Air India AI-171 Crash: Investigators Probe Sensor Malfunction and System Errors as Possible Causes

As scrutiny intensifies over the initial findings in the Air India AI-171 crash investigation, authorities are now exploring whether a stabilizer sensor malfunction — detected and addressed just hours before the ill-fated flight — may have triggered a cascade of sensor failures, potentially causing "un-commanded" flight control actions.

According to a report by The Indian Express, a pilot operating the same Boeing 787-8 Dreamliner on a Delhi-to-Ahmedabad flight, shortly before the June 12 AI-171 service from Ahmedabad to London Gatwick, had recorded a “Stabilizer Position Transducer Defect” in the aircraft's technical log. This transducer is a critical component responsible for detecting and communicating the aircraft's pitch position to the flight control system. Any malfunction in this sensor can lead to incorrect control inputs, including unintended engine or fuel system responses.

An official familiar with the investigation confirmed that the fault was reportedly resolved in line with Boeing’s maintenance protocols. However, investigators are now examining whether the transducer issue may have led to a broader systemic fault, including multiple sensor failures that may have contributed to the crash.

"The transducer malfunction itself may not have directly caused the crash," the official noted, "but the critical question is whether it acted as a catalyst for a series of sensor errors that led to loss of control."

Flight data analysis is underway to investigate what the official described as a “trail of errors” documented in the aircraft’s recent technical logs. The AI-171 aircraft had previously experienced at least two major technical issues: one in December 2024 involving an “unresolvable electrical snag” that forced a flight cancellation, and another in 2015 involving a cabin air compressor surge that led to an emergency landing — a known issue in the Boeing 787-8 model.

On December 12, 2024 — six months before the crash — the same AI-171 flight had to be grounded after a significant electrical failure was detected on arrival from Delhi. Though resolved by the following day, the incident raised red flags about the aircraft’s electrical reliability.

Detailing the sequence of events on June 12, the official explained: “The AI-171 flight crew followed all standard protocols during takeoff. After reaching Vr speed, the aircraft lifted off and transitioned to ‘air’ mode. But within seconds, something went wrong — an apparent engine failure triggered a loud bang, followed by the deployment of the Ram Air Turbine (RAT) and a sudden transition of fuel switches to cut-off mode."

Given the stabilizer transducer defect recorded hours earlier, investigators are not ruling out the possibility of a software or electrical failure causing the aircraft’s Full Authority Digital Engine Control (FADEC) system to misinterpret signals. Such a malfunction could potentially have led to the disengagement of switch locks or other uncommanded inputs from the aircraft's microprocessor-based control unit.

“The probe is focused on whether the FADEC’s Engine Control Unit — effectively the aircraft’s brain — misread data and initiated uncontrolled actions,” the official added.

The investigation is ongoing, with flight data and cockpit voice recorders expected to provide further clarity in the coming weeks. The incident has renewed calls for more rigorous diagnostic protocols and preventive checks in long-haul aircraft operations, particularly in aging fleets.