What happened
On August 13, 2006, a Lockheed L-382G (registration 7T-VHG) was operating a cargo flight from Algiers, Algeria, to Frankfurt, Germany. While cruising at FL240 near Piacenza, Italy, the crew encountered significant cloud formations and adjusted their heading to avoid them. The flight atmosphere was initially described as relaxed.
At approximately 18:14 UTC, the co-pilot reported an autopilot failure. Immediately following this, the aircraft entered a period of intense instability. Radar data showed a rapid loss of altitude and increasing airspeed, accompanied by a constant rightward drift. The cockpit voice recorder captured the crew's struggle to regain control, with the commander expressing an inability to level or turn the aircraft. Within 76 seconds of the initial autopilot failure, the aircraft struck the ground at an estimated speed of 440 knots in a near-inverted attitude. The impact caused the aircraft to disintegrate, resulting in 3 fatalities among the crew.
The investigation
The ANSV investigation faced significant challenges due to the extreme fragmentation of the wreckage and the unavailability of usable Flight Data Recorder (FDR) data. Investigators examined the wreckage, performed laboratory analyses on hydraulic fluid, and conducted flight simulator tests.
Technical examinations of the hydraulic actuators showed no evidence of contamination or thermal stress that could have caused the event. While the mechanical integrity of the flight control chain appeared intact at the time of impact, simulator tests revealed that a simultaneous double failure in the flight controls could reproduce the observed "AP FAIL" warning and the subsequent irreversible loss of control. The investigation also noted discrepancies in the aircraft's technical logs regarding total flight hours.
Findings
- The primary cause of the accident was a sudden loss of aircraft control induced by a technical malfunction within the flight control system.
- The crew was unable to identify or counteract the developing malfunction before the aircraft entered an unrecoverable descent.
- The aircraft struck the ground at a high angle of impact (approximately 45/50 degrees) and high velocity.
- The impact caused significant secondary damage, including a local power outage in Piacenza caused by a landing gear wheel striking an electrical pole.
Safety action
- The ANSV issued a safety recommendation to the Algerian Ministry of Transport to ensure that Flight Data Recorders (FDR) installed on Algerian-operated aircraft comply with ICAO Annex 6 standards.