Delta Glitch - Power Outage - Failed Switchgear
650 Delta flights canceled, costing millions of dollars, due to Delta's Data Center Power Outage caused by a failed Switchgear. The backup system wasn't successfully switched over from the primary system. Although event like this happens in-frequent, when it does, business hurts, not just financially. Why companies should invest in monitoring and proactive/predictive maintenance to avoid such failure. Sometimes the consequences of failure are unrecoverable such as the loss of lives and trust to the brand.
https://topics.wsj.com/documents/print/WSJ_-A001-20160809.pdf