I can’t be certain what caused the Air India crash, but there’s one thing my pilot’s eyes can’t ignore David Evans
Former Qantas captain
June 13, 2025 — 1.58pm
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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.
The Boeing Dreamliner was filmed shortly after take-off descending and crashing into a residential area.Credit:The Age
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.
A safety feature of modern twin-engined aircraft such as the B787 is the RAT, or Ram Air Turbine, which would deploy automatically into the airflow to supply the minimum hydraulic and electrical power to keep the aircraft controllable should both engines fail. The RAT is a small propeller that pops out into the airflow, much like a small wind turbine.
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Unfortunately, from the available footage, it’s impossible to tell if the RAT has deployed on AI 171. The aircraft clearly becomes airborne and climbs to approximately 500 to 600 feet. Everything appears normal up to this point. Then it starts descending before it impacts some two kilometres downrange from the runway.
At this early stage, I’m reluctant to label this accident “human error” but it’s worth observing that at around the time the aircraft started its terminal descent into the ground, the undercarriage was still deployed. Landing gear retraction is the first configuration change after lift-off. As soon as the aircraft is confirmed airborne and with a positive rate of climb the pilots retract the gear. It has no more use and simply creates aerodynamic drag so it is raised into the airframe.
The key question here is – were the flaps retracted after take-off instead of the undercarriage?
The investigation will be thorough and the cockpit voice and data recorders will be recovered. As always, the findings as to why AI 171 crashed – be it human or mechanical error – will be harnessed to make the aviation industry, despite tragic and attention-grabbing accidents such as these, still the safest form of travel.
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