The protracted, high-profile IT failure was caused by an error during an upgrade of the airline's booking and departure system. Technical problems with links into the mainframe network corrupted data in BA's passenger departure control system, which manages all departing domestic and overseas flights.
As Computer Weekly went to press, the corrupted data had still not been purged, although BA was hopeful that the issue would be resolved by the middle of the week.
Industry analysts said the upgrade glitch pointed to a weakness in BA's contingency planning and upgrade projects.
A number of flights had to be handled manually as IT staff worked through the night to purge IT systems of the rogue data. Inventory control, BA's Web site and World Cargo Systems were also hit by the upgrade complications.
BA is working with its outsourcing supplier Amadeus to resolve the error by clearing the corrupted data from the system's numerous links across the business.
BA plans to launch a review into the problem in partnership with Amadeus.
A spokesman for BA said, "An error occurred during the upgrade. The programs are complex and all the information feeds into different systems via links."
Only a handful of flights were cancelled because of the computer problems and passengers were either re-routed on other flights or offered a full refund, the spokesman added.