The number of birdstrikes reported annually in the U.S. rose from 1,759 in 1990 to 7,666 in 2007, and by Jan. 15, 2009, the statistics finally caught up with US Airways Flight 1549, piloted by the now famous Capt. Chesley “Sully” Sullenberger and first officer Jeffrey Skiles. After a flock of Canada geese flew in the path of their Airbus A320 one minute and 37 seconds into the climb out of New York La Guardia Airport, Sullenberger managed to glide the airplane safety into the Hudson River, saving the lives of all 155 passengers and crew.
The event drew attention not only for the deft piloting skills exhibited by Sullenberger, but the manner in which the airplane suddenly lost most of its engine power. Of course, any pilot knows birdstrikes happen, but they don’t often disable two engines simultaneously. Still, as 13 of the 14 species of birds in North America with mean body masses greater than eight pounds have shown “significant” population increase over the past three decades according to a June 2008 report issued by the FAA’s associate administrator of airports, airplanes face an ever-increasing threat of catastrophic bird strikes.
Perhaps most alarming, according to U.S. Department of Agriculture senior science advisor Richard Dolbeer, 37 percent of strikes occurring with birds weighing more than eight pounds have involved multiple animals. Of the 36 species in North America weighing more than four pounds, at least 24 have increased in number over the past 19 years while only two have declined, and most–33 species–travel in flocks, increasing the chances of dual-engine ingestion.
Embry-Riddle Aeronautical University (Booth No. 1279) this year established the International Center for Aviation and Wildlife Risk mitigation to help support data collection efforts and develop better ways to reduce animal strike occurrences. Professor of aviation environmental science Archie Dickey, who also created and has managed the FAA’s wildlife strike database since 1999, heads the center at the school’s Prescott, Ariz. campus.
“We’ve helped the FAA with its Web site and the database for years, and we felt that maybe we could expand that to some degree so that people would have a place to go for information,” said Dickey. “A lot of the stuff that goes on dealing with wildlife, especially around airports, is often talked about by wildlife biologists among themselves but it never gets to the operations people, it doesn’t get to the pilots, it doesn’t get to the public.”
With education must come funding, however, if anyone hopes to implement all the practices that programs such as Dickey’s recommend. “It’s one thing to point out and say, ‘Hey, you don’t have a wildlife [mitigation program],’ but then is there funding for it?” said Dickey. “That’s always been the problem with many things with the FAA. [It] mandates something but then doesn’t give the airport any money to do it.”
Perhaps most urgently, the FAA needs to update its standards for bird ingestion and airframe damage, said Dickey, simply because big birds such as Canada geese have proliferated so effectively in man-made grazing environments such as parks and golf courses. “I think the standard definitely needs to be revisited,” he said. “I’m not an engineer so I can’t tell you what it needs to go to, but I think it needs to be reassessed.”
Bird ingestion tests and certification apply various sorting criteria, and the weight limit for each class of bird has increased since the FAA introduced the certification standards. The FAA first adopted specific bird ingestion requirements into FAR Part 33 (engine certification) in 1974. The standards contained requirements for small and medium flocking birds, three ounces and one-and-a-half pounds in weight, respectively, and large single birds weighing four pounds. The flocking bird standards required a five-minute run-on with no throttle movements and a thrust loss of no greater than 25 percent. The number of birds required for the flocking tests depended on engine size. The large single-bird requirement did not require run-on, but rather a so-called safe shutdown of the engine, without uncontained fan blade failure or fires, among other criteria.
In 2000, the rules incorporated a change in the test weight of a medium-size bird to a mix of one-and-a-half and two-and-a-half pounds, depending on engine size. The new rules also required that larger engines tolerate the ingestion of more birds. In the new regulations, the weight of large single birds rose from four pounds to four, six or eight pounds, again depending on engine size. Meanwhile, the run-on requirement for flocking birds increased from five minutes with a locked throttle to 20 minutes with throttle movements that would simulate a return to the departure airfield.
Some seven years later the agency introduced large flocking birds to its list of categories and began testing ingestion of single four, four-and-a-half and five-and-a-half-pound birds, depending on engine size. While the 20-minute engine run-on allowance mirrors that for medium-size birds, the rules for large flocking birds allow for a thrust loss of 50 percent.
According to FAA engine and propeller directorate standards staff manager Robert Ganley, the agency continues to base the standards by which it certifies engines on data from 2000.
“Certainly this event [Flight 1549] is telling us something that I think we need to take a look at,” said Ganley. Still, he said, “it is not reasonable to assume that we can design an engine that can withstand birds of any size under any condition.” Investigators believe one of the CFM56 engines on the A320 operating as US Airways Flight 1549 ingested two eight-pound birds and the other ingested at least one eight-pound bird. At the time they received their certification, in the 1990s, the engines underwent ingestion tests with a four-pound bird. Under today’s certification standards, they would have had to ingest a six-pound bird, said Ganley.
“This event far exceeded our certification requirements,” he added. “The performance of the engine exceeded our certification requirements for the ingestion of a large bird. The requirements for ingestion of a large bird are a safe shutdown.”
Over the past 19 years the FAA National Wildlife Strike Database shows nearly 10,000 incidents of one engine struck, 505 cases of two engines struck, 3,239 cases where one engine sustained damage, 108 in which both engines suffered damage and 310 incidents that resulted in a shutdown of one or both engines. The vast majority of strikes occur at low altitude, at less than 500 feet agl, on or near airport grounds.
Dolbeer testified at an NTSB hearing this past June that aircraft collisions with wildlife cost the world’s civil aviation industry $1.2 billion annually, with U.S. civil aviation accounting for more than half of that amount. Based on FAA statistics, some 98 percent of the collisions involve birds. Since 1988 wildlife strikes have killed 229 people worldwide and destroyed more than 200 airplanes, according to the FAA.
Researchers have found that birds are less likely to avoid today’s quieter, jet-powered airplanes rather than the propeller- driven airplanes of decades past. Meanwhile, development has destroyed bird habitats, making airports often the most attractive environment for the animals to roost and feed.
Although the FAA began collecting wildlife strike data in 1965, it never performed more than a cursory analysis until 1995, when, through an interagency agreement with the USDA Wildlife Services, it launched a project to obtain more objective estimates of the problem for civil aviation. Statistics collected from 1990 to 2007 showed a quadrupling of strike reports. Still, only about 20 percent of all birdstrikes ever get reported, according to FAA estimates.
In 1999, the NTSB issued Safety Recommendation A-99-091, which proposed mandating that operators report birdstrikes. Although the FARs urge pilots to report bird or other wildlife strikes using FAA Form 5200-7, 10 years later reporting them remains voluntary. “Personally I think that it should be [mandatory],” Dickey told NBAA Convention News. “It’s hard to study the problem unless you know the degree of the problem.”
Maybe more importantly, only 26 percent of the birdstrike reports submitted since 1990 identified the species. “All of these birds behave differently,” said Dolbeer. “The management actions we need to mitigate these strikes vary depending on species. Most of them are protected by the Migratory Bird Treaty Act.”
Dolbeer also pointed to an uneven reporting record among airports. “It’s in an airport’s best interest that they do report on strikes because they need that information if they’re going to develop an effective management plan,” he said.
The FAA requires airports to conduct a wildlife hazard assessment by a qualified wildlife biologist if they experience a “triggering” event, such as multiple strikes of a particular aircraft, “substantial” damage caused by a wildlife strike or engine ingestion of wildlife. Part 139 also requires airports where there exists wildlife of a size, or in numbers, capable of causing a triggering event to conduct an assessment. The FAA’s Office of Safety and Standards on June 11 released a list of 96 U.S. airports that hadn’t performed an assessment despite experiencing at least one triggering event.
“We found out after the Hudson River situation, and after the FAA database became public [on April 24, after the FAA originally argued that public disclosure would discourage reporting and jeopardize safety], that people were calling us and saying, ‘Which is the worst airport?’” recalled Dickey. “I said, ‘You’re missing the point.’ Really, the airports that show the most strike reports are actually doing the best job. They’re the ones that are reporting everything, so it could be put into a database so it can be studied, so they can figure out how to handle it.”
Based on the available data, researchers estimate that waterfowl (31 percent), gulls (26 percent) and raptors (18 percent) account for 75 percent of the reported birdstrikes causing damage to U.S. civil aircraft. Most notoriously, the North American non-migratory Canada goose population increased from about one million birds in 1990 to more than 3.9 million last year.
Dolbeer explained that state wildlife agencies in the 1950s introduced the giant subspecies of non-migratory Canada geese, which nested in the northern Great Plains, into places such as New York, Virginia and Ohio to provide a ready supply of targets for hunters.
“The migratory birds continue to migrate and they nest up in Canada, but they’ve altered their migration habits because of the resident geese; instead of migrating far south like they used to–maybe down into the Carolinas or Tennessee Valley–a lot of those will stop in New York State and Pennsylvania and Ohio and hang out with the resident geese during the winter months,” said Dolbeer. “So we’ve really messed up the natural goose population in the U.S. because of these introductions of really an exotic species.”
The forced water landing of US Airways Flight 1549 prompted the USDA Wildlife Services to kill some 2,000 of the birds living in public parks and other open spaces near New York La Guardia and JFK Airports this past summer. Other measures proposed included a ban on feeding animals within five miles of La Guardia Airport and filling a depression that attracts water birds on Rikers Island, which sits in the East River just north of the airport.
La Guardia has also studied planting species of grass that, to some degree, appear less attractive to the geese. But simply cutting grass to between six and 12 inches in height also deters that particular species, according to Dickey, because the birds like environments where they can watch for predators while they feed.
“You’re never going to be able to stop that flock of geese or starlings that are moving from point A to point B and just happen to come across your path,” said Dickey. “But if you’ve got water catchments...and many medium-sized airports actually still have crops growing on their grounds. So between water retention, food supply, open beams and other material that provide great shelters…all those kinds of things need to be reduced as much as possible.”
Foiling Future Flocks
Manipulation of habitat stands as the foundation of the work performed by the USDA’s Airport Wildlife Hazards Program, led by national coordinator Michael Begier. Methods used in an airport employee training program coordinated by the USDA’s Wildlife Services range from propane cannons and other noise-making devices such as pyrotechnics to hanging certain bird species in effigy–a practice proven to repel other birds. Airports around the world also have found success using border collies and falconry to disburse wildlife, said Begier. Other options that have showed promise include hand-held laser devices and small mobile radar, which the military and NASA already use to some effect.
Dolbeer recommended the industry place more emphasis on systems such as pulsating landing lights that shine at wavelength frequencies and pulse rates not necessarily visible to the human eye, but detectable by birds. “We know that birds can see in the ultraviolet range beyond where humans can see,” he noted. “Birds are not suicidal. I’ve watched this many times; they try to avoid aircraft; they just don’t see them soon enough or recognize them as a threat.”
According to Dickey, such efforts have shown limited promise of success, however, due in large part to the fact that different groups of birds respond to different visual cues. “It’s kind of like with humans…you see certain things, some people ignore them and other people really react to them, and that goes for both sound and vision,” he said. “Birds hear in the same range we hear, and visually, depending on the species, they can see a little bit out of the infrared and see some different portions of the spectrum, but it varies so much between species of birds it’s hard to put something on an airplane that’s going to work… The biggest problem with any kind of cue like that is that birds get used to it.”