Bird Strikes Pose Growing Threat
Yet wildlife strikes–of which more than 97 percent have been birds–on civil aircraft in the U.S. currently occur on average about 26 times per day or just over one every hour, according to the 2012 joint FAA/Dept of Agriculture report, Wildlife strikes to civil aircraft in the United States, 1990-2010. The total cost to the aviation community of strikes between 1990 and 2010, including damage repairs and replacement parts, out-of-service time and other costs, added up to close to half a billion dollars.
Of course, few strikes cause an aircraft to crash, although bird and wildlife strikes worldwide have killed more than 229 people and destroyed more than 210 aircraft since 1988. However, severe strikes often require immediate landings, as a FedEx MD-11 at max gross was forced to perform in March after hitting 15 to 20 snow geese–typically weighing 20 pounds each–shortly after takeoff from Memphis.
The report notes that certain bird populations are increasing, including those you would least like to meet. Of the nation’s 14 largest bird species, 13 weigh more than eight pounds, including various pelicans, vultures, eagles and geese, with “several million” eight- to 15-pound Canada geese outnumbering all other large species. FAA engine-ingestion tests use just four-pound birds.
Strike Prediction Technology
Steve Osmek, wildlife biology manager at Seattle’s SeaTac International Airport (SEA), has been keeping birds and terrestrial animals away from aircraft at SEA for the past 12 years but feels that the report doesn’t give the full national picture. “Bird strike reports are voluntary, so we still don’t know the actual total number of strikes and their national distribution, or that of bird species across the U.S., and both are vital information in planning control measures.” He noted that when ICAO recommended mandatory bird strike reports, every country but the U.S. complied. “Apparently, it was decided that ‘it was not important.’”
Osmek is a strong advocate for new wildlife surveillance technologies, including avian radar, and is the wildlife specialist member of a team with the University of Illinois and Accipiter Radar, Ontario, that is developing a radar-based, bird-strike risk prediction program. The university is the FAA’s Center of Excellence for Airport Technology (CEAT) and CEAT’s point man, Professor Edwin Herricks, leads several safety projects, including improving bird strike prevention methods and evaluating automatic runway foreign-object detection systems.
Since earlier studies at SEA had shown radar’s ability in bird strike mitigation, one of the team’s tasks has been to apply the radar’s signal processing to differentiate between bird threats and all other objects which the radar beam captures, from aircraft, rain and bats to insects and even cottonwood seeds.
This in turn led to the team’s main objective of operationally testing a real-time bird strike risk assessment tool, based on Accipiter Radar’s current system. Accipiter has collaborated with CEAT for several years, and has provided CEAT with avian radars at SeaTac, the Navy’s Whidby Island, Wash., air station and Chicago O’Hare and New York Kennedy airports.
Traditionally, airport wildlife mitigation has concentrated on “inside the fence and below 3,000 feet,” based on surface patrols by biologists. Now, avian radar expands those limits, with current thinking extending them to 10 miles beyond the airport and up to 10,000 feet. This expanded area provides a much better perspective of the local environment, but it also presents the challenge of assessing the relative strike risks of the many separate, but simultaneous, activities occurring throughout the new area. The question then is just how to quickly, yet accurately, compare the threat posed by individual bird activities.
Accipiter’s engineers developed a simple but elegant solution. A large plan view of the total area scanned by the airport’s avian radar was compartmentalized into 11 user-selected segments and, as the radar’s beam sweeps through 360 degrees at 1 rpm, the system’s data processor refreshes each segment with its bird threat condition once every minute. Two of the eight outer segments (or zones) show severe bird threat conditions and two show moderate conditions. The three inner zones covering the runway area’s north half, its south half (SEA’s six runways are 16L/C/R and 34L/C/R) and the ILS localizers (not shown), have low-threat condition with no bird targets shown.
But while the plan view gives overall situational awareness, two additional graphical presentations give fine-grain detail of the threats associated with each of the 11 individual segments. The first display shows, in color-coded vertical bar-graph form, the threat count–from zero to moderate to severe–over the past 15 minutes in each segment, representing the amount of biomass or threat level detected in each segment. The second display is a threat prediction indicator, which presents the probability or exposure to a given threat level. These combined data displays therefore provide excellent prediction cues to a potential bird strike threat, with its movement clearly shown as it passes into adjacent segments. The latest radars also have a tilt function, similar to an airborne weather radar, which allows the biologists to examine higher altitude slices, as one would do in monitoring the upper levels of a large Cb.
The complete system is currently undergoing a six-month shakedown period at SEA, and the team anticipates full operations early next year. However, Herricks is quick to point out that it has not been designed, and is not intended, to provide specific bird strike avoidance headings to pilots. Its primary purpose is to provide much more reliable bird strike risk assessments in a larger area around an airport. As we all know, bird movements–especially with flocks of smaller species–are usually totally unpredictable, where an avoidance heading to an aircraft could suddenly put it directly in the path of the flock should it jink to the right or left unexpectedly. And while geese and other large birds tend to hold fairly steady headings, it should be remembered that the world’s worst bird strike accident occurred in 1960 at Boston Logan, when 62 died after a Lockheed Electra turboprop lost all four engines just after liftoff upon flying into a large flock of starlings.
So while the new SEA system is an important step forward, there are many more ahead. To that end, Herricks, Accipiter Radar president Tim Nohara and SEA’s Osmek are interested to hear from pilot associations such as NBAA, ALPA, AOPA and others, as well as individual pilots, about their views on reducing bird strikes.
Animal strikes are far rarer but they too can be costly, with 910 white-tailed deer the leading victims between 1990 and 2010. The second largest group were coyotes, and USDA data shows that 344 of them met their end colliding with aircraft.