The 10th anniversary of the Sept. 11, 2001, terrorist attacks this week reminded me of how much can go wrong in the airline industry to no fault of its own. Despite everything outside the airlines’ control, there are many reasons to criticize their performance. But how much slack should we cut them?

I’ve written several times about the increased scrutiny of the airlines by both the media and the public, compared to other industries, simply because of the nature of their business. A commercial carrier has more front-line employees than almost any other company, and it’s easier to complain about a person we see in front of us than about an invisible — and sometimes anonymous — representative…