Wednesday, 17 April 2024
WorldWhy didn't the crashed plane at Tokyo airport explode?

Why didn’t the crashed plane at Tokyo airport explode?

How did the 379 passengers and crew of the Japan Airlines plane that caught fire after colliding with another plane at Tokyo airport manage to escape almost unscathed? According to experts, one of the keys could be the low level of fuel, which probably prevented an explosion from occurring.

Around 17:45 local time on Tuesday, the Airbus A350-900 that had taken off from the city of Sapporo ninety minutes earlier with code 516 JAL collided with a Dash 8 aircraft of the Japanese Coast Guard, after landing at the airport in Haneda, and caused the death of five of the six people on board the smaller aircraft.

Engulfed in flames, the A350 did not explode when it collided with the other plane, but the fire quickly spread throughout the fuselage. It took authorities almost three hours to extinguish the flames and they managed to put them out at 8:30 p.m. local time.

Although a significant proportion of carbon fiber, which burns more easily, was used in the manufacture of the plane, experts do not believe that it was decisive in this case. The way the A350 burned, they say, is a relatively new phenomenon in aviation. As Sonya Brown, professor of aerospace design at the School of Mechanical and Manufacturing Engineering at the University of New South Wales, explains, the main components of the first generation of airliners of the 20th century were made of metal but, in order to To improve weight and efficiency, aeronautical engineers have been increasing the proportion of carbon fiber composite materials.

According to Brown, the proportion of carbon fiber reinforced polymers in the A350 is one of the highest for a passenger aircraft, being approximately 50%. The wings and fuselage are some of the main aircraft structures made of these materials. Aluminum, steel and titanium are still used, but to a lesser extent. “Of course, materials influence fire behavior and, although in relation to this incident we do not know the details of the resins used in the plane, [lo que sí sabemos es que] They need lower temperatures than aluminum to lose their structural capacity,” says Brown.

The importance of materials

Japan Airlines took delivery of the A350 in November 2021, according to a statement from Airbus. The large European manufacturer has announced the sending of a team of specialists to Japan to collaborate in the investigation of this Tuesday’s incident.

The initial flame started on the left wing and was so large that a metal-bodied plane would have also caught fire, Brown says after analyzing the images. “Carbon fiber composites can start to lose rigidity at about 200 degrees, while aluminum melts at about 700, but the fire we saw in that fuselage will have reached temperatures above 1,000 degrees Celsius,” he adds.

“[La presencia de fibra de carbono en la composición] “It will have had some impact on the way it burned, because the resins combust at lower temperatures, but even if they changed the evolution of the fire, the carbon fiber composites were not going to change the final result,” he says.

According to the professor, the fire was contained to the left wing long enough for the evacuation of all people on board, thanks to materials used as firebreaks that require much higher temperatures to combust, a way to prevent the flames from spreading. extend to engines and fuel tanks.

The crews are trained to evacuate all passengers in 90 seconds, but it probably took them longer due to the impossibility of using the doors that open on the wings. Once the passengers were evacuated, the intensity of the flames depended largely on what the aircraft was carrying. “It is not only the materials that airplanes are made of, there are also batteries, electrical systems, other luggage or merchandise in which there can be anything, which can also burn,” Brown highlights.

In his opinion, it is possible that the relatively low amount of fuel in the plane’s tank at the time of landing may have minimized the intensity of the fire and prevented an explosion.

For his part, Neil Hansford, aeronautical sector consultant at Strategic Aviation Solutions, points out that commercial aircraft usually maximize efficiency by carrying the fuel necessary for a trip plus a 10% reserve. “It is industry standard to always carry the fuel necessary for the trip, plus 10%, plus what is necessary to reach the alternative airport programmed in the flight plan, which would probably be Narita (Tokyo) in this case,” he details. .

Regardless of the materials used in its construction, the exterior of a plane will always burn in a fire like the Haneda one, Hansford says, but the interior is designed to allow safe evacuation by preventing the spread of flames for as long as possible. . “Everything inside the plane is designed to mitigate combustion, the seats are made of fireproof material.”

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