What happened
On April 4, 2022, an Air Tahiti ATR 72-212A, registered F-ORVS, was performing a commercial passenger flight to Hiva-Oa-Atuona in the Marquesas Islands. Due to reported variable winds and a tailwind component on the preferred runway, the crew opted for an RNP approach to runway 20. During the final stages of the approach, the aircraft encountered significant turbulence and windshear.
As the aircraft descended through 90 feet, the airspeed dropped sharply due to a shift from a headwind to a tailwind. In response to the sudden loss of altitude, the captain performed a reflex nose-up input on the control column. Simultaneously, the co-pilot, attempting to correct the flight path, applied a nose-down input. This simultaneous opposite dual input caused the Pitch Uncoupling Mechanism (PUM) to activate, disconnecting the left and right elevators. The aircraft subsequently experienced a hard landing with a vertical load factor of 2.97 g, causing the main landing gear to sustain slight damage. The crew initiated a go-around and eventually completed a visual landing on runway 02.
The investigation
The BEA examined flight data from the CVR and FDR, alongside meteorological studies. The investigation focused on the aerological conditions at Hiva-Oa-Atuona, the reliability of local weather reporting, and the mechanical behavior of the ATR's pitch control system. Investigators also analyzed the crew's approach stabilization and the impact of the windshear on the aircraft's energy state.
Findings
- The approach was destabilized below 500 feet, characterized by excessive airspeed and descent rates exceeding 1,000 ft/min.
- The crew failed to reject the approach despite meeting criteria for a missed approach, likely due to the frequent occurrence of turbulence on this specific runway.
- Opposite dual inputs from the captain and co-pilot triggered the irreversible uncoupling of the elevators.
- The airport lacked reliable meteorological services; the available wind information was provided by uncertified sensors and lacked the precision of a formal METAR/TAF service.
- The absence of windshear detection systems, both on the ground and on board, hindered the crew's ability to react to the sudden change in wind vector.
Safety action
Following the investigation, ATR updated its training programs to include the management of dual inputs and the prevention of undesired elevator uncoupling. Air Tahiti revised its operating manual to better address stabilization criteria for steep-slope approaches. Additionally, the BEA issued recommendations to ensure adequate meteorological service levels are provided at French Polynesian airports.