On September 28, 2012, Sita Air Flight 601 became the latest suspected victim of a bird strike when it crashed shortly after take-off from the Tribhuvan International Airport (KTM) in Kathmandu, Nepal.
According to news reports, the pilot informed air traffic control (ATC) that an eagle had hit one of the Dornier 228’s two engines and the aircraft was returning to KTM for an emergency landing.
The turboprop never reached the airfield, crashing instead into the bank of the Manohara River about one kilometre east of the gateway. Witnesses later told authorities that one of the Do228’s engines was ablaze as the airplane descended. All three crew members and 16 passengers died in the incident.
There are thousands of collisions between birds and aircraft each year. Indeed, a Birdstrike Committee USA webpage claims that bird and other wildlife strikes annually cause well over $600 million in damage to US civil and military aviation.
It goes on: “Furthermore, these strikes put the lives of aircraft crew members and their passengers at risk: over 219 people have been killed worldwide as a result of wildlife strikes since 1988.”
The Federal Aviation Administration (FAA) states on its website that impacts involving wildlife and aircraft cost civil aviation in excess of $1 billion annually and that “the proper management of birds on and around airports can do much to reduce the risk of bird strikes.”
What has become clear in recent years is the vast majority of bird-aircraft collisions happen in the vicinity of airports, with nine out of ten in the US occuring within 500 feet (152 metres) of the ground, and 40% taking place while aircraft are taking off or landing.
In the US, about 100 bird strikes per annum occur at altitudes of up to 5,000 feet (1,520m), and the impact on the aircraft can be significant as the energy of bird strikes can be enormous.
An aircraft flying at 250 knots (463 km/h) that collides with a 10-pound (4.5 kg) goose, for example, is struck with seventeen times the force of a nail being propelled by a pneumatic gun into a piece of wood.
There are three categories of bird threat situations – Migration events (seasonal, for instance); Regular recurring events (daily commutes between roosts used at night and daytime foraging and loafing sites, for example); and Irregular, unanticipated events such as starlings invading an airfield to feed on grasshoppers.
One possible solution to help mitigate against the risk of bird strikes, avian radar, is a relatively new development and the technology has been significantly designed and enhanced over the past 12 years.
Its evolution has been monitored by the FAA, which in Advisory Circular (150/5220-25) explains that “specific radar-based detection systems have been developed to support two critical efforts: the monitoring of bird movements in support of an airport’s WHMP [Wildlife Hazard Management Plan] and the surveillance of airspace to identify potential threats to the safe operation of aircraft.”
Dr Edwin Herricks, environmental biology professor at the University of Illinois and co-ordinator at the institution’s Center of Excellence for Airport Technology (CEAT), told Airport World that it has tested various avian radar systems during the past six years.
Testing sites have been at the Whidbey Island Naval Air station in Oak Harbor, Washington, as well as at four large US civil airports: Seattle Tacoma, Chicago O’Hare, New York JFK, and Dallas/Fort Worth (DFW).
“The overall programme recognised the need for performance assessments and differences in environmental conditions and bird species/behavior at different airports,” reveals Herricks.
“In general, deployments were planned for a minimum of two years. We are shifting the emphasis at the airports where radars are still deployed to more operational issues and have recently seen a threat warning capability developed at Seattle. We also maintain a test site on Whidbey Island that supports sensor testing and other research activities.”
Lisa Mondello, director of corporate communications for SRC, Inc, told Airport World that the company’s BSTAR system was deployed to “the Naval Air Station Whidbey Island as a participant in an FAA Stage 2 avian radar assessment”.
She also said that the plan is to eventually have two BSTAR radars at Dallas/Fort Worth International Airport.
“One was installed in October 2011 for the purposes of a two-year FAA Stage 3 Operational Evaluation conducted by CEAT. The other, purchased by the FAA, will be installed in the first quarter of 2013 on the opposite side of the DFW airport,” says Mondello.
Elsewhere, US based DeTect, Inc has installed more than 100 MERLIN detect and deter bird radars at sites across North America, Asia and Europe for customers ranging from Louisville (USA), Durban–King Shaka (South Africa), Riga (Latvia) and Warsaw–Modlin Mazovia (Poland) airports to the US Air Force and NASA.
According to DeTect, Modlin Mazovia became the first European airport to permanently install bird radar technology for real-time aircraft birdstrike prevention when it installed its MERLIN system last summer, while King Shaka is said to be the first airport in the world to use bird radar for tower operations.
“We have over 20 bird radar systems operating in aviation safety that includes permanent, operational installations at commercial airports in Africa and Europe,” general manager and CEO, Gary Andrews, told Airport World.
“Our systems have a documented record of reducing bird-aircraft strikes while increasing airspace utilisation.”
In 2012, it was endorsed by the Canadian Association of Petroleum Producers (CAPP), which presented DeTect with a Responsible Canadian Energy Award based on MERLIN’s proven record of successfully protecting birds at Oil Sands facilities in northern Alberta.
A ‘critical need’ for bird information
In February 2009, less than a month after US Airways Flight 1549 ingested geese in both engines and was flown, glider-like, down to the Hudson River in New York City for an emergency landing, Herricks spoke with CNN about avian radar.
“There is a critical need to have the data moved into the decision-making process of controllers and pilots,” he said, adding, “You want to be absolutely sure when you say something is there that something is there.”
A key concern of the FAA, which sponsors the Center of Excellence for Airport Technology, has been that controllers and pilots could become distracted from their principal tasks by bird radar alerts.
CEAT staff have been helping the federal agency determine exactly what information should be made available to the two groups of aviation professionals.
Detecting birds in 3D
Dr Tim Nohara, president and CEO of Accipiter Radar Technologies, is among a team of scientists and engineers from the US government, industry and academia to evaluate and validate the ability of digital radar systems to identify and track biological targets.
Their work forms part of the US’s Integration and Validation of Avian Radars (IVAR) project funded by the Department of Defense Environmental Security Technology Certification Program.
Nohara told Airport World: “We (Accipiter) have developed the technology to localise bird activity in 3D and can integrate off-airport coverage. During the trials at Sea-Tac, JFK and Chicago O’Hare, the FAA and airport authorities wanted to see on and off-site data, which our radar system provided in abundance.
“At O’Hare, our equipment revealed that birds habitually migrated south during a one-hour period each day for three weeks, resulting in a severe threat to aircraft that had not been previously detected.”
Depending on the manufacturer, an avian radar system:
- Displays on a computer monitor or networked monitors colour-coded bird information, relative to the airport
- Sends threat alerts to users (wildlife control officers, air traffic controllers and airline operations staff, for example) via cellphones or smartphones
- Plays back recorded bird movements at a variable accelerated rate for ease of viewing and for a selected time interval
- Shows an average daily bird track count over a period of time (monthly, for instance)
- Provides software filters so that only birds up to a certain size, speed, and altitude are displayed
- Automatically generates one-hour avian traffic patterns and publishes them to a restricted-access Intranet site and/or a public website
- Generates abundance graphs (bird counts) for a selected time interval
- Creates reports (weekly bird threat advisories by day/time and zone, for instance)
In the past few years, multi-beam avian radar systems have been developed that provide 360 degrees of scanning by employing a dual-axis dish that rotates horizontally and adjusts vertically under software control.
The associated computer not only records the latitude, longitude, and altitude of birds and corresponding detection time, it establishes the threat level (low, moderate, or severe) posed by bird activity and issues alerts.
The recorded flight patterns can be easily reviewed and the data provides tactical and strategic information to airport wildlife control personnel. The information also enhances the situational understanding of controllers in terms of birds relative to aircraft, and allows air traffic service staff to issue precise ATIS (Automatic Terminal Information Service) recordings and NOTAMs (Notice to Airmen) about avian activity on and near the airport.
Such information is useful to pilots, who can delay starting their engines, taxiing or take-off and/or change their departure or approach path (with permission from ATC) to avoid birds.
Avian radar benefits
At the Bird Strike Association of Canada’s 2012 conference, Accipiter’s Nohara explained that the risk of impacts is the product of the threat posed by birds over a period of time and the probability they will hit aircraft, both of which are mathematically determined based on algorithms.
Smaller birds foraging in grass many hundreds of metres from a runway’s midpoint, for example, are less of a threat than an airborne flock of larger birds transiting the same runway’s departure or approach path.
A threat alert is generated by the avian radar system when the threat prediction indicator – a measure of the probability of a strike based on biomass, flock size, and bird speed and direction – exceeds a user-defined threshold. Threat levels are low, moderate (displayed in yellow) and severe (shown in red).
“We have pushed avian radar development over the past ten years, and associated information networks have matured greatly to meet airports’ requirements,” says Nohara.
“The information provided by an avian radar system can be seamlessly integrated into the airport enterprise and supports greater safety through threat awareness.
“The airport enjoys a great return on its investment through more efficient use of wildlife control resources, marketing and public relations benefits, support for safety management systems, monitoring of night-time avian activity, and, fewer bird strikes.”