According to The Times, inside sources believe that a "contractor doing maintenance inadvertently switched the [power] supply off." Per this account of events, someone flipped the wrong switch or pulled the wrong plug, causing one of the world's largest airlines to be plunged into darkness. Agents lost access to any records, the website went down for days, baggage records were lost and all flights were canceled.
Not surprisingly, the IT contractors managing the site dispute this version of events. A statement from the outside contractor published by The Guardian notes, "No determination has been made yet regarding the cause of this incident. Any speculation to the contrary is not founded in fact."
Whatever the cause, it seems those in charge were in such a hurry to get the systems back up that they did so in a way that made the situation worse. From an internal BA email leaked by The Times, we learned that the system was "turned back on in an unplanned and uncontrolled fashion, which created physical damage to the system."
Failures happen, but what's quite unbelievable is that BA didn't have a functioning backup system ready to jump in when the primary system went down. This isn't the first time that this has happened for an airline. Delta's August 2016 outage was also blamed on a power failure, with backups failing to keep the system running.
If you were affected by the system outage, make sure that you file for compensation. We go into all the details here, but British Airways has a responsibility to get you to your destination; the airline will pay for hotel, food and ground transportation expenses; you're entitled to additional compensation per EU law. If BA doesn't cover all of your expenses, look into the delay protection on the credit card you booked the flights with.
