Guidebook for Energy Facilities Compatibility with Airports and Airspace (2014)

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7 Airspace and Airports The U.S. National Airspace System (NAS) is a public good, administered by the FAA to ensure safety, while also accom- modating various user groups, including scheduled air car- riers (passenger and cargo), business aviation (air taxis and on-demand commuters), general aviation (private operators), and military. However, the NAS is also a finite resource in the sense that its capacity is fixed, limited by international airspace boundaries but also by the operational capabilities of its airports (i.e., the number of arrivals and departures that airports can collectively support). As a finite resource, air- craft operators compete for scheduling and routing priorities. However, contention over airspace use also occurs closer to ground level, where non-aviation activities may impede safe use of the airspace above. Structures rising above a certain height may be considered obstructions to airspace use (e.g., wind turbines). Land use on or near airports may also be considered harmful to airport operations or airspace use (e.g., oil and gas drilling equipment, glare from solar panels, thermal plumes from electricity generating facilities). Energy technologies can function effectively in low-altitude airspace environments and on or near airport property, so long as projects are sited and implemented safely. The FAA has regulatory authority to ensure that energy projects abide by relevant legislation and adhere to certain evaluation cri- teria. Thus, project stakeholders must be familiar with rel- evant review processes that may determine approval of their projects. Moreover, as many energy technologies have evolved in recent years and installation of certain technologies (e.g., natural gas, wind, solar) has increased exponentially, the FAA is continually updating review requirements, so stakeholders must be aware of recent developments to ensure compliance. This chapter provides an overview of FAA management of the NAS, including infrastructure used to support flight operations. Critically, the FAA’s plans to implement the Next Generation Air Transportation System (NextGen) will result in significant technological and procedural advances for in-flight operations, so this chapter also provides an overview of key NextGen operational improvements as they may relate to energy technologies. The remainder of the chapter then high- lights fundamental legislation and regulatory requirements intended to ensure flight safety, followed by an overview of applicable evaluation procedures and criteria that would be required for approval of energy technology installations and operation in the aviation environment. Chapter 3 provides additional detail about the specific regulatory requirements and evaluation process for each energy technology examined in this Guidebook. 2.1 Governing U.S. Airspace The Federal Aviation Act of 1958 delegates various responsi- bilities to the FAA including control over the use of the nation’s navigable airspace and regulation of civil and military opera- tions in that airspace in the interests of safety and efficiency.8 Within the U.S. NAS, the FAA manages aircraft takeoffs, land- ings and the flow of aircraft between airports through an infra- structure of air traffic control and navigation facilities; people (e.g., air traffic controllers, maintenance personnel); and tech- nology (e.g., radar, communications equipment). The U.S. NAS is one of the most complex aviation networks in the world and when the FAA proposes changes to its design and operation, four principles must be preserved: 1. Maintain or improve system safety. 2. Increase system flexibility, predictability, and access. 3. Improve efficiency and reduce delays. 4. Support evolution of emerging technologies. As a public service, the FAA provides the network of infra- structure, people, and technology that is used to monitor, guide, and direct aircraft along routes within the NAS. This service is known collectively as air traffic control (ATC). Inside C H A P T E R 2 8U.S. Code (U.S.C.), Title 49, Section 40101(d)4.

8the FAA, the Air Traffic Organization (ATO) is responsible for managing day-to-day ATC operations, including the main- tenance of safe separation distances between aircraft and the efficient flow of air traffic with as little delay as possible while maintaining safety standards. Additionally, the FAA Airports organization (ARP) is responsible for maintaining a safe and efficient national airport system, including airport safety pro- grams and development of standards for airport design and construction. With respect to energy technology projects on or near airports, or with potential impacts on airspace use, ATO and ARP conduct evaluations to ensure compliance with certain safety requirements. Other offices within the FAA may also be involved in different components of project review. 2.2 Airspace Operations In order to ensure the safety of aircraft operating to and from airports, the FAA has established procedures for aircraft operations based on the complexity or density of aircraft move- ments, operation type, safety requirements, and the national and public interest. The FAA Aeronautical Information Manual (AIM) organizes the national airspace into four categories: (1) controlled, (2) uncontrolled, (3) special use, and (4) other.9 Controlled airspace includes the airspace around busy air- ports, along aircraft routes, and above 18,000 ft. It is further divided into five classes (A, B, C, D, and E), as depicted in Figure 2.1. Each class is distinguished by different altitude and spatial dimensions and by the types of aircraft operations within the airspace following different rules. Uncontrolled airspace (Class G) includes the airspace that the FAA has not designated as Class A, B, C, D, or E airspace.10 Special use air- space includes restricted, prohibited, warning, and alert areas, as well as military operations areas (MOAs). The energy tech- nologies examined in this Guidebook can be installed in a variety of geographic areas, subject to different airspace clas- sifications, including controlled airspace on or near airport property or uncontrolled airspace in remote areas, potentially near an airfield without ATC service. Aircraft operate under two distinct categories of flight rules: Visual Flight Rules (VFR) and Instrument Flight Rules (IFR).12 These flight rules generally correspond to two catego- ries of weather conditions: Visual Meteorological Conditions (VMC) and Instrument Meteorological Conditions (IMC). VMC generally exist during fair to good weather, when good visibility conditions exist. IMC occur during periods when visibility falls to less than 3 statute miles or the cloud ceiling13 drops to lower than 1,000 ft. Correspondingly, under VFR a pilot is responsible to “see and avoid” to maintain safe sepa- ration from other aircraft and obstacles. IFR procedures are designed for use when separation from other aircraft and ter- rain is maintained by cockpit instrument reference or radar. Pilots must follow IFR during IMC. Regardless of weather conditions, however, the majority of commercial air traffic operates under IFR. Standard instrument procedures define routes along which aircraft operate. For aircraft operating under IFR, air traffic controllers maintain separation by monitoring and directing pilots of aircraft following standard instrument procedures. Controllers monitor the aircraft routes, altitudes, and airspeeds using various sensors (e.g., radar and satellites). Effectively, this system of procedures defines the routes along which IFR aircraft operate. Procedures are published in order to ensure safe clearance from obstacles and adequate recep- tion of communications between pilots and air traffic control. “Conventional” standard instrument procedures rely on verbal instructions from controllers to the pilot, in conjunction Figure 2.1. Types of controlled airspace.11 9U.S. Federal Aviation Administration (FAA), “Aeronautical Information Manual: Official Guide to Basic Flight Information and ATC Procedures,” August 22, 2013: http://www.faa.gov/air_traffic/publications/atpubs/aim/index.htm. 10FAA, Order JO7400.2J, “Procedures for Handling Airspace Matters, Part 4 Terminal and En Route Airspace,” Change 2. 11FAA, “Course Name: ALC-42: Airspace, Special Use Airspace and TFRs,” https:// www.faasafety.gov/gslac/ALC/course_content.aspx?cID=42&sID=505&preview =true, U.S. Federal Aviation Administration. 12Code of Federal Regulations (CFR), Title 14, Part 91. 13Ceiling: the distance from the ground to the bottom layer of clouds, defined as the point where the clouds cover more than 50 percent of the sky.

9 with instrument guidance transmitted from ground-based Navigational Aids (NAVAIDs). The aircraft flies above the NAVAIDs along a point-to-point route while the aircraft cock- pit instruments receive instructions via data communication with the NAVAIDs below. Recently, FAA has begun to employ innovative technologies to enhance routes defined by stan- dard instrument procedures. Area Navigation (RNAV) is one such technology, which enables RNAV-equipped aircraft to fly more precise and efficient routes. RNAV procedures are based on instrument guidance transmitted from a net- work of ground-based NAVAIDs operating in concert, as well as space-based navigational aids that use Global Positioning System (GPS) technology. To understand the types of potential impacts that energy technologies may have on aircraft and ATC operations within airspace, it is useful to understand the flow of an aircraft through the NAS, from one airport to the next. After departing its origin airport, an aircraft passes through multiple airspace types, controlled by multiple ATC service facilities, using var- ious NAVAIDs (e.g., radar), finally approaching, and landing at its destination airport. See Figure 2.2 for a visual depiction of these phases of flight. Control of a typical aircraft flight begins with a control- ler in an air traffic control tower (ATCT) issuing departure clearance instruction to the pilot. ATCTs control departing and arriving flights that are normally within a few miles of the airport as well as aircraft on the ground at the airport. ATCTs normally use visual contact to track arriving and depart- ing aircraft and those on the ground. Due to this requirement for visual contact, the FAA evaluates potential obstructions on or near airport property for safety implications. As dis- cussed in Chapter 3, certain energy technologies are capable of impeding ATC visual contact, including physical obstruc- tions (e.g., wind turbines) or non-physical air safety hazards (e.g., solar panel glare, visible plumes). Once the aircraft leaves the vicinity of the airport, a Ter- minal Radar Approach Control (TRACON) facility normally assumes responsibility for guiding the flight. Controllers in a TRACON use short-range radar to identify and track aircraft out to an approximate distance of 50 miles from the airport. Airspace assigned to a TRACON is divided into sectors.14 A controller, or team of controllers, manages the safe, orderly, and expeditious flow of air traffic within the sector. As aircraft move through the TRACON-controlled airspace, management responsibility is transferred and the aircraft is “handed off” from a controller in the previous sector to the controller in the new sector. As with ATCT visual guidance, the reliance upon ground-based NAVAIDs and radio communications in the terminal area necessitates that sources of transmission interference must be cleared or mitigated, including wind tur- bines and other energy technologies. As the aircraft moves further from the airport and climbs to higher cruising altitudes, control is passed to an Air Route Traffic Control Center (ARTCC), a much larger airspace than a TRACON. Controllers in an ARTCC, or “Center,” use long- range radar to identify and track aircraft. In remote areas without proximity to an ATCT or TRACON, the Center also assumes responsibilities that would otherwise be designated to airport and terminal area controllers. As the aircraft pro- ceeds toward its destination, control is typically transferred to succeeding Centers along the flight route and then back to a TRACON and ATCT as the aircraft approaches its destination airport. Again, similar to reliance upon short-range radar in Figure 2.2. Phases of flight. 14Sector: a portion of positively controlled airspace having defined geographic and altitude boundaries.

10 the terminal area, the Centers’ reliance upon long-range radar necessitates the removal or mitigation of all obstructions of air safety hazards near NAVAIDs, including wind turbines and other energy technologies. This phases of flight scenario applies to aircraft operat- ing in a controlled airspace environment. However, many aircraft operate in non-controlled airspace, either for the entire duration of the flight or involving departure/arrival in non-controlled airspace. The ATC facilities described in this section may not be applicable for aircraft operating in a non-controlled environment. 2.3 Airspace Users As a public resource, many airspace user groups share the NAS, each with different operating requirements and/or business models. The FAA accommodates these user groups in daily operations by balancing scheduled operations with on-demand requests, as well as prioritizing military use. The following terms are used to distinguish among these user groups: • Air carriers refer to airlines that offer scheduled air service for passengers and/or cargo. • Air taxi/commuter refers to commercial operations, usually using small aircraft, for on-demand flights, often for short distances. • General aviation (GA) refers to all civil aviation operations other than scheduled air services and non-scheduled air transport operations for remuneration or hire. • Military aviation refers to the use of aircraft and other fly- ing machines for the purposes of conducting or enabling warfare, including national airlift (i.e., cargo) capacity to provide logistical supply to forces stationed in a theater of battle or along a front. Figure 2.3 displays the historical and forecast aircraft opera- tions in the United States based on data from the FAA “Aero- space Forecast: Fiscal Years 2013–2033.”15 The FAA estimates total aircraft operations at more than 60 million per year by 2033. GA operations have declined significantly since year 2000 and the FAA estimates they will stabilize but remain lower than year 2000 levels. In contrast, the FAA estimates air traffic demand for air carriers to increase continuously from 2013 to 2033, which could be due to population growth as well as the growing demand for travel. In addition to the airspace users described above, demand for operation Unmanned Aircraft Systems (UAS) has increased in recent years. UAS were initially developed for military pur- poses but have demonstrated potential for valuable commercial and civil applications. UAS range in size from less than 1 lb. to several tons. Rapid demand growth for UAS and the broad range of design types are adding complexity to the NAS and raising potential safety issues. Several U.S. government agencies at the federal, state, and local levels have stated intentions to utilize UAS for official operations, including the use of small UAS for “first responder” missions. The increased demand for civilian use of UAS in the NAS will significantly affect airspace usage, regulation, and air traffic control. Therefore, the FAA is currently developing rules for incorporating UAS into NAS operations. Approved by Congress in February 2012, the “FAA Modernization and Reform Act of 2012” required the FAA to streamline the process for public agencies to safely fly UAS in the nation’s airspace. In response to this legislation, the FAA created a new UAS Integration office to incorporate civil and public N um be r o f A irc ra ft O pe ra tio ns Figure 2.3. Historical and forecast of aircraft operations (thousands). 15FAA, “FAA Aerospace Forecast: Fiscal Years 2013–2033”: http://www.faa.gov/ about/office_org/headquarters_offices/apl/aviation_forecasts/aerospace_forecasts/ 2013-2033/media/2013_Forecast.pdf.

11 use of UAS in NAS operations and resolve related safety issues.16 For example, certain UAS may include extensive use of low-altitude airspace, necessitating that the FAA modify ATC procedures to accommodate UAS while ensuring safe operations of other aircraft through that airspace. Different airspace users and aircraft types may interact with energy technologies in specific ways. To illustrate, air carriers with advanced avionics may rely more on instrument pro- cedures for approach and landing procedures, even near the airport, whereas GA may be more visually dependent. In that case, a cluster of solar panels causing glare may be a significant hazard for GA pilots but only minimally intrusive for a com- mercial pilot. As another example, UAS operations at low altitudes near wind turbines may result in impeded operations and possibly even collisions. These sorts of potential issues must be taken into account when siting and implementing energy projects in the airspace and airport environments. 2.4 NextGen Implementation Approved by Congress in 2003, the “Vision 100—Century of Aviation Reauthorization Act” (P.L. 108-176) charged the FAA with planning and implementing the Next Generation Air Transportation System (NextGen), with the purpose of mod- ernizing the NAS in several critical functional areas through 2025. The primary goal of NextGen, as stated in Vision 100, is to “improve the level of safety, security, efficiency, quality, and affordability of the National Airspace System and aviation services.” In general terms, NextGen “includes satellite navi- gation and control of aircraft, advanced digital communica- tions, enhanced connectivity between all components of the national air transportation system, and a much larger role for advanced automation capabilities in the control of aircraft.”17 NextGen is composed of nine capability areas or functional groupings of new procedures for ATC and aircraft to operate within the NAS, new policies to set planning and investment priorities, advances in technology and automation, and incen- tives for airspace users to adopt that technology:18 1. Collaborative Capacity Management improves the abil- ity to balance system demand and allocate airport and air- space in real time, through improved coordination among ATC and airspace users and use of improved automation tools. 2. Collaborative Flow Contingency Management improves the management of major air traffic flows (e.g., during severe weather conditions) while minimizing overall NAS impact, through improved coordination and stakeholder response. 3. Efficient Trajectory Management provides the ability to assign and modify flight routes that minimize the fre- quency and complexity of aircraft conflicts within an air traffic flow, by incorporating real-time information about other aircraft and overall system usage. 4. Flexible Separation Management aircraft are safely separated from other aircraft, vehicles, protected airspace, terrain, weather, etc., by predicting conflicts and identifying resolutions (e.g., course, speed, altitude, etc.) in real time. 5. Integrated NextGen Information provides ATC and airspace users critical information (e.g., weather, surveil- lance, aeronautical, flight planning, and location data) to improve awareness and decision making through use of an Internet-based data-sharing network for authorized personnel. 6. Air Transportation Security improves the ability to respond to security situations with appropriate resources Pilots and Airspace Hazards The FAA, through its Aeronautical Information Management Office, manages PilotWeb, which provides information to assist pilots and aircrews for flight planning and familiarization. It may be used in conjunction with other pre-flight infor- mation sources needed to satisfy all the require- ments of Code of Federal Regulations, Title 14, Section 91.103 and is not to be considered as a sole source of information to meet all pre-flight action. PilotWeb includes Notice to Airmen (NOTAMs), which is “a notice containing information con- cerning the establishment, condition, or change in any component (facility, service, or procedure of, or hazard in the National Airspace System) the timely knowledge of which is essential to personnel concerned with flight operations.” Pilots are initially informed that “the main refer- ences for changes to the NAS are the Aeronauti- cal Charts and the Airport/Facility Directories (AFD) and that most changes to the NAS meeting NOTAM criteria are known sufficiently in advance to be carried in these publications. When this can- not be done, changes are carried in the Notices to Airmen publication (NTAP) and/or the Service A telecommunications system as a NOTAM D item.” 16FAA, “FAA Makes Progress with UAS Integration,” May 14, 2012: http://www. faa.gov/news/updates/?newsId=68004. 17Joint Planning and Development Office (JPDO), “NextGen Topics”: http:// www.jpdo.gov/Nextgen_Topics.asp. 18Ibid.

12 and tactics, while also minimizing impacts on civil liber- ties, and airspace operations, through use of improved risk assessment and risk management techniques. 7. Improved Environmental Performance identifies and attempts to prevent or proactively address environmen- tal impacts as consistent with national and international regulations, by incorporating environmental analysis into operations, policies, and automated decision support tools, as well as adoption of sustainable energy technologies. 8. Improved Safety Operations integrates safety consider- ations in all NAS operations, with an enhanced focus on information sharing and coordination, improved safety risk analysis, incorporation of safety information into automated decision support tools, improved awareness of safety vulnerabilities, and consistent application of safety techniques. 9. Flexible Airport Facility and Ramp Operations pro- vides the ability to reallocate or reconfigure the gates and other airport resources (e.g., maintenance, refueling, and cargo equipment) to accommodate real-time operational requirements through infrastructure upgrades; improved information sharing among stakeholders (e.g., airports, service providers, ATC, security organizations, and airspace users); and automated planning tools. The FAA is currently implementing many of NextGen’ s early stage operational improvements, including infrastruc- ture upgrades and procedural changes that will enable more advanced, late-stage developments by 2025. As presented in the FAA’s “NextGen Implementation Plan” for 2013, the three major thrusts of current NextGen activities are installation of Automatic Dependent Surveillance-Broadcast (ADS-B) tech- nologies, incorporation of Performance-Based Navigation (PBN) technologies and related procedures, and coordinated implementation in key metropolitan areas with multiple air- ports and significant congestion (“Metroplexes”).19 Automatic Dependent Surveillance-Broadcast (ADS-B) is a “satellite-based successor to radar [that] enables more accu- rate aircraft tracking” 20 through use of GPS technology that is transmitted from (or broadcasted from) aircraft to ATC facili- ties, providing a more complete and instantaneously updated picture of the NAS with precise location and timing informa- tion. ADS-B information is displayed to pilots and controllers in a manner similar to radar data, but the displays update in real time and are not degraded by obstructive terrain or long distances. Furthermore, as technology platforms continue to develop, ADS-B will enable automated weather and flight management services by disseminating location data and flight characteristics to decision support tools.21 The FAA has already installed more than 500 ADS-B radio stations in the U.S., with coverage along the East, West, and Gulf coasts, and along the Canadian border. The ultimate benefits of ADS-B will be realized with maximum equipage among airspace users, so the FAA has issued a plan to require full ADS-B equipage by 2020 for access to ADS-B designated airspace.22 The FAA is collaborating with air carriers and airports to obtain ADS-B operational data in order to validate its benefits and encourage equipage.23 Performance-Based Navigation (PBN) is a framework for defining performance requirements in “navigation specifica- tions,” which can be applied to an air traffic route, instrument procedure, or defined airspace. In essence, it “enables aircraft to fly more direct routes, [increasing] airspace efficiency.”24 PBN provides a basis for the design and implementation of automated navigation along flight paths, as well as for airspace design and obstacle clearance. Once a required performance level is established, an aircraft’s own capability determines whether it can safely achieve the specified performance and qualify for the operation. The two main components of the PBN framework are Area Navigation (RNAV) and Required Navigation Performance (RNP). “RNAV enables aircraft to fly on any desired flight path within the coverage of ground- or spaced-based navigation aids, or within the limits of the capa- bility of aircraft self-contained systems, or a combination of both capabilities.”25 RNP is essentially RNAV with the addition of an onboard capability to monitor an aircraft’s navigation performance and inform the crew if the requirement is not met during an operation.26 Several NextGen capabilities, as described above, are dependent upon the implementation of RNAV and RNP technologies. For that reason, the FAA has begun to aggressively publish PBN routes and procedures, with over 800 published in 2012.27 The precision, accuracy and reliability of PBN flight paths (especially RNP) gives ATC the ability to sequence air traf- fic predictably so that an advanced arrival procedure, called an Optimized Profile Descent (OPD), can be accommodated without interrupting conventional operations (illustrated in Figure 2.4, in comparison to an Instrument Landing System 19FAA, “NextGen Implementation Plan, 2013”: http://www.faa.gov/nextgen/ implementation/. 20Ibid. 21FAA, “ADS-B General Information,” January 12, 2012: http://www.faa.gov/ nextgen/implementation/programs/adsb/general/. 22FAA, “ADS-B Frequently Asked Questions (FAQs),” May 13, 2013: http://www. faa.gov/nextgen/implementation/programs/adsb/faq/. 23FAA, “ADS-B General Information,” January 12, 2012: http://www.faa.gov/ nextgen/implementation/programs/adsb/general/. 24FAA, “NextGen Implementation Plan, 2013”: http://www.faa.gov/nextgen/ implementation/. 25FAA, “Fact Sheet—NextGen Goal: Performance-Based Navigation,” March 12, 2010: http://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=10856. 26Ibid. 27FAA, “NextGen Implementation Plan, 2013”: http://www.faa.gov/nextgen/ implementation/.

13 [ILS] approach). An OPD is a procedure in which the aircraft’s flight management system (FMS) facilitates a continuous descent from the top of descent to touchdown, without level-off (i.e., step-down) segments. The FMS chooses the optimum point to begin an aircraft’s descent to landing and then selects the lowest possible thrust setting (often flight idle) to keep the aircraft on a desired descent profile, adjusting for wind, tem- perature, and other flight variables throughout the descent. This reduces carbon dioxide (CO2) emissions and fuel burn. In order to achieve immediate efficiency gains in congested metropolitan areas, the FAA has instituted the Optimization of Airspace & Procedures in the Metroplex (OAPM) initiative. OAPM improvements are designed to streamline arrival and departure traffic by implementing PBN procedures and other airspace design improvements.28 “By optimizing airspace and procedures in the Metroplex, the FAA provides solutions on a regional scale, rather than focusing on a single airport or set of procedures.”29 “Seven active Metroplex sites are in or entering the design and evaluation phases.” The first three sites (Washington, D.C., North Texas, and Houston) were intended to be in implementation by the end of 2013”30 but are now expected in early 2014. Two additional components of NextGen that are critical in achieving early-stage operational improvements are Airport Surface Detection Equipment—Model X (ASDE-X) and Data Communications (Data Comm). “ASDE-X is a surveillance system that uses radar and satellite technology to help control- lers track the movement of aircraft and vehicles on the airport surface [e.g., runways and taxiways] . . . [which] helps control- lers make better decisions that support the safety and efficiency of ground surface movements.”31 The concept of Data Comm itself is not an operational improvement, but the replacement of the current analog voice system to advanced digital com- munication technologies is a fundamental element of Next- Gen, enabling more efficient data transmission and supporting system automation for both aircraft and air traffic control.32 The fundamental changes NextGen will make to NAS opera- tions may alter the context for how the aviation safety impacts of energy technologies are evaluated. Technologies that may be obstructions or aviation safety hazards today may be largely avoidable in the future as aircraft capabilities change and air- space use becomes more flexible. The following scenarios bear examination during NextGen implementation: • With reduced separation between aircraft and condensed air traffic flows, an energy technology installation near new flight paths may need to be re-evaluated as obstructions or air safety hazards; alternatively, increased flexibility and precision under NextGen could make re-routing air traffic a safe distance away from the installation an easier solution. • Increased reliance on PBN technologies for approach and landing will likely reduce use of VFR at many airports, mitigating glare issues from solar panels installations on pilots, and potentially providing greater flexibility for siting solar projects close to airports. • The effect of wind turbulence and signal disruption will be reduced with increased use of ADS-B and Data Comm, which could lead to fewer design constraints for wind tur- bines, augmented farm densities, and an increase in turbine height, potentially leading to increased energy production. • NextGen capabilities like PBN and ASDE-X will lead to several operational changes in terminal airspace and on the airport surface, potentially necessitating revision of Obstruc- tion Height Zone requirements under 14 CFR Part 77. In sum, NextGen implementation will raise additional ques- tions on the topic of energy technologies and aviation safety, but it will also likely offer innovative solutions to problems we are just beginning to understand. 2.5 Protecting Airspace through Airport and Land Use Planning The FAA is responsible for guarding the NAS against intrusions that may impede safe use of airspace and airport resources. As stated previously, the FAA regulates such intru- sions as obstructions (physical) or aviation safety hazards Figure 2.4. Optimized profile descent. 28FAA, “NextGen Implementation Plan, 2013”: http://www.faa.gov/nextgen/ implementation/. 29ATAC, “OAPM Environmental—OAPM”: http://oapmenvironmental.com/ oapm.html. 30FAA, “NextGen Implementation Plan, 2013”: http://www.faa.gov/nextgen/ implementation/. 31FAA, “A Better View of Operations at World’s Busiest Airport,” August 8, 2013: http://www.faa.gov/nextgen/snapshots/slides/?slide=20. 32FAA, “Program Overview—About Data Comm,” June 23, 2008: http://www. faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/atc_ comms_services/datacomm/general/.

14 (non-physical). The FAA’s ability to regulate obstruction intrusions into the NAS is extremely limited, as it is restricted to monitoring the erection of obstructions (i.e., charting) and mitigating hazards by modifying aviation procedures. The FAA’s ability to enforce on-airport land use is based entirely on contractually based grant assurances, rather than regula- tions. However, off-airport land use regulations are largely at the discretion of local government. This lack of regulatory authority outside of airport boundaries is a fundamental rea- son for the publication of the findings in this Guidebook. One of the primary means of protecting airspace on airport property is through the preparation of Airport Layout Plans (ALPs) and Master Plans. The FAA and airports utilize Advi- sory Circular (AC) 150-5300-13A, “Airport Design,” to guide development on airport property and prepare the ALPs. For land uses off airport property, the FAA must work with airports and their local communities to achieve conformance of existing and proposed natural and developed features to airspace protection criteria. Because protection criteria are well defined for physical penetrations of airspace and less so for non-physical impacts, the criteria and guidance for land use planning can vary among project types. The following are examples of legislative and regulatory guidance to protect airspace and airport resources from unsafe intrusion: • Runway Protection Zones, as defined by FAA Advisory Circular (AC) 150-5300-13A, Airport Design. • Obstruction Height Zones, as defined by 14 CFR Part 77 and local zoning ordinances. • The United States Standard for Terminal Instrument Pro- cedures (TERPS), as defined by FAA Order 8260.3B. • Land use controls, as defined by local zoning ordinances (new Land Use Compatibility AC, 150/5190-4A). Much of the airport property is limited for development based on height of structure and distance from airport facili- ties (see Obstruction Height Zones and TERPS). The Runway Protection Zones (RPZs), however, are specific areas at each end of a runway that are limited for development based on land use type. While the criteria noted in FAA AC 150/5300-13A, Air- port Design, states that the FAA requires that all objects must be cleared from the RPZ, some uses are permitted provided they do not attract wildlife, are outside of the runway object free area (OFA), and do not interfere with navigational aids. In Sep- tember 2012, the FAA issued a memorandum entitled “Interim Guidance on Land Uses in the Runway Protection Zone (RPZ)” to provide enhanced clarity on FAA policy. The Interim Guid- ance memo states that certain new or modified land uses in the RPZ require coordination with the FAA Office of Airport Planning and Programming (APP-400). Included in the list of land uses is “above-ground utility infrastructure (i.e., electrical substations), including any type of solar panel installations.” 2.5.1 Obstruction Height Zones Obstruction Height Zones are used to limit and regulate the height of objects that could otherwise cause a loss of navigable airspace, particularly within the vicinity of an airport. Local municipalities often regulate the height of buildings and other structures by establishing zoning ordinances, based on 14 CFR Part 77. This regulation (abbreviated as Federal Aviation Regu- lations (FAR) Part 77) establishes standards and notification requirements for objects affecting navigable airspace. The regu- lations define a set of imaginary surfaces in the airspace around an airport. Any object (including structures, trees, movable objects, and even the ground itself) that penetrates one of the airspace surfaces is considered an obstruction. Wind turbines and power plant stack towers are examples of energy technolo- gies that would require evaluation under Part 77 whereas solar panels often are not tall enough to impinge into airspace (see Figure 2.5). There are other parts of the Airport Design AC that also affect location of structures as obstructions on airport property including proximity to NAVAIDs (and potential for interference) and potential effect on air traffic control visibility. Part 77 functions chiefly as a device for notifying the FAA about proposed construction near an airport so that the agency can assess whether the object would be a hazard to flight. Proj- ect proponents provide notification to the FAA using FAA Form 7460-1, Notice of Proposed Construction or Alteration. Receipt of the notice enables the FAA to evaluate the effect of the proposed object on air navigation and chart the object or take other appropriate action to ensure continued safety. The FAA evaluates height concerns for land uses within the follow- ing five surface area classifications: (1) Approach, (2) Transi- tional, (3) Horizontal, (4) Conical, and (5) Departure. Part 77 specifies height and slope restrictions based on the surface area type. A graphical illustration of the Part 77 surfaces surround- ing airport runways is provided in Figure 2.6. Additionally, any proposed object with a height of more than 200 ft. requires notification, regardless of proximity to an airport. Refer to Part 77 for exceptions and additional reporting requirements. 2.5.2 TERPS The U.S. Standard for Terminal Instrument Procedures (TERPS) defines another set of airspace protection surfaces for airports that utilize standard instrument procedures. The FAA uses these surfaces to design instrument procedures. In most cases, TERPS surfaces are higher than those of Federal Aviation Regulations (FAR) Part 77 and less restrictive on the heights of objects. The FAA publishes (and regularly updates) charts showing the approved instrument approach and depar- ture procedures for individual airports. These charts define where aircraft must fly to remain clear of obstructions near the airport. Any new object that penetrates one of the sur- faces would require a modification to the procedure. The

15 Figure 2.5. Examples of structures that may impinge on airspace. Figure 2.6. Civil airport imaginary surfaces.

16 implementation of RNP technologies and procedures under NextGen will result in narrower TERPS flight corridors and improved obstacle clearance, resulting in improved perfor- mance and safety. Land use controls are also necessary to ensure that certain ground-based activities do not compromise aviation safety. The public safety element of aviation compatible land use is established through zoning to limit certain activities that pose risks to aircraft operations. Potential risks to public health and safety are minimized by regulating land use near airports with the following characteristics: • Congregation of people. • Presence of flammable, explosive, or hazardous material. • Presence of intervening structures, objects, excavations or bodies of water in the immediate area of runways. • Emission of smoke, light, or other phenomenon that could obscure the pilot’s vision during take-off and landing or create unstable air through which the aircraft must pass. • Unshielded electromagnetic or high energy device emissions that could interfere with ground or airborne electronic systems used for aircraft flight control or navigation. • Attracting birds or animals in areas where aircraft could strike them during take-off or landing either in flight or on the runway. Land use controls may establish specific building size limita- tions, population density limitations, reflectivity and emission controls, materials use prohibitions and storage requirements, or land slope/grading limitations. Most controls are only nec- essary in close proximity to airport runways. Criteria defin- ing land use characteristics that can cause visual or electronic hazards to flight are qualitative in nature and the FAA has not yet set precise standards. In general, visual hazards to flight include sources of dust, steam (e.g., thermal plumes), smoke, or glare (e.g., solar panels) that can impair pilot visibility, as well as distracting lights that can be confusing for the airport. Electronic hazards cause interference with aircraft communi- cations or navigation (e.g., wind turbines). The FAA is currently developing a new Land Use Compat- ibility AC (AC 150/5190-4A) which is scheduled for release in mid-2014. This new guidance will provide local governments and airport owners a comprehensive approach to maximizing safety, economic development, and quality of life. While research for this Guidebook shows that the standards of review are inconsistent between physical and non-physical impacts to airspace, it is important to note that the FAA has a rigorous process, which involves several lines-of-business with technical expertise for considering potential hazards. Table 2.1 provides a listing of FAA divisions and their cor- responding evaluation responsibilities. 2.6 Aviation Safety Evaluation of Energy Technologies ACRP Synthesis 28 presented a synthesis of airport practice regarding energy technologies and airports.33 It summarized five types of energy facilities that could affect airports and aviation: Solar Photovoltaic, Concentrating Solar Power, Wind Farms, Traditional Power Plants, and Electrical Transmission. It also identified six types of potential impacts on airspace and airports from energy technologies. This is the starting point for research and guidance undertaken as part of this project. 1. Physical Penetration of Airspace: All energy technologies (and other structures for that matter) have the potential to penetrate airspace depending on proximity to airports. However, any structure rising more than 200 ft. above exist- ing ground elevation penetrates airspace. Utility-scale wind turbines currently in design and construction are 400 ft. or taller. Concentrating solar power towers can be over 400 ft. Power plant stacks and parabolic cooling towers are often more than 200 ft. For other structures under 200 ft. (e.g., drill rig or transmission tower), a physical penetration will occur when located in relatively close proximity to an air- port. At least these potential impacts are well quantified. 2. Radar Interference: Because radar interference is most often caused by a physical barrier between a radar and a receptor (i.e., plane or airport) sending or receiving a radar signal, most energy technologies can produce an impact if sited too close to a radar installation. However, the greatest problem has been the construction of thousands of 400-foot- tall wind turbines that have been located in radar commu- nication corridors. The wind farms create radar shadows Office Evaluation Responsibility Air Traffic Obstruction Evaluation Office (AT OES) Part 77 requirements Air Traffic Operation Service Group (AT OSG) Coordination with air traffic control to identify any operation impacts Technical Operations (Tech Ops) Impact of NAVAIDs, electromagnetic and line-of-sight shadow interferences Flight Standards (FS) Review of proposals to determine the safety of aeronautical operations Flight Procedures (FP) Review of proposals to determine impacts on instrument procedures Airports (ARP) Identify impacts on different airport operations characteristics Table 2.1. FAA divisions and evaluation responsibility for aeronautical studies. 33Barrett, S. and P. DeVita, ACRP Synthesis 28: Investigating Safety Impacts of Energy Technologies on Airports and Aviation, Transportation Research Board of the National Academies, Washington, DC, 2011.

17 behind which the radar signal cannot reach, producing a “blind spot.” The rotation of the wind farm blades also creates a signal received by radars that produces clutter, degrading the effectiveness of the radar. 3. Visual Impact from Glare: Glare is produced when light from a source or reflected from a surface impairs a recep- tor’s view. Impacts of glare in the energy sector have been primarily associated with solar power facilities including photovoltaic (PV) panels and concentrated solar power (CSP) systems. Glare impacts from CSP systems are expected, as they use mirrors at centralized power plants, but glare impacts from PV installations may be unexpected, as they produce electricity by absorbing (rather than reflecting) sunlight. However, solar PV is being located on airport property to provide cost savings and produce alterna- tive revenue and their close proximity to sensitive airport receptors such as the air traffic controllers and pilots on final approach is producing potential glare effects. 4. Thermal Plume Turbulence: There are two primary sources of thermal plume turbulence from traditional steam gen- eration power plants: (1) heated exhaust from a stack and (2) waste heat from cooling towers. Power plants fired by combustion fuels (e.g., coal, oil, natural gas, and biomass) produce a heated exhaust that is released from a stack. In addition, all steam power plants, whether powered by combustible fuels or concentrating solar power, produce waste heat that must be released into the atmosphere more often through dry cooling (e.g., an Air-Cooled Condenser). In each of these cases, hot, rising, invisible air is released, and poses a potential destabilizing effect on aircraft, par- ticularly smaller ones, flying above these structures. When power plants have been proposed close to airport approach routes, aviation stakeholders have been particularly con- cerned about impacts of thermal plume turbulence. 5. Vapor Plume Visual Impact: Similar to thermal plume turbulence, electricity generation facilities that run a steam turbine with evaporative wet cooling produce a poten- tially hazardous vapor plume, which can cause a visual impediment. 6. Wind Turbine Rotor Turbulence: Wind turbines destabi- lize the air after it passes by the rotors. In wind farms, the turbines are spaced in part to limit impacts to downstream wind turbines. The destabilized air cannot be seen and can produce a safety hazard to particular aircraft including emergency medical helicopters and agricultural applicators. These issues can be of concern downwind of a single row of wind turbines or on the edge of a wind farm. As an introduction to Chapter 3, Table 2.2 provides a sum- mary of findings from research for this Guidebook, organized according to energy technology type and including the aviation infrastructure that could be affected, potential impact types, and possible mitigation countermeasures. Table 2.3 defines the major safety impacts of various energy technologies and provides regulatory or literature resources for citation and further review. Energy Technology Infrastructure Affected Potential Impacts Mitigation Options Wind Farms Primary radar, Secondary Surveillance Radar (SSR), Avionics, Doppler voice messages, Navigation aids, Physical hazard for aircraft 1. Error on radars due to clutter interference, Doppler shift or spread reflection, refraction and diffraction 2. Shadowing or masking effect if turbine is between radar and a target 3. Collision with structure including Meteorological Evaluations Towers (METs) 1. Design modification in wind turbines. 2. Reduction of telemetry from turbines to radar and reduce radar signature 3. Upgrading radar system 4. Adding gap fillers, Moving Target Indicator (MTI), Moving Target Detection (MTD) filters to remove echoes and unnecessary clutter 5. Lighting and marking including METs Solar Photovoltaic Cells (PV) Human receptors specifically air traffic controllers and pilots 1. Glare can visually impair airport sensitive receptors, producing a hazardous safety condition 1. Appropriate siting of PV plants relative to airports 2. Use of PV modules that mitigate glare Concentrated Solar Power (CSP) Radars, Visual issues for pilot and air traffic controller, Physical hazard for aircraft 1. Glare from mirrors or receivers can impair human receptors or optical sensors 2. Thermal emissions from receivers may interfere with infrared sensors 3. Thermal plumes from receiver or cooling towers may impact small aircraft 1. Appropriate siting of CSP plants relative to airports Drill Rigs Physical hazard for aircraft, Visibility issues for pilot and air traffic controller 1. Flares from drill rigs can cause reduced visibility 2. National Environmental Policy Act (NEPA) issue of wildlife hazards due to ponds for drill rigs 1. Appropriate siting 2. Prohibitions on flares 3. Filling ponds after constructions Table 2.2. Potential impacts of energy technologies on aviation and related mitigation options. (continued on next page)

18 Safety Impacts Definition Regulation/Documents Physical Penetration of Airspace The height of energy facilities leads to visibility issues for pilots and controllers. The structure impedes by being in the line of sight of air traffic control. a. FAA Order JO 7400.2J, “Procedures for Handling Airspace Matters”1 b. 14 CFR Part 772 c. ACRP Report 38: “Understanding Airspace, Objects, and Their Effects on Airports”3 Communications Interference The physical height or the frequency bands of the different energy facilities interfere with the communication aids of air traffic control. The other factor that interferes with the communications is the electromagnetic interference. a. FAA, “Technical Guidance for Evaluating Selected Solar Technologies at Airports”4 b. U.S. Transportation Command, “Assessment of Wind Farm Construction on Radar Performance, Cooperative Research and Development Agreement, Research Conclusions and Recommendations”5 c. ACRP Synthesis Report 28, “Investigating Safety Impacts of Energy Technologies on Airports and Aviation”6 d. FAA Order 6310.6, “Primary/Secondary Terminal Radar Siting Handbook”7 e. FAA Order 6340.15, “Primary/Secondary En Route Radar Siting Handbook”8 f. FAA Order 6820.10, “VOR, VOR/DME and VORTAC Siting Criteria”9 g. NTIA, “Assessment of the Effects of Wind Turbines on Air Traffic Control Radars”10 Other Visual Impacts The other visual impacts are due to thermal plume, vapor plume turbulence, and glare and glint from reflective surfaces of the energy facilities. a. FAA, “Technical Guidance for Evaluating Selected Solar Technologies at Airports”4 b. FAA, “Safety Risk Analysis of Aircraft Overflight of Industrial Exhaust Plumes” 11 c. FAA, “Aeronautical Information Manual,” Section 5, Potential Flight Hazards.12 Rotor Turbulence The turbulence of rotors of wind turbines causes cluttering and several other issues that leads to radars detecting moving objects (aircraft) incorrectly. a. JASON, “Wind Farms and Radar “13 b. ACRP Synthesis Report 28 Investigating Safety Impacts of Energy Technologies on Airports and Aviation6 Sources: 1. FAA, Order JO 7400.2J, “Procedures for Handling Airspace Matters,” February 9, 2012. 2. 14 CFR Part 77 3. Leigh Fisher Associates, “ACRP Report 38: Understanding Airspace, Objects and Their Effects on Airports,” Washington, DC. 4. FAA, “Technical Guidance for Evaluating Selected Solar Technologies at Airports,” November 2010. 5. U.S. Transportation Command (TRANSCOM), “Assessment of Wind Farm Construction on Radar Performance, Cooperative Research and Development Agreement, Research Conclusions and Recommendations,” 2010. 6. Barrett, S., and P. DeVita, “Synthesis 28: Investigating Safety Impacts of Energy Technologies on Airports and Aviation,” Airport Cooperative Research Program, Transportation Research Board, Washington, DC, 2011.FAA, Order 6310, Primary/Secondary Terminal Radar Siting Handbook, 1976. 7. FAA Order 6310.6, “Primary/Secondary Terminal Radar Siting Handbook,” 1976 8. FAA, Order 6340.15, “Primary/Secondary En Route Radar Siting Handbook,” 1983. 9. FAA, Order 6820.10, “VOR, VOR/DME, and VORTAC Siting Criteria,” 1986. 10. Lemmon, J., et al., “Assessment of the Effects of Wind Turbines on Air Traffic Control Radars,” National Telecommunications & Information Administration, Technical Report TR-08-454, 2008. 11. FAA, “Safety Risk Analysis of Aircraft Overflight of Industrial Exhaust Plumes,” DOT-FAA-AFS-420-6-1, 2006. 12. FAA, “Aeronautical Information Manual: Official Guide to Basic Flight Information and ATC Procedures,” August 22, 2013: http://www.faa.gov/air_traffic/publications/atpubs/aim/index.htm. 13. Brenner, M. et al. “Wind Farms and Radar,” JASON, MITRE Corporation, JSR-08-125, January 2008. Table 2.3. Regulation and research—safety impacts of energy technologies. Table 2.2. (Continued). Energy Technology Infrastructure Affected Potential Impacts Mitigation Options Electrical Transmission Lines Physical hazard for aircraft, Radars, other navigation aids 1. Unnoticed/unmarked structures becoming a hazard to air navigation 2. Communication system interference due to electromagnetic release for line above 345kv 1. Siting guidelines and avoiding locations which interfere with the airspace Power Plant Stack Destabilizing conditions for pilots 1. Thermal plumes, which can cause air turbulence leading to communications interference and visual impacts 2. Vapor plumes, which can reduce the visibility for pilots and air traffic controllers 1. Modifications in siting and height of power plant towers 2. Modifying the aircraft procedures to avoid the thermal plumes and vapor plumes effects Cooling Tower Destabilizing conditions for pilots 1. Thermal plumes and vapor plumes 1. Modifications in siting and height of towers

19 The premise of this research is that energy technolo- gies may pose an air safety hazard, so it is logical to look at accident reports to see if there is any docu- mented supporting evidence. Research for this Guidebook included a review of National Transportation Safety Board (NTSB) aircraft accident database records between January 1, 2001, and June 23, 2013, for key words related to wind tur- bines and meteorological evaluation towers (METs) used to measure wind. The search resulted in 1,498 individual records key word matches, containing the following list of aircraft accidents and their likely contributing causes: Accident Report Number Noted Cause State WPR11LA094 MET Collision (CA) DFW05LA126 MET Collision (TX) SEA04LA027 MET Collision (OR) WPR11LA375* 80 ft. Unmarked Tower (AZ) CEN11CA545 Collision with a Windmill Blade (IA) CHI04LA225 Collision with a 25’ Windmill (ND) LCHI08LA080 Possible Rotor Wake Turbulence (MN) AX01FA253 Possible Rotor Wake Turbulence (CA) * In reviewing the text in this report, a clear determination could not be made on the type of tower. A separate research effort involved a review of the Aviation Safety Reporting System (ASRS) for a variety of keywords related to energy technolo- gies, indicating 17 safety events, related mainly to power plants. The primary causes for these events included airspace violation (i.e., physical obstruc- tion encountered by unaware pilots) and critical aircraft equipment problems. However, that search included no events related to solar energy or other technologies. To obtain more information related to other causes for safety events, researchers then performed a modified search that examined types of impacts that might result from energy projects (e.g., glare or turbulence that could be caused by energy facili- ties), indicating 106 incidents from 2007 to 2012 for which glare was a noted cause of a safety event. Search results included day and night reports dem- onstrating the difficulty in equating “glare” impacts to those produced by an energy technology (e.g., solar PV). See Appendix C for additional information on accident report data. What do accident reports tell us about Energy Facilities’ Compatibility with Airports and Airspace?