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On June 12, 2025, Air India flight AI 171, a Boeing 787-8 Dreamliner en route from Ahmedabad to London Gatwick, tragically crashed shortly after takeoff, killing 260 people—including 19 on the ground—in what is now the deadliest aviation disaster involving an Indian airline in four decades. A preliminary report by the Aircraft Accident Investigation Bureau (AAIB) has placed the aircraft’s fuel control switches at the centre of the crash investigation.

Fuel Control Switches: Function and Design

Fuel control switches are critical safety components that regulate the flow of fuel to aircraft engines. On a Boeing 787, equipped in this case with two GE engines, these switches are located below the thrust levers and are spring-loaded and bracket-protected to prevent accidental activation. They require a deliberate two-step manual action—lifting the switch and moving it between two positions:

• RUN: Allows fuel flow for engine operation.
• CUTOFF: Cuts fuel flow, effectively shutting down the engine.

These switches are typically used on the ground for engine startup and shutdown, and only in-flight during an engine failure or critical damage. Modern twin-engine aircraft like the 787 are capable of continuing flight on a single engine, making the simultaneous use of both switches highly unusual and dangerous.

Sequence of Events: Preliminary Findings

According to flight data from the Flight Data Recorder (FDR) and Cockpit Voice Recorder (CVR), both engine fuel control switches were moved from ‘RUN’ to ‘CUTOFF’ within seconds of each other, shortly after takeoff. This led to simultaneous loss of thrust in both engines. Moments later, both switches were returned to the ‘RUN’ position, but by then the aircraft had lost critical altitude and control.

The cockpit recording captured one pilot asking the other why the fuel was cut off. The other responded that he had not done so. The pilots—Captain Sumeet Sabharwal with over 8,600 flying hours on the 787, and Co-pilot Clive Kundar with 1,100 hours—were both adequately experienced.

Technical and Human Factors under scrutiny

Aviation experts argue that accidental activation of both switches is nearly impossible due to the stop-lock mechanism and protective brackets. However, speculation persists over a possible technical malfunction, human error, or incorrect engine identification. A theory suggests that one engine may have failed and the pilots mistakenly shut down the working engine, though this remains unconfirmed.

Attention has also turned to the switches themselves, manufactured by Honeywell (Part No. 4TL837-3D). A 2018 FAA advisory had flagged potential issues with their locking mechanisms but did not mandate corrective action. Air India reportedly did not conduct voluntary checks, raising questions about maintenance protocols.

Conclusion:

The AI 171 crash highlights critical lapses in cockpit procedures, technical maintenance, and possibly design flaws. It underscores the need for stringent implementation of safety advisories, thorough crew training, and the use of redundant safety mechanisms. As investigations continue, the incident may prompt global regulatory reviews on cockpit ergonomics and fuel system safety protocols, reinforcing the imperative of fail-safe systems in civil aviation.