Air India 171: Unraveling the Mechanics of Flight
“Thrust not achieved… falling… Mayday! Mayday! Mayday!”
These were the desperate final calls dispatched from Air India Flight 171, just seconds before the 250-ton aircraft plummeted into the nearby urban infrastructure of Ahmedabad. After failing to gain sufficient flight altitude, barely gliding above the rough pavement for just 30 seconds after takeoff, the Boeing 787-7 Dreamliner made its fatal descent before erupting into flames.
The tragedy certainly achieves its place in the history of aviation as not only one of the deadliest but also one of the most puzzling accidents of the 21st century. What makes the incident uniquely distinct from other crashes is that, despite modern engines being incredibly reliable—enough so that a plane could operate on just one—the aircraft likely suffered a dual engine failure, an improbable event that only happens once in a blue moon.
Regardless of the unresolved mystery surrounding Flight AI-171, the pilots’ final words—‘thrust not achieved’—and the airplane’s improper flight pattern establish that the aircraft could not maintain a stable aerodynamic balance.
Lift, drag, weight, and thrust are the four fundamental forces of flight that allow aircraft to soar the skies. Each force varies in strength and has a respective counterpart; they each play a role in ensuring that such an incident does not occur.
Weight
To start, force is a push or pull on an object that is capable of changing its motion. Force allows movement, and it is also the gravitational pull that keeps you from drifting off to the skies.
Weight is simply the downward force exerted on a plane due to gravity. It also explains the strict weight limits required by commercial airlines, which would want to minimize the force that actively limits a plane’s ability to rise. Weight is considered a limiting factor in aerodynamics; thus, it must stay weaker than or equal to its counterpart—lift—to keep a plane airborne.
Lift
If you have ever flown a kite at the beach, you probably remember how it magically lifted itself into the air. Although a plane might not float as easily as a kite, it does eventually surpass one with the help of lift.
Most of an aircraft's lift is generated from its wings, which have a special shape called an airfoil. Just like how a kite needs to be at a certain angle to take off, airfoils are shaped in a way so that once the aircraft charges down the dusty runway, air is deflected downwards to create an upward force. The strength of lift constantly changes throughout a flight, thanks to the adjustable parts on a wing.
Drag
Drag is the resistance opposite to the direction an aircraft faces when moving. Similar to weight, drag is another limiting factor that constantly holds the plane back from reaching its destination. Think of it as trying to sprint underwater, where your limbs will not move as freely as you wish. More or less, every single plane to take flight faces drag, but the amount of drag varies depending on its size, speed, texture, shape, and other factors.
Thrust
Engines are arguably the most critical piece on a plane, as without them, there will be no thrust—the force for moving forward—and without thrust, there will be no movement. Moreover, the engines also determine the direction in which a plane moves. Without thrust, there would also be no lift. As the plane dashes forward, there will be enough airflow over its wings to generate lift.
Unlike weight, lift, and drag, thrust is the only machine-generated force, meaning it can be directly adjusted from the cockpit. However, this also means that when all goes wrong, there is little to no control over mechanical failures, which could result in disaster, as demonstrated in Flight AI-171.
While the science of aviation extends into far more complex systems of engineering, the four fundamental principles are considered the backbone of flight. Cases such as Flight AI-171 highlight that even in the most technologically advanced period of aviation, understanding the balance between the four forces is essential for keeping every journey in the air safe.
Sources:
https://www.bbc.com/news/articles/c626y121rxxo
https://web.mit.edu/16.00/www/aec/flight.html
https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/four-forces-on-an-airplane/
https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/what-is-lift/
https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/what-is-thrust/