In the blue skies above western India, flight AI171 was struggling to gain altitude.

In a video, the aircraft is seen slowly sinking behind residential buildings, before a huge fireball blasts upward.

Among those killed were passengers on the flight, including some minors, local residents, and people who were inside the BJ Medical College and Hospital hostel when the plane crashed into it.

A CNN analysis geolocating multiple social media videos and examining flight tracking data shows how the deadly incident unfolded.

When and where did the Air India flight take off?

The Air India flight, AI171, took off from Ahmedabad’s Sardar Vallabhbhai Patel International Airport in India’s western state of Gujarat.

The Boeing 787-8 Dreamliner was headed to London Gatwick, and scheduled to land at 6.25 pm local time (3.25 am Friday AEST).

Air India said 242 passengers and crew members were on board. That included 169 Indian nationals, 53 Britons, seven Portuguese and one Canadian.

Due to Britain’s large Indian diaspora, many of those on board may have been returning home after visiting family in India, or traveling to Britain to visit family there.

FlightRadar 24, a flight tracking site, said the plane used the full length of the 11,499-feet-long Runway 23 at the Ahmedabad airport in its takeoff.

The flight took off at 1.39pm (8.09pm Thursday AEST), and was due to land around nine hours later.

Did the pilots issue a Mayday call?

Data from FlightRadar 24 shows the plane leaving the airport – before, suddenly, the tracking stops.

The aircraft had reached an altitude of 190 metres when its signal was lost, the tracker said.

FlightTracker24 data said it began to plunge down to earth at a speed of about 475 feet per minute (about 145m per minute).

Realizing that something was wrong, staff on the plane gave a Mayday call to air traffic control (ATC), Indian civil aviation authorities said. That call came less than a minute after take-off.

Did onlookers realise the plane was in trouble?

In a video shared on social media by a person just under 200m from the airport perimeter, the plane is seen struggling to stay aloft.

As the plane gets closer to the ground, its tail begins to sag more deeply beneath its nose.

The aircraft gets further and further from the person filming, before it disappears below apartment buildings.

A huge red fireball then shoots into the sky. Other videos, shot from different locations in the city show massive plumes of black smoke.

Where did the plane crash?

The plane that had just a minute ago been safely on the Ahmedabad runway had now gone up in flames, just under a mile (just under 1.6km) from the airport.

Shocking images showed the plane’s tail lodged in a concrete building. Officials said the bulk of the plane had crashed into a hostel housing doctors working in the local hospital.

Inside the building, images showed metal plates of uneaten food on cafeteria-style tables – with a wall now blown out from the impact.

Locals began to gather around the main crash site as black smoke poured from its windows.

Videos showed grisly scenes unfolding on the street, as people began to try to put out the blaze and search for survivors.

The charred remains of the plane’s fuselage – still showing part of its registration, “VT-ANB” – can be seen lying on the debris-strewn street. Closer footage showed burned bodies being pulled from the ruins. In one video, a man retrieves a suitcase from the wreckage.

How did Vishwash Kumar Ramesh survive the crash?

At least one passenger on board the flight survived, local police said. According to Reuters, senior police officer Vidhi Chaudhary said the man had been in seat 11A and added that there may be a few more survivors in the hospital.

The Hindustan Times said it spoke to Ramesh in a local hospital, and quoted him as saying: “Thirty seconds after takeoff, there was a loud noise and then the plane crashed. It all happened so quickly.”

It is also not clear if others – on the street, or in the hostel – were killed when the plane came crashing down.

The Federation of All India Medical Association said between 50 and 60 students have been admitted to local hospitals after the flight crashed into the hostel at the BJ Medical College and Hospital. It said four or five students are missing and another two or three others are in intensive care.

Is this the deadliest air crash of the 21st century?

If most of the rest of the passengers are confirmed dead, the crash will be the deadliest worldwide since 2014, when MH17 jet was shot down over eastern Ukraine, killing all 298 people on board, including a number of Australians.

Indian Prime Minister Narendra Modi said the incident was “heartbreaking beyond words” and that he was working with the authorities involved in the disaster. The plane crashed in India’s western Gujarat region, where Modi was born and where he served as chief state minister from 2001 to 2014.

British Prime Minister Keir Starmer said the scenes were “devastating.” His foreign minister, David Lammy, said the United Kingdom had activated a crisis team in both India’s capital, New Delhi, and in London.

While the authorities’ immediate focus is on confirming the number of casualties and providing support to the victims’ families, attention will soon turn to what caused the crash.

Investigators will focus on whether human error, mechanical failure, poor maintenance, or a combination of those factors, played a part in a the crash.

Last year, a whistleblower claimed that Boeing was taking shortcuts in its manufacturing of the 787-Dreamliner model, claims disputed and described as “inaccurate” by Boeing. The Federal Aviation Administration in the US is investigating the whistleblower’s formal complaint.

Shares in Boeing tanked by more than 7 per cent in pre-market trade today. Stocks in many other airlines also fell.

For Boeing, the crash is the latest in a series of incidents that have shaken consumers’ fears in the safety of its aircraft.

For Air India, the crash will likely damage a years-long effort to overturn its image as a struggling, debt-ridden airline to a safe, modern carrier appealing to India’s burgeoning middle class.

Air India last suffered a crash this deadly in 2010, when 158 people were killed after one of its jets overshot a runway in southern India.