Investigators probing the June crash of Air India Flight 171, which killed 260 people, have uncovered a perplexing clue: both fuel-control switches on the 12-year-old Boeing 787 Dreamliner were moved to the "cut-off" position seconds after take-off, causing a total engine power loss.
The cockpit voice recorder reveals one pilot questioning, “Why did you do the cut-off?” with the other responding, “I didn’t,” deepening the mystery.
The flight, which crashed into a crowded Ahmedabad neighbourhood less than 40 seconds after departing Ahmedabad International Airport, climbed to 625 feet before losing location data, according to Flightradar24.
A 15-page preliminary report released Saturday, compiled by Indian authorities with experts from Boeing, General Electric, Air India, and US and UK regulators, highlights critical questions.
The fuel-control switches, equipped with a lever-lock mechanism and protective guard brackets to prevent accidental activation, require deliberate action to move.
“It’s nearly impossible to flip both switches simultaneously by accident,” a Canada-based air accident investigator told the BBC anonymously. Yet, the switches were briefly set to “cut-off”—a manoeuvre typically performed post-landing—before being returned to their normal position, triggering an automatic engine relight. At the time of the crash, one engine was regaining thrust, but the other had not yet recovered power.
The investigation, focused on the wreckage and cockpit recorders, is grappling with whether the switch activation was intentional or erroneous.
Shawn Pruchnicki, a former airline accident investigator at Ohio State University, noted, “There’s no indication of pilot confusion or an emergency prompting such an action. This type of error is rare without an evident issue.”
Peter Goelz, former NTSB managing director, added, “The voice recorder suggests someone shut off the fuel valves, but who and why remains unclear. Identifying the speakers is critical.”
The report notes a 2018 US FAA Special Airworthiness Information Bulletin (SAIB) flagging disengaged locking features on some Boeing 737 fuel-control switches, a design also used in the Boeing 787-8 involved in the crash (VT-ANB).
While the SAIB was advisory and not mandatory, Air India did not conduct the recommended inspections.
Pruchnicki questioned whether a disengaged lock could allow a switch to flip inadvertently, calling it a “serious issue” if true. However, Goelz downplayed the concern, noting no widespread pilot complaints about the switches.
Capt Kishore Chinta, a former investigator with India’s AAIB, raised the possibility of an electronic glitch, asking, “Could the plane’s electronic control unit have triggered the switches without pilot intervention?”
Fuel samples from the refuelling tanks were deemed satisfactory, ruling out contamination for now, and no advisories have been issued for the Boeing 787 or its GE GEnx-1B engines.
The report confirms the deployment of the Ram Air Turbine (RAT), indicating a major systems failure, and notes the landing gear was found in the “down” position, likely due to insufficient time for retraction.
A Boeing 787 pilot explained, “Gear retraction completes by about 400 feet, roughly eight seconds after take-off. With both engines failing, the pilots had no time to focus on anything but the flight path.”
Investigators emphasized the need for clear voice identification, a full cockpit transcript, and a review of all communications from pushback to crash.
The NTSB’s recommendation for cockpit video recorders could clarify who operated the switches. Both pilots, based in Mumbai, passed breathalyser tests and were rested before the flight. As the investigation continues, the cockpit voice recorder remains key to unravelling this baffling disaster.