Investigation Summary
The chain of events began during maintenance in Tunis when a technician, unable to find an ATR 72-specific FQI in the database, selected a part number for an ATR 42 indicator based on a misinterpretation of the parts catalog. Although the ATR 42 and ATR 72 indicators are physically interchangeable, their internal calibrations differ because the ATR 72 has larger fuel tanks. The aircraft actually flew the preceding leg from Tunis to Bari with the incorrect gauge already installed. Upon arrival in Bari, the gauge indicated 2,300 kg of fuel when only 305 kg actually remained. Because the crew and ground staff relied on these false readings, they calculated an uplift that resulted in the aircraft departing for Djerba with only 540 kg of fuel, despite the gauge showing 2,700 kg.
Final Conclusions
The Italian Agency for the Safety of Flight (ANSV) concluded the primary cause was the installation of an incorrect FQI, which led the crew to believe they had sufficient fuel. However, the severity of the outcome was attributed to significant pilot errors: the crew failed to cross-check the fuel quantity against the fuel loading logs before departure, and following the double engine failure, they failed to feather the propellers. Simulation data suggested that had the propellers been feathered to reduce drag, the aircraft could have successfully glided to Palermo.
Video Analysis
No video analysis linked for this case file yet.
Systems & Failure Modes
Fuel Quantity Indicator (FQI)
The cockpit instrument that displays the mass of fuel in the tanks based on signals from capacitance probes.
Propeller Pitch Control
The system used to feather propellers to a 90-degree angle to minimize drag during an engine-out glide.
Interesting Facts
- 01The ATR 42 gauge indicated 2,700 kg of fuel when the tanks actually held only 540 kg.
- 02The aircraft broke into three sections upon impact with the water.
- 03The captain and six other employees were later sentenced to prison by an Italian court for manslaughter.
- 04The flight crew failed to feather the propellers, which would have extended their glide range.
- 05The maintenance error was facilitated by a confusing electronic parts catalog that listed the ATR 42 part as compatible.
Safety Actions & Advisories
FQI Design Modification
ATR modified the design of fuel quantity indicators to ensure that parts for different aircraft models (ATR 42 vs ATR 72) are not physically interchangeable.
Maintenance Documentation Reform
The manufacturer updated the Illustrated Parts Catalog (IPC) to clearly distinguish between non-interchangeable components for different aircraft variants.
Known Controversies & Unanswered Questions
Criminal Prosecution of Crew
Reference ↗The sentencing of the pilots and maintenance staff to lengthy prison terms by Italian courts was controversial within the aviation community, as many argued it criminalized human error and would discourage open safety reporting.