On June 12, 2025, Air India Flight AI 171, a Boeing 787-8 Dreamliner, crashed shortly after takeoff from Ahmedabad’s Sardar Vallabhbhai Patel International Airport. The flight, bound for London Gatwick, went down in the Meghani Nagar residential area, resulting in at least 274 fatalities, including 241 of the 242 passengers and crew onboard and the rests are people on the ground, including medical students and teachers. The sole survivor onboard was British citizen Biswas Kumar Ramesh.
Aviation experts and various analysts are engaged in extensive discussions and debates regarding the cause of the accident. Theories includes the failure or shutdown of both engines to provide thrust, improper flap settings for the aircraft’s weight and high ambient temperature during takeoff, failure to retract the landing gear in time, errors in calculating the aircraft’s weight, use of incorrect fuel grade, pilots mistakenly reducing flaps without retracting the landing gear, air or vapor buildup in fuel supply lines, or bird strikes in both the engibes etc. Some even speculated with so much paranoya that, they went so far so early that the crash could be linked to sabotage by Bangladeshi, Rohingya, or Turkish terrorists allegedly involved in the aircraft’s maintenance service.
Experienced pilots from various countries have shared their perspectives on the crash’s cause. Initially, some emphasized pilot error, such as, they have mistakenly reduced flap settings while retracting the landing gear etc. However, clearer video evidence later shifted focus away from this theory, confirming that the flaps were not fully retracted and confirming that the deployment of the aircraft’s Ram Air Turbine (RAT). This led experts back to the square one, the possibility of both engines shutting down simultaneously. Though no clear explanation has emerged for why both the engines would fail so rapidly at the same time. If the engines had shut down due to contaminated fuel or a bird strikes, videos should have shown sparks or smoke from the engines, which were absent. There is no incident of both engine failure of Boeing 787 except except one on ground due to quick reverse thrust issue and another for cleaning agent contamination for which the both engine failure was not simultaneous. So there is no incident for on air simultaneous both engine failure. Boeing 787 pilots noted that everything—from wheel rotation to reaching maximum altitude during takeoff—appeared normal.
As an electrical and electronics expert with a long-standing interest in aviation, I find the Boeing 787 Dreamliner particularly significant due to its ‘more-electric’ design philosophy. As an electrical and electronics specialist, I am skeptical of this approach for an aircraft so far. Electrical systems are prone to sudden, catastrophic failures, akin to a nationwide power grid collapse where all electricity is lost simultaneously, including power plants shutting down. Imagine such a ‘grid failure’ occurring in a ‘more-electric’ aircraft during takeoff or landing.
The Boeing 787 Dreamliner is a cutting-edge technology aircraft that relies heavily on electrical systems, replacing many traditional pneumatic (air-pressure-driven) and hydraulic (fluid-pressure-driven) systems. Known as a ‘more-electric’ aircraft, its flight controls, hydraulic pumps, and even engine controls depend on electrical power. While the landing gear operates on hydraulic power, its pumps require electricity. Even the landing gear doors need electrical power to open.
To reduce production and operating costs, as well as weight for fuel efficiency, the 787 relies more on electrical systems than pneumatic or hydraulic ones. Electrical systems are lighter, smaller, cheaper, and easier to maintain. However, this design requires a consistent and substantial power supply.
To ensure this, the Boeing 787-8 incorporates multiple redundancies. Its ‘more-electric’ design relies on four Variable Frequency Starter Generators (VFSGs)—two per engine—two Auxiliary Power Unit (APU) Starter Generators (ASGs), and two lithium-ion battery packs for backup power. Additionally, the Ram Air Turbine (RAT), a small propeller-like device, automatically deploys in three scenarios: complete electrical failure, complete hydraulic failure, or both engines becoming inoperative. While mechanical failure of both engines at the same time is rare, it can occur due to bird flock strikes, incorrect fuel, fuel exhaustion, or fuel pump issues. On 29 December 2024, Jeju Air Flight 2216 using the Boeing 737-800 was approaching Muan, South Korea when a bird strike occurred caused dual engine failure and a crash killing 179 onboard.
Each engine’s two VFSGs of Boeing 787-8 generate 235V AC power, unlike other aircraft with one generator per engine. If these generatos fail, the APU and lithium-ion batteries provide backup power. If all these systems fail, the RAT automatically deploys to supply emergency electrical power. While this complex electrical system enhances efficiency, it increases the risk of catastrophic electrical failure, and a fault in the power distribution system or bus could render all systems inoperative simultaneously.
The Boeing 787 Dreamliner has six main electrical buses: Left AC Bus (L AC), Right AC Bus (R AC), Left DC Bus (L DC), Right DC Bus (R DC), AC Essential Bus (AC ESS), and DC Essential Bus (DC ESS). These buses connect directly to various loads, such as flight controls, avionics, fuel pumps, cabin pressurization, and other critical electrical devices. Each AC bus is powered by an Integrated Drive Generator (IDG) on each engine, supplying AC power to its respective buses. Power from each AC bus is converted to supply the corresponding DC buses.
For backup, the APU can supply power to both AC buses when activated. The RAT, another critical backup, deploys in emergencies to power the AC ESS bus and hydraulic systems. Two lithium-ion batteries power the DC ESS bus and hot battery bus when all other sources fail.
Bus Tie Connectors (BTCs) facilitate power transfer between buses, automatically activating if a bus fails. For example, if the Left AC Bus fails, the Right AC Bus can supply power to both sides within capacity limits. However, if both AC buses fail simultaneously—due to IDG failure, Generator Control Unit (GCU) or Bus Power Control Unit (BPCU) software or circuit failure, or damage from electrical heat—and the APU or RAT does not activate in time, the aircraft relies solely on battery power.
Battery power only sustains the DC ESS Bus and hot battery bus, supporting limited emergency systems like the Full Authority Digital Engine Control (FADEC), standby displays, fuel valves, and cockpit lighting for a short period. However, AC motor-driven fuel pumps (ACMPs) stop, as they rely on AC buses. While Engine-Driven Pumps (EDPs) may function, they depend on gravity feed or suction, which is often insufficient during takeoff or when the aircraft’s nose is elevated.
Let us see the timeline of Air India Flight AI 171 Crash (Indian Standard Time, IST):
13:17: Pushback
13:31: Taxi begins
13:38:00: Takeoff climb, altitude 0 ft
13:38:10: Takeoff climb, altitude 150 ft, possible attempt to retract gear
13:38:15: Takeoff climb, altitude 250 ft, ADS-B signal lost
13:38:20: Maximum altitude 625 ft, 20 seconds after takeoff
13:38:25: RAT deployment and Mayday call, 25 seconds after takeoff
13:38:57: Crash, 32 seconds after the Mayday call
The flight pushed back at 13:17 IST, began taxiing, and started its takeoff climb at 13:38:00. Ten seconds later, the gear should have been retracted but it wasn’t, which was critical. Video evidence shows the gear in a partially retracted state, indicating an attempt to raise it that failed. During takeoff or landing, an aircraft’s power demand is highest, and the 787’s ‘more-electric’ design amplifies this need.
I believe the aircraft operated normally during the initial takeoff. However, at 150 ft and within 10 seconds, a command to retract the gear likely spiked power demand, causing a failure in the main AC power bus system. This could result from a short circuit or multiple faults in the main power distribution panel or both AC buses. If both AC buses fail, the battery-powered APU activates briefly, providing power for only a few minutes—or less during takeoff. The fuel-powered APU, which takes about 90 seconds to start, requires its air inlet door to be open. If it doesn’t activate, the RAT deploys to provide minimal emergency power.
In the AI 171 crash, it seems from the video that the gear slightly raised and locked there, and the RAT deployed, indicating a complete loss of electrical power. If both engines did shut down simultaneously, it would cause a similar power failure. The question is whether the engines failed first, causing the power loss, or if the AC bus failure caused the engines to shut down.
The Boeing 787-8’s fuel system includes two pumps per engine: an electric ACMP, powered by the AC buses, and an EDP, driven by the engine. On the ground, the ACMP supplies fuel to start the engine, and once the engine is running, the EDP takes over. During taxi and takeoff, the ACMP maintains fuel pressure. Once the engine stabilizes, the EDP becomes the primary fuel supplier, and the ACMP may shut off.
If both AC buses fail, all ACMPs will stop immediately, leaving fuel delivery reliant on gravity feed and EDP suction. However, the 787’s fuel tank design makes gravity feed ineffective during takeoff or climb, especially with the nose elevated, causing insufficient fuel pressure and potential engine flameout. The engines may continue briefly on residual fuel in the supply lines.
Simultaneous engine failure within seconds is highly unlikely. Contaminated fuel would typically cause noticeable engine unsatbel behavior, such as smoke or vibrations, which wasn’t observed. The U.S. Federal Aviation Administration (FAA) has previously warned about the 787’s reliance on electric fuel pumps.
For AI 171, I hypothesize: After takeoff, at 150 ft, a gear retraction attempt caused a power surge, leading to both AC buses failing with a loud noise. The gear jammed partially retracted, cabin lights flickered, and the battery-powered APU activated. ACMPs stopped, and with only residual fuel, the aircraft climbed to 625 ft. Battery power sustained minimal systems, but the APU didn’t start. Fuel pressure dropped, EDPs couldn’t supply enough fuel, and both engines slowed or flamed out. Battery power depleted, the RAT deployed, providing minimal power for hydraulics and instruments. With engines losing power, the aircraft descended and crashed into a building. Note that the ADS-B signal lost when the aircraft was still climbing.
In 2015, Boeing identified a software bug in the 787’s Generator Control Unit (GCU), where a counter overflow after 248 days of continuous operation could shut down the VFSGs. The FAA mandated power cycling to prevent this. If Air India’s aircraft VT-ANB wasn’t power-cycled, it could explain the power loss, though maintenance schedules typically should prevent such issues.
Two hours before the crash, a passenger on AI 423 (Delhi to Ahmedabad) reported issues with cabin lights, seat-back screens, and crew call buttons, suggesting pre-existing electrical faults not addressed during maintenance of the same aircraft VT-ANB. Air India’s 787 fleet has had 32 reported electrical and hydraulic issues between 2015 and 2024.
This analysis of AI 171’s crash is my personal perspective, based on limited information and situational analysis, attributing the incident to Boeing’s ‘more-electric’ design. Official investigations, including analysis of the flight data recorder and cockpit voice recorder, will reveal the true cause. However, official reports, including those from U.S. agencies, have sometimes been criticized for concealing the truth.
For example, United Airlines Flight 811, a Boeing 747-122, experienced a cargo door latch failure on February 24, 1989, shortly after departing Honolulu, causing explosive decompression, loss of several seat rows, and nine passenger deaths. The U.S. National Transportation Safety Board (NTSB) attributed the crash to ground crew error, potentially to protect the airline from significant losses. Among the victims was New Zealander Lee Campbell. His parents, Kevin and Susan Campbell (former engineers), stole NTSB documents and conducted a private investigation, concluding that the crash resulted from electrical issues and a design flaw in the cargo door-latching mechanism, which they presented to the safety board. While official investigations are legal and mandatory, but private inquiries are also necessary.