Pilots are focusing on the configuration of the Air India aircraft as it struggled to climb away from runway 23 in Ahmedabad before running out of lift and descending to the ground.

There is so far no single line of expert speculation over the cause, with theories on aviation sites ranging from possible engine failure on the Boeing 787 to crew errors before or after take-off.

The video images show that the landing gear remained extended, which is not normal, and it appears that there may have been an issue with the wing flaps.

• Air India plane crash: follow latest

The wheels are retracted on airliners as soon as soon as they establish a “positive climb” after take-off. This reduces the drag from the air and enables the aircraft to climb better. Pilots trying to coax a defective aircraft into a climb would quickly raise the gear.

The images also prompted some pilots to conclude that the flaps and associated slats on the front of the wings were not deployed as they should have been. These surfaces are partially extended to improve lift on taking off. Premature retraction has been the cause of past crashes. The Boeing 787, which has multiple automated safety systems, is capable of lifting off on a single engine, although the margins would have been thin at Ahmedabad. The aircraft was loaded with passengers and fuel for a nine-hour flight, weighed about 230 tonnes, and was taking off in very hot air.The aircraft was loaded with passengers and fuel for a nine-hour flightThe Air India disaster, which was the first operational loss of a Boeing 787 Dreamliner since its introduction in 2009, follows three major airline disasters and one major crash in the past six months.On December 24, an Azerbaijan Airlines Embraer 190 airliner crashed in Kazakhstan after being hit by Russian anti-aircraft fire over the Russian town of Grozny. Of the 67 people on board 38 were killed. Both pilots and a flight attendant were among the survivors.• Worst aviation disaster for Britain since 9/11On December 29, only two flight attendants survived when a Boeing 737 of Korea’s Jeju airlines slammed into an embankment while trying to land after an engine failure at Muan airport. A bird strike and possible crew errors have been blamed for the disaster, which killed 179.In the first airline disaster in the USA since 2009, a Canadian-built Bombardier CRJ700 airliner collided with an army Blackhawk helicopter over the Potomac river in Washington DC on January 29. All 67 people aboard both aircraft died in the crash, which followed the apparent failure of the helicopter pilot to spot the airliner as it approached Washington National Airport.On February 17, a Delta airlines Bombardier CRJ900 sheared off a wing and flipped over when it made an exceptionally hard landing in poor weather at Toronto airport in Canada. All 80 people on board survived but 21 were injured.