US Airways Flight 1549 introduced much of the non-aviation world to the hazards that birds pose to airplanes. But data gathered since the January 2009 day that the US Airways A320 lost power in both engines after plowing through a flock of Canada geese and was piloted safely down in New York’s Hudson River suggest that the accident boosted wildlife mitigation’s visibility within the industry as well.

Last year, the FAA’s wildlife strike database collected 11,315 strike reports—96% of them involving birds. In 2008, FAA collected 7,651 strike reports. While bird populations are climbing, the difference between the pre-2009 figures and today’s numbers is explained by an increase in something else: awareness.

Given that the FAA does not mandate strike reporting and requires airports to conduct wildlife assessments only if certain hazards are detected (although most have or plan to do them anyway), increased awareness is a good thing. Add in that the vast majority of airport wildlife mitigation is done with low-tech tactics that seem more at home at a backyard fireworks display than a modern airport, and the importance of grassroots buy-in becomes even clearer.

The FAA’s approach to mitigating wildlife strike risks includes regularly updated guidance, blanketing industry with awareness posters, making strike reports easier to file and working closely with wildlife experts to make airports less attractive to birds and anything they eat. The tactics seem to be working, especially at commercial airports. 

Despite the absence of mandates or magic-bullet technology, the number of so-called damaging strikes at commercial airports totaled only 241 last year, a 37% decline from the peak of 380 in 2000. The decline in damaging strikes has been most pronounced for commercial aircraft on the airfield or below 500 ft. above ground level (AGL), FAA data show. 

Factoring in general aviation (GA) airports, damaging strikes totaled 601 last year, down from 2000’s peak of 764. The number of damaging strikes involving GA aircraft has not fallen—one reason that the FAA has stepped up outreach to GA airports in the last several years.

More telling evidence of the FAA’s success at commercial airports is the damaging strike rate, which factors in numbers of operations. Last year’s rate was 0.98 damaging strikes per 100,000 aircraft movements, down 19% year-over-year—the lowest rate since 1996.

Rates of damaging strikes are a better risk indicator than calculations of total strikes for two reasons: Strikes that cause damage almost always get reported, and—by definition—affect aircraft operations. But the more widely used risk-calculation metric is strikes per 100,000 (or sometimes 10,000) operations. Judging by this measure, bird strikes are a runaway epidemic—2013’s rate of 20.45 per 100,000 movements where an operator was identified is the third-highest rate ever, and is nearly four times 1990’s rate.

But the combination of non-mandatory reporting and steadily increasing awareness with occasional spikes—year-over-year reports jumped 25% in 2009 after US Airways Flight 1549—means that assessing risk based on strike quantities is almost meaningless. Last year, strikes were reported at a record 649 airports—379 commercial facilities and 270 general aviation airfields. In 1990, the first year in FAA’s database, 331 airports reported strikes. The difference does not reflect new migratory patterns, but rather suggests a heightened awareness that boosts reports of harmless, but still potentially telling in aggregate, strikes.

While it is impossible to make a definitive link between the increase in total reports and the decrease in serious ones, industry stakeholders believe they understand the connection. More reports yield more data, which wildlife experts and airport personnel use to help understand factors like bird migration patterns. Once such variables are understood, targeted strategies can be developed to mitigate risk, which cuts down on serious incidents.

“We’re showing a decline in damaging strikes due to the management actions at individual airports,” says Richard Dolbeer, a wildlife mitigation expert and former U.S. Department of Agriculture (USDA) biologist.

Documented bird strikes are nearly as old as powered flight itself, even if their risks have not always been apparent. The first recorded strike, in September 1905, happened as Orville Wright was chasing a flock of birds over an Ohio cornfield. While US Airways 1549 gets credit for bringing unprecedented awareness to wildlife strikes, the Oct. 4, 1960, accident involving Eastern Airlines Flight 375 departing Boston’s Logan International Airport is what first illuminated bird strikes as a grave danger to aircraft. The Eastern Lockheed Electra struck a flock of European starlings shortly after takeoff, ingesting birds into three of its four engines. The aircraft yawed left, stalled, and went down in Boston Harbor, killing 62 of 72 onboard.

The Civil Aeronautics Board concluded that the “unique and critical sequence of loss and recovery of engine power” following the strike caused the accident, and urged the FAA to improve engine tolerances to bird ingestion. 

The report did not discuss improving wildlife mitigation tactics. Despite this, airports responded, kicking off decades of largely voluntary efforts that laid the groundwork supporting today’s wildlife mitigation strategies. New York’s John F. Kennedy International Airport conducted its first wildlife study in 1965, and pioneered the airport bird strike database a decade later—part of a series of efforts that gained more momentum after a 1975 accident caused when an Overseas National Airways DC-10 hit a flock of gulls on its takeoff roll.

In 1976, Seattle-Tacoma International became the first airport to add a full-time wildlife biologist. Dennis Bulman was brought on to combat rodents, but birds soon became his primary focus.

By the 1980s, aviation safety and wildlife mitigation experts recognized that harnessing the power of data was key to reducing risk. FAA began collecting strike reports in 1965, but for years used them only during cursory trend reviews. In 1995, the FAA and USDA Wildlife Services division teamed up to analyze both new strike reports and those dating back to 1990. Among its goals: Develop a consistent, deep data set to be used to help guide national policy and identify areas of risk.

The effort became the FAA’s Wildlife Strike Database, which now has 142,600 reports dating back to 1990. Online reporting was added in 2001; 83% of last year’s reports were filed online.

Despite the progress in reporting, experts estimate that 60% of all civil strikes go unreported. While nearly all are believed to be non-damaging strikes or ones that involve very small birds, the opportunity to bolster data sets and boost awareness of factors like migration patterns has some urging the FAA to mandate strike reporting. 

The mandate debate is not new, and an informal survey at Birdstrike Committee U.S.A.’s recent annual meeting showed that many stakeholders are convinced the current approach is sufficient. Mandating reports would introduce myriad challenges such as what information should be required to ensure the best data set, and who should be required to file reports. While most reports come from airport staff who find carcasses on the ground, many come from pilots and maintenance technicians doing routine work on engines.

Enforcement also is an issue. Determining whether a reporting system is in place is one thing. Proving a known strike was not reported is more of a challenge. But some believe following the lead of agencies like the U.K. Civil Aviation Authority, which mandated reporting in 2003, is the FAA’s only prudent step.

“If reporting is not mandatory, it sends the message that it is not important,” says Ron Merritt, president of avian radar manufacturer Detect.

The debate over whether to mandate strike reporting has been deepened by a related question: should the FAA revamp the way strike data are used to calculate basic risk metrics? 

Convinced that the long-standing strikes-per-100,000-operations and damaging-strike metrics leave room for improvement, wildlife mitigation experts and FAA have pitched a new basic standard for calculating bird-strike risk at airports. The new approach would calculate an airport’s average bird mass per strike. This, proponents say, would be a better measure of risk for dangerous strikes, going beyond the current damaging strike rate metric by removing the relationship of a strike’s outcome from its potential risk.

Calculating mass-per-strike is easier than it sounds, so long as some part of the bird is recovered. Bird strike reporting usually involves sending DNA samples to the Smithsonian Institution’s Feather Identification Lab, which identifies strike remains for the FAA, U.S. Air Force and Navy. The new standard would rely on species weights listed in a globally accepted Smithsonian handbook. It also would factor in variables such as the number of birds involved—a strike of 20 birds in a flock would be counted as 20 strikes, with masses calculated accordingly.

The idea of a new standard was introduced to kick-start a public discussion, says John Weller, national wildlife biologist in the FAA’s Office of Airport Safety and Standards. If the standard is adopted, it could be published in an FAA advisor circular, continuing a series of recent guidance updates aimed at improving wildlife mitigation efforts.

When Chesley Sullenberger landed Flight 1549 on the Hudson, the FAA was in the midst of revamping wildlife mitigation guidance. Airport construction requirements that unintentionally encouraged wildlife to gather—such as gradual slopes on stormwater ponds and using on-airport land to offset wildlife areas wiped out through building—were gradually changed. Since 2012, the agency has published new guidance on reporting wildlife strikes, minimizing wildlife attractants at or near airports, and developing wildlife hazard management plans.

The agency also was pushing airports to conduct voluntary wildlife assessments. Flight 1549 put a charge into those efforts, says Weller, who joined the agency weeks after Flight 1549 went down.

When Weller started at FAA, about 50% of the U.S.’s 570 commercial service airports had completed a wildlife assessment. By the end of 2015, all Part 139 airports will either have them or be working toward them, he says. This despite the fact that the FAA in 2012 put the brakes on a proposed rule that would have mandated both assessments and hazard management plans for all commercial airports.

Going through an assessment does more than check a box. Each completed study helps an airport define specific risks and sets the parameters for crafting a plan to address them.

“Typically, wildlife has been considered an act of God or nature,” Weller says. “People understand it is a threat like so many other threats. [But] people who say you can’t do anything about it are not understanding wildlife.”

As airports become more aware of what they need to do to reduce strike risks, they are better positioned to leverage the USDA’s expertise. The agency has been working on airport issues since the 1950s, and partners with the FAA to manage data and support wildlife mitigation efforts. USDA has full-time biologists at about 140 civil and military airports, says Mike Begier, the department’s Airport Wildlife Hazards Program national coordinator. The agency contracts with hundreds of other airports to conduct assessments, create plans and carry out mitigation efforts such as trapping and lethal culling.

While data show that on-airport efforts are yielding desired results, the Flight 1549 accident sequence spotlighted what many see as the next major challenge in airport wildlife mitigation: addressing threats beyond the airport perimeter. Flight 1549 encountered the flock of Canada geese about 8.5 mi. from LaGuardia Airport—well beyond the area that the airport’s wildlife plan can address directly. 

While strikes above 500-ft. AGL account for only 29% of the total number of reports in the FAA database, they make up 43% of the damaging incidents. After Flight 1549, New York City officials responded with a plan that targeted geese populations on city-owned land. Wildlife mitigation experts say similar, proactive approaches need to take place elsewhere.

“Damaging strikes are showing an increase outside [the airport] environment,” FAA’s Weller says. “Now is the time to do something about that. Airports have to put on sales hats and create partnerships with their neighbors.”

While active hazard management is the only way to eliminate threats, industry is developing technology that would help detect and avoid them. Motivated by a 2010 National Transportation Safety Board recommendation, USDA is advancing research into whether aircraft lights can be modified to help keep birds away—efforts that could eventually augment existing certification standards (see table) that focus on what happens after a bird hits an aircraft.

Another example is avian radar. In 2001 the FAA began working on a system to detect birds at and around airports. In 2006, the focus shifted to commercially available, portable radar. In 2010, FAA-published guidance included a performance specification airports can use to purchase the systems, and—working with USDA, suppliers and academia—the FAA continues to evaluate the technology’s effectiveness. 

Additional research is examining “the feasibility and practicality” of making avian radar available to pilots and air traffic controllers. 

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Certification Standards for Bird Impacts for Air Transport Aircraft

Airframe: EASA CS-25; FAA Part 25     Engine: EASA CS-E; FAA Part 33

Airframe (EASA/FAA)

• Airframe must be capable of continued safe flight and landing after hitting a 4-lb. bird at either cruise speed at sea level, or 85% of cruise speed at 8,000-ft. altitude, whichever is the most critical.

• Windshield must be capable of absorbing the impact of a 4-lb. bird at cruise speed at sea level without the bird penetrating the windshield or splintering the inner ply.

• Pitot tubes must be far enough apart to prevent a single bird from breaking both.

(FAA only)

• Aircraft must be capable of continued safe flight after the empennage structure is hit by an 8-lb. bird at cruise speed at sea level.

Engine (EASA/FAA)

At typical initial climb speed and takeoff thrust:

• Must be able to ingest a single bird weighing 4-8 lb. (dependent on engine inlet area) without catching fire, suffering an uncontained failure, or becoming impossible to shut down. Must maintain at least 50% thrust for 14 min. after ingestion. Requirements must be met without thrust level movement for at least 15 sec. after ingestion.

• Must be able to ingest a single bird weighing as much as 3 lb. without losing more than 25% thrust. Must operate after the impact for at least 5 min. without hazardous conditions.

• Must be able to simultaneously ingest up to seven medium-sized birds of various sizes (0.77–2.5 lb.), with number and size depending on engine inlet area, and continue generating “usable but slowly decreasing” minimum thrust for 20 min. after ingestion.

• Must be able to simultaneously ingest up to 16 small birds (each weighing approximately 1.9 lb.), with number of birds depending on engine inlet area, and continue generating “usable but slowly decreasing” minimum thrust for 20 min. after ingestion.

Small Aircraft: EASA CS-23, FAA Part 23

• Windshield integrity: Impact with a single bird weighing 2 lb. at maximum approach flap speed must leave at least one pane intact with sufficient forward vision to allow for continued safe flight.

Large Helicopter: FAA Part 29

• Must have a structure that will ensure continued safe flight and landing after impact with a single bird weighing up to 2.2 lb. at the lesser of never-exceed speed (Vne) or maximum speed in level flight (Vh) at 8,000-ft. altitude.





A version of this article appears in the September 1 issue of Aviation Week & Space Technology.