At 1.38 pm on June 12, Air India flight AI171 bound for London from Ahmedabad crashed five minutes after taking off just outside the Ahmedabad airport. The flight had 230 passengers and 12 crew. Videos of the incident showed a large orange fireball erupting moments after the crash at the site in Meghaninagar.
The exact cause has yet to be identified or ascertained.
The AI171 flight was a Boeing 787-8 Dreamliner, a wide-bodied aircraft powered by twin jet engines. The design, introduced in the late 2000s, was part of the wider aircraft industry’s trend towards aircraft with more electrical parts in order to improve operational efficiency.
Earlier this year, Boeing celebrated 787-8 aircraft worldwide carrying 1 billion passengers in 30 million flight-hours. There are currently more than 1,170 aircraft of this variety operating around the world. Air India 171 represents the first major incident involving a 787-8 flight.
When it was first introduced in 2011, the 787-8 was touted as a gamechanger because it had specific advantages that promised to move the industry in a new direction. Later, however, its reputation came to be marred by problems with the carbon composites used for the aircraft, grounding orders over lithium-ion battery packs onboard, and concerns over the company’s quality control practices.
In fact, on June 12, U.S. President Donald Trump’s new nominee to head the Federal Aviation Administration (FAA), Bryan Bedford, vowed to hold Boeing accountable over “the failure of a key safety system tied to two fatal Boeing 737 MAX crashes in 2018 and 2019 that killed 346 people,” Reuters reported.
New route types
Dreamliner 787-8 aircraft use the General Electric GEnx or the Rolls Royce Trent 1000 engines. Both these engines are turbofans: they combine an air-breathing jet engine with a ducted fan.
The engine design is an important reason for 787-8 aircraft’s higher fuel-efficiency per seat (over other aircraft at the time of its introduction). The other factors contributing to this feature include the use of carbon composite structures of lower weight and low-drag aerodynamics.
Thanks to the engines, a 787-8 aircraft burnt around 20% less fuel than earlier twinjet models of a similar size. This allowed the aircraft to undertake nonstop flights between cities with lower passenger traffic than that required to fill Boeing 777 or Boeing 747 aircraft. In fact, Boeing had explicitly marketed this change in efficiency as a way for carriers to “open new, nonstop routes”.
The use of these particular engines was also responsible for the 787-8 being called an “electric aircraft”. Before the 787-8, it was typical for aircraft to divert some compressed air from the engines to hydraulic systems that in turn powered onboard facilities like maintaining cabin pressure. The 787-8 instead powered aircraft from generators (which drew power from the engine) and auxiliary systems.
Thus engines that generated around 250 kW onboard a Boeing 767 had to produce around 1,500 kW on board a Boeing 787-8. This in turn led to the use of larger starter-generators, high-capacity distribution boxes, and a strict new battery safety regime. It also reduced the specific fuel burn by around 4%.
How the engines work
During flight, the engines draw air from the surrounding atmosphere into a duct. There, a large fan slightly increases their pressure. Then about 20% of the air passes through the core of the duct into the turbine while the remaining 80% bypasses the core and flows in a separate channel around it.
The air mass that flows through the turbine is pressurised in two stages — first in the low-pressure compressor and then in the high-pressure compressor. As the air is compressed by up to 40-times more than the surrounding air, it’s sent into the combustion chamber. Here, it’s sprayed with jet fuel and the mixture is set aflame, producing a high-speed stream of gas at 1,600° C.
The high-energy gas emerging from the combustion chamber is flowed over the high-pressure turbine, which spins very fast, generating electric power. Energy from this stage is used to drive the high-pressure compressor at about 10,000 rpm. Then the gas passes through the low-pressure turbine, generating more power; and energy from this stage is used to drive the low-pressure compressor and the front fan (~3,000 rpm).
Finally the gas exits via the core nozzle at the rear. The nozzle is shaped such that the air is accelerated as it moves towards the rear. The nozzle through which the air bypassing the turbine is also shaped to have the same effect. In fact, the latter process generates the bulk of the thrust.
Flight experience
Splitting the incoming air mass into two streams allows the front fan and the compressors to spin at different speeds, separately maximising their efficiency. The mixer ducts and the shaped nozzle edges also blend the hot core and cool bypass streams and control the way in which they interact with the surrounding air. The result is lower shear noise.
This is important because the aircraft needs less noise-insulating material as a result, further lowering its weight and improving fuel efficiency. It also improved the in-flight passenger experience.
Wired reported in 2009 that Boeing also installed a “computer-controlled turbulence-reduction system to … provide an eight-fold reduction in the number of people experiencing motion sickness.” This was achieved by sensors around the aircraft that tracked changes in air pressure and sent signals to structures on the wings that controlled the craft’s vertical motion.
In the 2000s, Airbus was promoting its A380 — a large, voluminous double-decker sporting luxury amenities — as the future of passenger flights because the company had also assumed the industry’s hub-and-spoke model of travel would continue. Here, passengers take flights to large airports (the hubs) and from there fly in smaller aircraft to smaller airports (the spokes). This in turn presumed high traffic between the hubs, thus the A380 could seat 500-800 passengers.
Boeing overturned this assumption with the 787-8 design, which focused less on lowering ticket prices and more on reducing travel time.
Safety concerns
In 2009, the delivery of the first 787-8 units had been delayed by two years. One reason was that Boeing was no longer making the aircraft body with aluminium and switched instead to carbon-based plastic composites for the weight advantage. For the first units, Boeing’s suppliers had been expected to deliver the aircraft’s fuselage and wings with all the systems installed, with Boeing simply having to snap them together on its assembly floor. But this hadn’t been the case — the New York Times reported then that the suppliers had been “too overwhelmed”. The delay in deliveries resulted in at least 60 orders being cancelled.
Then, in early 2013, commercial air travel regulators in Chile, India, Europe, Japan, Qatar, and the U.S., among others, ordered all their Boeing 787 aircraft to be grounded after a new kind of battery onboard two aircraft, on each in the U.S. and Japan, failed. The regulators said the grounding order would be in effect until they could determine the cause(s) of failure. The issue was considered serious because of the 787’s greater dependence on electric power than many other aircraft designs. Onboard the aircraft that had made an emergency landing in Japan, a corrosive liquid had appeared to leak out of a lithium-ion battery pack.
There were also significant quality control issues in 2019 that forced Boeing to slow down production and cease delivering new aircraft between January 2021 and August 2022.
This said, the most significant red flags over 787-8 aircraft safety emerged when an engineer at Boeing named Sam Salehpour alleged that parts of the fuselage were being joined together in a subpar way that could cause them to come undone after thousands of flights. In 2024, the U.S. FAA said it would take a closer look at Mr. Salehpour’s claims. While Boeing staunchly refused the allegations, Mr. Salehpour had also said that after he repeatedly flagged the problem, the company had transferred him to working on Boeing 777 aircraft instead.
A month earlier, another Boeing whistleblower named John Barnett — who had raised multiple concerns about “shoddy production and weak oversight”, in the New York Times’ words, at the company’s South Carolina facility where it manufactured its 787s — had been found dead with a seemingly self-inflicted gunshot wound. Barnett had worked at Boeing for almost three decades and had retired in 2017. He had previously also reported the presence of “clusters of metal slivers hanging over the wiring that commands the flight controls”. According to him, if the slivers had penetrated the wiring, the effects would be “catastrophic”.
Following this, the FAA directed Boeing to remove these slivers from all 787 aircraft prior to delivery. Boeing said it could comply while continuing to maintain that the metal pieces’ presence didn’t compromise the safety of the aircraft.
These problems with the 787s together with those dogging the 737 Max, another company workhorse, set off alarm bells among regulators, airline operators, and aviators alike as to whether Boeing was systematically cutting corners in order to not cede ground to Airbus and to keep up its hectic delivery schedule.
Published – June 12, 2025 10:17 pm IST