What happened
On September 21, 2024, an ATR 72-212A, registered F-HBCM, operated by Chalair Aviation, departed Caen-Carpiquet airport for Kerry, Ireland. During the pre-flight process, station agents at Caen were updating the aircraft's weight and balance information. Due to a manual update of the Dry Operating Index (DOI), a mathematical sign error occurred: the index was entered as 15.5 instead of -15.5.
During the preparation, the aircraft registration was manually added to the software, which triggered a new passenger seat allocation. To align the actual cabin configuration with the software's erroneous calculations, two passengers were moved from the rear to the forward section of the cabin.
During takeoff from runway 31, the captain experienced heavy flight controls during rotation. Upon trimming the aircraft, the pilot noted a trim setting of 2.2 UP, which deviated significantly from the 1.2 UP value recorded on the flight documents. After contacting ground operations, the error was identified. To correct the center of gravity for the arrival, the crew was instructed via air traffic services to move six passengers from the front of the cabin to the rear. The aircraft landed safely without further incident.
The investigation
The BEA examined the sequence of events, focusing on the data entry process and the software used by the station handling service. The investigation looked into the training of the traffic agents, the workload of the station supervisor, and the technical configuration of the iPort DCS software. Simulations were also conducted to determine how much weight redistribution would be required to move the aircraft outside of its certified weight and balance envelope.
Findings
- The primary cause of the incident was a sign error during the entry of the Dry Operating Index, where the negative sign was omitted.
- The traffic agent's lack of regular practical experience and recent, non-standardized training contributed to the error.
- The station supervisor was managing high workloads and time pressure to ensure an on-time departure.
- The software configuration allowed the pre-filled DOI to be easily overwritten, increasing the risk of manual entry errors.
- The crew did not notice the error on the final Load and Trim Sheet, and the unusual passenger seating arrangement noted by the cabin crew was not communicated to the flight deck.
Safety action
Chalair Aviation has suspended the use of the iPort DCS software at the Caen station for producing weight and balance sheets, reverting the task to the Operations Control Centre (OCC) until software or procedures are updated. The operator also issued a directive restricting DOI modifications to qualified personnel. Additionally, Caen airport is implementing a new training and proficiency check plan for traffic agents and reviewing staff fatigue cycles.