The Switch That Shouldn’t Fail: How a Known Flaw May Have Doomed AI-171

Air India A1-171 Crash Preliminary Report Out: When Air India Flight AI-171 lifted off from Ahmedabad on the morning of June 12, 2025, everything appeared normal. The Boeing 787-8 had cleared all preflight checks, the weather was stable, and its engines roared at full takeoff thrust. But just seconds after liftoff, disaster struck — and investigators now believe a small but critical switch in the cockpit could be at the center of it all.  

At the heart of the preliminary findings by Aircraft Accident Investigation Bureau (AAIB) is a pair of switches that rarely draw attention — the fuel control switches. These switches regulate fuel flow to each engine and are designed with a locking mechanism to prevent accidental movement, especially during high-workload moments like takeoff.

But in AI-171’s case, both fuel control switches were somehow moved from, ‘RUN’ to ‘CUTOFF’ mid-air, just three seconds after the plane lifted off the runway. The result: both engines lost thrust simultaneously. The aircraft began to lose altitude almost immediately and crashed into a nearby building less than a minute later, killing 260 people — including crew, passengers, and civilians on the ground.

A Known Risk Ignored?

What’s deeply concerning is that this wasn’t an unforeseen defect. Back in December 2018, the US Federal Aviation Administration (FAA) issued a Special Airworthiness Information Bulletin (SAIB No. NM-18-33). It warned that certain fuel control switches — including those installed on Boeing 787 aircraft — had been reported to disengage from their locking mechanism. The issue, while not deemed hazardous enough for a mandatory directive, was flagged for operator awareness and voluntary inspection.

The part number mentioned in that bulletin — 4TL837-3D — is the exact switch installed on VT-ANB, the aircraft that crashed in Ahmedabad.

Despite the advisory, Air India did not perform any inspection or modification related to the fuel switch mechanism on VT-ANB. The airline maintained that the SAIB was advisory in nature and not binding.

Investigators confirmed that the throttle control module — which houses the fuel control switches — had been replaced twice in the past (2019 and 2023), but not because of any fuel switch-related defect. There were no reported issues with the fuel control switch on this aircraft since the last replacement.

The Chilling Cockpit Clue

The cockpit voice recorder provided perhaps the most damning insight. In the moments after the engines shut down, one pilot can be heard asking the other:

“Why did you cutoff?”

“I didn’t.”

The exchange suggests neither pilot intentionally moved the switches — raising the likelihood that the levers were moved inadvertently or mechanically failed. Investigators have not yet concluded whether the switches failed mechanically or were accidentally triggered due to cockpit ergonomics or pilot action under stress.

Bigger Questions for Boeing & Regulators

While the investigation is still in progress, this revelation raises pressing questions:

• Should the FAA have made the 2018 bulletin mandatory?
• Why didn’t operators like Air India act on the advisory, especially when it involved engine control at critical flight phases?
• Should Boeing revisit the design of a switch that can shut down an engine with a single motion?

Experts say that in modern aircraft, any control capable of disabling both engines during takeoff should be virtually fail-proof — or at least protected by physical or software-level redundancy, a question Boeing and aviation authorities must answer for the safety of millions of flyers.

A switch meant to ensure safe engine operation may have played a fatal role in the crash of AI-171. It was known to regulators. Its risk was acknowledged. But because action was left optional, no fix was made.

Now, investigators, regulators, manufacturers — and grieving families — are left with the question:

How could something so small bring down something so big?

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