Happily, pilots don't have to reckon with dense fog or driving rain this afternoon at San Francisco International Airport. Yet just now another natural hazard dots the sky. At 1 p.m., the space above a runway is partially occupied by feathers, beaks and noisy caws. Two crows have elected to turn this prime real estate into their afternoon swooping, diving and careening playground.
Alexis Esguerra, 37, an SFO airfield safety officer, is trying to persuade the real birds to move out of the way of the big metal ones. Usually the simple presence of his Ford F150, in which he cruises around the airfield, frightens away the birds that hover around SFO, which stretches into San Francisco Bay, the largest estuary on the West Coast. By now the birds have learned the yellow pickup truck spells trouble for them.
The crows, though, aren't budging, so Esguerra pulls a 12-gauge Remington shotgun out of his truck. He loads it with a "cracker shell," which when fired speeds into the sky like a Fourth of July firework and explodes with a bang and a puff of smoke. As he takes out the weapon, Esguerra relays word to the air traffic control tower. A man with a shotgun in the middle of a runway? Not a surprise any pilot or controller wants to experience.
But before Esguerra can get a shot off, the crows have taken the hint and flown away. "Of all my supposed enemies out here, crows are my worst nightmare, because of their intelligence," says Esguerra, stowing his weapon. "They're stubborn. The moment we leave, they're going to come right back. They're probably keeping an eye on us right now." Trim, energetic and efficient, Esguerra clearly takes his feathery work seriously, yet also finds humor in it. Every day, he and his fellow officers try to keep the birds off the runways and taxiways, and out of the airspace where planes take off and land, sometimes every two minutes. In 2008, SFO recorded 32 bird strikes.
Prior to U.S. Airways Flight 1549, which last month made a remarkable emergency landing on the Hudson River after, reportedly, a flock of Canada geese crashed into and disabled its engines, few people ever thought about the clash between birds and planes. Esguerra, who has been on the job five years, grins as he explains how many times the press asked about bird control at SFO before Flight 1549. "Zero," he says.
But in fact it is war without end between Homo sapiens and birds at airports all over the country. And guess who's winning? "Bird strikes are rarely damaging to aircraft, but it's always damaging to the bird," says Russell DeFusco, a retired Air Force officer who does consulting on preventing bird strikes for civilian and military flights.
Even so, some plane and bird encounters have been fatal to humans. Calbraith Rodgers, the first person to fly across the continental United States, became the first person to die from a bird strike, in April 1912, when his Wright Pusher struck a gull, causing the plane to crash into the surf at Long Beach, Calif., where Rodgers was pinned under the wreckage and drowned. (A fascinating historical timeline of bird strikes can be found here.)
In more recent times, since 1988, over 218 people have been killed worldwide due to bird strikes. During those years, the problem has cost the civil aviation industry in the United States about $620 million a year. It's more common, though, for a plane involved in a serious bird strike to be forced to shut down an engine and return to ground. Just days after my visit to the San Francisco airport, a United Airlines flight out of Denver bound for SFO had to return to Denver after a bird struck one of its engines shortly after takeoff.
Bird strikes appear to be on the rise, but how much is hotly disputed, due to spotty data. Between 1990 and 2007, the number of wildlife strikes reported to the Federal Aviation Administration quadrupled, rising from 1,759 to 7,666. Birds accounted for more than 98 percent of the strikes, with mammals and reptiles making up the rest.
The FAA attributes the dramatic rise to better reporting of strikes -- it's voluntary for pilots and airline personnel to report the strikes -- and to an increase in air traffic. Commercial jet engines must be designed to withstand a single four-pound bird being sucked into them. Pelicans or geese, which can weigh up to 10 pounds, are big trouble. "There's no engine in the commercial fleet in the United States that is required to withstand a Canada geese strike," says DeFusco, who would like to see the bird-strike standards for commercial engines improved.
The problem is also an accident of history: Many of today's modern airports are built on or near bodies of water, natural congregating sites for countless birds. Those include JFK in New York and Logan in Boston. "If we knew what we do today, we would never build an SFO or a JFK," says DeFusco. Given the danger and costs of bird strikes, he says, airport developers would avoid wetlands and populous bird habitats. "Back in the early 20th century, these areas were undesirable for industrial or urban development, so the marginal land was used for airports or landfills that nobody wanted in the middle of the city," he says.
Literally millions of birds live, winter or drop by San Francisco Bay on their biannual migrations. At the airport, starlings roost on the airport's enormous antenna. Just offshore, ducks float and dip in marshy areas. Pesky gulls like to catch crabs or clams offshore and drop them down on the runways to crack them open. The airport's frequent antagonists include Canada geese, ducks, gulls, starlings, sandpipers, herons, cormorants, great egrets, hawks and owls.
Esguerra has physically dragged a brown pelican, a protected species, off the runway, before having the local humane society come by to pick it up. Feral cats and stray dogs make appearances on the taxiway. In local airport lore, a seal once got out of the water, lumbered across the runways and made it all the way to baggage claim before being intercepted by airport safety officers.
The airport's first line of bird defense is modifying the airfield to make it unattractive to them. You might think that the deafening roar of planes taking off would scare the birds away. It's so loud here that Esguerra wears custom-designed ear plugs on the job. But over time the birds become habituated to the racket.
Despite the noise, airports can be appealing to some birds. "This big, broad flat space, which for the most part doesn't have a lot of buildings, and isn't very populated with people and dogs, can actually attract some bird species, especially in a place like San Francisco Bay," says Michael Lynes, conservation director for Golden Gate Audubon Society.
One great bird attractor at airports is standing water. One natural drainage ditch at SFO has been filled in with thousands of plastic balls, which prevent birds from landing on it and still allow the ditch to fill with water during rains. Paving ditches with concrete to prevent the growth of foliage also helps birds think twice about trying to nest or look for food.
Unfortunately, the grass lawns in between runways is also appealing to birds. Grass can mean food like worms, moles or rabbits. Some birds even eat grass. "Canada geese will actually just graze on grass like a horse or a cow does," says Greg Butcher, director of bird conversation at the National Audubon Society.
But SFO doesn't pave over the green lawns, because they absorb rainwater and help keep it off the runways. One of SFO's solutions: Make the birds think that they're about to be eaten alive. "These are our equivalent of scarecrows," says Esguerra, pointing to a solar-powered device armed with speakers embedded in one of the lawns. "They're called Phoenix wailers. It's an electronic noise-making device." The device periodically emits the predatory call of a red-tailed hawk, along with other alarming sounds, such as a helicopter followed by machine-gun fire.
When the habitat modifications and auditory scarecrows fail, it's up to Esguerra and his fellows on wildlife detail -- SFO has one airfield safety officer assigned to wildlife at all times -- to get the birds to move it. While patrolling the grounds, Esguerra will receive reports of sightings called in by air traffic controllers, pilots or airport employees.
For birds that don't flee the yellow truck, Esguerra turns on a blaring siren, flashes strobe lights and guns the engine while driving toward the birds. In about 80 percent of cases, as with a flock of starlings today, that tactic sends birds flying. Of course, the trick is not to scare the birds into the path of the planes. "There is a little bit of chess mentality going on," Esguerra says. "Well, maybe more like checkers mentality."
When that fails, there are the pyrotechnic devices, like the cracker shell, "whistler" and "bird bomb," which are fired from guns. As a last resort, an airfield safety officer can become Dirty Bird Harry. Once, Esguerra was forced to shoot a Canada goose. "He, unfortunately, decided to squat on the runway and wouldn't leave," he says.
Esguerra, who in his free time is an amateur pilot, can see the conflict from both sides of the cockpit. "I kind of empathize with the birds," he says. "They're just doing what is natural. At the same time, as a pilot, I can appreciate the whole danger." Yet he hopes the publicity surrounding Flight 1549 doesn't cause the public to view birds as killers in the sky. "Right now the rap on birds is bad because everyone knows about this new danger," he says. But at SFO, "I wouldn't say that bird strikes are a major hazard as long as we continue our programs."