What happened
During the loading process of a flight, a leading hand relocated baggage from section 21 to section 31 within the Load Control System (LCS). This movement caused the aircraft to become out of balance. As a result of this change, the LCS entered a locked state, indicated by greyed-out buttons and a status change to ‘LL’ on the display. The leading hand, unaware of the significance of this status change, reset the system. Upon resetting, the system became functional again, but the user did not realize that the load distribution changes had not been officially approved.
Simultively, the load controller identified an error message indicating the aircraft was out of trim. The controller attempted to notify the leading hand using the LCS messaging system. However, because the leading hand had not subscribed to the system's notifications, the messages were never received. While the loading continued, the error in the load distribution was not identified by the leading hand until after the aircraft had departed.
The investigation
The investigation examined the interaction between personnel and the LCS software. It was found that the leading hand was not subscribed to the messaging network, preventing the receipt of critical updates from load controllers or AMCOs. The investigation also looked into the clarity of the LCS interface, noting that the ‘LL’ status and greyed-out buttons did not provide sufficiently clear feedback to indicate that a load controller's acceptance was required.
Furthermore, the investigation reviewed the operator's communication protocols. There were two conflicting procedures regarding how load controllers should notify staff of denied change requests. One procedure required a phone call, while the controlling document for out-of-balance operations suggested using the LCS messaging system. In this instance, the reliance on the messaging system failed due to the lack of subscription by the receiving party.
Findings
- The leading hand was not subscribed to the LCS messaging system, which prevented the delivery of messages from the load controller.
- The LCS interface failed to provide clear indications that the load distribution change required formal acceptance by the load controller.
- There was a discrepancy between two operational procedures: one mandated a phone call for denied changes, while the other suggested using the LCS messaging system.
- The leading hand did not successfully cross-check the final load distribution against the Load Distribution Report (LDR) prior to departure.