Bocas Air flight 524, a Beech 1900D, was retracting the undercarriage after takeoff from Panama City Albrook-Marcos A. Gelabert International Airport (PAC) when the cargo door detached from the aircraft and fell into the grass area of the runway 19 threshold. According to the pilot in command’s statements, after boarding the passengers and closing the aircraft doors, the crew proceeded with the checklist, confirming everything was normal. After taxiing and arriving at the MPMG runway 01 holding point, the control tower authorized them to enter The crew heard a loud noise, vibration and indication of cargo door open light. They notified ATC and requested to return to PAC, proceeded to make a right pattern and performed procedures established in the Quick Reference Handbook (QRH). A safe landing was made. Cause of Accident The cause of the accident was the loss of the cargo door. The Air Accident Investigation Bureau determined the contributing factor to the accident to be Human Factors, due to lack of training.