since its control is under singular management, change has been slow. There is frequent time lag of messages between the control tower and the airplane though this does not seem to affect the dependability of the flight. Its usually considered more reliable than the Sourcesafe airline where the communication loss between the tower and the airline results in an immediate stall.

Someone wrote a nice (though brief) description of ClearCase in the article comments:

ClearCase flies aircraft that resemble battleships being brought aloft by 25,000 parakeets, all of whom are weighed down by 25,000 pages of documentation, which none of them have ever read.

Some companies have a cultural need to give IBM thousands of dollars and employ multiple professionals to keep their VCS working. I will say ClearCase can intelligently handle branching, to a point. But it mostly exists to fill that cultural need.