Incident to the ATR72 registered F-HBCM operated by Chalair on 21/09/2024 at Caen

On finalizing the weight and balance sheet, the traffic agent entered an erroneous index (sign error) in the calculation software. Subsequently, still in the software, the traffic agent’s modification of the registration resulted in a new passenger seat allocation based on the erroneous index. The captain checked the sheet without seeing the entry error. Several passengers were moved to new seats to take into account this new seat allocation.

The unusual passenger seat allocation in the cabin was detected by the cabin crew member who mentioned this to the purser.  This information was not shared with the captain as he had just validated the weight and balance sheet.

During the take-off, the captain detected that the flight controls were heavy. After take-off, he observed a trim setting that was inconsistent with the calculated value. He contacted the nominated ground operations manager in order to check the LTS data. After verification and detection of the error, the OCC had a new passenger seat allocation sent to the crew via the ATC in order to correct the centre of gravity for landing. The aeroplane landed without any anomaly.