That is the question that investigators will be asking in the coming days, weeks and months to come. On Thursday June 12, a Boeing 787 Dreamliner took off from Ahmedabad in northwest India, bound for London. On board were 242 passengers and crew. It was a hot, clear day. Videos taken from the ground show that after rolling down the runway, the plane "rotated" into the air (orienting flight surfaces to make the plane take off), and assumed a nose-up attitude. But after rising for about fifteen seconds, it began to sink back toward the ground and plowed into a building housing students of a medical college. All but one person on the plane were killed, and at least 38 people on the ground died as well.
This is the first fatal crash of a 787 since it was introduced in 2011. The data recorder was recovered over the weekend, so experts have abundant information to comb through in determining what went wrong. The formal investigation will take many weeks, but understandably, friends and relatives of the victims of the crash would like answers earlier than that.
Air India, the plane's operator, became a private entity only in 2022 after spending 69 years under the control of the Indian government. An AP news report mentions that fatal crashes killing hundreds of people involved Air India equipment in 1978 and 2010. The quality of training is always a question in accidents of this kind, and that issue will be addressed along with many others.
An article in the Seattle Times describes the opinions of numerous aviation experts as to what might have led to a plane crashing shortly after takeoff in this way. While they all emphasized that everything they say is speculative at this point, they had some specific suggestions as well.
One noted that the appearance of dust in a video of the takeoff just before the plane becomes airborne might indicate that the pilot used up the entire runway in taking off. This is not the usual procedure at major airports, and might have indicated issues with available engine power.
Several experts mentioned that the flaps may not have been in the correct position for takeoff. Flaps are parts of the wing that can be extended downward during takeoff and landing to provide extra lift, and are routinely extended for the first few minutes of any flight. The problem with this theory, as one expert mentioned, is that modern aircraft have alarms to alert a negligent pilot that the flaps haven't been extended, and unless there was a problem with hydraulic pressure that overwhelmed other alarms, the pilots would have noticed the issue immediately.
Another possibility involves an attempt to take off too soon, before the plane had enough airspeed to leave the ground safely. Rotation, as the actions to make the plane leave the ground are called, cannot come too early, or else the plane is likely to either stall or lose altitude after an initial rise. Stalling is an aerodynamic effect that happens when an airfoil has an excessive angle of attack to the incoming air, which no longer flows in a controlled way over the upper surface but separates from it. The result is that lift decreases dramatically. An airplane entering a sudden stall can appear to pitch upward and then simply drop out of the air. While such a stall was not obvious in the videos of the flight obtained so far, something obviously caused a lack of sufficient lift that led to the crash.
Other more remote possibilities include engine problems that would limit the amount of thrust available below that needed for a safe takeoff. It is possible that some systemic control issue may have limited available thrust, but there was no obvious mechanical failure of the engines before the crash, so this possibility is not a leading one.
In sum, initial signs are that some type of pilot error may have at least contributed to the crash: too-early rotation, misapplication of flaps, or other more subtle mistakes. A wide-body aircraft cannot be stopped on a dime, and once it has begun a rollout to takeoff there are not a lot of options left to the pilot should a sudden emergency occur. A decision to abort takeoff beyond a certain point will result in overrunning the runway. And depending on how much extra space there is at the end of the runway, an overrun can easily lead to a crash, as recently happened when Jeju Air Flight 2216 in Thailand overshot the runway and crashed into the concrete foundation of some antennas in December 2024.
The alternative of taking off and trying to stay in the air may not be successful either, unless sufficient thrust can be applied to gain sufficient altitude. Although no expert mentioned the following possibility and there may be good reasons for that, perhaps there was an issue with brakes not being fully released on the landing-gear wheels. This would slow down the plane considerably, and the unusual nature of the problem might not give the pilots time enough to figure out what was happening.
Modern jetliners are exceedingly complicated machines, and the more parts there are in a system, the more combinations of things can happen to cause difficulties. The fact that there have so far been no calls to ground the entire fleet of 787 Dreamliners indicates that the consensus of experts is that a fundamental issue with the plane itself is probably not at fault.
Once the flight-recorder data has been studied, we will know a great deal more about things such as flap and engine settings, precise timing of control actions, and other matters that are now a subject of speculation. It is entirely possible that the accident happened due to a combination of minor mechanical problems and poor training or execution by the flight crew. Many major tragedies in technology occur because a number of problems, each of which could be overcome by itself, combine to cause a system failure.
Our sympathies are with those who lost loved ones in the air or on the ground. And I hope that whatever lessons we learn from this catastrophe will improve training and design efforts to make these the last fatalities involving a 787 in a long time.
Sources: I referred to AP articles at https://apnews.com/article/air-india-survivor-crash-boeing-e88b0ba404100049ee730d5714de4c67 and https://apnews.com/article/india-plane-crash-what-to-know-4e99be1a0ed106d2f57b92f4cc398a6c, a Seattle Times article at https://www.seattletimes.com/business/boeing-aerospace/what-will-investigators-be-looking-for-in-air-india-crash-data/, and the Wikipedia articles on Air India and Air India Flight 171.