A pivotal question has emerged in the ongoing investigation into the tragic crash of Air India Flight 171 in Ahmedabad, which claimed 241 lives in June 2024. The Federation of Indian Pilots (FIP) has challenged a key aspect of the preliminary accident report, raising concerns about the sequence of events immediately following takeoff. At the heart of the debate is a crucial four-second window and whether the aircraft's emergency power system, the Ram Air Turbine (RAT), deployed before or after the engines' fuel supply was cut off, a detail that could fundamentally alter the understanding of India's deadliest air disaster in decades.
Key points
- The Air India 171 crash, involving a Boeing 787-8 Dreamliner, resulted in 241 fatalities shortly after takeoff from Ahmedabad, bound for London Gatwick.
- An initial narrative suggested deliberate pilot action in cutting off fuel to both engines, leading to the crash.
- The Federation of Indian Pilots (FIP) has formally questioned the official preliminary report's timeline regarding the deployment of the Ram Air Turbine (RAT) and the movement of fuel control switches.
- FIP highlights a discrepancy: the preliminary report indicates RAT hydraulic power supply began four seconds after fuel cutoff, while the RAT manufacturer's documentation states a 10-15 second trigger time after electrical loss.
- New visual evidence from CCTV footage, cited by FIP, suggests the RAT may have begun deploying while the aircraft was still on the runway, predating any recorded fuel switch movements.
- The resolution of this timeline discrepancy is critical, impacting whether the accident was caused by a technical failure or deliberate crew action, and holding significant implications for the deceased pilots' legacies and future aviation safety.
What we know so far
On the afternoon of June 12, 2024, Air India Flight 171, a Boeing 787-8 Dreamliner carrying 242 people, departed Ahmedabad airport (runway 23) en route to London Gatwick. Just 32 seconds after lifting off, the aircraft began to fall, ultimately striking the BJ Medical College hostel complex approximately 1.6 kilometers from the runway's end. This catastrophic event led to the deaths of 241 individuals, with only one passenger surviving.
The Aircraft Accident Investigation Bureau (AAIB) preliminary report, drawing data from the Enhanced Airborne Flight Recorder (EAFR), established a specific sequence of events (timings in UTC):
- 1:38:33 pm: Aircraft crossed take-off decision speed (153 knots indicated airspeed).
- 1:38:35 pm: Vr speed (liftoff speed) achieved (155 knots).
- 1:38:39 pm: Air/ground sensors transitioned to air mode, indicating liftoff.
- 1:38:42 pm: The aircraft reached its maximum recorded airspeed of 180 knots.
- Immediately thereafter (approx. 1:38:42-1:38:43 pm): Engine 1 and Engine 2 fuel cutoff switches reportedly transitioned from RUN to CUTOFF, sequentially.
- 1:38:47 pm: The Ram Air Turbine (RAT) hydraulic pump began supplying hydraulic power, following both engine N2 values dropping below minimum idle speed.
- 1:38:52 pm: Engine 1 fuel cutoff switch was observed returning from CUTOFF to RUN.
- 1:38:56 pm: Engine 2 fuel cutoff switch was observed returning from CUTOFF to RUN.
- 1:39:05 pm: A "Mayday" call was transmitted from the cockpit.
- 1:39:11 pm: The EAFR recording ceased.
The preliminary report also noted a cockpit voice recording where one pilot asked another why the fuel was cut off, to which the other pilot denied doing so. Additionally, the report mentioned a 2018 US Federal Aviation Administration (FAA) bulletin concerning potential disengagement of the fuel control switch locking feature on Boeing aircraft, though it was advisory and Air India had not conducted inspections on this specific aircraft (VT-ANB).
Context and background
In the aftermath of the Air India 171 tragedy, a narrative gained considerable traction, particularly in media and online aviation forums, suggesting that the accident was the result of a deliberate act. This theory posited that the Pilot-in-Command had intentionally moved both fuel control switches to the CUTOFF position during the initial climb, thereby starving the engines of fuel and causing the aircraft to crash. This explanation, while seemingly straightforward, was never officially confirmed by the investigation. The AAIB's preliminary report, while factual, contained certain details that were interpreted by some as supporting this "pilot action" theory.
Central to the emerging questions is the Ram Air Turbine (RAT). The RAT is a critical emergency power system on aircraft like the Boeing 787. It is a small, retractable wind turbine usually stowed in the aircraft's belly. In the event of a complete loss of primary electrical power, the RAT automatically deploys into the airstream. Its spinning propeller drives a hydraulic pump and a generator, providing essential power to maintain minimal flight controls, giving the crew a chance to manage the emergency. The visible deployment of a RAT is a stark indicator of a severe, catastrophic emergency, as it should never be seen on a healthy aircraft.
The Federation of Indian Pilots (FIP) has formally intervened, submitting two letters to the AAIB director general, highlighting technical discrepancies in the preliminary report. Their core argument hinges on the timing of the RAT's deployment relative to the fuel switch movements. If the RAT deployed first, it would suggest an electrical failure or other technical malfunction initiated the emergency, making the subsequent fuel switch movements a potential consequence or a desperate attempt by the crew to address an already unfolding crisis, rather than the cause of the disaster. This distinction is paramount, as it challenges the "deliberate act" theory and shifts focus towards potential systemic or mechanical failures.
Under the International Civil Aviation Organization (ICAO) Annex 13 conventions, preliminary accident reports are intended to be purely factual, presenting technical data without apportioning blame. The FIP argues that the structure and language of the AAIB's preliminary report, while not explicitly stating blame, implicitly leaned towards a "pilot action" scenario, prompting the need for a more rigorous and transparent investigation into the sequence of events.
The FIP's technical challenge specifically points to documentation from Hamilton Sundstrand (now Collins Aerospace), the original equipment manufacturer (OEM) of the B787 RAT system. This documentation indicates that the RAT deployment signal is generated 10 to 15 seconds after a complete loss of electrical supply. The AAIB's preliminary report, however, records only a four-second interval between the second fuel cutoff switch movement and the RAT beginning to supply hydraulic power. This discrepancy forms the crux of the FIP's inquiry: if the RAT requires 10-15 seconds to trigger after power loss, how could it begin supplying power just four seconds after the fuel switches were cut off, unless an electrical failure preceded the fuel cutoff?
Further supporting their concerns, the FIP has presented CCTV footage showing the RAT door appearing to open or the RAT itself deploying while the aircraft was still on the runway, prior to liftoff and before the fuel switches could have been moved (as black box data confirms fuel switch transitions occurred after the aircraft was airborne and at 180 knots). This visual evidence, if correlated with the EAFR data, could significantly bolster the argument for an early technical malfunction.
What happens next
The Federation of Indian Pilots has formally requested that the AAIB address several specific, technically documented questions in its final report. These include clarifying the precise EAFR-recorded timestamp for the RAT deployment command (not just hydraulic output), identifying the specific EAFR parameter used to determine the 1:38:47 pm timing for hydraulic power supply, and reconciling the OEM's 10-15 second trigger thresholds with the recorded four-second interval.
Beyond these questions, the FIP has called for a comprehensive flight simulator reconstruction. This reconstruction would involve overlaying the actual photographic sequence from the CCTV footage with the flight data recorder (DFDR) information, under two distinct scenarios: one simulating an electrical failure leading to automatic RAT deployment, and another simulating manual selection of fuel control switches to CUTOFF by the flight crew. Such simulator exercises are standard tools in modern accident investigations and are crucial for understanding complex sequences of events.
The deadline for the AAIB's final report on the Air India 171 accident is June 12, 2026. The FIP has urged that this report only be released after the requested simulator evaluation is completed and formally documented. The stakes for this investigation are exceptionally high. A conclusive finding without exhaustively ruling out a technical failure could unjustly tarnish the reputations of the two deceased pilots, who cannot defend themselves, potentially labeling them responsible for a mass casualty event. Conversely, if an undetected systemic failure in the Boeing 787's electrical architecture or fuel control system exists, and is not thoroughly investigated and addressed, it could pose a risk to future flights and undermine the fundamental purpose of aviation accident investigations, which is to learn lessons and prevent recurrence.
The AAIB's response to the FIP's detailed inquiries and its approach to the final report will be closely scrutinized by the aviation community, the victims' families, and the public. A complete, transparent, and technically rigorous answer to the "four-second question" is now paramount for ensuring accountability and enhancing aviation safety.
FAQ
- What was Air India Flight 171?
Air India Flight 171 was a Boeing 787-8 Dreamliner that crashed shortly after takeoff from Ahmedabad, India, on June 12, 2024, while en route to London Gatwick. The accident resulted in 241 fatalities. - What is the main question in the investigation?
The central question is whether the Ram Air Turbine (RAT), an emergency power system, deployed before or after the aircraft's fuel control switches were moved to the CUTOFF position, as this could indicate whether a technical failure or pilot action initiated the emergency. - What is a Ram Air Turbine (RAT)?
The RAT is a small, retractable wind turbine that deploys automatically in an aircraft after a complete loss of primary electrical power. It generates hydraulic power and electricity to keep essential flight controls operational in an emergency. Its deployment signifies a catastrophic system failure. - Why is a four-second discrepancy important?
The preliminary report indicates the RAT began supplying power four seconds after fuel cutoff. However, the RAT manufacturer's documentation states it takes 10-15 seconds for the RAT to trigger after an electrical power loss. This discrepancy suggests the possibility that an electrical failure might have occurred *before* the fuel was cut off, challenging the initial narrative of deliberate pilot action. - What is the Federation of Indian Pilots (FIP) requesting?
The FIP is asking the investigation authority (AAIB) to answer specific technical questions about the RAT deployment timeline and to conduct a flight simulator reconstruction using visual and flight data to determine whether a technical failure or deliberate crew action was the root cause of the crash.
