At the risk of being contrary, I think many, if not most, of the posts in this thread are a bit too dismissive of BA's IT procedures. While it is satisfying to chalk this
to incompetence or cost-cutting, we don't know the answer yet. Just as airliner accidents now-a-days typically result from a confluence of multiple unexpected or untoward circumstances, so too do IT disasters.
I suspect that rather than being juvenile, BA's IT procedures are pretty advanced and very cognizant of the damage wrought by failures, with a lot of redundancy built in. Let's wait until the true facts become known.
But I worry that there will be a substantial noncomparability between this IT incident and an airliner accident. The latter is investigated professionally by the AAIB, and the results made public, while who knows what transparency will exist with the former?