Round the clock, D/FW International Airport employees are scouring the grounds looking for dangerous intruders. Not human terrorists. Those with feathers.
One recent morning, Larry Creel, an airfield operations employee, spots a potential problem, and alerts Cathy Boyles, D/FW’s wildlife biologist.
“We had a multiple bird strike on (runway) 36 right. Six pigeons,” Creel reports.
This bird strike, like most other strikes, caused little or no damage to the plane. The half-dozen pigeons weren’t so lucky, though. The big concern is that the remaining flock will settle near another flight path.
“What we’re in the process of doing is moving one cannon from the north down to the south,” Creel says.
Boyles hops into a vehicle, radios her team, and heads toward runway 36 right. She wants to take a look at removing vegetation that may have attracted the birds.
She’s glad to see the propane cannon that's been deployed -- a noise maker -- has caused the pigeons to move. It’s a cylinder that sits on the ground. When a small amount of propane gas is fed into the tube and ignited, it creates an explosive sound that’s blown out of the barrel’s open end.
“It startles them; makes them feel uncomfortable staying here so they’ll move somewhere else,” Boyles explains.
Coyote and deer, too
Boyles’ job is to keep birds and other wildlife -- the occasional coyote or deer -- away from aircraft.
She knows it’s the feathered fliers, and not the planes, that usually lose out when they crash into each other. But not always.
Seared into the memory of many is what happened to U.S. Airways Flight 1549 on the East Coast five years ago. The jet, with 155 passengers aboard, hit a flock of geese. Pilot Sully Sullenberger radioed that he was ditching the plane in the Hudson River. He recalled that moment in 2009 during an interview on KERA’s Think with host Krys Boyd.
“My first thoughts were human ones of disbelief when we struck the birds," Sullenberger said. "The engines began to roll back and we began to lose thrust. It felt like the bottom fell out of our world. It felt like the forward momentum of the airplane nearly stopped.”
Miraculously, everyone survived. Sullenberger became a national hero.
But the Federal Aviation Administration says wildlife strikes -- mostly birds -- have killed more than 250 people worldwide and destroyed over 229 planes since 1988.
Watching avian radar
At D/FW, Boyles looks at a screen with an image of the sprawling airport that’s the size of Manhattan.
“These are live detections of birds moving on or around the airport according to density," she says as she points to colored markers. “Green means it’s a lighter or smaller bird and red goes to heavier or flocks of birds.”
Boyles is watching avian radar, an experimental tool that allows her to pinpoint the type and number of birds that are gathering.
“If we’re looking at a bird at a certain altitude, what size it might be," she said. "We also get a sense of what direction that bird is moving into so we know if we need to go out and disperse that bird away from traffic.”
The propane cannons are only one of many effective sound launchers. With earplugs in place, Boyles demonstrates a variety of pyrotechnic shells fired from a special handgun. Each has a unique sound aimed at dispersing specific species.
“That’s a screamer,” she says after firing a shell that emits a shrill whining sound. She also has “cracker” and “whistler” shells.
Release the falcon
When there are flocks of birds that don’t respond to sound, Boyles may call in the falconers. She remembers how effective it was to release a falcon at nightfall when thousands of black birds had roosted in the airport’s live oaks.
“The birds have let down their guard by now," she says. "They think they’re there for the night and they’re safe. And you release a predator into their midst and they’re gone.”
Last year, doves led the list of 333 birds that collided with D/FW planes. Boyles stores the carcasses in a 4-by-2 foot freezer in labeled bags.
She sends unidentified birds to the Smithsonian, and voluntarily reports the casualties to the FAA’s Bird Strike Database.
John Weller, the FAA’s national wildlife biologist, says the information coming from more than 2,500 airports is helping the agency pin down the threat.
More than 60 percent of bird strikes happen during the day, he says.
“Most strikes occur during the landing of flight instead of the take-off phases," he says. "The landing phases are quieter. The engines are spooling down and the birds do not detect them as much."
Summer is prime time for strikes
At D/FW, this is high season for bird strikes. The greatest number of strikes last year occurred in July and August as baby birds are learning to fly.
Avian radar will help Boyles identify their favorite gathering spots and remove vegetation that attracts them.
And if that’s not enough to keep them out of the flight path, she always has her arsenal of annoying noise makers -- they're guaranteed to ruffle a few feathers.