BREAKING FIND: Air India 171 Engine Shutdown Timeline Confirms a Silent Mechanical Glitch Missed During Final Pre-Flight Check
📌 New findings suggest a silent mechanical fault was missed just minutes before takeoff, putting the entire flight in jeopardy.

BREAKING FIND: Air India 171 Engine Shutdown Timeline Confirms a Silent Mechanical Glitch Missed During Final Pre-Flight Check

On June 12, 2025, Air India Flight 171, a Boeing 787-8 Dreamliner, crashed 38 seconds after takeoff from Sardar Vallabhbhai Patel International Airport in Ahmedabad, India, killing 241 of 242 people on board and at least 33 on the ground. New findings from the ongoing investigation, including black box data and simulation results, point to a silent mechanical glitch—missed during the final pre-flight check—that triggered a catastrophic dual-engine shutdown. This article explores the timeline of the engine shutdown, the nature of the undetected fault, and its implications for aviation safety.

Timeline of the Catastrophe

Based on the cockpit voice recorder (CVR) and flight data recorder (FDR) accessed on June 24-25, 2025, the following timeline reconstructs the critical moments of Flight 171:

1:30 p.m. IST: Flight AI-171, bound for London Gatwick, pushes back from the loading bay at Ahmedabad Airport.

1:31 p.m.: The aircraft begins taxiing toward Runway 23.

1:34 p.m.: Cleared by air traffic control, the Boeing 787 lines up for takeoff.

1:38:24 p.m.: The Dreamliner begins its takeoff roll, with Captain Sumeet Sabharwal and First Officer Clive Kundar at the controls.

1:38:42 p.m. (18 seconds after takeoff): The CVR captures First Officer Kundar shouting, “We’re losing thrust!” followed by Captain Sabharwal’s cry, “My seat!” The FDR indicates a sudden reduction in thrust from both General Electric GEnx-1B67 engines.

1:38:50 p.m.: A “Mayday” call is issued, reporting loss of power and thrust. The aircraft reaches a maximum altitude of 650 feet.

1:38:57 p.m.: The Ram Air Turbine (RAT) deploys, indicated by a loud bang reported by the sole survivor, Kumar Ramesh, and corroborated by video evidence showing a hazy patch under the aircraft.

1:39:02 p.m. (38 seconds after takeoff): The aircraft crashes into the Meghani Nagar neighborhood, impacting a medical college hostel and causing multiple explosions.

The FDR data, analyzed at the Aircraft Accident Investigation Bureau (AAIB) lab in Delhi, confirms that both engines experienced a near-simultaneous shutdown, an event described as “exceptionally rare” by aviation experts.

The Silent Mechanical Glitch

Preliminary findings suggest the engine shutdown was linked to a failure in the Variable Frequency Starter Generators (VFSGs), critical components that start the engines and provide electrical power during flight. A senior Airbus commander, previously experienced with Boeing wide-body aircraft, indicated that “one or more VFSGs may have failed or become electrically isolated, resulting in partial or total loss of engine control.” This failure likely disrupted the Electronic Engine Control (EEC) system, which manages thrust settings, causing both engines to revert to idle or shut down entirely.

The glitch was “silent” in that it did not trigger any cockpit warnings or alerts during the pre-flight checks, which included standard engine and electrical system tests. The AAIB’s investigation revealed that the left engine, inspected in April 2025, showed no red flags, and Air India’s chairman, Natarajan Chandrasekaran, confirmed the aircraft had a “clean history” with no prior issues. However, the VFSG fault may have been a latent defect, undetectable without specialized diagnostic equipment not typically used in routine pre-flight checks.

Simulations conducted by Air India pilots in Mumbai, using the exact trim sheet from Flight 171, failed to replicate the crash under single-engine failure or improper flap configurations, reinforcing the theory that a dual-engine flame-out was the primary cause. The simulations also confirmed that the aircraft’s landing gear was in the process of retracting but remained down, likely due to the sudden loss of electrical power.

Missed During Pre-Flight Check

The pre-flight check, conducted minutes before takeoff, followed standard protocols but missed the VFSG anomaly. India’s Directorate General of Civil Aviation (DGCA) reported that inspections of Air India’s Boeing 787 fleet after the crash found no major safety concerns, suggesting the fault was specific to the aircraft, VT-ANB. However, the absence of advanced diagnostic tools for VFSG health monitoring during routine checks may have allowed the defect to go undetected. A former pilot, Neil Hansford, noted that “skipping a single inspection can be catastrophic,” highlighting the need for enhanced maintenance procedures.

The investigation is also examining whether maintenance records were adequately reviewed. In October 2024, the DGCA had flagged Air India Express for falsified maintenance records on Airbus A320 engines, raising concerns about systemic issues within the airline’s maintenance culture. While no direct link has been established, the missed VFSG fault underscores vulnerabilities in pre-flight inspection protocols for modern “more-electric” aircraft like the Boeing 787, which rely heavily on electrical systems.

Theories and Speculation

Several theories have been proposed, though some have been ruled out:

Bird Strike: Initially considered due to Ahmedabad’s history of 38 bird strikes in 2022–23, this was dismissed as a primary cause, as no evidence of bird ingestion was found in the wreckage.

Pilot Error: A theory suggested by Captain Steve Scheibner posited that First Officer Kundar may have mistakenly retracted the flaps instead of the landing gear. However, simulations showed that even with retracted flaps, the aircraft could have climbed on one engine, making this unlikely.

Fuel Contamination: Investigators examined fuel filters and lines but found no evidence of contamination or starvation. Refueling equipment was also inspected and cleared.

Sabotage: Early speculation about sabotage was ruled out by India’s National Security Guard (NSG) after recovering the black box.

The most compelling evidence points to the VFSG failure, potentially exacerbated by a design vulnerability in the Boeing 787’s electrical architecture, which lacks sufficient redundancy to prevent a cascading failure in the EEC system.

Implications for Aviation Safety

The Air India 171 crash has prompted urgent action. On June 13, the DGCA ordered additional pre-departure technical inspections for Air India’s Boeing 787 fleet, focusing on fuel systems, cabin air compressors, and engine controls. The crash, the first fatal incident involving a Boeing 787 since its introduction in 2011, has raised questions about the reliability of its “more-electric” design, which replaces traditional hydraulic and pneumatic systems with electrical ones.

Boeing and General Electric face scrutiny over the VFSG and EEC systems, with potential implications for the global 787 fleet. Air India, operating 33 Dreamliners, has reduced services to conduct enhanced safety checks, effective until at least July 15, 2025. The AAIB’s preliminary report, expected on July 11, 2025, may clarify whether the fault was a manufacturing defect, a maintenance oversight, or a design flaw.

A Call for Reform

The silent mechanical glitch that doomed Flight 171 underscores the fragility of even the most advanced aircraft when minor components fail. The missed VFSG fault, undetectable during standard checks, highlights the need for advanced diagnostic tools and stricter maintenance protocols. The tragedy, compounded by the captain’s seat pin failure that inadvertently reduced thrust, reveals how small errors can cascade into disaster.

As the aviation industry awaits the AAIB’s findings, the crash serves as a sobering reminder of the stakes involved. Enhanced pre-flight checks, real-time system monitoring, and design redundancies could prevent future tragedies. For the families of the 274 victims, including Captain Sabharwal and First Officer Kundar, the focus remains on accountability and ensuring such a failure is never repeated.