What happened
On October 30, 2005, at 21:04 UTC, a Let L-410-25, registration 9A-BTA, crashed near the Orio al Serio airport in Italy. The aircraft, operated by Trade Air, was performing a cargo flight from Orio al Serio to Zagreb. On board were two crew members and one passenger.
Following takeoff, the aircraft was cleared for the ORI 5Q standard instrument departure (SID). However, shortly after departing the runway, the aircraft began a left-hand turn that progressively steepened. This maneuver was accompanied by a rapid loss of altitude. Within approximately one minute of flight, the aircraft impacted the ground in a plowed field near the localities of Azzano di San Paolo and Grassobbio, approximately one kilometer southwest of the runway. During the descent, the aircraft struck and severed medium-voltage power lines. The impact and subsequent fire resulted in the three fatalities on board and the complete destruction of the aircraft and its cargo.
The investigation
The ANSV investigation examined the flight data, cockpit voice recorder, and the wreckage. The investigation focused on the aircraft's performance, the crew's actions, and the environmental conditions, which were characterized by dense fog and visibility of less than 400 meters.
Investigators analyzed the flight parameters, noting a slight difference in engine torque and RPM between the two engines during takeoff. The investigation also reviewed the aircraft's weight and balance calculations, finding that the aircraft's mass exceeded prescribed limits because the passenger's weight had not been included in the takeoff calculations. Furthermore, the investigation found that the cargo was secured with insufficient materials.
Findings
Several factors contributed to the loss of control:
- Loss of situational awareness: The crew failed to maintain awareness of the aircraft's attitude during the initial climb.
- Spatial disorientation: The pilot may have experienced an optical illusion caused by runway lights filtering through the dense fog, leading to an unintended turn.
- Cargo shift: The movement or improper positioning of the cargo may have induced a rolling moment on the longitudinal axis that was not immediately corrected.
- Inadequate Crew Resource Management (CRM): The limited experience of the co-pilot and a failure to apply effective CRM techniques prevented the crew from identifying the developing danger and executing recovery maneuvers.
- Weight and balance errors: The aircraft was operating with an incorrect mass calculation, as the passenger was omitted from the weight and balance figures.