Violent turbulence, dancing on board: how far the plane's wing can flex without breaking

A few days ago we read about the Violent turbulence that hit a Latam Boeing 787 over the Pacific Ocean, causing 50 injured of whom 13 needed hospital treatment.

In addition to the safety of passengers and crew, such weather phenomena also put a strain on the structure of the airplane, which is subjected to forces equivalent to several G. Phenomena that, on a smaller scale, anyone who has flown a little has experienced, perhaps observing between fascinated and concerned the wings visibly fold and undulate, especially near the extremities.

Now, those who fly with some frequency know that this is perfectly normal. Indeed, the wings must be able to fold and must be able to undulate when the plane encounters turbulence, then order to absorb kinetic energy by transmitting less of it to the fuselage.

By the way, being the latest generation of aircraft built to a good extent from very light materials such as carbon, their wings sway more than those of passenger jets of 20-30 years ago, which were made mostly of aluminum, could.

The overall champion of the category is the Boeing 787, which when it takes off fully loaded with passengers and fuel before a 15- to 16-hour trip, appears to have rubber wings, so they arc upward. In flight, normally, the wing of the Dreamliner folds down to 10-12 feet (i.e., 3-4 meters) upward. But in testing it can flex up to 26 feet, or nearly eight meters.

Still, the question is understandable: in particularly severe turbulence, an aircraft's wing can break off? The answer is no. And not just because it never happened. But because commercial aircraft wings are designed to withstand the stress of forces that, in nature, do not even exist. During the certification process of the Boeing 777, for example, wings are 'folded' to 150% of the maximum deflection found in the worst conditions of flight.

Many people, then, do not know that Airplanes do not actually have 'two' wings. But a single wing, a single internal structure that runs through the fuselage and that runs all or most of the wingspan and makes it impossible for the wing to break.

The case of structural defects or structural failure caused by poor or insufficient maintenance is different, that weaken certain key-components of an airplane to such an extent that those components separate and severely affect the entire structure of the aircraft, such that its ability to stay in the air is impaired. But, in these very rare cases, more than the wings it may be tailplanes, vertical and horizontal, that are affected.

• B777
• B787