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Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids (2011)

Chapter: Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal

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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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Suggested Citation:"Chapter 4 - Increased Use of Spot Deicing for Aircraft Frost Removal." National Academies of Sciences, Engineering, and Medicine. 2011. Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids. Washington, DC: The National Academies Press. doi: 10.17226/14517.
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56 Introduction Deicing for Frost Removal Frost occurs when aircraft surfaces cool below 0°C (32°F) due to radiation effects, and water vapor in the air sublimates on the aircraft surfaces. Aircraft frost deicing (defrosting) with deicing fluids generally consists of a one-step deicing approach. Defrosting is usually performed using a heated mixture of deic- ing fluid sprayed in a sweeping motion using a fan shaped noz- zle spray pattern. Holdover times are not required if the frost is not active. Frost conditions typically affect aircraft that are parked out- side overnight. Thus, frost deicing activities are a concentrated effort to deice aircraft prior to their first departure of the day. A survey conducted in 2004 indicated approximately one third of all aircraft de/anti-icing activities worldwide occur in frost conditions (see Figure 16). In recent years, air carriers have begun to examine different ways for deicing aircraft in frost conditions, as morning deic- ing events can be very disruptive to operations. At airports with centralized deicing facilities, the aircraft first pushes back from the gate, taxies to the designated deicing pad or facility, is defrosted, and then taxies to the runway threshold for takeoff. Spot Deicing for Frost Removal The term “Spot Deicing for Frost Removal” is defined as the use of deicing fluids to treat small affected aircraft wing upper surfaces areas (patches of frost that are typically ≤ 20% of wing upper surface area) to remove (non-active) frost that may have formed during a ground overnight stay. The entire wing is not treated; however, both wings are treated symmetrically, regard- less if they both require defrosting. If any frost is observed on the leading edge of the wings, it must be removed. Depending on ambient temperature and precipitation conditions, the wing may not require anti-icing. If the wing is not anti-iced, then holdover times do not apply. The primary benefit of using spot deicing is a reduction in the amount of glycol used to achieve aerodynamically clean air- craft wings prior to takeoff, compared to the amount used in treating an entire upper wing surface. Reduced glycol con- sumption leads to lower fluid purchasing costs, lower fluid recovery costs, and reduced environmental impact. Another benefit of spot deicing is a significant reduction in defrosting time (to as short as 10 minutes, depending on air- craft size, extent of frost coverage and ambient conditions). This reduced time leads to greater efficiencies in the use of deic- ing and other airport facilities. At remote deicing facilities, where aircraft are deiced with engines running, reduced engine run-time lowers fuel burn and its related carbon emissions, and lowers aircraft operating costs. Several other relevant features of spot deicing for frost removal are: • Additional operator and flight crew training is required to implement this procedure; • Adoption of this procedure requires closer checking and inspections by qualified personnel; and • Conventional ground deicing equipment, suitable for nor- mal defrosting usage, can be used to perform spot deicing for frost removal. Objective The objective of this task was to gain a better understanding of the current practices employed for spot deicing for frost removal, quantify its potential benefits, and provide tools for decision makers to determine whether this procedure is suit- able for their operation. The objective was met by completing the following activities: • Conducting a literature review of current government and industry regulations, guidance material, and standards to C H A P T E R 4 Increased Use of Spot Deicing for Aircraft Frost Removal

57 document industry regulations and practices related to spot deicing for frost removal; • Conducting phone interviews with deicing service providers and airlines; • Developing a survey to gather pertinent information from a wider audience, including airlines, deicing service providers, deicing consultants, deicing instruction facilities, and regulators; • Designing and conducting tests to examine appropriate fluid strength, temperature and quantities for spot frost deicing applications; • Identifying if changes to any industry standards, recom- mended practices, or both are required and supporting the changes and/or development of guidance material as necessary; • Developing a cost-benefit model; • Developing presentation aids to influence and aid decision makers; and • Preparing a technical report to document the work com- pleted for this task. Research Approach and Methodologies This section presents the research approach and method- ologies employed to examine the current practices and regu- lations, opportunities, limitations, obstacles, and potential benefits associated with the usage of spot deicing for aircraft frost removal. Four activities were conducted, and they are addressed herein as follows: • Literature review; • Laboratory tests; • Focus group survey; and • Cost-benefit model. Examination of Current Government and Industry Regulations, Guidance Materials, and Standards A review of current government and industry regulations, guidance material, and standards related to spot deicing for frost removal was conducted to determine the need for changes or further approvals to accommodate the use of this procedure. The primary literature and documents that were reviewed and found pertinent to the use of spot deicing are listed below (a complete list of documents is contained in Appendix A): • Society of Automotive Engineers (SAE) guidelines in Aerospace Recommended Practice (ARP) 4737 and ARP 5149 that address procedures for spot deicing for frost removal; • Holdover time guidance material and documentation pub- lished annually by Transport Canada and the FAA; and • Association of European Airlines (AEA) Recommenda- tions for De/Anti-Icing of Aircraft on the Ground. Laboratory Tests Laboratory tests were conducted to collect data to support the development of guidance material for spot deicing of frost, specifically to provide procedural guidance on fluid strength, fluid temperature at application, and fluid amounts. Background Frost can form in local areas on the wing surface by two dif- ferent mechanisms. The first is the ordinary type of frost that results from radi- ation cooling of the wing surface under a clear night sky. Not all areas on the wing surface cool to the same extent. For exam- ple, control panels may cool to a lower temperature than the main wing due to their different construction and skin thick- ness. If they cool sufficiently, frost may form on these local colder areas while the main wing remains frost-free. As morn- ing approaches, frost generation may cease, however the affected areas remain frost covered. This is considered to be non-active frost. A second type of local frost condition is related to cold- soaked wings. Wing surface temperatures can be considerably below ambient due to contact with cold fuel and/or close prox- imity to large masses of cold-soaked metal in the wing struc- ture. In these areas, frost can build up. If localized frost patches still exist at the departure time of the subsequent flight, the operator may assume that it is no longer active, and treat it as ordinary frost. However, if the fuel is still cold, as might be the case for short aircraft ground-times, then frost generation could still be active. In the spot deicing procedure under examination, a heated deicing fluid would be applied only to the frosted areas, some- times prior to departure. The equipment used for applying fluid could vary from portable sprayers, to fluid impreg- nated mops, to standard deicing vehicles. Accordingly, the fluid quantity and temperature could vary widely. As well, the Figure 16. Worldwide deicing operations in various precipitation conditions. Frost 33% Snow 56% ZP 7% Other 4%

interval from time of fluid application to flight departure could vary considerably. Although spot deicing for frost is generally considered to apply only to non-active frost conditions, its feasibility for active frost conditions is also of interest. If its application in active frost conditions is deficient, then field operators must be cautioned that an unsafe condition may result from such use. Because of this concern, test procedures were developed to examine spot deicing during both non-active and active frost conditions. Objective The laboratory tests were conducted to collect data to sup- port the development of guidance material for spot deicing of frost. The following work elements were planned: • Examine whether fluid mixed to 18°F (10°C) fluid freeze point buffer is adequate or whether full strength fluid is required to protect wing surfaces that are colder than out- side air temperature (OAT); • Determine the fluid temperature at which fluid should be applied; • Determine strength of fluid required at different tempera- tures, especially at cold OATs; and • Gather data on amounts of fluid required for spot deicing applications. Methodology Initial work to prepare for frost testing in natural frost con- ditions was begun in March 2008. The limited outdoor tests conducted proved inconclusive due to insufficient frost accu- mulation occurring at the end of the 2007–08 winter. Alternate plans were subsequently made to conduct labora- tory tests indoors with frost generated artificially on test plate surfaces. Tests were conducted at the National Research Coun- cil (NRC) Climatic Engineering Facility in Ottawa, Canada, from July 7 to July 10, 2008. In an effort to minimize the finan- cial impact of indoor testing, the tests were conducted at the same time as tests that were being conducted in the facility for a TC project. The advantage of the “pigging-backing” of proj- ects was that the costs for the test facility were shared; the dis- advantage was that the conditions available in the climatic chamber were not always optimal. A complete description of the laboratory test procedure is provided in Appendix B. This procedure is based on the nat- ural frost test procedure and includes the modifications required for indoor laboratory testing. A short description of the procedure is provided in the following subsections. General Methodology for Simulating Non-Active/Active Frost. A procedure to develop frost in laboratory conditions was developed prior to testing. This procedure involved filling aluminum boxes with Type I fluid that had been cooled to a temperature approximately 18°F (10°C) lower than ambient temperature. Because the surface of the box was colder than ambient temperature, frost readily formed. The aluminum boxes employed were the same wing-leading- edge thermal equivalent boxes used for measuring heated Type I fluid endurance times in natural snow and for measur- ing Type I/II/III/IV fluid endurance times in simulated rain on cold soaked wing. The box upper surface consists of an alu- minum plate of the same dimensions (20 in. × 12 in.) as a stan- dard fluid endurance test plate. For testing, the boxes were placed on a test stand, at a 10° slope (Figure 17). To simulate non-active frost conditions, the filled box was exposed to the laboratory environment for one hour, then emptied of its cold fluid content, and kept open to bring the temperature of the air in the box close to ambient temperature. The box top-surface temperature thus warmed to match that of the test chamber, and frost stopped accumulating. Simu- lated non-active frost testing followed. To simulate active frost, the filled box was exposed to the laboratory environment for one hour. Testing began immedi- ately with the box remaining filled as shown in Figure 18. The ongoing temperature differential between box surface and ambient continued to generate frost throughout the test. This test simulated the particular condition where frost is generated by cold-soaked wings, as opposed to the condition where frost is generated by radiative cooling of wing surfaces. The amount of frost that had accumulated on the test sur- face at the beginning of the test was determined from a paral- lel set of boxes, which were treated in the same manner as the test surfaces. The frost on the parallel boxes was scraped off, collected and weighed as shown in Figure 19. Test Surfaces, Fluids, and Application Techniques. Tests were conducted on test surfaces that were subjected to both 58 Figure 17. Set-up for leading edge thermal equivalent boxes on test stands at NRC climatic engineering facility.

59 non-active and active frost conditions at various ambient temperatures, including: −13°F (−25°C), 6.8°F (−14°C), 14°F (−10°C), 26.6°F (−3°C), and 33.8°F (+1°C). Type I Propylene Glycol (PG) fluid prepared at Standard Mix (63% glycol) and at a fluid freeze point buffer of 18°F (10°C) was used for these tests. Fluids were tested either heated to 86°F (30°C) or cooled to the chamber’s ambient test temperature. The selection of the 86°F (30°C) fluid temperature for the heated fluid tests was based on previous field tests on aircraft that measured the actual at-wing fluid temperature for frost deicing sprays when the fluid temperature at the spray nozzle was 140°F (60°C). These tests showed a considerable drop in fluid temperature between the spray nozzle and wing surface for the typical fan-shaped spray patterns used for defrosting. A fluid application method was developed to represent the manner in which fluid is applied from a deicer spray nozzle in the field. The method consisted of spraying the fluid from a standard push-spray bottle as shown in Figure 20. In addition, each test set included one test where the Type I heated fluid was applied according to the conventional test method with the use of a fluid spreader as shown in Figure 21. Equipment, Personnel, and Data Forms The test procedure (see Appendix B) provides the detailed equipment and personnel required for testing. The procedure also includes copies of the data forms that were used. The data forms were used to record frost accretion, fluid strength, tem- perature, and fluid endurance times. Tests Conducted Eight sets of tests were conducted producing a total of 75 individual tests. The test variables are described below. 1. Quantity of fluid used per test: 0.003 US gal (10 mL), 0.005 US gal (20 mL), 0.011 US gal (40 mL), 0.021 US gal (80 mL), and 0.042 US gal (160 mL); Figure 19. Scraping frost off test plate surface to measure rate. Figure 20. Spray method for fluid application on a test plate surface. Figure 21. Standard method for fluid application on a test plate surface. Figure 18. Active and non-active frost simulation method.

2. Fluid strength: 18°F (10°C) buffer or standard mix (63% glycol); 3. Fluid temperature: 86°F (30°C) or ambient; 4. Method of fluid application, sprayed or standard application; 5. Ambient temperature of test chamber: −13°F (−25°C), 6.8°F (−14°C), 14°F (−10°C), 26.6°F (−3°C) and 33.8°F (+1°C); 6. Active or non-active frost condition; and 7. Fluid strength and test plate surface temperatures: recorded progressively at 1 min, 5 min, 15 min, 30 min, 45 min, 60 min, 90 min, and 120 min after application as show in Figure 22 and Figure 23. Test Plan Table 38 presents the test plan used for each set of tests. Fluid strength was mixed to either an 18°F (10°C) below ambient temperature fluid freeze point buffer or at the standard fluid mix as delivered. Eight sets of tests were conducted at a range of temperatures as shown in Table 39. Two “baseline” tests were designated for each test set: 1. 0.1321 U.S. gal (500 mL) of fluid prepared at 18°F (10°C) buffer, poured at 68°F (20°C) with a spreader; and 2. 0.011 U.S. gal (40 mL) of fluid prepared at 18°F (10°C) buffer, applied at 86°F (30°C) with a sprayer. Baseline Test #1 was similar to the procedure used in hold- over time testing in active frost conditions except the frost was not removed from the test surface prior to fluid application. Baseline Test #2 was a baseline test for spot deicing, and was based on results from preliminary tests conducted dur- ing outdoor active frost conditions. Test variables for the remaining tests were changed or modified in reference to this baseline test. The objective of all tests was to remove the frost accumulated on the test surfaces by spraying fluid at various strengths, amounts, and temperatures. Success was indicated by complete frost removal without early freezing of the applied fluid. Fluid endurance time was also measured for tests in active frost. 60 Figure 22. Fluid brix measurements taken from 6-inch line on test plate surface. Figure 23. Surface temperature measurements taken from 6-inch line on test plate surface. Table 38. Spot deicing test plan. TEST # 1 HOT baseline 2 spot baseline 3 4 5 6 7 8 9 10 11 12 Plate # 1 2 3 4 5 6 7 8 9 10 11 12 Fluid Qty. (mL) 500 40 40 40 40 10 20 80 160 40 40 40 Fluid Strength 10°buffer 10° buffer std. mix 10° buffer std. mix 10° buffer 10° buffer 10° buffer 10° buffer 10° buffer std. mix 10° buffer Fluid Temp. (°C) 20°C 30°C 30°C OAT OAT 30°C 30°C 30°C 30°C 30°C 30°C OAT Frost Event Type active active active active active active active active active non- active non- active non- active Method of Fluid App. pour w/ spreader spray spray spray spray spray spray spray spray spray spray spray

61 Log of Tests A log of tests is given in Table 40. Each row in the log con- tains data specific to one test set. Chamber temperatures for Test Sets 1, 2, 3, and 3a were lower than planned due to the location of the test stands in the cold chamber. For the remain- ing tests, the stands were repositioned to an area of the cham- ber where temperatures were more suitable. Focus Group Survey Preliminary phone interviews were conducted with sev- eral deicing service providers (Contego Systems, Integrated Deicing Solutions), several airlines (Alaska, Northwest, US Airways), a major freight hauler (FedEx) and the FAA to examine current spot deicing for frost removal practices and to ascertain the current extent of its usage. Information gathered from these interviews varied. Replies covered a wide range: • “We have been using a spot defrosting procedure for sev- eral seasons;” • “We do not allow this procedure on our aircraft since it is not covered by FAA guidance documents;” and • “This procedure would require additional inspections and training.” Following the preliminary phone interviews, a focus group consisting of key individuals from the deicing industry was put together to gather a more thorough and detailed understand- ing of the industry’s perceptions and current usage of diluted fluids. Feedback was obtained from the focus group through an online survey. Survey Objectives The objectives of the survey were: • To determine which frost removal methodologies the industry is familiar with and which frost removal method- ologies the industry currently employs; • To determine the relative cost of frost removal method- ologies; • To determine the perceived effectiveness of frost removal methodologies; • To determine the perceived advantages and disadvantages of using spot deicing for frost removal; • To document current practices of companies using spot deicing for frost removal; • To determine what is preventing companies who are not using spot deicing for frost removal from using this methodology; • To determine what changes (regulatory or otherwise) need to take place in order for these companies to employ spot deicing; and • To quantify fluid savings that would be realized by using spot deicing for frost removal. Table 39. Planned OAT for test sets. Table 40. Log of tests. Test Set # OAT (°F) OAT (°C) 1 -13.0 -25 2 6.8 -14 3 26.6 -3 3a 26.6 -3 3b 26.6 -3 3c 26.6 -3 4 14.0 -10 5 33.8 +1 Test Set Date Total Tests Active Frost Tests Non- Active Frost Tests Test Plan Chamber Temp. (°C) Average Chamber Temp. (°C) Avg. Plate Temp. Before Pour (°C) Frost Accumulated on Plate Before Pour (g/1 hour) Frost Accumulated on Plate After Pour (g/2.5 hours) 1 July 7 12 9 3 -25 -28.6 -28.5 1.1 2.1 2 July 7 12 9 3 -14 -16.6 -20.5 2.1 3.6 3 July 8 12 9 3 -3 -4.2 -6.3 1.4 4 3a July 8 6 4 2 -3 -4.2 -6.7 0.5 0.7 3b July 10 12 9 3 -3 -3 -13 3.8 10.9 3c July 10 6 6 0 -3 -3 -7.2 4.5 4.2 4 July 9 12 9 3 -10 -10.3 -13.7 0.8 0.6 5 July 10 3 3 0 1 1.9 -4.1 3.2 3.2

Composition of Focus Group The focus group included individuals from a number of organizations, including deicing service providers, passenger airlines of varying sizes, cargo airlines, government agencies, and airport authorities. These individuals were invited to the focus group because they are key decision makers for aircraft ground operations in winter conditions in their respective organizations. In addition, several key consultants in the deicing industry were included. These individuals have many years experience in the deicing industry and are now involved in training programs. The following organizations were represented in the focus group: • Aero Tech Consulting • Aeroflot • Aeromag 2000, Montreal • Aeromag-Contego, Cleveland • Air Canada • Air France • Alaska Airlines • All Nippon Airways • American Airlines • Basic Solutions • British Airways • Contego Systems • Contego Systems, Denver • Continental Airlines • Delta Airlines • East Line Techniques • EFM Munich • FAA • FedEx • Horizon Air • Hungarian Airlines • Integrated Deicing Systems • KLM • Leading Edge Deicing Specialists • Malmö Aviation • MeteoGroup • N*ICE Aircraft Services, Frankfurt • Northwest Airlines • Port of Portland • Salzburg Airport • Servisair Canada • Servisair, Toronto • Swissport • Transport Canada • UK CAA • United Airlines • United Parcel Service • US Airways • WestJet It should be noted that a concerted effort was made to include individuals involved in deicing operations in North America, Europe, and elsewhere in the world. The following countries were represented in the focus group: United States, Canada, United Kingdom, Finland, Norway, Sweden, Ger- many, France, Netherlands, Austria, Hungary, Russia, and Japan. Survey Format The survey consisted of 25 multiple choice and short answer questions. The final question was an optional open-ended question used to collect additional comments/observations on the topics that were not addressed by the survey questions. A copy of the survey is included in Appendix C. Not all of the survey questions were applicable to each person in the focus group. For example, questions related to amounts of fluid used in actual operations were not relevant to individuals from government organizations, as their organiza- tions do not conduct de/anti-icing operations. The survey soft- ware described in the next section was used to set up the surveys to ask respondents only those questions that were applicable to their organization type (the first question ascer- tained their organization type). A matrix showing the ques- tions that were asked to each organization type is included in Appendix C. The applicability of some of the questions in the survey was determined by respondents’ answer to Question 7, which asked if their affiliated organization was currently using the spot deicing methodology, planned to use it in the future, or did not plan to use it in the future. The survey software was used to route respondents to the appropriate questions based on their response to this question. The questions that were asked upon each of the three responses are provided in the spot deicing routing diagram given in Appendix C. Survey Administration Specialized software was used to administer the survey online. The software was used to create the survey, publish it to a secure website, and collect and collate the responses. Response Rate The survey was sent to 41 focus group members. Twenty- seven individuals (66%) completed the survey. Table 41 shows a breakdown of the survey respondents by organiza- tion type. 62

63 Cost-Benefit Model A cost-benefit model was developed to assist operators in determining the financial feasibility of implementing spot deicing for frost. Development of the model was completed using a two-step approach. The first step identified potential parameters for use in the model, assessed their typical values and estimated their influence from a cost-benefit perspective. The second step used the selected parameters to develop and test a model. Step 1: Examination of Potential Cost-Benefit Model Parameters A detailed examination of potential parameters was under- taken to determine their impact on model outcome. In the course of this examination, typical values for each parameter were established. These values were then combined in a pre- liminary cost-benefit assessment. The preliminary assessment showed substantial benefits per aircraft deiced, with savings ranging from eight gallons of fluid and $35 in operational cost savings for a small turbo-prop aircraft to 60 gallons and $280 in operational cost savings for a heavy wide body transport. A detailed examination of potential cost-benefit model parameters is provided in Appendix D. In addition to its use for selecting parameters to be included in the model, the examination provided parameter values that may be useful to operators in their application of the model. Typical amounts of deicing fluids utilized in conventional frost deicing operations and the anticipated amounts for spot deic- ing are documented for different aircraft types. Average cost savings per aircraft spray are calculated based on a stated value for fluid costs. Estimates of operational costs for additional training and inspection are stated. Use of these parameter val- ues may enable the user to conduct a preliminary feasibility study using the model, before going to the effort of developing costs specific to their own situation. The potential parameters considered for the cost-benefit model are: • Additional equipment; • Addition training of deicing personnel; • Additional inspection requirements; • Additional training documentation; • Additional training of flight crews; • Deicing fluid amount savings; • Deicing fluid cost savings; • Additional guidance provided by north american regulators; • Savings in deicing time through-put; and • Savings to the environment. In the examination of potential parameters, it was con- cluded that any additional guidance provided by North Amer- ican regulators would not be a direct cost to the operator so that parameter was excluded. The direct saving in deicing time throughput was estimated to be a small value, mainly because the staff must be available and equipment must be kept at the ready in any case, and was not included in the model. However there may be an impact on aircraft block times, which is included as a model parameter. And while there may be a quantitative value associated with reduced environmental impact of lower fluid usage, this is not a factor lying within the potential users financial budget, and thus that factor was eliminated from the model development. The remaining parameters were incorporated into the cost- benefit model. The preliminary examination addressed the effect of spot deicing individual aircraft, but did not extend to the overall deicing process because of the complexity involved. The intro- duction of spot deicing may substantially change the local Table 41. Survey respondents by affiliated organization type. Airlines 44% (12) Major Airline 30% (8) National Airline 7% (2) Regional Airline 4% (1) Major Air Carrier (non passenger) 4% (1) Small (on demand) Air Carrier 0% (0) DSPs 33% (9) Deicing Service Provider (non airlines) 26% (7) Airport Authority 7% (2) Others 22% (6) Deicing Trainer 4% (1) Regulator/Government 11% (3) Other 7% (2) All Respondents 100% (27)

deicing process, for example, relocating frost deicing from remote deicing sites and central deicing facilities to on-gate deicing. Such a change may necessitate a capital expenditure for additional equipment, whereas the preliminary examina- tion assumed there would be no need for such an expense. Similarly, the preliminary examination assumed no change to deicing times and thus no effect on costs, whereas a relocation of the frost deicing from remote facilities to on-gate deicing may have a considerable effect on aircraft block times, which are high value factors. Thus the final model incorporated sev- eral parameters not included in the preliminary examination. Step 2: Cost-Benefit Model Development and Testing The cost-benefit model went through several iterations before the final version was completed. The various aspects of the model and its functionality are described below. Model Objective The objective of building the cost-benefit model was to cre- ate a model that can determine the number of years required to recoup the initial investment required to implement spot deicing for frost. The model does this by comparing the cost of current (standard) frost operations to the cost of frost spot deicing to determine the annual operational savings that will be gained, and then comparing the annual savings to the initial investment required to determine the number of years until the initial investment is recouped. Model Structure The model was developed as a Microsoft Excel workbook. There are five worksheets (or pages) in the workbook. The user works sequentially from the first page to the last page, following the instructions provided on the first page and at the bottom of each subsequent page. Specific instructions and/or comments for some cells are provided in notes attached to the cells. The content of each of the five pages is described below. Instructions: This page describes what the model will do, provides general instructions for using the model, and provides a disclaimer about the use of assumptions in the model. Background: This page requires user input. It contains a number of questions to assess the current operation and to determine how the future spot deicing operation will be conducted. Costs: This page also requires user input. The user is required to enter costs under four categories: capital costs (new equip- ment), set-up costs, fixed annual costs, and variable annual costs. Not all of the costs input cells are applicable to all oper- ations. The model categorizes the user’s scenario by when and how both standard deicing and spot deicing will take place (determined by user input on the background page) according to Table 42. For example, the cost to move frost deicing from a remote location to gates is not applicable for scenarios A, D, E, F and G. Therefore, “not applicable” appears in this cost input cell (L18) when the user fits into this scenario. The cost input cells that are not applicable to the user’s scenario are automatically filled with “not applicable.” Results: This page provides the results of the model analysis. The key results are the annual financial savings, annual glycol savings, and number of years to breakeven. Breakeven Schedule: This page shows the annual change in cash flow year by year. The key item on this page is the year that the initial investment (capital costs and setup costs) is paid off by the annual operational savings. User Inputs Required In order to complete the model, users must have the follow- ing information available: • Where and when standard/spot frost deicing are/will be performed; • Who (contractor or operator) performs/will perform standard/spot frost deicing; • The amount of glycol used annually for frost deicing; • The annual number of frost deicings conducted; • Whether new/different equipment will be required for spot deicing: • Cost of new equipment required for spot deicing*; • Cost of new access equipment for spot deicing inspector*; • Cost to gain in-house approval from all affected branches to proceed; 64 Table 42. User scenarios. Where/When Spot Frost Deicing Occurs Remote Location following scheduled departure Gate following scheduled departure Gate prior to scheduled departure Remote Location following scheduled departure A B C Gate following scheduled departure n/a D E W he re /W he n St an da rd F ro st D ei ci ng O cc ur s Gate prior to scheduled departure n/a F G

65 • Cost to develop, publish, and approve new procedures; • Cost to include new procedures in airline deicing program and get approval; • Cost to develop training materials for spot deicing; • Cost to move frost deicing from remote location to gate*; • For both standard and spot frost deicing: annual equipment maintenance costs and annual equipment operation costs; • Additional flight crew and ground crew training costs for spot deicing; • Contractor cost, block time cost, glycol cost, staff cost, inspector cost, and cleanup; and • Cost per deicing for both standard and spot frost deicing*. All inputs are not required in all scenarios. Model Output The primary output of the model is the number of years until initial investment is recouped (years to breakeven). The financial and glycol savings to be gained annually by imple- menting spot deicing for frost are also calculated. The annual financial savings are determined by: • Comparing the annual fixed costs of standard frost deicing only with the annual fixed costs of operating with a mix of standard and spot frost deicing to determine the annual fixed cost expense or savings; • Comparing the per-deicing variable cost of standard frost deicing only with the per-deicing variable cost of a spot frost deicing to determine the variable cost savings per spot frost deicing conducted; and • Multiplying the variable cost savings per deicing by the number of spot deicings that will be conducted (total annual frost deicings times percentage of frost deicings that will use a spot frost deicing procedure) and adding the annual fixed cost savings (or subtracting the annual fixed cost expense). The annual glycol savings are determined by: • Multiplying the annual glycol consumption by the addi- tional glycol required for a standard deicing relative to a spot deicing multiplied by the percentage of frost deicings that will use a spot frost deicing procedure. The years to breakeven are determined by: • Comparing the annual financial savings of implementing spot deicing for frost to the initial investment required (set- up costs and capital costs) and determining how many years it will take for the annual savings to pay for the initial investment. Model Testing The cost-benefit model was refined and validated through a testing process. The testing process involved running the devel- oped model through a variety of scenarios and situations cre- ated by inputting various parameter values representing both typical and extreme operations. This process confirmed that the model can provide reasonably accurate outcomes for a variety of situations and users. Findings and Applications The findings and applications of the work completed to examine the current practices and regulations, opportunities, limitations, obstacles, and potential benefits associated with the usage of spot deicing for frost removal are discussed in this section: • Findings of the literature review; • Results of laboratory tests; • Findings of the focus group survey; and • Application of findings to create cost-benefit model. Examination of Current Government and Industry Regulations, Guidance Material, and Standards Aircraft ground deicing procedures used by most North American air carriers are prepared by the airlines and are based on general guidance information contained in the appropriate aircraft manufacturer’s maintenance manuals, aircraft deicing industry documents, and regulatory guidance. Specific guide- lines for deicing are contained in SAE, AEA, FAA, International Civil Aviation Organization (ICAO), and Joint Aviation Authorities (JAA) documents. Of these documents, SAE ARP 4737 is the premier document and is referenced by all major air carriers internationally. SAE There are two SAE documents where guidance on spot deicing procedures may appear: ARP 4737 (Aircraft De/Anti- Icing Methods document) and ARP 5149 (Training Guide- lines for Deicing and Anti-Icing Aircraft on the Ground). At the time the literature review was conducted, there were no specific guidelines in either of the SAE documents that addressed procedures for spot deicing for frost removal. The general guideline in ARP 4737 for removal of frost and light ice, i.e., paragraph 6.1.2.2, simply stated: A nozzle setting giving a fan spray is recommended. NOTE: Providing that the hot fluid is applied close to the aircraft skin, a minimal amount of fluid will be required to melt the deposit.

However, at the May 21, 2009 meeting of the SAE G-12 Aircraft Ground Deicing Methods Subcommittee, the addi- tion of wording related to spot deicing was discussed. The fol- lowing proposed wording for paragraph 6.5 was agreed to by the subcommittee: For non-active frost limited to a small patch on the upper wing surface or horizontal stabilizer, and when no precipitation is falling or expected, ‘local area’ deicing may be carried out. Spray the affected area with a heated fluid/water mix suitable for a One-Step Procedure, and then spray the same area on the other wing. Both wings must be treated identically (same areas, same amount and type of fluid, even if the frost is only present on one wing. (Refer to aircraft manufacturers requirements for specific guidance) The trained and qualified person releasing the aircraft must visually check that the treatment was done symmetrically and that all frozen deposits have been removed, and then report the details of the treatment to the Flight Crew. CAUTION: Holdover times do not apply. Adoption and passage of the revised version of ARP 4737 (ARP 4737H) is anticipated prior to the start of the 2009–10 winter deicing season. AEA A specific AEA recommended procedure for spot deicing for frost is found in paragraph 3.9.1.3.2 of the AEA docu- ment, Recommendations for De/Anti-icing of Aircraft on the Ground: For frost limited to a small patch on the upper wing surface only, and when no precipitation is falling or expected, ‘local area’ deicing may be carried out. Spray the affected area with a heated fluid/water mix suitable for a One-Step Procedure, then spray the same area on the other wing. Both wings must be treated identically (same areas, same amount and type of fluid, same mixture strength), even if the frost is only present on one wing. The trained and qualified person releasing the aircraft must check that the treatment was done symmetrically and that all frozen deposits have been removed, and then report the details of the treatment to the Commander. CAUTION: Holdover times do not apply. FAA The FAA Ground Icing Research Lead participated in the survey discussed above and indicated the following position on spot deicing for frost removal: “currently spot deicing is not prohibited by the FAA; however it is not specifically encour- aged. Generally the FAA would expect the operator to follow instructions from the airframe manufacturer in the aircraft maintenance manual. . . .” Aircraft Manufacturers In performing spot deicing for frost removal, standard fluid application procedures are typically employed, in which a fan spray nozzle setting is used. Also, Type I fluids applied at a 60°C temperature (at the nozzle) are used extensively. Of the air car- riers that have adopted spot deicing for frost removal proce- dures, the survey indicated that this practice is performed on most current commercial aircraft, thus precluding the need for additional guidance from aircraft manufacturers. As an example, page 307, paragraph 9 of the Boeing Aircraft Maintenance Manual (AMM-12-33-01) for the B-737 600-900 series of aircraft states: The right and left side of the wing and the horizontal stabilizer must get the same ice removal/anti-icing treatment. a) If contamination exists only in a limited area (such as spoiler panel) and there is no active precipitation, it is per- mitted to deice only that area, but the same area should be treated on the other wing. Summary Although government and industry regulations, guidance material, and standards current at the time of the literature review did not appear to provide sufficient guidance for con- ducting spot deicing for frost removal, changes recommended to SAE ARP 4737, which are expected to be adopted for the winter 2009–10 operating season, should correct this defi- ciency. Changes in FAA and aircraft manufacturer guidance materials do not appear to be necessary. Laboratory Tests This section examines results of the laboratory tests from the perspectives of spot deicing for non-active frost (due to radia- tion cooling) and for active frost (due to cold-soaked surfaces). A detailed log of tests showing test variables and measured results is provided in Appendix E. Assessment of Frost Severity The test plates were allowed to accumulate frost for a one- hour period prior to conducting the spot deicing tests. The amount of frost on the plate at test time is of interest as the water content of the melted frost can trigger early freezing due to fluid dilution. To assess frost severity for non-active frost deicing, the frost amounts for the various test sets were simply com- pared, using the highest as the base case. The results shown in Table 43 indicate that test surfaces for test sets 3b, 3c and 5 had collected considerably more frost than for the other test sets. 66

67 To assess frost severity during the active frost tests, mea- sured frost rates were compared to rates proposed for frost testing in natural conditions. These rates were proposed in previous studies to determine test methodology for fluid endurance times in natural frost, and vary for different ambi- ent conditions. The results are shown in Table 44. Test 3b experienced a rate of frost generation much greater than proposed for standard testing as shown in Figure 24, while tests 1 and 2 were close to proposed standard test rates. Quantity of Fluid Needed to Remove Frost Results from both active and non-active frost tests generally indicated that 10 mL of fluid was not enough to cover and de- ice the entire surface plate area, 20 mL was barely enough, and 40 mL was sufficient to remove frost from test plate surfaces. Results for Spot Deicing in Non-Active Frost Forty (40) mL of fluid (0.011 U.S. gal) prepared at an 18°F (10°C) buffer and applied at 86°F (30°C) was of sufficient amount and strength to de-ice non-active frost surfaces. Most non-active frost test surfaces subjected to spot deicing with this fluid condition remained clean for the duration of the test (2.5 hrs). The shortest interval until refreezing was 115 minutes. Forty (40) mL of fluid on a test plate is equivalent to 0.27L/m2. The application of fluid at a minimum rate of 1⁄3 L/m2 (approximately 1⁄3 US quart per 10 ft2) could be used as a guide to field operations. The fluid should be applied at a temperature not less than 140°F (60°C) at the spray nozzle as this generally produces an on-wing fluid temperature of 86°F (30°C) due to cooling between nozzle and wing. Table 43. Assessment of frost severity for frost spot-deicing. Table 44. Assessment of frost severity for anti-icing in cold-soak conditions. Test Set Chamber Temp °F (°C) Test Surface Delta Temp °F (°C) Frost for Deice* (g/hr) Frost for Deice* (g/dm2/h) Ranking of Frost Accumulation (% of greatest amount) 1 -19.5 (-28.6) 32 (0) 1.1 0.09 0.24 2 2.1 (-16.6) 5.4 to 10.8 (3 to 6) 2.1 0.16 0.47 3 24.4 (-4.2) 3.6 to 5.4 (2 to 3) 1.4 0.11 0.31 3a 24.4 (-4.2) 1.8 to 7.2 (1 to 4) 0.5 0.04 0.11 3b 26.6 (-3.0) 12.6 to 19.8 (7 to 11) 3.8 0.29 0.84 3c 26.6 (-3.0) 7.2 (4) 4.5 0.35 1.00 4 13.5 (-10.3) 7.2 (4) 0.8 0.06 0.18 5 35.4 (1.9) 10.8 (6) 3.2 0.25 0.71 * Test surfaces were exposed to chamber conditions for one-hour prior to test to accumulate frost on test surfaces. Test Set Chamber Temp. °F (°C) Test Surface Delta Temp °F (°C) Anti-ice Test Rate (g/2.5hr) Anti-ice Test Rate (g/hr) Anti-ice Test Rate (g/dm2/h) Recommended Standard Test Rate* (g/dm2/hr) % of Standard Rate 1 -19.5 (-28.6) 32 (0) 2.1 0.84 0.07 0.08 81% 2 2.1 (-16.6) 5.4 to 10.8 (3 to 6) 3.6 1.44 0.11 0.13 86% 3 24.4 (-4.2) 3.6 to 5.4(2 to 3) 4 1.6 0.12 0.21 59% 3a 24.4 (-4.2) 1.8 to 7.2(1 to 4) 0.7 0.28 0.02 0.21 10% 3b 26.6 (-3.0) 2.6 to 19.8 (7 to 11) 10.9 4.36 0.34 0.23 147% 3c 26.6 (-3.0) 7.2 (4) 4.2 1.68 0.13 0.23 57% 4 13.5 (-10.3) 7.2 (4) 0.6 0.24 0.02 0.15 12% 5 35.4 (1.9) 10.8 (6) 3.2 1.28 0.10 0.28 35% * Recommended frost generation rate for Type I fluid tests; see Transport Canada report TP 14145E, Figure 4.10.

Results for Spot Deicing in Active Frost In this examination of endurance times for active frost with cold-soaked surfaces, the degree of cold soaking is indicated by the value of ΔT (surface temperature minus OAT). Of the eight test sets, only three experienced an active frost rate considered to be more than light frost (Table 44). Those test sets were 1, 2, and 3b. These three tests were examined to assess whether they are realistic representations of cold-soaked wing surfaces, and if so, the measured fluid endurance times were reviewed. Test 1 is not a realistic representation of cold soaking as the test surface temperature was essentially equal to OAT. Test 3b is not realistic due to its very large ΔT at −18°F (−10°C). This large ΔT resulted in very short endurance times. Test 2 is viewed as a good representation of active frost on cold-soaked wing surfaces. Its ΔT at −8.6°F (−4.8°C) falls within the range of ΔT values measured for previous cold- soaked wing studies, which generally identified a maximum ΔT of −12.6°F (−7°C). As well, the frost rate is close to that pro- posed for fluid endurance testing in natural frost. In Test 2, the endurance times differ by fluid strength: • For fluid strength at an 18°F (10°C) buffer, endurance times are in the order of mid-20 to mid-30 minutes, regardless of fluid quantity; and • For the standard mix, endurance times are about 1.5 hrs. Results from this test indicate that applying the spot deicing procedure to cold-soaked surfaces may not produce endurance times adequate to protect the aircraft surface until takeoff. The times produced by the 18°F (10°C) buffer fluid ranged from 24 to 36 minutes, considerably less than the current HOT guide- lines for Type I fluid for natural frost at 45 minutes. This result is of particular concern because more and more operators are introducing deicers equipped with on-board fluid blenders to enable the use of Type I fluids diluted to the 18°F (10°C) buffer. Based on the results from this single test, the spot deicing procedure should clearly indicate that it is not intended for application on cold-soaked surfaces. This test result also raises a question regarding the applica- bility of the current HOT frost guidelines to the condition of frost resulting from cold-soaked wings. The current fluid endurance test in natural frost is conducted on a special frost insulated plate that has been developed to represent wings sub- jected to heated fluid spray. The heat from the fluid raises the wing surface temperature, resulting in fluid enrichment due to evaporation and in a delay to frost initiation until the surface cools to below OAT. If the wing is cold-soaked with cold fuel, the additional heat sink would cause a quite different wing sur- face temperature response, and the same endurance times may not be produced. Focus Group Survey The detailed results of the focus group survey are provided question by question in Appendix F. For multiple choice ques- tions, the percentage of respondents selecting each response is listed. For most multiple choice questions, the responses are also additionally broken out by organization type (i.e., airlines, deicing service providers, others). Each and every response provided for the short answer questions and comments areas is provided. Some key findings from the survey include: • Approximately half of the survey respondents (48%) are familiar with the spot deicing for frost removal procedure; slightly fewer (43%) currently employ the procedure in their operations. • Spot deicing for frost was believed by the respondents to be one of the cheapest frost removal methodologies and also one of the most effective. • The majority of respondents (89%) were aware of the AEA guidelines for local wing frost removal. 57% indicate they already use a local wing frost removal methodology; 19% would consider using one; and 24% would not consider using one. • Of those respondents indicating they already use a local wing frost removal methodology: – Most (75%) use Type I fluid mixed to a 10°C buffer; the remainder (25%) use ready-to-mix Type I fluid for spot deicing; – All respondents (100%) indicated that the fluid used for spot deicing is maintained at 60°C; and – The majority (92%) apply fluid for spot deicing with a regular deicing vehicle. • Training, lack of qualified individuals to make assessments about its usage, and resulting risks to safety were identified as the key obstacles in employing spot deicing for frost removal. Lack of specific guidance in SAE ARP 4737 was also mentioned. 68 Figure 24. Simulation of a severe frost event on test plate surfaces.

69 • Respondents listed the need for symmetrical application and the need to follow AEA recommendations as the key restric- tions they impose or would impose on spot deicing. • The key benefits of spot deicing for frost removal were listed as: time savings, fluid savings, cost savings, and reduced environment impact. • Respondents believe a fluid savings of 30 to 60% could be achieved by employing spot deicing in place of conventional methods for frost removal. Percentage savings were seen to increase with aircraft size. • Respondents indicated that a spot deicing methodology would be less suitable at lower temperatures (86% indicated it would be suitable at 0°C or above; only 10% indicated suitability at below −25°C). • There was a general lack of knowledge and acceptance among the respondents of the frost polishing methodology for frost. Cost-Benefit Model The cost-benefit model is a user-friendly tool that can be used by operators to determine if switching from standard to spot deicing for frost removal is financially advantageous. The model will estimate the annual financial savings, annual glycol savings, and number of years until the initial investment has been recouped. The model was tested for different situations by inputting various parameter values representing typical and extreme operations. The model was refined and validated by this process. The final version of the model may be downloaded at the link found at http://apps.trb.org/cmsfeed/TRBNetProject Display.asp?ProjectID=122. When applied to typical airport conditions, the model out- put clearly shows the value of implementing spot deicing. In many cases, the financial outlay to implement spot deicing for frost removal can be recouped in a year or two. Sample Completed Model The figures here provide an example of running the cost- benefit model. Figure 25—Instructions Page: The user is not required to enter any information on this page. The page does not change from user to user. Figure 26—Background Page: The user has indicated on this page that (1) a contractor currently conducts standard frost deicing at a remote location following the scheduled departure time and (2) the operator will conduct spot frost deicing at the gate, prior to scheduled departure time. This cat- egorizes the scenario as a “scenario C” according to Table 42. The user has also indicated 2,400 frost deicings are conducted annually (using 400,000 liters of fluid) and spot deicing could be used for 50% of them. The default value of 40% glycol usage for spot deicing is selected, as is the need to purchase new equipment. Figure 27—Costs Page: The user has estimated the required costs on the costs page. In this scenario (scenario “C”), equip- ment operation and maintenance costs are not required for standard deicing, as standard deicing is performed by a con- tractor. For the same reason, staff, inspector, and cleanup costs per deicing are not required for standard deicing. Contractor costs are not required for spot deicing as the operator will be doing the operation. Finally, block time costs are not applica- ble for spot deicing, as it will be done prior to the scheduled departure time. Figure 28—Results Page: This page provides the results of the model analysis. It shows there is an annual fixed cost expense of $68,000 and cost savings of $530 per deicing if spot deicing for frost is implemented. The operator will save $568,000 and prevent 120,000 liters of fluid from entering the environment annually by implementing spot deicing. The initial investment required (setup costs and capital costs) will be recouped in the second year. Figure 25. Sample instructions page. INSTRUCTIONS To begin, go to the next page (Background) Welcome to the spot deicing for frost cost-benefit model. This model will calculate the number of years it will take to breakeven from the initial investment required to implement spot deicing. Instructions: Fill in all cells that are shaded blue, except those where "not applicable" is indicated. When you have filled in all cells on a page, follow the instructions that appear in red at the bottom of the page. Further comments/instructions are provided in some cells. These comments/instructions are indicated by red triangles that appear in the upper right corner of the cell and can be seen by hovering over the cell. Disclaimer: This model has been prepared by APS Aviation Inc. for the Transportation Research Board. The model makes several assumptions that may not be accurate in every business and/or operational environment. The user is recommended to conduct further analysis if required.

70 Figure 26. Sample background page. BACKGROUND QUESTIONS 1. Where/when is standard frost deicing performed? 2. Who performs standard frost deicing? 3. Where/when will spot frost deicing be performed? 4. Who will perform spot frost deicing? 5. How much glycol is used for frost deicing annually? 400,000 liters 6. How many frost deicings are conducted annually? 2,400 7. What percentage of frost deicings will use a spot frost deicing procedure? 50% 9. Relative to a standard frost deicing, how much glycol will be used for a spot frost deicing? 40% 8. Will new/different equipment (i.e. trucks) be required for spot deicing? yes This page is complete. Please go to the next page (Costs). At a remote location, following scheduled departure time At the gate, prior to scheduled departure time Contractor Operator Figure 29—Breakeven Schedule Page: This page shows the initial investment will be recouped in year two. This case study uses typical parameter values to examine the costs and benefits of relocating frost deicing from a remote cen- tral deicing facility to the gate. Even with the one-time capital costs for new deicing equipment, this examination shows cost- recovery within one year, and substantial operational savings thereafter. This is an interesting situation, involving a significant reduction in aircraft block time and engine run time. For this operator, using a spot deicing procedure for frost deicing is a financially sound and environmentally advantageous decision. Conclusions, Recommendations, and Suggested Research The conclusions, recommendations, and suggested research resulting from this task are provided in this section. Conclusions The review of current government and industry regulations, guidance material, and standards related to spot deicing for frost removal found that: • Changes to FAA and aircraft manufacturer guidance mate- rials were not required; and • SAE ARP 4737, the premier document referenced by all major air carriers nationally and internationally for aircraft de/anti-icing methods, was lacking guidance material related to spot deicing for frost removal. However, changes to ARP 4737 were proposed and accepted at the May 2009 meeting of the SAE G-12 Aircraft Ground Deicing Methods Subcom- mittee. These changes are expected to be adopted for the 2009–10 winter operating season, and should provide ade- quate guidance for operators wishing to implement spot deicing for frost removal. Experimental tests were conducted to quantify the required amount, strength, and temperature of fluid to conduct spot deicing for frost operations. The following conclusions were drawn from the tests: • The application of fluid at a minimum rate of 1⁄3 L/m2 (approximately 1⁄3 quart per 10 ft2) can be used as a guide to field operations; • Application of fluid mixed to an 18°F (10°C) freeze point buffer is adequate for the spot deicing application; • The fluid should be applied at a temperature not less than 140°F (60°C) at the spray nozzle; • Unless further testing is conducted and proves otherwise, spot deicing should be used only for non-active frost condi- tions; and • Additional testing with positive results would be needed before spot deicing could be approved for active cold-soak frost deicing. A group of key individuals from the deicing industry were surveyed to gather a more thorough and detailed

71 CAPITAL COSTS - NEW EQUIPMENT a) Cost of new equipment required for spot deicing 500,000$ b) Cost of new access equipment for spot deicing inspector 200,000$ FIXED COSTS - ONE TIME SETUP COSTS a) Cost to gain in-house approval from all affected branches to proceed 2,000$ b) Cost to develop, publish and approve new procedures 2,000$ c) Cost to include new procedures in airline deicing program, get approval 3,000$ d) Cost to develop training materials for spot deicing 5,000$ e) Cost to move frost deicing from remote location to gate 5,000$ FIXED COSTS - ANNUAL Costs for standard frost deicing : a) Equipment maintenance costs (annual) not applicable b) Equipment operation costs (annual) not applicable Costs for frost deicing if spot deicing implemented (assume mix of standard/spot operations) : a) Equipment maintenance costs (annual) 5,000$ b) Equipment operation costs (annual) 15,000$ c) Additional flight crew training costs employees 50 x cost per employee 800$ 40,000$ d) Additional ground crew training costs employees 40 x cost per employee 200$ 8,000$ VARIABLE COSTS Costs for standard frost deicing : a) Contractor cost (per deicing) 200$ b) Block time costs (per deicing) 400$ c) Glycol cost (per deicing) liters 200 x cost per liter 4$ 800$ d) Staff cost (per deicing) not applicable e) Inspector cost (per deicing) not applicable f) Cleanup cost (per deicing) not applicable Costs for spot frost deicing : a) Contractor cost (per deicing) not applicable b) Block time costs (per deicing) not applicable c) Glycol cost (per deicing) liters 80 x cost per liter 4$ 320$ d) Staff cost (per deicing) 100$ e) Inspector cost (per deicing) 100$ f) Cleanup cost (per deicing) 350$ This page is complete. Please go to the next page (Results). Figure 27. Sample costs page.

understanding of the industry’s perceptions and current usage of diluted fluids. Key findings are: • Although a reasonable number of operators are currently using spot deicing, there are many operators who are not familiar with this methodology for frost removal. • Spot deicing is seen to be a cheap and effective methodology for frost removal. Cost and fluid and time savings are notable benefits of spot deicing compared to conventional deicing. Fluid savings are estimated to be between 30 and 60%. • Spot deicing for frost removal is currently being employed using Type I fluid mixed to a 10°C buffer heated to 60°C and applied using a regular deicing vehicle. • Training, lack of qualified individuals to make assessments about its usage, and asymmetrical application resulting in risks to safety, were identified as the key obstacles in employ- ing spot deicing for frost removal. • The methodology was seen to be more suitable for opera- tions at warmer temperatures. A cost-benefit model was developed for use by operators to determine if making a switch from standard to spot deicing for frost removal would be financially advantageous for their oper- ation. The model estimates the annual financial savings, annual glycol savings, and number of years until the initial investment has been recouped. When applied to typical airport conditions, the model output clearly shows the value of implementing spot deicing. In many cases, the financial outlay to implement spot deicing for frost removal can be recouped in a year or two. If implementation of spot deicing enables relocation of the defrosting activity from remote sites to passenger terminal gates, very significant benefits can be achieved in reduced oper- ating costs, improved on-time performance, and reduced envi- ronmental impact from spent fluid and from carbon emissions due to fuel burn. Recommendations The following recommendations resulted from the work conducted for the spot deicing for frost removal task: • Although it does not appear to be required in order for operators to implement spot deicing for frost removal, it is recommended that the regulatory authorities (FAA and 72 RESULTS Fixed Costs of Frost Deicing (per winter season) Using Standard Deicing Only $0 Using Mix of Spot and Standard Deicing $68,000 Cost Savings from Implementing Spot Deicing -$68,000 Variable Costs of Frost Deicing (per operation) Using Standard Deicing Procedure $1,400 Using Spot Deicing Procedure $870 Cost Savings from Implementing Spot Deicing $530 Impact of Implementing Spot Deicing (per winter season) * Financial Savings $568,000 Glycol Savings 120000 liters Initial Investment Required to Implement Spot Deicing Set-up Costs $17,000 Capital Costs $700,000 Winter Seasons to Breakeven 2 See next page (Breakeven Schedule) for further details *Assumes: 2400 frost deicings conducted annually; 50% of frost deicings use spot procedure; and spot deicing procedure uses 40% of the glycol of a standard procedure. Figure 28. Sample results page.

73 TC) incorporate appropriate spot deicing for frost removal clarification/guidance information in the annual FAA- Approved Deicing Program Updates (Notice 8900.xx) and the Transport Canada Guidelines for Aircraft Ground Icing Operations (TP 14052). • It is also recommended that the AEA harmonize language contained in paragraph 3.9.1.3.2 of the AEA De/Anti-icing Recommendations Document to agree with the new word- ing of paragraph 6.5 of ARP 4737. (These changes are deemed to be minor editorial changes.) • It is recommended that spot deicing be applied only to non- active frost resulting from natural frost generation. • As part of this project, a cost-benefit model and presenta- tion aids were developed (see Appendix G) to assist air- lines and deicing service providers to better understand the benefits of employing spot deicing for frost in their operations. The cost-benefit model will also assist users by forecasting the financial benefits of employing spot deic- ing and a promotional campaign be implemented to mar- ket these tools. Suggested Research The application of current Type I fluid HOT guidelines to de/anti-icing frost from surfaces subjected to cold soaking should be examined to ensure suitability as the large cold-sink presented by the mass of cold wing structure and cold fuel may decrease the fluid endurance time. BREAKEVEN SCHEDULE Winter Season Capital Costs Setup Costs Operational Savings Total Savings Lifetime Savings Breakeven Year 1 $700,000 $17,000 $568,000 -$149,000 -$149,000 no 2 n/a n/a $568,000 $568,000 $419,000 yes 3 n/a n/a $568,000 $568,000 $987,000 reached prior 4 n/a n/a $568,000 $568,000 $1,555,000 reached prior 5 n/a n/a $568,000 $568,000 $2,123,000 reached prior 6 n/a n/a $568,000 $568,000 $2,691,000 reached prior 7 n/a n/a $568,000 $568,000 $3,259,000 reached prior 8 n/a n/a $568,000 $568,000 $3,827,000 reached prior 9 n/a n/a $568,000 $568,000 $4,395,000 reached prior 10 n/a n/a $568,000 $568,000 $4,963,000 reached prior 11 n/a n/a $568,000 $568,000 $5,531,000 reached prior 12 n/a n/a $568,000 $568,000 $6,099,000 reached prior 13 n/a n/a $568,000 $568,000 $6,667,000 reached prior 14 n/a n/a $568,000 $568,000 $7,235,000 reached prior 15 n/a n/a $568,000 $568,000 $7,803,000 reached prior 16 n/a n/a $568,000 $568,000 $8,371,000 reached prior 17 n/a n/a $568,000 $568,000 $8,939,000 reached prior 18 n/a n/a $568,000 $568,000 $9,507,000 reached prior Figure 29. Sample breakeven schedule page.

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TRB’s Airport Cooperative Research Program (ACRP) has updated Report 45: Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids provides guidance on procedures and technologies designed to help reduce the use of aircraft deicing and anti-icing fluids (ADAF) while maintaining safe aircraft operations across the wide range of winter weather conditions found in the United States and Canada.

The report includes a series of best management practices that have the potential to be immediately implemented, and highlights the detailed findings and recommendations of experiments to evaluate holdover time determination systems, spot deicing for aircraft frost removal, and ADAF dilutions.

In 2016, the 16 Fact Sheets were reviewed to assess if they reflected current technologies and practices in the industry. That review resulted in updates to Fact Sheets 45, 55, and 56, and the creation of a new Fact Sheet 112. describing promising technologies and procedures from Chapter 2, in the form of readily implementable best management practices.

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