First, the plane landed at Ahmedabad Airport (AMD), Sardar Vallabhbhai Patel International Airport. 

Now the plane was getting inspected and refueled by the ground crew and the maintenance crew checking the plane, as well as the pilots. 

Flight 171 took off from runway 23 of Ahmedabad Airport at 13:38 IST (08:08 UTC) en route to London Gatwick. According to METAR reports issued around the time of departure, the surface winds at the airport were light, ranging from 3 to 6 knots; the visibility was 6 kilometres (3.7 mi); and there were no significant clouds.

The aircraft's ADS-B transponder reported a maximum pressure altitude of around 625 feet (191 m) above mean sea level while still over the runway before the signal was lost at 08:08:50 UTC. The flight crew issued a mayday call after 36 seconds, reporting a loss of power and thrust shortly after takeoff. The aircraft was airborne for 30 seconds.

Now the plane was ready to take off, all clear, all set. No issue coming. The pilots asked, "Permission to take off, Permission to take off Air India 171 heading to London Gatwick airport.

The ATC granted permission to the plane to take off at runway 01R. Then the plane did its final checks and took off in seconds.

The flight was carrying 242 people, including 230 passengers—11 of them children and 2 infants—along with 2 pilots and 10 flight attendants. The passenger manifest included 169 Indian nationals, 53 British, 7 Portuguese, and 1 Canadian.

The flight was commanded by Captain Sumeet Sabharwal, aged 55, with 8,200 hours of flying experience, and First Officer Clive Kunder, aged 32, with 1,100 hours of flying experience. The plane was at full tank thing to remember later on.

The plane was normal for the first fifteen seconds, the plane was gaining altitude perfectly, and no issues were coming.

After around 15 seconds into the flight, the plane suddenly lost altitude rapidly at 625 ft 191 meters and experienced engine failure And Normally, if 1 engine failed, the Boeing 787 Dreamliner could use 1 engine for 220 minutes, almost 5 hours, to get to another airport, but in this case, both engines failed!