What happened
On April 9, 2013, a Boeing 737-400 was prepared for departure from Katowice Airport (EPKK). Due to terrain obstacles on the planned departure route, the maximum allowable takeoff mass for the specific departure direction was limited to 61,500 kg, which was below the aircraft's maximum structural takeoff weight of 62,822 kg.
Because of this weight restriction, the ground handling agent determined that a portion of the passenger baggage could not be loaded and had to remain at the departure airport. The pilot disagreed with this decision. To justify loading the remaining baggage, the pilot performed an independent weight and balance calculation. However, the pilot used an incorrect load sheet template intended for a 154-seat configuration instead of the actual 162-seat configuration present on the aircraft. Additionally, the pilot assumed a standard passenger weight of 35 kg per person, justifying this by noting that 90% of the passengers were minors who likely weighed less than 30 kg.
The pilot argued that the flight preparation by the charter department was inadequate, as the assigned aircraft should have met all client requirements. The pilot also noted that leaving the baggage behind would have caused significant travel disruptions for passengers using the destination as a transit point. Ultimately, all baggage was loaded, and the aircraft departed using runway 25, which bypassed the weight restrictions associated with runway 07. Flight parameter recorder analysis confirmed that no operational weight limits were exceeded during the flight.
The investigation
The PKBWL examined the pilot's decision-making process and the accuracy of the manual calculations. The investigation reviewed the flight data recorder to verify if the aircraft's structural or operational limits were breached during takeoff. The investigation also looked into the operational procedures of the charter department and the handling of the weight and balance documentation.
Findings
- The pilot utilized an incorrect weight and balance form that did not match the actual passenger capacity of the aircraft.
- The pilot used an arbitrary passenger weight assumption (35 kg) based on the demographic of the passengers.
- Inadequate operational preparation of the charter flight was identified as the primary cause of the incident.