From takeoff to crash: The 98-second life of doomed Air India flight

India Today

6 days ago

The Aircraft Accident Investigation Bureau's 15-page preliminary investigation report details the fateful 98 seconds of AI171, the London-bound flight from Ahmedabad — from the takeoff roll to the moment the Boeing 787-8 Dreamliner crashed outside the airport boundary wall — in which 241 people on board were killed, with only one survivor.The flight took off at 1:38 pm after receiving take-off clearance. The AI 171 Dreamliner was just 32 seconds in the air, before it eventually crashed. By 1:38 pm, one of the engines had reached a speed of 284 km/h during the takeoff roll. Within the next two seconds, the aircraft achieved Vr speed — the rotation speed — at 287 km/h, according to the preliminary investigation report. Following that, the aircraft lifted off, meaning the wheels left the ground four seconds later.advertisementOver the next three seconds, the aircraft recorded a maximum airspeed of 334 km/h. Immediately afterward, both engines shut down, prompting the deployment of the RAT (Ram Air Turbine) as the aircraft began losing altitude.
RATs are deployed in the event of a dual engine failure or a loss of electrical or hydraulic power.However, aviation experts noted that RAT deployment is often ineffective at lower altitudes, particularly during takeoff, due to insufficient airflow required to power the turbine at low speeds.Key Time Stamps05:47 UTC – Aircraft arrived in Ahmedabad (from Delhi, flight AI423)06:40 UTC – Aircraft released for flight after tech check06:25 UTC – Crew underwent preflight Breath Analyser test — found fit07:05 UTC (12:35 IST) – Crew seen arriving at the boarding gate via CCTV07:48:38 UTC – Aircraft departed from Bay 3407:55:15 UTC – Received taxi clearance07:56:08 UTC – Began taxi08:07:33 UTC – Take-off clearance issued08:07:37 UTC – Aircraft began take-off roll08:08:33 UTC – V1 speed (153 Kts IAS) achieved08:08:35 UTC – Vr speed (155 Kts) achieved08:08:39 UTC – Aircraft lifted off (air/ground sensors show air mode)08:08:42 UTC – Max recorded airspeed: 180 Kts IASImmediately after: Engine 1 & 2 fuel cutoff switches moved to CUTOFF08:08:47 UTC – RAT (Ram Air Turbine) deployed; aircraft losing altitude08:08:52 UTC – Engine 1 fuel cutoff moved back to RUN08:08:54 UTC – APU Inlet Door began opening (Auto Start logic)08:08:56 UTC – Engine 2 fuel cutoff moved back to RUN08:09:05 UTC – MAYDAY call made08:09:11 UTC – EAFR recording stops, flight crashesFive seconds later, Engine 1's fuel cutoff switch was moved back to the RUN position, indicating signs of recovery, the report stated, citing data from the Enhanced Airborne Flight Recorder (EAFR).The APU inlet door began to open two seconds later, triggered by the auto-start logic. Engine 2 also began to stabilise within the following two seconds.The report stated that while Engine 1 began to recover after its core speed deceleration stopped, Engine 2, although able to relight, could not arrest its core speed deceleration.advertisementThe MAYDAY call was made at 1:39 pm (08:09:05 UTC). Six seconds later, at 08:09:11 UTC, the EAFR stopped recording, according to the report.When the Air Traffic Control officer enquired about the MAYDAY call, there was no response, as the aircraft was observed crashing outside the airport boundary at that moment, the report noted.- EndsMust Watch