saltytheseagull

You said that DL is being undercut by all the carriers you mentioned. If they were not selling at the current rates, DL would lower fares. DL has made the decision to sell at the current rate or fly empty. AA in particular has been in the news within the last month or two for aggressive (cheap) pricing compared to other carriers. DL has a recent history of extracting a revenue premium.

I see this going into the intricacies of revenue management. As other prior posts have pointed out, we do not know the whole revenue mix of the plane so we cannot say if the flight is profitable or not. At a very high level, the flights would not be flown if they were not making money (with some minor exceptions now due to the first airline bailout), but this will especially come true October 1.