I have some, relatively small scale, experience in such matters and no "Power Surge" short of a massive nuclear EMP, is going to take out my systems.
All this hand-waving about "power surges", as if it were some kind of excuse, is a straight out lie (even if it were true, which we know was another lie). A big essential system like BA's should properly be architected in such a way that NOTHING will take it right down for days on end.
Degraded for a few hours has to be the worst case scenario.
There is simply no excuse at all that would cut it with any competent systems manager - ergo, they had no competent systems manager either in house or out.
And for any big company to outsource their IT management is very very foolish. One largish company that I am familiar with has someone reasonably senior in their server room 24/365 and at least two other branches with spare capacity to take over within minutes.
Incompetence, lies, injudicious outsourcing and penny-pinching on one of their core resources.
Plain stupid.