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Airport Surface Weather Observation Options for General Aviation Airports (2019)

Chapter: Chapter 6 - Conclusions and Future Research

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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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Suggested Citation:"Chapter 6 - Conclusions and Future Research." National Academies of Sciences, Engineering, and Medicine. 2019. Airport Surface Weather Observation Options for General Aviation Airports. Washington, DC: The National Academies Press. doi: 10.17226/25670.
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66 This synthesis is intended to present the current state of surface weather observation system options for use at general aviation airports. Conclusions from the research on the current state of practice are presented here. Conclusion—Relevance of Weather General aviation aircraft and airports represent, by number, the largest category of civil aviation. General aviation aircraft operate from a hugely diverse collection of airports that rep- resent every geographic and climatic region of the country. This diversity of airport locations exposes GA aircraft to nearly every possible weather scenario. While all aircraft are affected by weather, general aviation aircraft are particularly susceptible, given that the majority of the fleet is smaller and less well equipped than the commercial fleet. This broad exposure to weather, coupled with an increased vulnerability to weather, means that information on local and en route weather is critically important for GA aircraft. Federal Aviation Regulations (FAR) require pilots to obtain weather information for all IFR flights, and for all VFR flights that leave the vicinity of an airport. Conforming to this regulation is typically achieved by a pilot obtaining a weather briefing. Legal weather brief- ings are provided for free by the FAA and NWS through multiple sources. They also are increasingly provided by private companies that provide customized products for a fee. Conclusion—National Weather Collection The National Weather Service holds the primary responsibility for the collection and dissemi- nation of weather data to support aviation purposes. The FAA works with the NWS to ensure that weather information disseminated for aviation purposes is derived from sources that are approved by the FAA. These approved sources will provide weather observations from equip- ment that is certified by the FAA to provide this information. One of the sources of weather data over which the FAA exercises control is automated equip- ment that generates reports of surface weather observations. This equipment is frequently located at airports and therefore has relevance to the operators of those airports. This equipment is also something that general aviation pilots interact with during most flights. Conclusion—Aviation Weather Dissemination The dissemination of FAA-approved weather to the NWS is accomplished through a data connection to the WMSCR, which is accomplished via the NADIN. The NADIN is a multi- purpose FAA data network that conveys a wide range of aviation communications between various FAA customers. C H A P T E R 6 Conclusions and Future Research

Conclusions and Future Research 67 Only surface observation systems that are certified by the FAA are currently allowed to trans- mit over the NADIN to the WMSCR. The WMSCR outputs this weather data to a variety of users, including the NWS, but also to private companies which may repackage the weather data into customized products for use by pilots. Conclusion—Airport Surface Observation Option Types Surface weather observations for aviation use may be taken manually, may be automated with manual augmentation, or may be fully automated. While the FAA and the NWS do sup- port several systems that utilize human observers (SAWRS, A-PAID, CWO, LAWRS), these programs are increasingly being phased out. They are also typically only found at commercial service airports or large and busy airports, or those with complex weather demands, such as many found in Alaska. However, the relevance of human observers to general aviation airports (excluding possibly Alaska), as either a primary weather source or for system augmentation, is very low. Overwhelmingly, surface weather observations completed at general aviation air- ports are by automated equipment. Conclusion—System Certification The FAA maintains a set of specifications for the design, testing, installation, monitoring, and maintenance of automated surface weather observation systems approved for aviation use. When equipment meets all of these performance criteria, the system is said to be certified. Only data from certified systems is output to the WMSCR and the NAS. Certified systems exist at different levels based on what information the systems report. Only those systems that provide a minimal level of information, defined as that information comprising a complete METAR, are eligible for national dissemination through the WMSCR. Systems that report information that does not constitute a complete METAR may only have their information available locally, but it is still considered certified. For a system to maintain its certification, it must: 1. Be from an approved manufacturer. 2. Be installed in compliance with the system siting criteria. 3. Be commissioned by the FAA. 4. Be inspected on the schedule required by the FAA, with varying levels of inspection being required every 4 months, every year, and every 3 years. These inspections are documented through official agreements the system owner executes with the FAA. 5. Be maintained in satisfactory operating condition. When a system maintains its certification through these criteria, its output information, such as an altimeter setting for an instrument approach, or ceiling and visibility data to determine VFR and IFR conditions, is legal for pilots to utilize for safety of flight decisions, or to conduct certain Part 135 operations. Additional certified information provided, such as wind, tempera- ture, and density altitude, may also be relevant as it affects aircraft performance calculations (also regulated by FARs) and safety. Conclusion—Certified System Types Currently there are only two types of automated surface weather observation systems certi- fied by the FAA: the Automated Surface Observing System (ASOS) and the Automated Weather Observing System (AWOS).

68 Airport Surface Weather Observation Options for General Aviation Airports The ASOS systems are owned by either the NWS, the FAA, or DOD, and none have been installed since 2004. These systems may be present on an airport but will be maintained and paid for by the NWS. AWOS systems are provided in multiple levels, from an AWOS A, providing only an altimeter, up to an AWOS IV Z/R. The most common type is the AWOS III (including P and T variants). This system provides altimeter, visibility, wind, temperature, dew point, density altitude, precipitation accumulation, cloud height, and sky condition data. The P model adds present weather, and the T model adds thunderstorm detection, with the P/T including both features. The AWOS III is the lowest model that is permitted to report to the WMSCR, and it is the lowest model that can provide a complete METAR. The models AWOS A, AWOS A/V, AWOS I, and AWOS II are not permitted to report to the WMSCR. Certified systems are to be located per the siting criteria stated by the FAA. The wind sensor is often the critical siting variable, as it requires a 500-foot radius free from obstructions around the wind sensor tower. Certified systems transmit data locally via a discrete VHF frequency for aircraft, via telephone, to displays in the terminal building, to third-party websites if facilitated by the owner, and to the WMSCR through a NADIN connection when the system level allows for this. A NADIN connection for eligible systems is not mandatory, except where required by AIP funding rules. Conclusion—Approved Manufacturers The FAA publishes a list of manufacturers that are approved to produce certified equipment. The current list as of this study is dated June 27, 2018, and includes four manufacturers that can produce AWOS A and AWOS A/V equipment, with only two of those manufacturers approved to produce systems higher than an AWOS A/V, which includes up to the AWOS III and beyond. Thus, only two manufacturers produce equipment certified to transmit to the WMSCR. A company named DBT Transportation Systems, LLC, acquired both of the AWOS III (and higher) certified manufacturers (Vaisala, Inc., and All Weather, Inc.) in 2016 and 2017, respectively. Conclusion—Noncertified Systems By definition, if a system is not certified by the FAA, it is not certified to provide approved information for safety of flight decisions. For example, information from a noncertified altimeter cannot be used to satisfy a local altimeter source for an instrument approach. If information is reported from a noncertified system, it must be reported with the prefix “advisory.” This applies both verbally and in writing. The FAA maintains no standards for the siting, quality, or accuracy of noncertified systems. Thus, there is no FAA guidance to determine if one system is “better” than another. Noncertified systems may report data locally via either a dedicated VHF frequency (the same as an ASOS or AWOS) or via a shared frequency, such as through an automated UNICOM. Noncertified systems may also report to a website facilitated by the equipment manufacturer, which includes a nationwide network of the same system, or to the airport’s website. In these cases, the information must be prefixed as advisory. Noncertified equipment information is sometimes appended to the end of information pro- vided by certified equipment. A common example is an AWOS A/V providing certified altimeter

Conclusions and Future Research 69 and visibility conditions, followed by advisory conditions for wind, sky condition, temperature, etc. In such cases, this system is not eligible to report to the WMSCR even if the data set includes all METAR variables. This is because portions of the data are not certified. Noncertified systems include weather cameras. There is no FAA standard for weather cameras comparable to the standards provided for ASOS and AWOS. Because there is no FAA-certified system for weather cameras to attempt to model, their implementation varies widely. Alaska maintains an extremely robust weather camera system that is accessible through an FAA website. The program was developed in conjunction with the FAA, perhaps the only exam- ple of the FAA supporting the dissemination of noncertified data. However, Alaska has many special rules and exemptions within the FAR due to its unique geography and climate, so this camera program appears to be consistent with other considerations the FAA gives to Alaska operations. The FAA Aviation Weather Cameras website for Alaska is highly interactive and provides a wealth of noncamera weather data from around the state, both certified and noncertified. In all cases, noncertified weather conditions are noted as advisory. The FAA describes the Alaska weather cameras as supplemental information. As standalone devices, they are not legal to deter- mine safety of flight conditions, such as ceiling or visibility. The website includes not only FAA cameras, but also cameras managed by third parties, including more than 50 cameras in Canada. For operations in noncontiguous states (Alaska and Hawaii) the FAA Reauthorization Act of 2018 includes a waiver to certain Part 135 operating rules when weather cameras are available but certified weather data is not available at the destination airport. Additional requirements include the need for a published instrument approach and a current area forecast. The implementation of weather cameras beyond the Alaska system varies. Some states provide airport camera networks, sometimes tied to their greater DOT network. Some private compa- nies facilitate website access to cameras, although geographic coverage may be sporadic. There is no standard for camera clarity, position, location, number, viewing angles, update frequency, and so on, and even the cameras in the highly organized Alaska system vary on these metrics. This topic is discussed further under Future Research. The survey results indicate 25 respondents say their installed system is fully FAA certified, while only two respondents say their systems are not. No respondents said their systems were a combination of certified and noncertified. A cross-check of the information indicated that two of the respondents who represented their system as fully FAA certified actually have systems that are a mix of certified and noncertified. In addition, the two respondents who indicated their systems were advisory or noncertified also have systems that are a combination of certi- fied and noncertified. These discrepancies may indicate some confusion as to what system certification means to airports. Conclusion—VHF Frequency Congestion Both ground-based navigational aid information and verbal communications for aviation are accomplished using VHF transmissions. The FCC has allocated a finite frequency band for aviation purposes. Different frequencies can create certain harmonic interference with other frequencies, and the FCC seeks to separate these from each other. Improper frequency assign- ment or separation can cause the information from one frequency to “bleed” over to another frequency. The limited number of frequencies also means the FAA seeks to disperse frequencies geo- graphically to minimize confusion in the air. For example, when the new Tappahannock-Essex

70 Airport Surface Weather Observation Options for General Aviation Airports County Airport (KXSA) opened in Virginia in 2007, it was assigned a CTAF of 122.8. This was the same CTAF as the New Kent County Airport (KW96) located 25 miles away. While this is a common CTAF, both airports have a Runway 10-28, and traffic pattern transmissions from each airport were easily heard at the other. The airport manager at New Kent reported signifi- cant confusion in the months following the opening of KXSA as pilots were constantly surprised by others reporting conflicting traffic pattern positions for Runway 10-28, only to realize the other pilot was at KXSA. (Note that KW96 was renumbered to Runway 11-29 subsequent to the installation of its new AWOS due to a change in the local magnetic declination.) The AWOS frequencies assigned for a Virginia Department of Aviation project required expanded work on behalf of the FAA and the FCC to provide the required frequencies. Even then, one location had significant issues that, once resolved, resulted in a decrease in the trans- mission strength of the signal. VHF bleed-over is common where multiple VHF antennas are in use, and the problem can usually be resolved by separating the antennas. However, this is not always practical, as the antennas themselves are limited by cable run length and signal attenuation. With an increase in VHF transmitters and frequency assignments within the finite VHF avia- tion band, unanticipated interference issues may become more common. Conclusion—Ownership The survey conducted for this project indicated that 22% of the systems were owned by the FAA or the NWS, and 78% were owned by the airport. All ASOS systems are owned by the federal government, and all costs associated with their operation and maintenance are paid by the federal government. An airport owner will incur no costs for these systems but will be required to ensure on-airport development does not obstruct the siting conditions. Approximately 250 AWOS systems are owned by the FAA. Airport responsibilities for these are the same as those for an ASOS. The FAA is currently not installing any new FAA-owned AWOS systems but does maintain existing systems through a service life extension program. An AWOS installed today at a general aviation airport will be installed under the FAA Non- Federal Program for NAVAIDs and AWOS. This means that while the FAA does not own the equipment, the equipment is still designed, maintained, and installed to meet federal require- ments to report to the NAS. That is, it is a certified system. This will necessitate ongoing O&M costs for an airport. Conclusion—Acquisition Costs The FAA supports the installation of AWOS equipment of all levels through the AIP grant program. Those systems rated AWOS III and higher must pass a benefit-cost analysis, unless one of the exceptions noted in the AIP Handbook or the FAA Reauthorization Act of 2018 apply. For airports that cannot pass a BCA, an option may be to install a certified AWOS II and then later add a ceilometer through other funding to create a full AWOS III, and thus secure access to the WMSCR. However, sponsors should review the AIP Handbook guidance on this strategy as it prevents specifying the original system as “upgradable” in the procurement action using the AIP funds. A ceilometer is the most expensive single component of an AWOS, at an average cost of $40,000. The survey results also indicate the ceilometer was the item most replaced. AIP funding does not support the installation of noncertified equipment.

Conclusions and Future Research 71 Funding for new AWOS systems and upgrades to existing systems may also be available through state grant programs. Participation levels for this vary greatly by state. Funding may also be secured from other federal programs or from local private partnerships at the airport. Per the survey, 41% of respondents indicate a cost of between $100,000 and $200,000 to install the system, with only 7% indicating between $200,000 and $300,000. Eighteen percent of respondents indicate spending less than $100,000 to install the system. The responses reporting lower costs did align with the noncertified systems. However, there was little correlation of the 13 respondents reporting between $100,000 and $300,000 in costs with system level (AWOS II, AWOS III, AWOS IV) or age of system. There is no evident cost growth over time. Perhaps the survey cost brackets did not provide sufficient detail. It is also possible some airports may not accurately know the true costs of their systems. One airport with an AWOS III reported a total cost of less than $50,000, as did one airport with an AWOS II. This is at odds with even the most optimistic cost data from the past 10 years for these systems. The total cost question has a relatively high response rate of “Unknown,” at 30%. This could coincide with the responses for AWOS II and III systems costing less than $50,000. Factors that may play into this include changes in management so that there is no firsthand knowledge of the work, lost or misleading records, or confusion over the question. After a review of recent construction costs for these systems (some of which are noted in the case examples), this synthesis recommends a planning value of $250,000 installed cost for a new AWOS III. This cost excludes procurement and engineering costs, and it also assumes the site is conducive to simple power connections and does not require obstruction removal or land acquisition. Costs for engineering and procurement may vary depending on how an airport procures the project, but a minimum value of $50,000 should be considered for these engineering and administration costs. Conclusion—Operating Costs and Reliability This study identified several categories of mostly fixed operating costs, including power, WMSCR connection fees, and maintenance. One-third of the survey respondents indicated these costs average between $3,000 and $5,000 per year, with a quarter of respondents indicating more than $5,000 per year. A quarter of respondents indicated paying less than $3,000 per year. The most variable of these costs is likely the required maintenance and inspections, and 93% of respondents indicated this was performed by a contracted third party. Interviews with various airports and maintenance technicians indicate that the cost of these inspections when contracted out ranges from $2,500 to more than $6,000 per year and can be highly dependent on the airport location and how many technicians are in the area. Seventy percent of the respondents reported paying all of the annual maintenance costs themselves. While federal (AIP) funding is not available for AWOS maintenance, the avail- ability of state support varies widely across the country. When considering annual costs to maintain a certified AWOS system, an airport should budget from $5,000 to $7,000 per year. WMSCR fees are included in this and may be estimated at $100 per month savings should an airport decide to forgo this cost. Costs to maintain a noncertified weather system would not include FAA-mandated inspec- tions unless a portion of the system were certified, such as an AWOS A or AWOS A/V with advisory weather. Under the pricing model of a fixed charge per visit plus hourly rates for time on site, there may not be much savings for maintenance and inspections for such a system.

72 Airport Surface Weather Observation Options for General Aviation Airports Nearly 45% of respondents indicated that the annual maintenance and inspection costs rep- resented a significant or higher burden on their airport budget, and 18% noted the costs are paid by others. That costs of $5,000 per year represents a significant impact for nearly half of the respondents shows the pressure many general aviation airport budgets are under. One survey respondent noted in the survey remarks, “I wish I could find a training for staff to do tri-annual services and coordinate FAA annual Cert. This would save $5,000/year.” For system reliability, only two of the 27 sites indicated they are unaware of any repairs to their systems, although both of these respondents have their maintenance handled by either the NWS or the state DOT and indicated they may not be fully aware of the system reliability. Six system components were reported as requiring at least one replacement: • Ceilometer = 4 each • Anemometer = 3 each • Data processor = 2 each • VHF radio = 2 each • Tail vane = 1 each • Temperature probe = 1 each The ceilometer is widely reported to be the most expensive single sensor on a certified system, and unfortunately it also reports as the most replaced. The planning cost to replace this compo- nent is approximately $40,000. For occasional or frequent repairs, the least reliable components are reported as: • Data processor = 13 each • Telephone link = 12 each • Visibility sensor = 11 each For occasional or frequent repairs, the most reliable components are reported as: • Freezing rain sensor = 1 each • Thunderstorm sensor = 1 each • Digital barometer = 2 each Because the wind tower on a weather station is often the highest structure within a largely flat area, it may attract lightning. While the towers are typically protected against lightning, damage can still occur. Seven of the 27 respondents reported damage from lightning, with two reporting the costs exceeded $10,000 and one that the costs exceeded $50,000. The system manufacturers include provisions for the grounding and lightning protection of their equipment, and if light- ning is a concern, owners should verify the electrical continuity and resistance of the protection system and address any faults. Additional lightning protection measures can be added without impacting system performance. Some respondents noted unique local conditions that contributed to overall system reliability, such as local wildlife fouling the equipment or heavy thunderstorms that necessitated the addi- tion of a battery backup power system to mitigate frequent power outages. Conclusion—Siting Requirements While a certified system imposes restrictions on a large ground area due to the wind and visibility sensors, only two respondents indicated the siting requirements have the potential to affect future development opportunities. One respondent indicated that the airport modified crop plantings around the AWOS to avoid affecting the system.

Conclusions and Future Research 73 The case examples present one example where adjacent development did impact an exist- ing ASOS, requiring its relocation, and where the final cost of that relocation greatly exceeded the costs estimated when the conflict was first identified. The case examples identify another airport where a proposed AWOS III relocation is conflicting with a proposed solar farm develop- ment that otherwise has mutual airport, community, and industry benefits. Solar is one example of increasingly popular development and one that more sponsors are proposing at airports; however, by its very nature it requires several acres of land itself and has regulatory guidance relating to certified weather systems. A third case example shows that a new system constructed at the location of an existing system raised the issue of existing trees, which the FAA is requiring to be mitigated; and this is proving challenging for the airport owner to complete. The statewide project for the Virginia Department of Aviation installed 17 AWOS III systems, and nine of those required wind towers from 40 to 50 feet tall to mitigate close-in obstructions that could not be mitigated. These nonstandard conditions had to be coordinated with and approved by the FAA Non-Fed coordinator, but a negative evaluation could have prohibited those systems from being installed. This project also utilized split systems to take advantage of siting criteria differences for the wind sensor and visibility sensors. Airport owners should familiarize themselves with the siting requirements of certified weather systems. The airport’s approved airport layout plan should depict the current/future weather system with the 500-foot wind radius shown, so that noncompatible land uses are more evident. When any development is proposed which may impact a certified weather station, an owner should contact the FAA AWOS Non-Fed coordinator to review the project and determine the best path forward. Conclusion—Value to the Airport The installation of a certified weather system that is rated AWOS III or higher will provide an airport with a national reach through access to the WMSCR. This may allow more pilots to find the airport through FAA-approved sources and allow them to choose that airport over others. Noncertified systems and those less than an AWOS III are not nationally disseminated through FAA-approved sources and may make an airport less discoverable. The installation of a certified weather system will provide increased utility for certain GA oper- ations conducted under 14 CFR Part 91K and Part 135. These operations typically involve corporate turbine aircraft and are often the types of operations most valued by many general aviation airports. Operators of these aircraft are unlikely to base them at an airport that cannot support the aircraft’s complete mission profile in all weather. The use of certified AWOS A and AWOS A/V weather may still provide utility to Part 91K and Part 135 operators, but the limitations on obtaining this data may hinder flight planning. The use of at least a certified altimeter setting at an airport will allow aircraft to avoid a Remote Altimeter Source Setting (RASS) penalty for an instrument approach. The RASS penalties for the 27 airports included in the survey are included as an appendix to this report. These penalties vary, but can be significant. For example, the RASS penalty at the Dillant-Hopkins Airport (KEEN) in Keene, NH, is 543 feet for the RW 2 ILS and localized performance with vertical guidance (LPV) approaches. The Madisonville Regional Airport (K2I0) in Madisonville, KY, has RASS penalties over 500 feet for its LPV to both Runway 5 and Runway 23. In total, 23 of the 27 surveyed airports have a RASS

74 Airport Surface Weather Observation Options for General Aviation Airports penalty to at least one instrument approach. Three of the surveyed airports have approaches that are fully not authorized if there is no certified local altimeter. In an interview conducted for the Saline County Airport (see Case Example 3), the airport manager expounded on the benefits of the utility of adding a ceilometer to the airport’s AWOS II to create an AWOS III and connect the system to the WMSCR. He noted the tenants perceive a higher level of safety and can also file directly to the airport using national flight planning tools. Between 20% and 40% of survey respondents indicate increased activity as a result of their system, whether it be through securing new tenants (33%) or increasing charter operations (22%), or simply from an increase in business operations (37%). None of the three airports with the partially noncertified systems reported any of these increases. However, two of the three did indicate they have seen an increase in higher-performance aircraft at their airports. A robust 85% of respondents indicate a higher perceived level of safety simply by having an on-airport weather station. This study did not conduct a cost-benefit assessment of any type of system to quantify the benefits of one system type over another, or over none at all. Instead, the study includes the technical and operational benefits provided by certified weather systems versus noncertified systems, and lists the benefits different airports have either measured or perceived themselves. Perceived safety ranks the highest of these benefits, and as one surveyed airport manager noted during an interview about his system, “You really can’t put a price on safety.” Conclusion—Air Ambulance Services This study presented a case example addressing Part 135 air ambulance service in the state of Mississippi. The issues raised in that case example were discussed within the context of Mississippi, but as in many of the examples extend to other states as well. The applicable Part 135 regulations dictate the proximity of certified weather reporting for air ambulance services. The actual coverage area provided by certified weather systems in Mississippi is approximately half of the state. This lack of coverage has the potential to deny air ambulance service to a portion of the population, or at least to delay access to it as a result of increased ground transport time required. The decision to locate certified weather reporting stations is usually made with regard to the benefits provided to a specific airport, as opposed to taking a more system-wide approach to see what other areas of the NAS might benefit. The air ambulance discussion shows that there are general aviation users who may benefit from certified weather data even if they do not utilize the airport directly. Furthermore, these users are providing a critical service to support public safety. The cost-benefit assessment of this value to public safety is likely very different from an assessment conducted to support a fixed-wing Part 135 operator with mostly com- mercial interests at an airport. The costs to install and maintain a certified weather system are discussed elsewhere in this report. Smaller airports and those with limited or no external support for maintenance may struggle financially to support a certified system. Because the FAA does not support AWOS maintenance on any level, other non-federal public resources may be needed to adequately support an expanded certified weather network. Air ambulance services operate in some of the most precarious flight situations in all of general aviation: all weather conditions, low level, unfamiliar terrain, unimproved landing fields, marginal access to present weather reporting, high risk due to mission failure (patient life and death), and also a high-stress environment in which to accomplish the mission. These forces combine to constantly challenge the safety record for air ambulance operators. The FAA

Conclusions and Future Research 75 has supported numerous programs in the past 20 years to increase the safety of people and equipment operating in the NAS. Increased availability of certified weather reporting for air ambulance operators may both enhance their mission safety and expand their mission role, as well as enhance public safety beyond the NAS. The relationships among increased certified weather access for Part 135 air ambulances, patient care metrics, and system installation and maintenance costs are an area recommended for future research. Conclusion—Effects of FAA Reauthorization The FAA Reauthorization Act of 2018 was passed in September 2018. The act has a few effects on general aviation operations as they relate to certified weather systems. 1. It removes the requirement for a BCA for any AWOS installed at airports in states with a population density less than 50 people per square mile, provided the airport can demonstrate a benefit to emergency or medical services, fire protection, or search and rescue operations. 2. For the states of Alaska and Hawaii only, the act permits Part 135 operations at an airport not served by certified weather, provided: there is a published instrument approach; there is a current area forecast; local observations are supplemented by noncertified observations, such as a human observer or weather camera; the alternate airport has certified weather available; and the operator has approved procedures for departure and en route weather evaluation. Conclusion—Additional Items The following items are included because they were mentioned by multiple sources during the literature review, survey responses, and interviews conducted for this project, and they are not easily categorized into other areas of this report. 1. There is frustration from sources of disparate geographic, operational, and monetary means that only certified AWOS III systems and higher report to the WMSCR. 2. There is concern over industry consolidation of the only two FAA-approved manufacturers of certified AWOS III systems under one corporate roof. These concerns extend to the poten- tial for increased prices for parts and service. 3. The FAA has had internal discussions about changing its policies in the future to certify only information from systems rated AWOS III or higher. 4. It is apparent from some of the survey responses that there is not a universal understanding of system certification and the costs to acquire, operate, and maintain automated weather systems. 5. An industry representative indicated the service life of most equipment is 10 to 15 years. It is unlikely that airports consider this overhaul/replacement time frame in their budgets. 6. The FAA maintains numerous databases relating a wide and complex variety of airport data. Sometimes these databases are not consistent with the physical infrastructure on the ground as it relates to weather equipment. 7. The cost-benefit assessment of certified weather systems does not account for the benefits provided to public life and safety in areas beyond the NAS. 8. Localized interference affecting certain sensors can create erroneous data reporting. This can include localized fog around the system and birds or insects corrupting visibility and ceilometer sensors. 9. The relative infrequency of METAR reporting by AWOS and ASOS systems to Flight Service may hamper the ability of Flight Service to adapt to rapidly changing weather conditions.

76 Airport Surface Weather Observation Options for General Aviation Airports 10. A weak link in the dissemination of data to Flight Service is sometimes a failure of the data transmission system localized at the airport; e.g., power, modem, or broadband failure. 11. Replacement of a certified system that has been damaged or destroyed in a natural disaster can be a lengthy and complex process, and this can hinder emergency response times as well as overall recovery time. Items for Future Research The following topics are recommended for future research and study: 1. Aviation Weather Cameras A. How are these being used in practice by pilots and airport observers? B. Quantify operational benefits, especially considering diversity and severity of climate. C. Development of FAA-approved guidelines or standards for camera placement, acuity, refresh rate, and data dissemination, even if this data remains only supplemental. D. Ability to provide real-time motion as opposed to time-delayed photos. E. Inclusion of low-light and infrared technology. F. Leverage experience from the Alaska program to develop system standards. 2. Data Transmission—The VHF spectrum is increasingly crowded. What other technologies may mitigate the limitations of VHF in terms of congestion, transmission range, FCC license restrictions, or related issues? 3. There are portions of the general aviation world that operate outside of traditional point- to-point flying. This could include air ambulance operations, agricultural operations, infra- structure inspection, back-country tourism, and medicine delivery. 4. Are the current regulatory definitions of IFR and VFR still appropriate, given the capabilities of today’s aircraft and technologies? 5. How can the nationwide collection of aviation weather data, which is highly structured and controlled, contribute to other uses for Big Data that may expand the utility of the national airspace system? 6. Part 135 air ambulance operations • Impacts of weather coverage limits on access, denial of access, and response times to incidents • Impacts of increased response times caused by weather limitations on patient outcomes • Cost-benefit assessment of increased certified weather access versus patient outcomes • Alternate funding resources to support increased certified weather access • Assessment of access as a result of weather reporting limitations to different areas based on socioeconomic factors

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The needs of airports may vary depending on the types of operations typically conducted at the airport, as well as the type of weather common to the airport.

The TRB Airport Cooperative Research Program's ACRP Syntheis 105: Airport Surface Weather Observation Options for General Aviation Airports aims to provide the operators of general aviation (GA) airports a comprehensive source of information about airport-based weather observation options so they may make informed decisions to support the specific operational needs of their airport.

Weather observations at airports can come from either FAA-approved (certified) or advisory (non-certified) sources. Weather reporting at a GA airport, whether certified or not, typically comes from automated sources, as human observers are increasingly being phased out or are stationed mainly at commercial service airports.

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