I wonder how long it will be for Delta to have a redundant system set up say at MSP? If they had done that the failure could have been transparent to the airline apart from the people directly involved at ATL. It seems that all the airline beancounters would prefer to upset their customers and give dispatch a really hard problem to solve at vast expense to the airline (just think of the EU mandated payments!) rather than have an efficient system that is fault tolerant. Perhaps, if IT had asked for the back up and it been refused the costs of the global ground stop and recovery could be put on the accountancy head count budget? That might concentrate their minds.