Just does not sound right.
I work in a Bank DC in the UK, and we have 5 mirrored DC's throughout the country.
Ours has 3 different incoming power supplies from different Counties.
Plus out the back, we have 8 massive V12 Diesel Generators that would power a small town.
Now i would imagine that BA would at least have something on the same scale, if not bigger.
So why the outage ?......
We do Power tests every month. An incoming power feed is killed, to check redundancy.
We also shut off 1 of the 2 power rails going into each cab, again to test redundancy.
Perhaps BA are running their backbone on some beefed up PC in someones bedroom ?.