Probably the most critical dealing with 'disaster' was in a position I held as IT manager for a food distribution company starting in 1974 where we started up a brand new istallation and within a couple months were operating 24 hours a day, Sunday through Friday. We were shipping 20-25 truckloads of customer food and supply orders daily to hundreds of accounts such as hospitals, nursing homes, schools, restaurants and the like. I had six staff doing interactive date entry and billing because many orders were COD so invoices had to go on the delivery trucks. There were about 30 outside sales people sending orders remotely and an inside department taking phone orders and organizing delivery documents 24 hours day. Then there were warehouse people picking orders and loading trucks, and drivers who arrived at the scheduled departure time and went on the clock even if the loads were not ready.
My operations staff was all union, so I had to deal with seniority issues when callling them for overtime, even in the middle of the night. And since they were on a staggered schedule, the whole period was unpredictable.
Any issue from mainframe, disk drives, printers, CRT terminals, air conditioning, or absent operators was in truth a disaster, either from the standpoint of lack of people or people unable to be productive. Then after the problems were resolved, there was the issue of time and overhead to catch up. In the early days of this installation, before databases with recovery capability, we had to back up files every couple hours during rest breaks just to avoid having to repeat so much work.
What I learned from that is, when you have a crisis to deal with, DON'T call a meeting. Let everyone focus on fixing things. And you better have a plan.
Disaster Recovery = Backup ( Backup ( Your Backup ) )