When the U.S. National Transportation Safety Board (NTSB) convenes a public hearing in mid-2009 on a few aspects of the Jan. 15, 2009, ditching of a US Airways Airbus A320 into the Hudson River, attention to digital avian radar likely will be more intense than at any time since 2006. That year, a proposal for civilian-military and public-private collaboration — the North American Bird Strike Advisory System: Strategic Plan (NABSAS) prepared by the U.S. Federal Aviation Administration (FAA), the U.S. Air Force and Transport Canada1 — was shelved, and the FAA decided to limit most subsequent avian radar research to performance assessments.
Aspiring to deploy a network of airport avian radars and real-time bird hazard alerting within 10 years, the NABSAS addressed issues that may resurface in the current NTSB investigation. But the plan may have been most prescient in expecting mitigation of bird strike risk to be impeded primarily by human, not avian, factors.
Preliminary NTSB factual information said that Flight 1549 was “ditched into the Hudson River shortly after the aircraft struck Canada geese, resulting in an immediate loss of thrust in both engines.” Two people were seriously injured among the 155 passengers and crew. One of four focus areas planned for the hearing is “new and developing technologies for detection of large groups of birds and procedures to avoid conflicts with birds in the general vicinity of airports,” the NTSB said.
NTSB member Robert Sumwalt on Feb. 24 told a congressional committee hearing that the first officer, the pilot flying, “spotted a group of dark birds slightly to the right of the flight path” and an instant later, about 1.5 minutes after takeoff, the flock filled the windscreen and multiple bird strikes occurred at an altitude of about 2,750 ft. The captain took control of the airplane, and the aircraft touched down about 3.5 minutes after the bird strikes.
Margaret Gilligan, FAA associate administrator for aviation safety, at the hearing characterized avian radar as a limited technological solution so far. “Bird detection radar may have the most promise as tools to help airport operators manage their wildlife control programs,” Gilligan said. “However, as many airports routinely have birds in the area, we do not yet know if this system would be capable of providing alerts that would be operationally suitable for making specific time-critical decisions on landing or takeoff.”
In The Spotlight
The avian radar systems intended for civil or military airport use typically are designed from commercial off-the-shelf marine X-band, S-band or combined radar sensors; advanced digital radar signal processors; personal computers programmed with proprietary bird-tracking algorithms that process target data; geographical information system (GIS) mapping software; and network communication. Some are on mobile platforms, others have been installed in airport buildings with roof-mounted antennas.
In the wake of the Flight 1549 accident, some have asked the FAA and its Center of Excellence for Airport Technology (CEAT) at the University of Illinois–Urbana Champaign to explain what has impeded the development of real-time alerting for air traffic control (ATC) and pilots (see “Other Countermeasures,” ASW, March 2009 p. 40). The possible timing and relative safety of envisioned alerts to pilots have yet to be determined, however, in the context of the maneuverability limitations of transport jets, visibility restrictions from the flight deck and air traffic conflicts. Nevertheless, Edwin Herricks, a professor at the university and principal investigator on avian radar use at civil airports for CEAT, says that because of this accident “the paradigm has shifted — we are no longer working in obscurity” given new public expectations.
“Now that we have radars deployed and collecting data, the CEAT team is working on a group of reports,” Herricks said. “One report on the deployment of avian radars hopefully will help people who are contemplating using them to have a realistic sense of what an avian radar can do. We then will produce a shorter technical publication on mapping clutter — the electronic background noise and the radar returns from buildings, trees, etc. Our third report will talk about our nearly two years of experience with three radar systems at Seattle-Tacoma [International Airport, Washington, U.S.] and discuss the operational applications and their utility from the perspective of a user.” During the deployment phase, the FAA has required only letter reports and updates on progress, he said.
The current situation of inadequate validation of avian radar performance and little peer-reviewed literature on avian radar applications in airport settings will be rectified by studies that both CEAT and the U.S. Department of Defense have under way, Herricks said. Another issue has been inadequate basic engineering research that could lead to new bird-specific radar sensors to supersede today’s marine sensors.
In 1999, the NTSB said in Safety Recommendation A-99-086 that the FAA should “evaluate the potential for using avian hazard advisory system technology for bird-strike risk reduction in civil aviation and, if found feasible, implement such a system in high-risk areas, such as major hub airports and along migratory bird routes nationwide.” The FAA launched this research in 2000.
In addition to studying how the existing U.S. Air Force Avian Hazard Advisory System (AHAS) might be modified/adapted for use in commercial aviation and the application of Next Generation Weather Radar (NEXRAD),2 the FAA looked into the possibility of using microburst-prediction radar and airport surveillance radar system model 9 for monitoring bird movements within 5 nm (9 km) of an airport.
The decision was made around 2002 by the U.S. Air Force and the FAA to look at commercially available avian radar technologies, Herricks said. “Since these were untried and unproven in civil airport environments, this meant deploying these technologies to airports and conducting performance assessments so that the FAA could obtain technical information that would allow it to identify standards and requirements that could be used in an advisory circular,” he said. “The advisory circular will be critical because it basically will define characteristics that technologies must meet to allow reimbursement from the FAA Airport Improvement Program for avian radar funding.”
The NABSAS aimed to overcome problems in developing avian radar in 2000–2005. “The purpose of this strategic planning document is to fully integrate all the disparate systems currently under deployment, development or proposal,” the plan said. “Many have argued that further and much greater advancement could be made if the current fragmented and competitive efforts could be consolidated in a single cooperative venture.”
One phase of the plan would have integrated “small-scale mobile radars … available to monitor local bird movements in real time at select locations,” the plan said, building on similar Canadian efforts to upgrade commercial airports. “At the airport or airfield level, dedicated radars must be able to detect birds in the critical airspace, defined as three-dimensional coverage out to 5 nm and up to 3,000 feet above ground level,” the plan said. “The goal is to provide effective bird strike warnings to pilots flying from one location to another. … Automated warnings [would] be issued when the system has identified potentially hazardous concentrations of birds. One example is heavy migration of large birds in critical airspace.”
In 2005, FAA grants sponsored assessment of prototype bird detection radar at the Fermi National Laboratory near Chicago O’Hare International Airport. “Large-bird detection tests using radar were confirmed against … visual observations at various ranges up to 3.5 km [1.9 nm],” an FAA report said. “In addition, specific calibration tests were conducted using a calibration sphere flown at various altitudes and ranges. These types of tests are labor intensive, bird specific and bird dependent. Overall, the tests were successful and the data will be used in the upcoming development of technical specifications for an improved prototype bird-detection radar. The long-term goal of this project is to develop a real-time detection tool that can be used as part of a National Airport Bird Strike Advisory System.”3
In 2006, the FAA shifted the focus of its airport-related avian radar research, as noted in the FAA 2008 National Aviation Research Plan. “The vision of the original [NABSAS] draft focused on providing near-real-time hazard advisory information to a variety of end users such as pilots, air traffic controllers, airport operators and wildlife control personnel,” the plan said. “While that long-term objective is still viable, recent lessons learned and advances in technology have shifted the approach toward initially validating current avian radar capabilities, and providing risk assessments for key flight operational zones in the airport environment.”4
By 2007, avian radar validation and risk-assessment exercises sponsored by the FAA and the U.S. Navy were being conducted at Marine Corps Air Station Cherry Point in North Carolina; Patuxent River Naval Air Station, Maryland, and Naval Air Station Whidbey Island, Washington. “As part of the validation effort, researchers set up a single radar unit in the center of the operational area of the [Cherry Point] air station for maximum coverage of the airport property,” an FAA report said. “Four teams of field observers were located at different posts around the airport property. This validation protocol, commonly referred to as ‘ground truthing,’ consisted of the radar detecting targets and then the field observers confirming whether the reported target was a bird.”5
The three-year U.S. Navy avian radar assessment will conclude this year under the Environmental Security Technology Certification Program’s Integration and Validation of Avian Radars (IVAR) project. “Our milestones for completion include demonstration and field data fusion; demonstration and field data streaming; delivery of functional performance specifications; delivery of the cost and performance plan; delivery of the final report; organization of visual, thermal and other field observation data into a central database; and comparison of [field observation data] with plots-and-tracks data,” said Matthew Klope of the Naval Facilities Engineering Center and Marissa Brand of the Space and Naval Warfare Systems Command, both working at Whidbey Island. “The premise of our project is to rigorously and objectively validate avian radar technology.” IVAR locations are Patuxent River; Cherry Point; Accipiter Radar Technologies in Fonthill, Ontario, Canada; Seattle-Tacoma; Whidbey Island; Elmendorf Air Force Base, Alaska; and a Clemson University facility at Edisto Island, South Carolina.
By the end of 2008, IVAR had demonstrated automatic bird tracking; radar return confirmation by ground-truthing observations using direct visual observations and unmanned aircraft system observations showing that eBirdRad — an early system recently enhanced by Accipiter — could continuously track hundreds of bird targets in three dimensions and real time. The project also generated thermal imagery of birds for comparison with radar data. “Placing the radar antenna close to the ground greatly reduced ground clutter,” Klope and Brand said. “[IVAR also has shown] the importance of near-miss events and the ability of avian radars to identify them, and showed that visual confirmations were strongly dependent upon observer experience, the range/height of targets and weather.”
The IVAR assessment continuing at Whidbey Island is typical. “To date, no avian radar system has been adopted for daily operational use,” they said. “When increased activity of birds in and around the airfield is observed by radar researchers, this information is given to the air traffic control tower personnel and wing safety officers to be disseminated to squadrons for preflight briefings. Until the research project is complete and this science is validated, the data will only be used in the context of research — which includes working with flight operations to get their input and recommendations.”
CEAT also uses two systems at Whidbey Island; its research team also assessed one mobile system temporarily sited at Vancouver, Canada. As of early 2009, the assessments by CEAT support the wildlife hazard manager’s work at Seattle-Tacoma. The FAA’s schedule calls for further performance assessments to begin this year at Chicago O’Hare International Airport, Dallas/Fort Worth International Airport (DFW) and John F. Kennedy International Airport (JFK).
Assessment work at Seattle-Tacoma illustrates how details of avian radar can differ from aviation industry assumptions and public expectations. “In cooperation with researchers at [CEAT], we are exploring enhanced wildlife monitoring through the use of an avian radar system that was installed in August of 2007,” said Mark Reis, the managing director of Seattle-Tacoma, in testimony at the hearing. “Are we able to accurately track the birds? Absolutely. … The question is, ‘What can we do with that data?’ At this point, we probably have too much data. The key thing for [future] operations is, ‘How do we filter down to the critical data that would be important to air traffic controllers and to pilots?’ Or long term, how could airports better understand the dynamics of the bird populations around the airport and what we can do about them?”
The safety factor of providing timely avian radar data to an airport wildlife hazard manager cannot be underestimated. “We are learning about bird population habits beyond what we already knew,” Reis said. “We are learning them with greater accuracy, and we can learn 24 hours a day, 365 days a year as opposed to when people are able to observe [bird activity].” FAA and airline flight safety specialists will have to determine how real-time tactical use of the data by ATC and pilots would occur later, he said.
Herricks remains resolute that avian radar validation at large civilian airports and resultant requirements and standards have to precede any real-time applications. “I don’t believe at this point that any avian radar is capable of operating within the complex environment of civil airport operations at even moderately busy commercial airports,” he said. “It is not a turnkey situation where we turn these radars on and automatically we prevent bird strikes. I agree with the FAA that these systems are not ready for prime time. … All of the data that we have to date — including lots of experience at Seattle-Tacoma — indicate that we have still got a ways to go. But that doesn’t mean that we can’t provide quality information to the airport system to make things safer now.”
Part of the reasoning behind this policy position is that avian radar is not just a matter of technology issues but concepts of operations, achieving buy-in of stakeholders, developing communications systems and deciding how to safely and reliably communicate alerts to ATC and pilots in time for them to take action, he said.
One example of a recurrent glitch seen in CEAT assessments is occasional disappearance of some bird targets on avian radar. “We see a big bird that shows up very well on the radar,” Herricks said. “We see it flying, and then all of a sudden, that track disappears. It may be that we can pick up that track a little later. If the clutter environment is relatively intense, the signal associated with the bird will be lost in that background noise. … We are now mapping the clutter environments at O’Hare, JFK and DFW from multiple locations; we have done 23 sites at O’Hare. We also discovered at Seattle-Tacoma that if we put the radar in a ground depression, this actually improves the performance of the radar by a significant amount.”
DeTect, a U.S. manufacturer of avian radar systems, disputes the basis of the policy position at the FAA and CEAT. “Advanced bird radars from several manufacturers are in operational use by the U.S. Air Force, U.S. National Aeronautics and Space Administration (NASA), the U.K. Royal Air Force and several U.S. and foreign airports, airfields and ranges,” said Gary Andrews, general manager and CEO of DeTect. Unlike systems assessed by CEAT at Seattle-Tacoma and elsewhere, “the DeTect Merlin avian radar system has been and is being used tactically by the U.S. Air Force at five U.S. locations since 2003 and by NASA launch controllers at Kennedy Space Center since 2006 with real-time bird radar displays in the control towers/launch control center and data used to make tactical decisions,” he said.
Most avian radars used at U.S. sites in this decade have been made by Accipiter, DeTect and Geo-Marine. “Much of the current level of technology is limited by what users will currently pay for a bird radar system,” Andrews said. “In March 2009, DeTect will announce its next-generation bird radar, which will be a solid state, all-weather system that will detect and alert bird strike risk in wet fog and moderate rain.” Merlin is not “blinded” by light rain or wet fog, he said. “We are also ‘Dopplerizing’ [adding Doppler marine radar sensors to] our first system and expect to introduce it in late 2009 or 2010. True three-dimensional systems will likely become available as the technology gains greater acceptance, return on investment is further demonstrated, and the additional cost for the system can be justified.”
DeTect’s tactical concepts of operation vary by site but generally include a specialized display — called Merlin ATC, designed with input from air traffic controllers and pilots in 2003 and 2004 — that provides “continuous, real-time display and monitoring of bird activity in the runway approach and departure corridors with the current ‘bird strike’ risk level displayed in color-coded text above each corridor with low risk as green, moderate risk as yellow and severe risk as red,” he said. “Merlin ATC is currently used in the control tower only at military installations,” Andrews said. “The Durban International Airport in South Africa will be the first use of Merlin ATC in the tower [of a civilian airport].”
The system is fully automated and does not require full-time monitoring because when the bird hazard risk level increases, an audible alert directs the controller’s attention to the risk condition, risk location and precise altitude on the display, he said. Risk thresholds are defined and set in the software so that insects do not contaminate the data, and only birds that pose a risk to specific airframes are factored into the ATC displays and alerting. Military wildlife personnel also have real-time radar displays on mobile wireless devices to help them respond more quickly to hazardous bird activity.
In February 2009, Andrews criticized the FAA–CEAT avian radar research effort as “not well designed or well managed,” noting that his company has had difficulty accessing detailed information about the CEAT validation processes and risk-assessment results. In contrast, he said, NASA’s selection of DeTect in a competitive bidding process, issuance of related operational procedures and avian radar system approval occurred in less than 12 months, enabling the July 2006 deployment of a Merlin-based system at Kennedy Space Center to support Space Shuttle launch safety. He also cited the deployment of Merlin systems with target and risk-level displays in the control towers of five U.S. Air Force Bases — completed since 2003 — as evidence that real-time alerts also would be feasible now for civilian airports.
CEAT has received funding to lease the DeTect Merlin system for assessment at DFW, Herricks said. The FAA hopes to broaden its knowledge from working with the Merlin system, he added. “We have been working madly for six to nine months to try to get the money out the door to go to DeTect,” Herricks said.
CEAT and the FAA recognize the need to use all available expertise, he said. “I don’t think there is any company that has thought more about how to get information into the ATC-pilot decision-making framework than DeTect,” Herricks said. “I also want DeTect in our performance assessment because nobody has the experience that they have with vertically spinning radars. They can provide information about altitude — the missing feature in virtually all our radar work to date. We get some altitude discrimination with dual four-degree radars — parabolic dish types — but it would be nicer to have greater discrimination.”
Responding to Andrews’ criticisms of assessment time spent by CEAT compared with military and NASA programs, Herricks said that these comparisons are not valid. CEAT’s position is that avian radar research for civilian commercial hub airport environments is significantly different in character, scope and complexity from these military and NASA contracts.
Seattle-Tacoma and the other U.S. civilian airports deploying avian radar through CEAT — except DFW — use systems from Accipiter. Accipiter’s current military installations also include Naval Base Ventura County in California and Elmendorf Air Force Base.
“Eventually, bird advisories generated in real time in response to significant and risky bird movements identified by radar will find their way into ATC operations in a manner analogous to weather advisories,” says Tim Nohara, president and CEO of Accipiter. “The public and news media may consider this the [ideal application] — which may in fact drive political support for federal funding — but I believe the more important application in improving flight safety is providing airport wildlife control personnel a greatly improved bird situational awareness.”
Two of the CEAT and U.S. Navy research sites — Whidbey Island and Cherry Point — each have generated a year’s worth of avian radar data, enabling for the first time retrospective overlays of bird tracks and aircraft flight paths on the same GIS map. “We are taking one month’s data at both sites and refining the process of identifying/extracting near-miss events,” Nohara said. “Once we’ve refined the procedure, we will apply it to the year’s data sets. We will analyze near-miss-event patterns over time, compare them with reported bird strikes over the same time and confirm correlation,” i.e., that they follow the same trend. “We are getting a measure of how tightly the airspace is packed with birds in the vicinity of an aircraft, rather than counting birds alone, or counting bird strikes alone, to provide a more sensitive indicator to a change in safety,” he said.
Manufacturers typically enhance performance with their own system design innovations or by adopting newly invented radar sensors, antennas or other components. “We have developed the first dual-beam, height-finding avian radar prototype — with patents pending — and it is ready to undergo three-dimensional tests against remote-controlled aircraft in spring 2009,” he said.
Each new generation of marine radar sensor can open possibilities of better avian radar performance at commercial hub airports. “Vendor literature suggests that improvement in bird detection in clutter will be achievable, but at a cost increase of about $100,000 per unit,” Nohara said. “Multi-sensor integration in the past year has included integration [of marine radar] with a number of cameras. … Having the radar automatically classify birds into different species or groups is still in the research and development domain.”
Staying The Course
Misunderstandings of what avian radar can do have the potential to set back CEAT’s process of moving avian radar toward acceptance and utilization, Herricks fears. “We can’t afford to have a tool that provides so much potential fall prey to that, so we have to have expectations that are realistic,” he said. Realism about avian radar also means understanding policies and procedures required for safe insertion of this technology into the ATC decision-making framework, he added.
The Flight 1549 accident report and the forthcoming reports by CEAT on its avian radar assessments may quell the current controversy about avian radar by clarifying logical next steps. Better information about detectable bird hazards — possibly including real-time alerts to ATC and pilots — will require better collaboration among all stakeholders willing to take time to understand the complexity of avian radar systems, the civil airport environment and the ATC implications while assessing risk under safety management systems.
- FAA; Transport Canada; U.S. Air Force. North American Bird Strike Advisory System: Strategic Plan. April 2005.
- NEXRAD is a network of about 158 S-band (10 cm wavelength) radar sites that remotely sense precipitation intensity, location and motion for various government uses including FAA applications.
- FAA Airport Technology Research and Development Branch. “Significant Activity Reports.” Oct. 21, 2005.
- FAA. 2008 National Aviation Research Plan. Feb. 4, 2008.
- FAA Airport Technology Research and Development Branch. “Significant Activity Reports.” April 4, 2007.
Dolbeer, Richard A. “Feathers in the Fan.” ASW, June 2008.
Shamoun-Baranes, Judy; Bouten, Willem; Ginati, Amnon; Haignere, Claudie; Garofalo, Giovanni; Dettmann, Jan. “Avian Information Systems for Aviation Flight Safety.” In proceedings of the 19th annual European Aviation Safety Seminar sponsored by Flight Safety Foundation and European Regions Airline Association, Amsterdam, March 2007.
Werfelman, Linda. “Risks on Feathered Wings.” ASW, January 2007.