I can already see some good illustrative material to brighten up Maintenance Human Factors and/or CRM training courses. I'd love to see the root cause analysis (if done properly) of exactly how this seemingly "impossible" event took place. I'm guessing it'll be a holes-in-the-cheese series of errors and/or omissions, rather than a single huge error, because it nearly always is, and that each of those will have been caused by one or more of the classic human factors aka the "Dirty Dozen."