When a plane crash occurs, usually there are hundreds of bits of plane shattered everywhere. I watch shows like “Air Disasters”, but they never explain how they know the “right wing flap came apart mid air” or know how the “fan blade dislodged on impact and not in the air”?
In: Engineering
Airplanes have a lot of data that’s constantly recorded and is stored in a very hard to destroy device called a flight data recorder. A recording of the last 2 hours of pilot’s voices and other sounds heard in the cockpit are stored in another really hard to destroy device called a cockpit voice recorder. Those two devices are fire resistant, impact resistant, water resistant, painted bright orange, and may or may not be combined in a single device, and are normally referred to as the black boxes.
Using that data, along with detailed simulators, radar coverage recordings from air traffic control, the plans for the plane and all of its parts, expected flight performance details and even the maintenance records of the plane, investigators can recreate how the plane was flying before the incident. They can tell if some system was running slow or if something wasn’t getting enough power or even if there’s a large dent on a wing, because the plane wouldn’t fly like it’s supposed to. They know how a plane is supposed to fly given a certain set of conditions because there are hundreds of other planes with the exact same design flying constantly, maintenance is very controlled and everything is designed to be consistent between individual planes. If something in the data recorders doesn’t match expectations they can find it.
The investigators can also hear what the pilots said in reaction to whatever happens, they’re trained to handle a lot of emergencies with a plane, so their reactions can tell investigators what happened a lot of times. Or maybe hear a loud explosion or rattle on the voice recorder to give them a hint of what to investigate.
Finally they can look at the actual crash debris. They map exactly where each piece is found and then try to reassemble the plane with all of the pieces they find. If there’s some fan blades from the engine embedded in the cabin wall but most of the blades are completely missing, then it’s reasonable to suspect that the engine might have been destroyed mid flight. This could be matched with the data log showing that the engine lost power and started throwing errors. They might find that a bolt that holds the tail rudder on has some threads sheared off, or that it’s been stretched, and match that with unresponsive steering pedal inputs or erratic flying behavior to suspect that the rudder could’ve fallen off or lost control.
Investigators will piece all of the clues together to determine the likely cause of an accident. Basically they know how a plane should work given the conditions, and use the recorded data and the debris to work backwards to find out why it didn’t in that case.
Latest Answers