What happened
The Lockheed Lodestar departed Coolangatta Airport and began its initial climb. At an altitude of approximately 250 feet, the aircraft exhibited erratic behavior, banking first to the right and then to the left. The crew lost control of the airframe, which subsequently impacted a swamp area. A post-impact fire broke out, partially destroying the wreckage. All 21 occupants on board perished in the incident.
Findings
Investigations determined that the primary cause was an aft center of gravity (CG) beyond the approved limits. The load sheet for registration VH-BAG indicated a CG at 39.2% of the Mean Aerodynamic Chord (MAC), slightly exceeding the 39% rear limit. However, this calculation relied on flawed data from the Department of Civil Aviation and the RAAF.
Key errors in the loading documentation included:
- Failure to account for the rearward shift of the CG caused by main undercarriage retraction.
- Incorrect seat spacing measurements, which were 25 mm further apart than documented.
- Exclusion of up to 18 kg of food and beverages stored at the rear of the cabin.
When these factors were recalculated, the actual CG after gear retraction was estimated at 43.4% MAC, placing the aircraft 4% MAC behind the safe limit. This configuration rendered the plane longitudinally unstable and tail-heavy. Additionally, investigators found the elevator trim tab spool positioned for landing rather than takeoff. The combination of this incorrect trim setting and the inherent instability caused a severe nose-up pitch that the pilot could not counteract, leading to a stall and crash.