I too have had many positive experiences. Some of the bad ones are usually just dumb, but I expect it to happen. I would suggest someone look at the folks you work with in your company and guess how often they may screw up. Then apply that to the 5,196 flights DL flies each day, which comes to over 150,000 flights a month (stats from annual report).

They have to make mistakes once in awhile.

I am still flying them.