British Airways has not released the official post-mortem or details yet, but a friend did find this interesting article which I had not yet read when I wrote this.
BA power system designed to cope with disaster failed and rebooted incorrectly Willie Walsh issues apology and says…www.dailymail.co.uk
While a decades old UPS is actually the thing that failed (and should have been replaced), as I outlined in my original argument that was probably a separate thread in analysis.
What is still interesting is why the outage lasted days instead of hours. How quickly was power restored versus how long it took to get the system working? We lose power to datacenters, UPSes fail all the time. It has been one constant in my IT career :)