A Delta flight en route to Tennessee from New York made an emergency landing Thursday evening when a bird crashed into the windshield, causing it to crack.

Delta Flight 4071, which originated from LaGuardia Airport, was headed to Nashville, but the incident forced it to make an emergency landing at West Virginia's Yeager Airport.

The exact moment of the impact is unclear, but airport spokesman Mike Plante reported that the Delta Jet CRJ 900 pilot told air traffic controllers they were going to make an emergency landing at 4:50 p.m., after the bird struck the plane.

He also added, "Windshields are engineered to withstand something like this and, uh, so again, in this case, the windshield fractured but did not break."

Plante's testimony raises two important questions: how often do bird strikes happen and how dangerous are they?

The fact that windshields are designed to withstand the impact of a bird crashing into it suggests that bird strikes happen frequently enough for engineers to design windshields accordingly.

As for how dangerous they are, Patrick Smith, author of "Cockpit Confidential," said strikes are occasionally dangerous. He referenced an incident in 2009 when US Airways flight 1549 was forced to make an emergency landing in the Hudson River after it collided with a flock of Canada geese, which caused the plane to lose thrust in both engines just moments after take off.

In that case, the issue wasn't the windshield, but the turbofans, which he says are quite resilient, but the blades inside can bend or fracture when colliding with foreign objects, which eventually cause power loss.

So what is being done to combat this avian menace? A team of Dutch researchers designed a robotic bird, called the Robird, which can be piloted from the ground to scare away birds that fly too close to a plane's flight path. However, this is only limited to areas closer to airports and unlikely to help planes mid-flight.

In the meantime, the Delta plane landed without incident and all 57 people onboard were unharmed during the encounter. Delta sent in a new plane to bring passengers to Nashville, which landed safely later that evening, according to a statement issued Friday morning.