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Bird Strikes On Aircrafts
What Really Happens When A Bird Hits An
Airplane?
Ashish
Bird strikes can sometimes result in loss of thrust in the
engine(s) or the cracking of the surface of the canopy or windshield.
These cracks can sometimes disrupt the air pressure inside
the cabin and result in altitude loss or other flight-related problems.
Human beings are constantly threatened by a number of potential
hazards; and the more we invent, the more we become vulnerable to the failures
of our inventions.
Presently, the number of threats that concern us are so great in
number that it is foolish to even try to make a complete list.
Let’s narrow this down a bit more and talk about the threats of
flying through the air in a giant metal-and-fiber container or, in other
words, an airplane.
The threat: bird strikes!
What’s a Bird Strike?
The event of an airborne animal (usually a bird or a bat) hitting an
airplane in flight is referred to as a bird strike.
It is known by a few other names as well, like a bird hit, bird
ingestion or BASH (for Bird Aircraft Strike Hazard).
Bird strikes also happen to other man-made objects on land, such as
cars, power lines and wind turbines, which usually result in death for the
birds.
The first ever case of a bird strike was reported by
Orville Wright (one of the Wright brothers who are credited with inventing and
flying the world’s first successful airplane) in 1905- that’s 114 years ago
(from the current year – 2019)!
But interestingly, the strike wasn’t totally accidental.
Orville was flying circles near a cornfield in Ohio; he had apparently
been chasing flocks of birds before he hit one. The dead bird lay on the wing
of his airplane until he made a sharp turn to dump it off.
Although bird strikes pose a sizable threat to flight safety, the
number of major accidents caused due to bird strikes are quite low.
The majority of bird
strikes do little damage to the affected airplane, but these collisions are
almost always fatal to the birds involved in the accident.
The Most Vulnerable Phase of Flight
Although it’s true that there is no way you can be completely sure of
avoiding a bird strike (unless you are flying in a world where there are no
aerial animals, which currently is unknown).
Bird strikes usually occur when an airplane is flying at low
altitudes.
Therefore, the most favorable conditions for a bird strike are during
take-offs or landings (or other related phases) of airplanes.
The reason for this is obvious; most birds fly at low altitudes, to
there is a greater risk of hitting an airborne machine.
However,
this doesn’t mean that there are no birds flying higher than “normal”
altitudes; in fact, bird strikes have also been reported at higher altitudes of
around 6000 meters (20,000 feet) to 9000 m (30,000 feet).
The world
record for a bird strike at the highest altitude ever is a staggering 11,300
meters (that’s 11.3 kilometers) above the ground!
What Happens During a Bird Strike?
Birds usually collide with any of the forward-facing edges of an
airplane, which include the wings, nose cone, and the most common site – the
jet engine.
There have been cases of birds hitting the windshield or canopy of
airbuses and fighter jets, which can (sometimes) result in the cracking of the
surface of the canopy or windshield.
These cracks can sometimes disrupt the air pressure inside the cabin
and result in altitude loss or other flight-related problems.
The severity of the damage done by the bird strike depends on a few
factors, including speed difference, direction of impact, and the weight and
size of the bird.
To put it in perspective, consider a 5-kilogram bird hitting an
airplane at a relative velocity of 275 km/h.
Can you figure out how much of an impact this translates into?
That impact is equivalent to the energy of a 100-kg bag being dropped
from a height of 15 meters!
Imagine what it would feel like to be hit by a sac weighing 100 kg
from that height. Go on, take a few seconds and imagine it for yourself. Not
too pleasant!
The most
dangerous conditions arise when a bird hits the turbine and gets caught in the
engine; this event is referred to as a jet engine ingestion (since the bird is
‘ingested’ by the engine).
After being ‘stuck’ in the engine, the bird can cause a disruption in
the rotatory motion of the fan blades, resulting in a partial or complete
failure of that engine.
Now, what can a sudden failure of one of the engines do to an
airplane, you may ask? Let’s not even talk about it.
Flocks of birds are even more dangerous, as they can have a much
nastier impact collectively.
The Miracle on the Hudson
There have been many cases of bird strike incidents, but the one that
got a lot of attention was the case of US Airways Flight 1549.
Back on January 15, 2009, an airplane (Airbus 320) made a miraculous
unpowered landing in the Hudson River after being hit by a flock of birds
shortly after taking off from LaGuardia Airport in New York City.
Quite incredibly, not a single casualty was reported. There is no
surprise why this event is known as the “Miracle on the Hudson”.
Although no lives were lost, this event did underline the catastrophic
failure that bird strikes can actually cause to an airborne machine, even one
as huge as an Airbus!
Ashish is a
Science graduate (Bachelor of Science) from Punjabi University (India). He
spends a lot of time watching movies, and an awful lot more time discussing
them. He likes Harry Potter and the Avengers, and obsesses over how thoroughly
Science dictates every aspect of life… in this universe, at least.
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Damaged
windshield due to a bird strike
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| The downed Airbus 1549 |
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The cracked
canopy of a F-16 after a bird strike
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