Airbus had already revealed that the fatal crash of an Airbus A400M military transport was caused by what was described as a "quality issue in the final assembly" of the electronic control units (ECU)—a fault in software configuration that led to a loss of control of the aircraft and resulted in the death of four crew members. Reuters reported additional details today provided by individuals familiar with the investigation into the crash, stating that a critical part of the configuration data in three of the aircraft's four ECUs—a file storing torque calibration parameters for each engine—was somehow "accidentally wiped" when the software was being installed. As a result, three of the aircraft's engines automatically shut down in flight.

Citing a safety document shown to Reuters, Tim Hepher reported that the pilot of the A400M would not have gotten an alert about the missing data until the aircraft was already at an altitude of 400 feet. No cockpit alert about the data fault would appear while the aircraft was on the ground. According to Hepher's sources, the lack of a ground warning was an issue raised during a safety review last year, but "regulators approved it on the basis that the chances of failure were small and the installation procedure included extra checks," people familiar with the matter said.

The A400M, which was on a final test flight before delivery to the Turkish Air Force, reached an altitude of 1,725 feet after takeoff before crashing during an attempted emergency landing. The aircraft struck an electrical pole at about 180 miles per hour.

The missing data made it impossible for the aircraft's central control system to interpret data coming from the engines' sensors. The aircraft's software is designed to shut down malfunctioning engines to prevent them from affecting the operation of the aircraft. But a software failure of more than two engines was never taken into consideration.

The data wipe appears to have been caused by the computer system used to install the flight control software and update calibration data. Airbus has instructed its European NATO buyers of the A400M not to use that software. Safety officials are still investigating how safety checks failed to spot that the calibration data had been deleted.