I received a text message today from my brother, waiting to board his flight home:
Flight delayed 3-4 hours because it hit a f***ing bird.
I didn’t reply why a banal “OMG,” only because I had done the math. Hitting a bird in flight is a serious situation. Why? Because the smack of an unfortunate fowl at the speed of your average airliner has the same force as hitting a brick wall at 100km/hr in your car.
Imagine the unfortunate scene of a bird hitting an airplane in flight.
Let’s assume a 1 pound (.45 kilogram) bird striking my brother’s airplane head on at 600 miles per hour (965 kph). Because forces don’t act instantaneously but over some time period, we’ll also assume the grisly spectacle takes around a millisecond.
From the equation in the diagram, you can see that the average impact force from the doomed bird is equal to its mass multiplied by its change in velocity–basically how quickly the bird decelerates when hitting the fuselage.
Inserting our numbers, you get an impact force of more than 12 tons or 24,200 pounds (107,650 N).
The numbers that we have assumed here can change, but the idea is the same: even a light object moving at serious speeds can produce a heck of a lot of force.
You can imagine what this kind of impact could do to a plane. If the poor bird strikes an engine, it can crash the whole plane. And hitting a flock of birds is even worse. Capt. Chesley B. “Sully” Sullenberger, who landed US Airways Flight 1549 in the Hudson river, had to make the desperate descent because he hit a flock of geese during the flight’s initial climb.
And it’s not a 1-in-a-million kind of hit either. The Federal Aviation Administration estimates bird strikes cost US aviation 400 million dollars annually and has resulted in over 200 worldwide deaths since 1988. In 2003 alone, 5,900 bird strikes were reported by civil airliners.
The whole thing is a gruesome consequence of airplane travel, but sometimes real-world physics is messy.
When I told my brother about the math, be no longer seemed mad. All I got was:
When communicating science, “jeez!” is one of my favorite things to hear.
[Image via HyperPhysics]