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On June 12, the Air India aircraft crashed shortly after the takeoff. 270 people died in this.
The initial investigation report of Air India flight AI-171 has come. The Aaib i.e. Aircraft Accident Investigation Bureau made a 15 -page report public on July 12.
Initial results suggest that the switches controlling fuel flows in both jet’s engines were closed, so the engine stopped soon after the takeoff and the aircraft’s thrust ended. The pilot tried to start them again but could not succeed.
Cockpit’s recording has revealed that a pilot asked the other if you have closed the switch? The other replied, no. The report has also revealed that there was a problem in a flight sensor before the flight which was corrected.
241 out of 242 passengers and crew members died in this accident. Only one Indian -origin British traveler was saved. This was the first crash in the history of Boeing 787-8. Here we are describing the technique of fuel control switch and the entire report of AAIB in detail.
In this picture, the landing gear of the aircraft is seen below. It is falling downwards even after the aircraft is up.
The entire aircraft was destroyed in the accident. Different parts of the aircraft were scattered at the scene.
Fuel control switch work and technology
The fuel control switch is near the Thrust Lever in the cockpit of the aircraft. They control the supply of fuel in the engine. Its main task is to start the supply of fuel in the engine (‘run’ position) or shut down (‘cutoff’ position).
Different fuel control switches for each engine. For example, Boeing 787 has two engines, so there will be two switches – for a left engine, for a right.
- Run Position: When the switch is on ‘run’, the fuel valve opens and the fuel supply starts in the engine. This keeps the engine on and the aircraft gets a thrust.
- Cutoff Position: When the switch is done on the ‘cutoff’, the fuel valve is closed and the supply of fuel in the engine stops. This stops the engine immediately.
Fuel control switches are spring-loaded and contain a kind of lock, which keeps them stable in their positions.
The switch requires three steps to move – holding, removing and releasing from the details. This is not a normal switch that gets buried by accidentally.
The fuel control switch is near the Thrust Lever in the cockpit of the aircraft.
Understand the AAIB report in easy language…
The day of 12 June 2025. Air India’s B787-8 aircraft reached Ahmedabad Airport from Delhi. The aircraft landed at 11:17 am and was parked at Bay 34. Crew recorded a pilot defect report (PDR) for ‘Stab Pos XDCR’ status message in Tech Log.
It is a sensor that measures the position of the horizontal stabilizer of the aircraft (part of the tail which controls the pitch).
If there is a malfunction, then this status message is recorded in the tech log, as in this case. Its function is to tell the flight control system to tell the exact position of the stabilizer, so that the stability and control of the aircraft remain. It was corrected according to the fault isolation manual and released the aircraft for flight at 12:10 PM.
The aircraft was to fly from Ahmedabad to London Gatwick Airport as Flight AI171. Its estimated departure time was 13:10 PM. The flight was to be operated by ATPL holder pic, CPL holder co-pilot and ten cabin crew.
- ATPL i.e., Airline Transport Pilot License. This is the highest level of license of the pilot, which allows to fly large commercial aircraft.
- PIC means pilot in command. It is the main pilot, which takes full responsibility of the aircraft. He has the final right to make decisions and flight operations.
- CPL i.e., Commercial Pilot License. These licenses are for commercial flights, but require less experience and responsibility than ATPL.
- The co-pilot is helpful of pic, which helps during flight, such as navigation, communication, and takes responsibility for flying the aircraft several times.
- In this flight, the CPL holder was the co-pilot pilot flying (PF), that is, he was controlling the aircraft during take-off and flight.
Both pilots were Mumbai based and reached Ahmedabad the previous day. Enough rest was taken before the flight. The co-pilot was pilot flying (PF) for this flight and pic pilot monitoring (PM). The flight pilots were Sumit Sabharwal and K-Pilot Clive Kunder.
Sumit had a flying experience of over 8,200 hours. The pilot also had a 1,100 -hour flying experience. That is, both were experienced pilots.
- 11:55 am: AI171’s crew reached the airport and passed through the pre-flight breath analyzer test. In this, he was found to be fit for flight. This is an important process before flying.
- 12:35 pm: In CCTV recording, the crew was seen reaching the boarding gate in the morning. The aircraft had 230 passengers. 15 were in business class. There were 215 in the economy, including two babies.
The aircraft had 54,200 kg of fuel and according to the load and trim sheet, the take -off weighing 2,13,401 kg (maximum permission – 2,18,183 kg). The take-off was under permission for the given conditions. There was no ‘dangerous items’ in the aircraft.
Calculated V speed for take -offs under available conditions: V1 – 153 knots, VR – 155 notes, V2 – 162 notes. The A-SMGCS replay was also performed after the accident.
V1, VR, and V2 are special speeds that tell when the aircraft can stop, when will it start flying, and how to get safe height after the flight.
A video-like record of antics on the ground of the aircraft was seen from the A-SMGCS Replay to investigate the accident, so that it could be understood what happened before the take-off.
- 1:18:38 pm: The aircraft was seen leaving Bay 34.
- 1:25:15 pm: The aircraft received taxi clearance.
- 1:26:08 pm: The aircraft started taxi with bay.
The aircraft went to runway 23 via Taxiway R4, Backetrack and line up.
- 1:37:33 pm: Tech-off clearance received.
- 1:37:37 pm: The aircraft started the roll.
According to EAFR data (records the voice of flight data and cockpit), the aircraft crossed the take-off decision speed V1.
- 1:38:33 pm: The aircraft acquired 153 knots IAS.
- 1:38:35 pm: The aircraft achieved 155 knots VR speed.
- 1:38:39 pm: The air/ground sensors of the aircraft turned into air mode.
- 1:38:42 pm: The aircraft acquired a maximum of 180 knots at IAS speed.
Shortly thereafter, the fuel cutoff switches of the engine 1 and engine 2 went from Run to the cutoff position with a interval of 1 second. The speed of the engine N1 and N2 began to decrease with the take-off value as fuel supply to the engines stopped.
In the cockpit voice recording, a pilot was heard asking the other why he cutoff. The second pilot replied that he did not do so. RAM Air Turbine (RAT) deployed. Rat is a small turbine and gives hydropholic power in emergency.
RAM Air Turbine (RAT) was seen to have a deployment of RAM soon after the liftoff.
- 1:38:47 pm: RAM Air Turbine (RAT) started work.
- 1:38:52 pm: The fuel cutoff switch of the engine 1 came in the run.
- 1:38:54 pm: The aircraft began to open the APU inlet door.
The APU is a small engine that gives electricity and hydrolyic power to the aircraft, especially when the main engines are closed or fail. The opening of the inlet door gives the APU air, so that it can be operational. In this case, the opening of APU Inlet Door starts to begin to open the aircraft system trying to turn on APU in an emergency.
APU is used to start the engine, cool/heat the cabin, and to power the electrical system, such as lights, avionics and other equipment. It works independently and it requires fuel of the aircraft.
This picture has been shared in the AAIB report. It states that both fuel control switches were in “run” positions. That is, the pilot tried to turn on the engine.
The RAM air turbine (RAT) aircraft is used to supply emergency hydrolic or electricity.
- 1:38:56 pm: The fuel cutoff switch of the engine 2 also came to run from cutoff.
When the fuel control switch is performed from cutoff to run during flight, the Full Authority Dual Engine Control (FADEC) of each engine automatically manages the relay and thrust recovery sequences, which includes ignition and fuel supply.
The EGT for both engines is seen to be increasing, indicating the release of the engine. EGT means exhaust gas temperature. It measures the temperature of gases emanating in the engine of the aircraft. If the EGT increases, it indicates that fuel is burning in the engine.
The speed of the engine 1 which was decreasing, stopped, then started growing and the engine slowly moved towards recovering. The engine 2 was turned on again, but did not stop with its speed being reduced. Repeated fuel was added to increase it, but did not succeed.
- 1:39:05 pm: A pilot transmitted “Mayday Mayday Mayday”.
The Air Traffic Control Officer i.e. ATCO asked about the call sign. ATCO received no response, but saw that the plane crashed outside the airport boundary and started an emergency response.
- 1:39:11 pm: The aircraft’s data was closed at the recordings of the recorder.
- 1:44:44 pm: Crash came out of the airport for fire tender rescue.
According to Aviation Expert and Commercial Pilot Captain Steve, pilots can cut off one or both switches in certain situations:
1. Single engine failure: Pilot does not touch anything before 400 feet when an engine failure in training. Pilots follow the checklist and double confirmation occurs at every step. Both pilots confirm before cutting the fuel control switch.
2. Dual engine failure: In this situation, the fuel switch has to be cut off and immediately on the run. But this did not happen in this case. There is no process in which both switches are left on cutoffs, especially immediately after takeoff.
Captain Steve has been Aviation Expert and Commercial Pilot. He has flew both Boeing 777 and Boeing 787 planes.
Both pilots confirm before cutting the fuel control switch.
So was it a pilot’s fault? If one engine failed and the pilot accidentally cut off another fuel control switch, is it possible?
It is very low. It seems impossible to accidentally put both the switches into the cutoff. Can this happen by mistake? No. These switches are not like normal light switches.
They need special hard work to operate them. They have to be caught with two fingers, to get out of the details, and then release in the cutoff position.
This cannot be a accidental mistake. Now the question is, why did this happen? We probably never get the answer.
Where did the investigation reach:
- Work on the wreckage area of the aircraft, such as taking photos and videos from drones, has been completed. The debris has been taken to a safe place near the airport.
- Both engines are removed from the rubble and are kept safe in a hanger in the airport.
- Necessary parts for further investigation have been selected and kept separate.
- Fuel samples taken from tanks and bosters used to fuel fuel in the aircraft were examined in DGCA’s lab and were found to be fine.
- APU filters and refuel samples have been found in a very small amount of fuel from the refuel/jetison valve of the left wing. They will be investigated in such a place which can test even in small quantities.
- The data downloaded from further EAFR is being investigated in detail.
- The statements of the witnesses and the remaining passengers have been taken by the investigators.
- Postmortem reports of crew and passengers are being fully analyzed so that medical and engineering findings can be mixed.
- More information is being collected based on initial clues.
- In this stage of investigation, no suggestions have been made to operators and manufacturers of B787-8 or GE GENX-1B engine.
- The investigation is still going on, and the investigation team will review more evidence, records and information from stakeholders.
