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27 CHAPTER FIVE TRADITIONAL POWER PLANTS AND POTENTIAL IMPACTS This section describes the existing body of information on the ated by the facilities can create turbulent conditions for aircraft potential impacts of traditional power plants on airports and that fly over or through the plumes. There are numerous exam- aviation. Potential impacts include physical penetration of ples, especially in California, of aircraft being affected by airspace, communications systems interference, and visual power plant plumes during takeoff and/or landing at airports impacts of vapor plumes. However, the greatest concern has (C. Ford, personal communication, 2010). This can be partic- been expressed about the potential impact of thermal plumes ularly troublesome for pilots unfamiliar with the airports and from air-cooled condensers and smokestacks. a potential hazard from flying through an exhaust plume. Thermal plume turbulence for traditional power plants is PHYSICAL PENETRATION OF AIRSPACE generally the same as that described in the Thermal Plume Tur- bulence section in chapter three for concentrated solar power Power plants may file a Form 7460 with the FAA for structures projects. The dry-cooling system, typically an air-cooled con- that result in a physical penetration of airspace. Facilities that denser, is the same structure regardless of how the power plant can rise high enough to penetrate airspace include the emis- generates steam that requires cooling. However, as a result of sions stack and the cooling system (see Figure 19). Because the increase in new fossil fuel-fired power plants constructed power plants are often high-profile projects that are subject over the last 15 years and concern raised about their impacts to several layers of federal, state, and local regulatory review, on aviation the FAA has provided guidance on the matter. the airspace review is typically undertaken early in the review process and a determination of hazard from the FAA is likely In January 2006, the FAA prepared a risk analysis on to be fatal for any proposed site. However, new peaker plants exhaust plumes titled Safety Risk Analysis of Aircraft Over- are constructed with shorter exhaust stacks that often do not flight of Industrial Exhaust Plumes (FAA 2006). This was an result in physical penetration. Critics have expressed concern advisory study that contained recommendations for changes that impacts into airspace could be produced by nonstructural to FAA Order 7400.2E, Procedures for Handling Airspace forces such as smokestack exhaust. Matters, regarding the effects of industrial plumes that are not included in the Part 77 evaluations. The safety risk analysis study findings indicated that the risk of an accident from a COMMUNICATIONS SYSTEMS INTERFERENCE small plane flying through a plume was low (i.e., below accept- able levels). The study recommended that pilots stay more Power plants can also present a physical obstruction to radar than 1,000 ft above the plume. The analysis was based on sta- and other communication signals. As discussed previously, tistical averages and not actual flight tests. because these projects are subject to a rigorous and open public process it is expected that issues such as proximity In 2010, the FAA updated the Aeronautical Information to radar facilities would be raised during public review and Manual (AIM) to include visible and invisible thermal plumes studies of potential impacts conducted. Many of the new facil- and their affect on aircraft and pilots. AIM is the FAA's guide ities are being constructed in congested urban areas where to flight information and air traffic control procedures. It is physical obstructions to radar communications may already basically a pilots guide to flying an airplane and incorporates exist. Potential impacts from power plants on communica- information such as medical considerations, factors affecting tions systems have not risen to a level of concern as other flight, emergency procedures, and air traffic control. The new impacts described herein. information on thermal plumes is contained in Chapter 7-5-15, "Avoid Flight in the Vicinity of Thermal Plumes" (FAA 2010b). The section has been updated to warn pilots to avoid THERMAL PLUME TURBULENCE flight in the vicinity of thermal plumes including smoke stacks and cooling towers. Exhaust plumes from cooling systems have the potential to create in-flight hazards that affect the control and maneuver- In addition to the AIM update, the FAA has recently under- ability of aircraft. Under certain conditions, the plumes gener- taken a study to evaluate the impact of vertical plumes and