How Did a 100-Ton Weight Error Cause the LATAM Boeing 777 Milan Tail Strike?

The Italian National Agency for the Safety of Flight (ANSV) released its final report. It detailed the cause of a serious accident involving a LATAM Airlines Boeing 777-300ER. The aircraft sustained a severe tail strike during takeoff from Milan Malpensa Airport (MXP) on July 9, 2024. Investigators determined the root cause was a catastrophic 100-tonne weight miscalculation. This human error led to incorrect takeoff performance data.

The 100-Tonne Miscalculation

The accident involved LATAM flight LA8073, bound for São Paulo, Brazil. The investigation found a 100-tonne discrepancy in the calculated takeoff weight. The correct weight was 328.4 tonnes (328,425 kg). However, the crew used an incorrect figure of 228.8 tonnes.

This significant pilot performance calculation error originated during pre-flight preparation. A line-training captain mistakenly subtracted the expected taxi fuel from the gross weight. This arithmetic error resulted in the massive weight underestimate. The incorrect figure was then verbally announced and entered into the Electronic Flight Bags (EFBs) by both pilots.

Procedural Failures and Cross-Check Breakdown

The investigation highlighted a breakdown in standard operating procedures. Because both pilots used the same erroneous figure, the required cross-check failed to catch the mistake. The crew did not independently validate the entered data against the official load sheet. This turned the independent check into a shared single point of failure.

• The incorrect weight led to invalid V-speeds (V1, VR, V2).
• Calculated rotation speed (VR) was far too low for the aircraft's actual mass.
• The crew continued the takeoff despite a "V-speeds unavailable" warning.
• The aircraft's tail contacted the runway during rotation.

The Boeing 777-300ER dragged its tail for 723 meters on the runway. The damage caused the event to be reclassified from a serious incident to an accident. The aircraft became airborne and later returned safely to Milan Malpensa (MXP) after dumping fuel. No injuries were reported among the 398 people on board.

Industry Impact and Safety Lessons

The ANSV investigation final report underscores the critical nature of aviation safety human factors. It shows how a simple arithmetic error can cascade through automated systems. The incident highlights the need for robust cross-checking and crew situational awareness.

Authorities like the ANSV and international bodies will use these findings. They will inform future operational guidance and pilot training. The event serves as a stark reminder for all airlines, including LATAM Airlines, about data verification. It stresses that technology must be paired with rigorous procedural adherence to ensure safety. The case also raises questions about EFB design and how it can better prevent such a significant takeoff performance data error.

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