When a modern aircraft crashes as tragically and sensationally as Air India Flight AI 171 did on take-off bound for London last night, it’s normal to search for the cause as soon as possible, especially as so many passengers around the world continue to travel on the same type of aircraft, in this case a Boeing 787, while the search for answers takes place.

And while it’s dangerous and irresponsible to speculate at the early stage of an aircraft accident investigation, or at any stage for that matter, it is worth analysing the risk mitigators that all airlines put in place at the commencement of any modern flight.

What we know is the B787 was scheduled to operate a direct flight from India to London. This, while not an extremely long flight, comes under the category of “long haul”. By this very definition, the aircraft would have been heavily laden with passengers, cargo and fuel and, as such, would have executed a heavyweight take-off.

We know that the temperature at Ahmedabad was 37 degrees – hot, but not unusually hot for around midday in this part of India. High temperatures mean “thin” air, which requires a higher speed on the runway to gain enough lift for take-off. These lift-off speeds are routinely calculated for every flight based on weight of the aircraft and conditions at the airfield. It can be seen from the tragic footage that AI 171 did indeed become airborne.

It’s worth pointing out that all modern airliners’ wings are designed for high altitude and high-speed flight. This is where they are most efficient. On the ground and at low speed the wing is not efficient. So, to increase its efficiency in circumstances such as take-off and landing, aircraft designers incorporate flaps both at the rear of the wing surface and also at the front to increase the wings size and “camber”. In other words, the wings become short and fat to create more lift at low altitude and low airspeed, and long and thin at high altitude and high speed for efficiency.

These high-lift devices are eventually retracted as the aircraft increases altitude and speed. A heavyweight aircraft, such as this B787, cannot maintain flight if these high-lift devices are not deployed before or during take-off.

To help prevent these flaps inadvertently not being deployed there are at least three separate checklists to confirm deployment before a take-off is attempted. The aircraft itself has a very loud warning system if take-off power is applied and the flaps are not extended. All pilots are trained to abort the take-off if the “take-off configuration warning” sounds. It’s quite a ruckus in the cockpit and impossible to miss.

This leads me to engine performance. As mentioned, it was a hot day and the aircraft was heavy. It would have required a lot of engine power to attain the required lift-off speed. Part of the take-off performance calculation would have included power requirements. Modern aircraft are designed to fly away on one engine if there is an engine failure during the take-off roll, but it will not fly if both engines fail.