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

Chapter: Chapter 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions

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Suggested Citation:"Chapter 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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 5 - Increased Use of Aircraft De/Anti-Icing Fluid Dilutions." 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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74 Introduction This part of the report documents the task that examined the use of aircraft de/anti-icing fluid dilutions. Background Industry Use of 10°C Type I Fluid Buffer SAE ARP 4737 states that Type I fluids used for either one- step de/anti-icing or as the anti-icing fluid in a two-step oper- ation must have a FFP at least 10°C (18°F) below the ambient temperature. Type I fluid holdover times are measured using fluids mixed with water to this FFP. In the past, the general industry practice when de/anti-icing with Type I fluid had been to apply Type I fluid at the standard, as-delivered fluid concentration, typically a 50/50 (50% water/50% glycol) or a 55/45 mix. Other specific mixes such as 60/40 are available from fluid manufacturers. These special mixes are selected to provide optimum FFP performance at colder temperatures and are usually based upon prior climatic records of prevail- ing OATs at a given airport. Although Type I fluid mixes are required to have only a 10°C buffer, the Type I fluid 50/50 mixes typically have FFP well below the required 10°C buffer for most prevailing temperatures during aircraft deicing oper- ations. This practice results in dispensing much more glycol content than is necessary, and could lead to unnecessary oper- ational costs and increased stress on the environment. Cur- rently, this trend is being reversed and many airlines that perform their own deicing and many deicing service providers (DSPs) have converted to the use of deicing equipment with proportional blending capabilities. In the recent past, deicer manufacturers have incorporated fluid blending systems into their deicing units that blend Type I fluid with water. In addition, at major hubs where a signifi- cant number of de/anti-icing operations are carried out annu- ally, such as Pittsburgh and Denver, the trend has been to install pedestal mounted deicing equipment that are supplied fluid mixes from remote blending systems with large storage capabilities. Broad application of such systems to dispense Type I fluid at the approved 10°C fluid freeze point buffer reduces the amount of glycol dispensed in Type I operations. Industry Use of Type II, III, and IV Fluids Mixes Type II, III, and IV anti-icing fluids are available at fluid con- centrations of 100/0, 75/25, and 50/50. Fluid holdover times are derived from endurance time test results measured using fluid mixed to these concentrations. Some 75/25 fluid concen- trations have published holdover times similar to 100/0 fluids. Also, most 50/50 anti-icing fluids have holdover times in excess of Type I fluids. Despite the opportunity to employ lower concentrations of Type II, III, and IV fluids, anti-icing opera- tions in North America use 100/0 Type IV fluid concentrations almost exclusively. As a result, there is considerable opportu- nity to reduce the amount of glycol dispensed by applying these fluids at lower, already approved concentrations. Objective The objective of this task was to examine current practices and regulations related to the increased use of fluid dilutions and to document the opportunities, limitations, obstacles, and potential benefits associated with their use. The objective was met by completing the following work elements: • Conduct a literature review of current government and industry regulations, guidance material, and standards to document current industry regulations and practices related to the use of fluid dilutions; • Conduct phone interviews with DSPs and airlines; • Conduct a survey to gather pertinent information from a wider audience, including airlines, DSPs, deicing consult- ants, deicing instruction facilities, and regulators; C H A P T E R 5 Increased Use of Aircraft De/Anti-Icing Fluid Dilutions

• Identify if changes to any industry standards and/or rec- ommended practices are required and supporting the changes and/or development of guidance material as nec- essary; and • Develop a cost-benefit model and presentation aids to influence and aid decision makers. Research Approach and Methodologies This section presents the research approach and method- ologies employed to examine the current practices and reg- ulations, opportunities, limitations, obstacles, and potential benefits associated with the usage of diluted aircraft de/ anti-icing fluids. Examination of Current Government and Industry Regulations, Guidance Materials, and Standards Related to the Use of Fluid Dilutions A literature review was conducted of current government and industry regulations, guidance material, and standards related to the use of fluid dilutions to identify if there is a need for changes or further approvals to accommodate the use of fluid dilutions. The documents that were reviewed included: • SAE guidelines in SAE ARP 4737 that address procedures for the application of Type I, II, III, and IV fluids in both one- step and two-step de/anti-icing procedures; • Various regulatory, government and industry documenta- tion, guidance material, and standards; and • Holdover time guidance material and documentation pub- lished annually by TC, AEA, and the FAA. All documents reviewed are referenced in Appendix A. Focus Group Survey Preliminary phone interviews were conducted with several DSPs (Integrated Deicing Systems and Contego Systems), sev- eral airlines (Alaska, US Airways, and North West), a major freight hauler (FedEx), and the FAA to examine current trends and practices associated with the use of dilutions and to ascer- tain the current extent of its usage. The replies were quite var- ied. The replies covered a realm of knowledge and activities. Some of the answers are quoted below. • “We don’t have equipment with proportional blending capabilities.” • “We have equipment with proportional blending capability, however we use a ready mix Type I most of the time.” • “We use the older conventional deicing equipment with two tanks at our regional sites.” • “We don’t use pre-mixed Type I fluid. The average mixture rate of Type I fluid loaded on the equipment which has no proportional mixing system is 30%. We always use Type IV undiluted fluid for the second step.” 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 quantify the amount of de/anti-icing fluid used during the de/anti-icing of an aircraft in different precipitation con- ditions on select aircraft types; • To determine if current regulations are perceived to be ade- quate to allow use of fluid dilutions; • To determine the extent that heated water is being used for deicing by the industry; • To determine the extent that diluted fluids (Type I/II/III/IV) are being used by the industry; • To determine which factors influence decisions to use ready- to-use mix Type I fluids rather than Type I fluids mixed to appropriate buffers; • To determine which factors influence decisions to use concentrated Type IV fluids rather than dilute Type IV fluids; • To determine what levels of fluid freeze point buffers are being used; • To evaluate the use of proportional blending systems; and • To determine whether use of fluid dilutions is different at regional airports compared to major/hub airports. Composition of Focus Group The focus group included individuals from a number of organizations, including DSPs, passenger airlines of vary- ing 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 75

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 24 multiple choice and short answer questions. The final question was an optional open-ended ques- tion 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 B. 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 was used to set up the surveys to ask respondents only those questions that were applicable to their organization type (the first question ascertained their organization type). A matrix showing the questions that were asked to each organi- zation type is included in Appendix B. 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 fluid dilution survey was sent to 38 focus group mem- bers. Twenty-four individuals (63%) completed the survey. Table 45 shows a breakdown of respondents by the type of affil- iated organization. Results The survey results are discussed under Findings and Applications. The detailed survey results are provided in Appendix C. 76 Table 45. Survey respondents by affiliated organization type. Airlines 45% (11) Major Airline 33% (8) National Airline 4% (1) Regional Airline 4% (1) Major Air Carrier (non passenger) 4% (1) Small (on demand) Air Carrier 0% (0) DSPs 25% (6) Deicing Service Provider (non 25% (6) Airport Authority 0% (0) Others 29% (7) Deicing Trainer 8% (2) Regulator/Government 13% (3) Other 8% (2) All Respondents 100% (24)

Cost-Benefit Model A cost-benefit model was developed to assist operators in determining whether incorporating diluted fluids into their operations would be financially advantageous. Development of the cost-benefit 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 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 assessment of potential savings by aircraft type, and an estimate of the number of deicing events necessary in order to recoup the investment. The preliminary assessment showed that use of fluid dilutions may be cost beneficial depending upon the cost of deicing equipment, cost of fluid, and the num- ber of deicing operations per season. 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 costs for purchasing different fluid blends are docu- mented, as well as supplemental capital costs for proportional blending systems, and operational costs for additional training and maintenance. The examination discusses typical fluid amounts dispensed for various aircraft types. Use of these parameter values 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 given in the following list: 1. Deicing equipment with proportional blending versus conventional equipment; 2. Cost of aircraft de/anti-icing fluids; 3. Additional training of deicing personnel; 4. Additional inspection requirements; 5. Additional training documentation; 6. Additional training for the flight crew; 7. Additional maintenance requirements; 8. Environmental concerns—savings; 9. Savings in de/anti-icing time; and 10. Preliminary estimate of cost/fluid savings using dilutions. In the examination of potential parameters, it was con- cluded that there is no need for additional inspections or for additional flight crew training. Time taken for deicing and anti-icing is not affected by the use of dilute fluid, so that parameter was also excluded. Finally, whereas there may be a quantitative value associated with reduced environmental impact of lower glycol usage, this is not a factor lying within the potential user’s financial budget, and thus this factor was also eliminated from the model development. The remaining six parameters on the list were incorporated into the cost-benefit model. 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 model was built to determine the financial and glycol costs/savings that operators could achieve by incorporating diluted fluids into their operations. The model evaluates two potential changes: 1. Switching from Type I ready-to-use fluid to buffer fluid; and 2. Switching from Type II/III/IV neat fluid to a combination of neat fluid and diluted fluids. The model can be used to evaluate the impact of a Type I change alone, a Type II/III/IV change alone, or the impact of changing both Type I and Type II/III/IV fluids. Model Structure The model was developed as a Microsoft Excel workbook. There are six 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 six pages is described below. Instructions: This page describes what the model will do, provides general instructions for using the model, describes some of the assumptions in the model, and provides a dis- claimer about the use of the model. Assumptions: This page lists the assumptions used in the model. The user is able to alter several default values on this page. 77

Background: This page requires user input. It contains a number of background questions. These questions determine if the model will be used for Type I fluid, Type II/III/IV fluid, or both. They also determine variables unique to the user and their current operation. Costs: This page also requires user input. The user is required to enter costs involved in making the change or changes to the type of fluid being used. There are four cost categories: capital costs, one time set-up costs, annual fixed costs, and variable costs. 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 plus one time set-up costs) is paid off by the savings in fluid consumption. User Inputs Required In order to complete the model, users must have the follow- ing information available: • Operations per winter season at different temperature ranges (for the fluid type or types that will be considered by the model); • Average amount of fluid used per winter season (for the fluid type or types that will be considered by the model); • Glycol percentage in currently used fluid(s); • Price of currently used fluid(s); • Price of fluid(s) to be used in diluted operation. Net cost of new equipment required to implement a diluted fluid oper- ation, i.e., blending and storage equipment; • Set-up costs, including: cost to gain in-house approval from all affected branches to proceed; cost to develop, publish, and approve new procedures; cost to include new proce- dures in airline deicing program and get approval; and cost to develop training materials; • Cost of additional annual training that will be required for ground crews; and • Additional maintenance costs for blending/storage equip- ment. Assumptions Used in the Model The model makes several assumptions in its calculations. Some of these assumptions are stated up front, some are user controlled, and some reside within the formulae in the work- book. The assumptions are listed on the assumptions page and described here: 1. If the user indicates a switch to a Type I buffer fluid and/or a diluted Type II/III/IV fluid is being considered, the model assumes the user is currently using a Type I ready- to-use and/or a Type II/III/IV neat fluid. 2. The model assumes if a switch is made to diluted Type I buffer fluid, all Type I fluids will be diluted to a selected buffer, even fluids used in the first step of a two step operation. 3. As glycol recovery costs are typically assessed on the amount of fluid, not glycol dispensed, no savings for gly- col recovery costs were built into the model. 4. The model makes no distinction between Type II, Type III, and Type IV fluid. This was done as most stations have only one of these fluid types available. 5. The model does not include a factor for inflation, nor does it include a calculation to determine current value of future cash flows. This is relevant to the breakeven analysis. 6. In the glycol savings calculation, it is assumed that Type I concentrate is 100% glycol. 7. The percentage concentrate of Type I fluid required to achieve a specific FFP is assumed to be the same for all Type I fluids (the percentages used in the model are the average values of twelve Type I fluids), even though small differ- ences are known to exist, specifically between propylene and ethylene based fluids. 8. The default FFP buffer for Type I fluids is 10°C. The user can modify the buffer to 15°C or 20°C on the assumptions page. 9. Assumptions were made in the calculation of fluid savings. These are described in detail in the following sections. Calculation of Type I Fluid Savings Several assumptions had to be made in order to estimate the amount of concentrate Type I fluid that would be required for diluted fluid operations. This section describes these assump- tions and the specific calculations that are used in the model. To calculate the volume of Type I concentrate required to produce the volume of Type I ready-to-use fluid currently used annually, three figures are required: • The volume of fluid required at each OAT; • The required FFP for each OAT; and • The percentage concentrate of fluid required to achieve the required FFPs for the OATs. To determine the volume of fluid required at different OATs, the user-entered data for annual number of operations at specific temperature ranges and the total amount of Type I fluid used per season were compared to determine the volume of fluid required in each temperature range. The lowest OAT in the range was assumed to be the OAT for all operations in the range. The FFP required for each OAT is determined by the FFP buffer selected. The default value in the model is a 10°C buffer, 78

but a 15°C or 20°C buffer can also be selected. For example, if the OAT is −3°C and a 10°C buffer is required, the fluid must have a FFP of −13°C. The percentage concentrate required for each FFP was determined using a FFP curve developed using FFP—fluid concentrate content data collected for 12 Type I fluids. The data for the 12 fluids are shown in Table 46. The percentage concentrate required for each FFP was then multiplied by the volume of fluid required at each FFP to deter- mine the annual volume of Type I concentrate required. For example, if 2000 liters of ready-to-use fluid are used in opera- tions at −15°C, then 2000 liters of fluid with a FFP of −25°C are required for a 10°C buffer operation. Since the average amount of concentrate required for a FFP of −25°C is 48%, the model will calculate 960 liters of concentrate (2000 L × 48%) are required to produce 2000 liters of Type I fluid at the appropri- ate FFP. Calculation of Type II/III/IV Fluid Savings Several assumptions had to be made in order to estimate the amount of neat Type II/III/IV fluid that would be required for diluted fluid operations. This section describes the assumptions and the specific calculations that were used in the model. To calculate the amount of neat fluid required for a Type II/III/IV diluted fluid operation, two figures are required: • The volume of fluid required at different OATs; and • The percentage of operations that will use neat, 75/25, and 50/50 fluid at each OAT. The volume of fluid required at different OATs is derived from the user-entered data for annual number of opera- tions at specific temperature ranges and the total amount of Type II/III/IV fluid used per season. The percentage of operations that use neat, 75/25 and 50/50 fluid at each OAT has to be estimated. The model uses the default values show in Table 47, but these values can be changed by the user on the assumptions page. The default val- ues were set based on consultations with several individuals responsible for operations currently using diluted fluids. To calculate the volume of neat fluid required for the diluted fluid operation, the volume of fluid required at each OAT is divided into the volume of fluid of each dilution. The volume of neat fluid required can then be calculated. For example, based on the usage information provided in Table 47, if 10,000 liters of fluid are required in the “< −3 to −6°C” temperature range, 50% of these operations would use neat fluid (50% × 10,000 liters × 100% = 5000 liters neat fluid required) and 50% would use 75/25 fluid (50% × 10,000 liters × 75% = 3750 liters neat fluid required) for a grand total of 8,750 liters neat fluid required (5000 + 3750 liters). Model Output The primary outputs of the model are the annual financial and glycol savings to be gained by implementing the selected changes in fluid use. The number of years until the initial investment is recouped (years to breakeven) is also calculated. The annual financial savings are determined by: • Calculating the annual savings in fluid costs by comparing the cost of fluid in the current operation (volume of fluid required in the current operation × price of current Type I ready-to-use and/or Type II/III/IV concentrate fluid) to the cost of the fluid in a diluted operation (volume of concen- 79 Concentrate Required for FFP FFP (°C) Fluid A Fluid B Fluid C Fluid D Fluid E Fluid F Fluid G -9 28% 26% 27% 28% 25% 26% 27% -13 32% 34% 35% 35% 30% 33% 33% -16 n/a n/a n/a 38% 35% 36% 37% -20 43% 44% 45% 43% n/a 41% 42% -25 n/a n/a 50% 50% n/a 48% 47% -30 n/a n/a n/a 53% 48% n/a 51% -35 57% 59% 59% n/a 55% n/a 55% -40 n/a n/a n/a 60% n/a 60% 58% Concentrate Required for FFP FFP (°C) Fluid H Fluid I Fluid J Fluid K Fluid L 12 Fluid Average -9 21% 28% 28% 31% 20% 26% -13 27% 35% 35% 35% 27% 33% -16 32% 40% 40% 38% 32% 36% -20 36% 45% 45% 43% 38% 42% -25 42% 53% 51% 48% 44% 48% -30 46% 58% 56% 53% 49% 52% -35 50% 63% 62% 57% 54% 57% -40 55% 68% 67% 60% 58% 61% Operations Using Each Fluid DilutionOAT Range Neat 75/25 50/50 > 0°C 0% 50% 50% < 0 to -3°C 25% 50% 25% < -3 to -6°C 50% 50% 0% < -6 to -10°C 75% 25% 0% < -10 to -15°C 100% 0% 0% < -15 to -20°C 100% 0% 0% < -20 to -25°C 100% 0% 0% < -25°C 100% 0% 0% Table 46. Concentrate required to achieve Type I FFPs. Table 47. Operations (%) using different Type II/III/IV fluid dilutions at given OAT ranges.

trate fluid required in a diluted operation × price of new Type I concentrate and/or Type II/III/IV concentrate); and • Subtracting the additional annual fixed costs. The annual glycol savings are determined by: • Type I: Subtracting the liters of concentrate fluid required in the diluted operation (concentrate is assumed to be 100% glycol) from the liters of glycol required in the current oper- ation (liters ready-to-use fluid required × glycol percentage in ready-to-use fluid); and • Type II/III/IV: Subtracting the liters of neat fluid required in the diluted operation from the liters of neat fluid required in the standard operation and multiplying by the glycol per- centage in the neat fluid. The years to breakeven are determined by: • Comparing the annual financial savings to the initial invest- ment required (set-up costs plus capital costs) and deter- mining 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 diluted aircraft de/anti-icing fluids are addressed in this section. Examination of Current Government and Industry Regulations, Guidance Material, and Standards Related to the Use of Fluid Dilutions Adequacy of Current Regulations Specific guidelines in SAE ARP 4737 address procedures for the application of Type I, II, III, and IV fluids in both one-step and two-step de/anti-icing procedures. These general guide- lines are also contained in the guidance documents published annually by TC, the FAA, and the AEA. The TC documents are provided in Table 48 (SAE Type I Deicing Fluid Application Procedures) and Table 49 (SAE Type II, Type III, Type IV Anti- icing Fluid Application Procedures) for reference. These tables are taken from the Transport Canada Holdover Time Guide- lines and are very similar to the tables in the SAE ARP 4737, FAA, and AEA guidance materials. Results from the survey indicate that both airlines and DSPs feel the information contained in these tables pro- vides adequate guidance for the use of fluids and their dilu- tions. Neither group recommended changes to the guidance material. However, deicing trainers and others expressed the need for a possible modification, with the objective of encouraging greater use of fluid dilutions. This possible modification could be summed up in a direct quote from one respondent: The FAA and Transport Canada could add more language not necessarily to regulation CFR 14 121.629, or the Canadian equiva- lent, but perhaps to TP 14052, AC 120-60, or any annual guidance published by either regulator. Language could be included to encourage dilutions, and examples provided showing that dilutions are not as difficult to accomplish as perceived by numerous deicing entities. The AEA Deicing recommendations could employ a sim- ilar strategy. Since ARP 4737 is a recommended practice, language again could be added to better show the merits of more closely fol- lowing FPD buffers instead of always using 50/50, or some other concentration where the buffer is much larger than needed. Implication of the Availability of Diluted Fluid Holdover Times Documents related to endurance time testing and the deter- mination of holdover times were reviewed as part of the liter- ature review. Type I holdover times have been derived from endurance time tests with various fluids mixed to a 10°C buffer (i.e., the fluids are applied at a concentration such that the freezing point of the fluid is at least 10°C below that ambient tempera- ture). The temperature and quantity of fluid applied in these tests is such that it replicates typical application of fluid on air- craft. In the course of the testing to develop these holdover times, associated research was conducted to compare the endurance times of fluids applied at a 10°C buffer versus fluid applied at standard 50/50 mixes which had more glycol. The research showed that the extra glycol 50/50 mixes did not pro- vide significant endurance time benefits; generally, it was found that the heat from the fluid was a greater contributor to holdover times than the additional glycol. This result was also found to be true when research was conducted to examine the use of negative buffers that can be used for the first step of a two-step application. This research is documented in a TC Report TP13315E, Aircraft Deicing Fluid Freeze Point Buffer 80

Requirements: Deicing Only and First Step of Two-Step Deicing, and in TP14714E, Evaluation of Fluid Freeze Points in First-Step Application of Type I Fluids. Type II/III/IV fluid holdover times are derived from endurance time tests of fluids that are in pre-set concentra- tions: these are 100/0, 75/25, and 50/50. What is interesting with Type II/III/IV fluids is that in many cases the holdover times of the 75/25 fluids are equivalent to the holdover times of the 100/0 fluids; in a few cases the holdover time of the 75/25 dilution is slightly higher. Many fluids are designed such that the viscosity is higher at the 75/25 dilution than the viscosity at the 100/0 dilution; this fluid design characteristic provides the enhancement in the holdover times of the 75/25 dilution. Type I and Type II/III/IV fluid holdover times have been developed at the concentrations that are described above. From a safety perspective, the holdover times are suitable for use with the described dilutions. The enhancement in holdover time is not significant as a result of using richer glycol mixes of Type I fluid nor when using a 100/0 mix of Type II/III/IV fluid versus a 75/25 mix. It can thereby be concluded that fluid dilu- tions provide an opportunity to reduce glycol without a signif- icant loss of holdover time. Findings of the Focus Group Survey The detailed results of the focus group survey are pro- vided question by question in Appendix C. For multiple choice questions, the percentage of respondents selecting each response is listed. For most multiple choice questions, the responses are also additionally broken out by organiza- tion type (i.e., airlines, DSPs, others). Each response pro- vided for the short answer questions and comment areas is provided. 81 Table 48. SAE Type I deicing fluid application procedures. Source: Table 6 of TC Holdover Time Guidelines

Some key findings from the survey include: • De/anti-icing fluid use varies considerably from an approx- imate average of 100 liters for frost removal on a small turbo-prop transport to 1,500 liters for an operation in light freezing rain on a super jet transport. • The majority of respondents (75%) feel that the current guidance material is adequate for conducting operations with diluted fluids. • The top five factors given for influencing use of fluid dilu- tions were: fluid storage requirements, prevailing OAT during the winter deicing season, cost of fluid, cost of blending equipment, and replacement cost of modern deicing equipment. • Of all anti-icing fluid types (Type II/III/IV) and dilutions (100/0, 75/25, 50/50) available, Type IV fluid 100/0 is used almost exclusively; diluted Type II/III/IV fluids are not com- monly used. 82 Table 49. SAE Type II, Type III, Type IV anti-icing fluid application procedures. Source: Table 7 of TC Holdover Time Guidelines

• Ready-to-use Type I fluid is the most common form of Type I fluid used; 65% of Type I fluid use reported by respondents was with ready-to-use fluid rather than fluid mixed to spe- cific FFP buffers. • The majority (85%) of respondents do not use Type II, III or IV fluid mixes for one-step procedures. • Of the respondents having proportional blending equip- ment, a 10°C buffer was most commonly used for Type I fluids. • The majority of respondents (82 to 88%) do not use hot water for deicing as the first step in a two-step procedure, regardless if Type I fluid or Type II/III/IV fluid is used for the second step; nor do they use hot water for defrosting operations. • Most operations at non-hub airports do not make use of diluted fluids. The survey results are discussed further in the next section. Application of Findings to Current Practice The combined findings of the literature review, phone interviews, and focus group survey are examined in this sec- tion as they relate to current practices. Extent of Use of Fluid Dilutions Of all survey respondents, 65% use a ready-to-use Type I fluid mix such as 50/50 or 55/45, and 76% use a Type II or Type IV 100/0 fluid mix. No respondents indicated current use of a Type III fluid mix at this time. For Type I fluid applications, the extent of use of a 10°C buffer and a 10 to 20°C buffer were about equal. A small per- centage indicated use of a buffer of 30°C or higher: no expla- nation was given for the use of this high buffer. A large number of airline respondents were unsure as to the extent of use of high buffer fluids; presumably this is due to operations per- formed for them by DSPs. Of those respondents who had Type I fluid proportioning equipment installed on deicers, 25% applied first-step deicing fluid with a FFP buffer of −3°C, while 41% used fluid with a FFP buffer of 10°C. For the same operators, 55% of anti-icing with Type I fluid was performed with a 10°C buffer. Interviews indicated that airports with limited facilities, milder temperatures, or both use Type I mixes for anti-icing. The main use of Type II and Type IV blends was for defrosting related activities. Over 85% of the airlines and DSPs interviewed do not use Type II, III or IV fluid mixes for the one-step de/anti-icing pro- cedure. The respondents who do use Type II/III/IV fluids for this procedure indicated Type II 50/50 and Type IV 100/0 as the most commonly used fluids/mixes for this procedure. 83 Most deicing and anti-icing procedures occurring in freezing precipitation are performed using the two-step pro- cedure. For the anti-icing step in the two-step procedure, 76% of all respondents indicated that they use a Type IV 100/0 fluid mix. A number of interesting comments on the use of diluted flu- ids were given (see details in Appendix C). In general, they addressed: • The respondents own particular situation or approach to using diluted fluids; • A desire for a different mix (60/40) for Type II fluid; • A lack of awareness or willingness of some DSP customers to accept use of fluid diluted to the full extent of the approved buffer; • The need for attention to wing temperature differences from OAT; and • Constraints due to limited labor skills. Of those operators and DSPs that used deicing equipment with fluid proportioning capabilities, it was indicated that sub- stantial savings in Type I fluid usage could be achieved. One respondent claimed reductions in Type I fluid glycol consump- tion as much as 63% in one season through use of dilutions. Factors Influencing Decision to Use Fluid Dilutions The survey asked respondents to rank the influence of a number of factors in the decision to use Type I ready-to-use mixes instead of fluids blended to appropriate buffer mixes, and 100/0 concentrations of Type IV fluids rather than 75/25 or 50/50 mixes. Tables 50 and 51 present the factors ranked in descending order of importance by the survey respondents for Type I fluid and Type IV fluid, respectively. Several respondents indicated that additional fluid savings could be realized if forced air could be used in conjunction with proportional blending for deicing. To proceed with this approach, research would be required to determine if the use of forced air either in conjunction with Type I proportional blend- ing or with full strength fluid is a suitable and safe procedure. Use of 0°C to −3°C Buffer for First-Step Deicing The optimum use of fluid dilutions occurs with the use of a 0/100 dilution or “Hot Water” for deicing. Regulatory guid- ance documents allow this procedure in the first step of a two- step application when the ambient temperature is −3°C and above. However, 88% of the survey respondents do not use this procedure. One concern mentioned was that the follow- up anti-icing fluid coating had to be a mix heated to 60°C, with the appropriate buffer, if Type I fluid was used. The 12%

that do use hot water for deicing reported no problems with its usage. Similarly, regulations allow use of Type I fluids mixed to a −3°C buffer for first-step deicing when OAT is below −3°C. Only 24% of respondents make use of this procedure. Use of Type I Ready-to-Use Mixes Ready-to-use mixes of Type I fluids have been a mainstay of aircraft deicing operations in the past. Currently these mixes are still prevalent at most commercial service airports (hub, non-hub, reliever/feeder airports, and, to a greater extent, gen- eral aviation airports). The ready-to-use mixes are typically supplied in ≥ 1000 gallon tanks and 55 gallon drums. They are used with older or conventional deicing equipment that do not have proportional blending capabilities. Fluid manufacturers supply these ready-to-use mixes in blends requested by the user. The mix ratio may change during the deicing season to accommodate the colder months of the winter, with lower strength blends being supplied in the late fall, early winter time frame and in the early spring time frame. In addition, many airports will opt for the stronger concentrations, i.e., 60/40, if their site has a history of extreme cold climatic conditions throughout the deicing season. Of these ready-to-use mixes, the 55/45 blend is possibly the mix used most often, as its freeze point is around −34°C for a propylene-glycol based fluid and is deemed to be adequate for most temperatures in the United States. The survey indicated that only 1 to 2% of airlines annual operations are delayed or suspended due to lowest operational use temperature (LOUT) inadequacies from deicing fluids. The freeze point of a typical Type I 50/50 fluid mix varies from approximately −26°C to approximately −38°C depend- ing primarily upon the type of glycol used. Thus, in the major- ity of deicing activities that occur in the −10°C to +3°C temperature band, an excessive fluid concentration is used. The survey indicated 35% of respondents do not use a Type I ready-to-use mix. Of the remaining 65% that do use ready-to-use mixes, 24% used them most of the time, and only 12% used them all of the time. Of those operators equipped with deicers having propor- tional blending capability, about 40% used ready-to-use mixes half of the time. Use of Type I Concentrated Aircraft Deicing Fluid Interviews indicated that many North American deicers at major hubs and large satellite airports procure Type I fluid in 100/0 concentration. These airports have blending capabilities (vehicular mounted or remote blending stations for pedestal mounted systems) and use 10°C buffer criteria for blend con- centrations. To a lesser extent, Type I neat concentrations are supplied to outlying stations, however these stations must have blending capabilities since Type I 100/0 must be blended before 84 Rank Decision Factors (Ranked in descending order of importance) 1 Fluid Storage Requirements 2 Prevailing OAT during the Winter Deicing Season 3 Cost of Fluid 4 Cost of Blending Equipment 5 Replacement Cost of Modern Deicing Equipment 6 Environmental Issues/Concerns 7 Cost of Fluid Application Equipment 8 Training of Deicing Personnel 9 Availability of Suitable Water to Effect Blending 10 Large Variations in OAT during a De/Anti-Icing Event 11 Protection Against Freeze up in Deicing Vehicle Systems 12 Fluid Quality Control Checks 13 Geographic Location of Airport 14 Location of Available Airport Space for Deicing Operations 15 Fluid Reclaim, Reuse, Reblending Factors 16 Fluid Availability 17 Checking/Inspection Equipment and Requirements 18 Need for Changes to Regulations/Guidance Documents 19 Fluid Application Time 20 Proximity to Fluid Manufacturer’s Plant Rank Decision Factors (Ranked in descending order of importance) 1 Cost of Blending Equipment 2 Prevailing OAT during the Winter Deicing Season 3 Cost of Fluid 4 Fluid Storage Requirements 5 Replacement Cost of Modern Deicing Equipment 6 Training of Deicing Personnel 7 Large Variations in OAT during a De/Anti-Icing Event 8 Environmental Issues/Concerns 9 Cost of Fluid Application Equipment 10 Geographic Location of Airport 11 Checking/Inspection Equipment and Requirements 12 Fluid Quality Control Checks 13 Fluid Reclaim, Reuse, Reblending Factors 14 Fluid Availability 15 Availability of Suitable Water to Effect Blending 16 Location of Available Airport Space for Deicing Operations 17 Fluid Application Time 18 Need for Changes to Regulations/Guidance Documents 19 Proximity to Fluid Manufacturer’s Plant Table 50. Decision factors for Type I fluid ready-to-use mix versus dilutions. Table 51. Decision factors for Type IV fluid 100/0 concentration versus 75/25 or 50/50 concentrations.

application. In areas where there is a large excursion in temper- atures, remote blending stations may require that the mixes be reblended often. Use of Type II Fluids Type II anti-icing fluids are a mainstay of the Western Euro- pean and some Asian aviation communities, and are used in all concentrations. Airports with warmer prevailing climates such as London Gatwick (LGW) typically opt for the lower concen- trations of 50/50 or 75/25 whereas many of the Northern Euro- pean airports use the stronger concentrations as dictated by holdover time requirements. There was no record of Type II fluids being used in North America in recent years. The survey respondents indicated that only diluted Type II (50/50 or 75/25) fluid is used in the one-step de/anti-icing pro- cedure. For the second step of the two-step procedure, Type II showed very little use and that only at 100/0 strength. Use of Type III Fluids This fluid type, introduced early in the first decade of the 21st century, was intended to fill the need for a longer holdover time than Type I fluids, while being able to be pumped and applied by the existing conventional deicing units with a pis- ton type pump system. Type III holdover times are significantly longer than those of Type I fluids. Of the DSPs and airlines sur- veyed, none use Type III fluids at this time; however, the fluid manufacturer has indicated that some airlines are using the fluid. This fluid is fully developed and approved. Endurance time tests have been conducted and holdover time guidelines are available for Type III fluid at all three concentrations. Use of Type IV Fluids Type IV fluid is the primary anti-icing fluid and is used by North American, Western European, and Asian deicers. In the 100/0 concentration it typically possesses the longest holdover times and is used in this concentration throughout North America, even though in many cases a 75/25 or 50/50 dilution would be sufficient to effect a safe takeoff in the prevailing freezing climatic condition. In several climatic conditions, the holdover times for 75/25 mixes of some Type IV fluids exceed those of the 100/0 concentration. This has been attributed to the fact that when water is added to the concentrated version of the fluid, the fluid builds up thicker on the surface, due to an increase in viscosity. This phenomenon in turn produces longer holdover times. Although most airlines are aware of this performance, Type IV fluid is still routinely applied in the 100/0 concentration. The survey indicated that 76% of users apply only full strength Type IV fluid for the second-step anti- icing application. In the few cases where dilutions of Type IV fluid are applied, these mixes are typically of a 50/50 concentration and are used in frost removal procedures. Deicing Equipment Requirements Current deicing equipment is available in several configura- tions that include conventional equipment with one, two, three, or four tanks. For operations at general aviation and small regional airports, the one-tank system may be employed. It is usually non-motorized, holds 250–500 gallons, and would be filled with a 50/50 mix of Type I fluid. At many satellite and major airports the two-tank system is used. Here, one tank would hold a ready-to-use Type I fluid mix and the other would hold a much smaller quantity of 100/0 Type IV fluid. The three-tank system usually has a medium-to-large tank with capacities of ≥1000 gallons up to 3000+gallons. In this sys- tem one tank would contain water, one would contain Type I fluid, and one would contain either Type II or Type IV fluid. Water would normally be blended with the Type I fluid to achieve mixes with the required freeze point. In the four-tank system there would be a small standby tank for instant mixing and heating of deicing fluids just before application. Some of these deicing systems may be equipped with a high velocity forced air system. This equipment has been shown to use less fluid than those of conventional design to achieve the same de/anti-icing capability. The least amount of fluid usage was obtained with those systems using a com- bination of forced air and a proportional blended Type I mix for deicing when climatic conditions permitted. Some deic- ing providers did not have the latter equipment with the forced air capability. The survey indicated that more DSPs than airlines had deicers equipped with proportional blending capability. Forty- nine percent (49%) of operations conducted by DSPs are con- ducted with deicers having proportional blending capability, compared to 28% of aircraft deiced by airlines. Use of Fluid Dilutions at Regional Airports The survey indicated that regional non-hub and general avi- ation airports are unlikely to have equipment with propor- tional blending capabilities. Type I ready-to-use mix is the most commonly used fluid at these airports. Manpower Requirements Additional manpower is not required for the application of de/anti-icing fluid dilutions. However, additional train- ing in the correct selection of dilution blends for ambient conditions, skin temperatures, or both is very important. Normally senior deicing inspection/checking personnel will 85

dictate the correct blend requirements for ongoing deicing events. At sites with remote blending capabilities, vigilance is required in checking fluid concentrations to ensure that required FFPs and associated holdover time guideline per- formance are met. Practice Limitations De/anti-icing fluid dilutions should be used in accordance with the general guidelines contained in Tables 48 and 49. The operator must ensure that the requisite buffer requirement is adhered to for Type I fluids. In addition, for Type II, III, and IV fluids, the fluid concentration must be selected such that the LOUT and aerodynamic performance requirements (fluid flow off criteria) are met. SAE AIR 5633 presents information on the aforementioned forced air systems. Application of Findings to Create Cost-Benefit Model The cost-benefit model is a user-friendly tool that can be used by operators to determine if making a switch from ready- to-use Type I fluid or neat Type II/III/IV fluid to diluted fluids is financially advantageous. The model will estimate the annual cost 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 the use of diluted fluids in the deicing operation. In many cases, the financial outlay to implement use of diluted fluids can be recouped in a year or two. A sample of a completed model run using typical values for evaluating the introduction of diluted Type I fluid is provided. In the example, the model indicates that an initial investment of just over $1 million can be recouped in the course of one season, leading to operational savings of over $1 million per season thereafter. Sample Completed Model The following figures provide an example of running the model. Figure 30—Instructions Page: The user is not required to enter any information on this page. The page does not change from user to user. Figure 31—Assumptions Page: The user is not required to enter any information on this page, but may alter the default values used for the percentage of Type II/III/IV operations by fluid dilution and temperature if desired and/or the FFP buffer for Type I fluid. The user in this case has not altered the default values. Figure 32—Background Page: The user has indicated on this page that he is considering a switch to Type I fluid mixed to a 10°C buffer, but not a switch to diluted Type II/III/IV fluids. The user has entered the number of annual operations with Type I fluid at the required temperature ranges, the amount of Type I fluid used per season (1,500,000 liters), the cost of the current Type I fluid ($2.00/liter), and the percentage of glycol in the current Type I fluid (55%). 86 Figure 30. Sample instructions page. INSTRUCTIONS To begin, go to the next page (Assumptions) Welcome to the fluid dilutions cost-benefit model. This model will calculate the estimated annual glycol savings and cost savings that can be achieved by switching from a Type II/III/IV neat fluid only operation to a fluid dilutions operation and/or by switching from a Type I ready-to-use fluid operation to a Type I 10° buffer fluid operation. The model will also calculate the number of years it will take to breakeven from the initial investment required to implement diluted fluid operations. 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 review the assumptions listed on the next page and consider conducting further analysis if required.

Figure 33—Costs Page: The user has estimated the costs asso- ciated with making a switch to diluted Type I fluid, including capital costs, setup costs, fixed annual costs and the price of the Type I concentrated fluid that will be used ($3.00/liter). It should be noted that in this scenario, the cost of the concen- trated fluid that will be used is more than the cost of the pre- mix fluid currently being used ($3.00/liter vs. $2.00/liter). Figure 34—Results Page: This page provides the results of the model analysis. It shows that by switching to Type I diluted flu- ids, the user in this scenario will save $1,111,122 annually, will prevent 203,307 liters of glycol from entering the environment, and will recoup the initial investment (capital costs and setup costs) in the second year. Figure 35—Breakeven Schedule Page: This page shows the initial investment required to switch to diluted fluid operations will be recouped in year two. Clearly for this operator, switching from a Type I ready-to- use fluid to a Type I concentrated fluid blended to a 10°C buffer is a financially sound and environmentally advanta- geous decision. Conclusions and Recommendations The conclusions and recommendations resulting from this study of the use of diluted fluids for de/anti-icing aircraft are provided in this section. Conclusions A review was conducted of current government and indus- try regulations, guidance material, and standards related to the use of fluid dilutions. Several important conclusions came out of the literature review. • Regulations do exist for the use of fluids and their dilutions and were deemed to be adequate. (A survey of airline and 87 Figure 31. Sample assumptions page. Type I FFP Buffer: 10°C buffer Temperature Range Neat 75/25 50/50 a) > 0°C 0% 50% 50% b) < 0 to -3°C 25% 50% 25% c) < -3 to -6°C 50% 50% 0% d) < -6 to -10°C 75% 25% 0% e) < -10 to -15°C 100% 0% 0% f) < -15°C 100% 0% 0% 8. The default fluid freeze point (FFP) buffer for Type I fluids is 8. 10°C. The user can modify this to 15°C or 20°C to the right. Go to the next page (Background) This model makes several assumptions about operations, fluid and fluid use that may not apply to every user. Users are encouraged to review the assumptions below to asses whether further analysis if required. 1. If considering a switch to diluted Type I and/or Type II/III/IV, the user currently uses Type I ready-to-use and/or Type 1. II/III/IV neat fluid. 7. The percentage concentrate of Type I fluid required to achieve a specific fluid freeze point (FFP) is the same for all 7. Type I fluids (the percentages used in the model are the average values of 12 Type I fluids). 3. Glycol recovery costs are not achieved by switching to diluted fluids, as they are assessed on the amount of fluid, not 3. glycol, dispensed. 9. The percentage of Type II/III/IV operations that will use neat, 75/25 and 50/50 fluid at each OAT range must be estimated. 9. The values below are the default values and are assumed to be correct unless modified by the user. 6. Type I concentrate is 100% glycol (for glycol savings calculation). ASSUMPTIONS USED IN THE MODEL 2. If a switching to diluted Type I fluid, all Type I fluid used will be diluted to the buffer, even fluid used in the first step of 2. a two step operation. 4. There is no distinction between Type II, Type III and Type IV fluid. 5. Inflation / current value of future cash flows are not relevant.

88 BACKGROUND QUESTIONS - GENERAL 1. Are you considering switching from a Type I ready-to-use fluid to 1. a Type I buffer fluid? 2. Are you considering switching from a Type II/III/IV neat fluid only 2. operation to a Type II/III/IV neat and diluted fluid operation? 3. How will you procure diluted Type II/III/IV fluid? 4. Do you prefer to complete this analysis using litres or gallons? 5. How many operations are conducted per winter season? Type I Fluid Type II/III/IV Fluid a) above 0°C 250 not applicable b) below 0°C to -3°C 500 not applicable c) below -3°C to -6°C 1,200 not applicable d) below -6°C to -10°C 1,700 not applicable e) below -10°C to -15°C 800 not applicable f) below -15°C to -20°C 450 not applicable g) below -20°C to -25°C 200 not applicable h) below -25°C 25 not applicable All temperatures 6. Average amount of fluid (in liters) used per winter season: 1,500,000 not applicable 7. Price (per litre) of currently used fluid: $2.00 not applicable 8. Glycol (%) in currently used fluid: 55% not applicable yes This page is complete. Please go to the next page (Costs). no liters 5,125 not applicable not applicable Figure 32. Sample background page.

89 Figure 33. Sample costs page. CAPITAL COSTS - NEW EQUIPMENT a) Cost of new blending trucks/equipment b) Cost of new fluid storage equipment FIXED COSTS - ONE TIME SETUP COSTS a) Cost to gain in-house approval from all affected branches to proceed b) Cost to develop, publish and approve new procedures c) Cost to include new procedures in airline deicing program, get approval d) Cost to develop training materials FIXED COSTS - ANNUAL a) Addtitional equipment maintenance costs b) Additional ground crew training costs employees 55 x cost per employee 160$ VARIABLE COSTS Type I a) Price (per liter) of Type I concentrate fluid 3.00$ Type II/III/IV a) Price (per liter) of Type II/III/IV neat fluid a) Price (per liter) of Type II/III/IV 75/25 fluid not applicable a) Price (per liter) of Type II/III/IV 50/50 fluid not applicable 1,000,000$ Please fill in ALL of the empty blue cells above 150,000$ 2,000$ 2,000$ 5,000$ 10,000$ 15,000$ 8,800$ not applicable

90 RESULTS Type I Fluid Costs (per winter season) Current ready-to-use operation $3,000,000 Proposed 10°C buffer operation $1,865,078 Type II/III/IV Fluid Costs (per winter season) Current neat fluid operation not applicable Proposed diluted fluid operation not applicable Annual Fixed Costs (per winter season) Additional fixed costs related to fluid switch $23,800 Impact of Implementing Fluid Switch (per winter season) Financial Savings $1,111,122 Glycol Savings 203307 liters Initial Investment Required to Switch to Diluted Fluids Set-up Costs $19,000 Capital Costs $1,150,000 Winter Seasons to Breakeven 2 See next page (Breakeven Schedule) for further details Figure 34. Sample results page. DSPs later confirmed that users also feel that current regu- lations are adequate, although several respondents noted some clarification or elaboration of the regulations could be useful.); and • Holdover times exist for diluted fluids and are published on an annual basis. In the case of Type I fluids, holdover times have been developed with fluids mixed to a 10°C buffer. In the case of Type II/III/IV fluids, holdover times have been developed for 100/0, 75/25, and 50/50 dilutions. Notably, the enhancement in holdover time is not significant as a result of using richer glycol mixes of Type I fluid nor when using 100/0 Type II/III/IV fluid rather than 75/25 diluted fluid. Therefore in many cases, glycol usage can be reduced without holdover times being reduced significantly. A focus group from the deicing industry was surveyed to gather a more thorough and detailed understanding of the industry’s perceptions and current usage of diluted fluids. Key findings from the survey are: • Deicing and anti-icing fluid use varies considerably depend- ing on aircraft size and precipitation condition. • The top five factors influencing use of fluid dilutions are: fluid storage requirements, prevailing OAT during the win- ter deicing season, cost of fluid, cost of blending equipment, and replacement cost of modern deicing equipment. • Of all anti-icing fluid types (Type II/III/IV) and strengths (100/0, 75/25, 50/50) available, Type IV 100/0 is used almost exclusively. • Ready-to-use fluid is the most commonly used mixture of Type I fluid; Type I fluids mixed to FFP buffers are not com- monly used. • Type II, III or IV fluid mixes are infrequently used for one- step procedures. • A 10°C buffer is the most common buffer used for Type I fluids by operators with proportional blending equipment. • Hot water is rarely used for deicing as the first step in a two- step procedure, nor is hot water often used for defrosting operations. • Most operations at non-hub airports do not make use of diluted fluids. • Proportional blending systems to provide deicing fluids at the required buffers are readily achievable, and their costs can usually be recovered in one or two deicing seasons, depending upon the amount of deicing fluid sprayed. • Additional training is required for both the deicing specialist and the senior deicing specialist on a yearly

91 Figure 35. Sample breakeven schedule page. BREAKEVEN SCHEDULE Winter Season Capital Costs Setup Costs Operational Savings Total Savings Lifetime Savings Breakeven Year 1 $1,150,000 $19,000 $1,111,122 -$57,878 -$57,878 no 2 n/a n/a $1,111,122 $1,111,122 $1,053,243 yes 3 n/a n/a $1,111,122 $1,111,122 $2,164,365 reached prior 4 n/a n/a $1,111,122 $1,111,122 $3,275,487 reached prior 5 n/a n/a $1,111,122 $1,111,122 $4,386,609 reached prior 6 n/a n/a $1,111,122 $1,111,122 $5,497,730 reached prior 7 n/a n/a $1,111,122 $1,111,122 $6,608,852 reached prior 8 n/a n/a $1,111,122 $1,111,122 $7,719,974 reached prior 9 n/a n/a $1,111,122 $1,111,122 $8,831,095 reached prior 10 n/a n/a $1,111,122 $1,111,122 $9,942,217 reached prior 11 n/a n/a $1,111,122 $1,111,122 $11,053,339 reached prior 12 n/a n/a $1,111,122 $1,111,122 $12,164,460 reached prior 13 n/a n/a $1,111,122 $1,111,122 $13,275,582 reached prior 14 n/a n/a $1,111,122 $1,111,122 $14,386,704 reached prior 15 n/a n/a $1,111,122 $1,111,122 $15,497,826 reached prior 16 n/a n/a $1,111,122 $1,111,122 $16,608,947 reached prior 17 n/a n/a $1,111,122 $1,111,122 $17,720,069 reached prior 18 n/a n/a $1,111,122 $1,111,122 $18,831,191 reached prior non-recurring basis. Additional maintenance training is required, since most modern blending systems incorporate microprocessor controllers and in-line refractometers. • Additional flight crew training is not required. A user-friendly cost-benefit model was developed for use by operators to determine if making a switch from ready-to- use Type I fluid or neat Type II/III/IV fluid to diluted fluids is financially advantageous. The model will estimate the annual cost 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 the use of dilute flu- ids in the deicing operation. In many cases, the financial out- lay to implement use of diluted fluids can be recouped in a year or two. Recommendations Several survey respondents expressed the need for clarifica- tion and possibly expansion of the current guidance material related to fluid dilutions; it is therefore recommended that lan- guage be added to the guidance material to encourage the use of dilutions. Examples could also be provided to show that diluted fluids are not as difficult to incorporate into operations as commonly perceived.

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Optimizing the Use of Aircraft Deicing and Anti-Icing Fluids Get This Book
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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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