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9 7. Non-glycol freeze point depressant fluids: Fluid formu- operational in New York). Use of this approach could lated with freeze point depressants other than propylene, reduce the amounts of glycol dispensed; and ethylene, and diethylene glycol; 18. Use of weather forecasting products for deicing process: 8. Point detection sensors to indicate fluid condition and Airport meteorological system product, such as NCAR contamination on aircraft surfaces: Ice sensors that are Weather Support for Deicing Decision Making (WSDDM) imbedded within aircraft surfaces enabling a determina- and SITA Met Office, that would enable better forecasting tion of aircraft surface condition; of oncoming weather and allow for better deicing planning. 9. Remote ice detection sensors to scan aircraft critical surfaces before departure runway: Ice detection systems Focus Group Survey Inputs on Final List that are mounted (fixed or mobile) close to the runway of Technologies and Procedures threshold, enabling the determination of aircraft surface condition prior to departure; In Section 3 of the focus group questionnaire shown in 10. Spot deicing for frost: Use of very limited quantities Appendix E, the focus group was asked for input on the use- of glycol-based fluids for frost deicing in a controlled fulness of the final 18 technologies and procedures. Focus application; group participants were asked to assess the usefulness of the 11. Spray-and-go deicing: De/anti-icing operation conducted optimization technologies and procedures in one of three near the runway threshold, enabling increased use of categories (not useful, somewhat useful, very useful), assum- Type I deicing fluids as the primary tool and less thick- ing that the technologies and procedures were available for ened fluid application; use at airports. The focus group assessment of all 18 opti- 12. Tempered steam as a non-glycol gate deicing or pre- mization technologies and procedures was generally very deicing tool: Tempered steam technology uses moisture- positive; the most that any of the technologies and proce- laden air to melt frozen contaminants from aircraft dures was deemed to be not useful by the focus group was surfaces during gate deicing actions or during pre-deicing by 32% of respondents. The focus group survey results events. It has shown great promise in testing to date; strongly supported the selection of the 18 technologies and 13. Threshold deicing: Development and use of remote procedures. threshold deicing pads at airports, similar to those built The focus group survey results pertaining to the usefulness in Munich, Germany. This approach would limit quanti- of the various proposed technologies and procedures are ties of thickened fluids employed, as the departure point shown in Table 4. is in close proximity to the application area; 14. Type III fluids: Type III is a low viscosity de/anti-icing fluid that could be used in a one-step, heated de/anti-icing Development of Analytical Criteria operation. Due to its low viscosity, it can be readily col- To assist with the analysis of new technologies and proce- lected at the point of spray application and less fluid would dures for de/anti-icing optimization, APS employed the Binary be carried by aircraft and deposited over the airfield; Decision Analysis Model. The model, used for ranking of alter- 15. Use of 10C Type I buffer: Standard deicing fluid con- natives, is an evaluation technique developed by Westing- centrations (typically 50% water/50% glycol) have been house, and was modified by APS. It is a systematic formalized employed by the industry, despite the fact that Type I procedure for solving complex decision problems. Considera- deicing holdover times are based on 18F (10C) buffer tion will be given to short-term and long-term implementation fluids. Use of proportional blending could easily limit the strategies. amounts of glycol dispensed in Type I operations. For the purpose of this report, the metric units (Celsius) will be Starting Point in the Development of Analytical Criteria. employed in the title for this item, as this is the common To evaluate the de/anti-icing optimization technologies and terminology employed within the aviation industry when procedures for future use, a series of analytical criteria was referring to this procedure; required. The development of the list of analytical criteria 16. Use of anti-icing fluid dilutions: Anti-icing fluids have considered the following: been used exclusively in 100/00 concentration in North America. Many 75/25 anti-icing fluids have holdover Safety enhancement due to the implementation of the times similar to 100/00 fluids, and many 50/50 fluids optimization technology or procedure; have holdover times well in excess of Type I fluids; Effectiveness of the optimization technology or procedure; 17. Use of infrared deicing technology: Infrared heat has Reliability of the optimization technology or procedure; been employed, with a quantifiable amount of success, by Capital costs of the optimization technology or procedure; the industry in the past decade (a system is currently Operating costs of the optimization technology or procedure;

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10 Table 4. Focus group results pertaining to usefulness of the selected technologies and procedures. Somewhat Very De/Anti-Icing Optimization Technology and Procedures Not Useful (%) Useful (%) Useful (%) 1. Blowers and/or other mechanical means to remove dry 5 58 37 contamination 2. Deicing-only fluid buffer reduction 11 74 16 3. First-step deicing fluid buffer reduction 28 44 28 4. Fluids applied before the start of precipitation to prevent 6 56 39 bonding 5. Forced air used to remove contamination 0 42 58 6. Implementation of holdover time determination systems 5 26 68 7. Non-glycol freeze point depressant fluids 5 58 37 8. Point detection sensors to indicate fluid condition and 17 61 22 contamination on aircraft surfaces 9. Remote ice detection sensors to scan aircraft critical 0 58 42 surfaces before departure runway 10. Spot deicing for frost 5 26 68 11. Spray-and-go deicing 11 26 63 12. Tempered steam as a non-glycol gate deicing or pre- 11 26 63 deicing tool 13. Threshold deicing 5 42 53 14. Type III fluids 32 53 16 15. Use of 10C Type I buffer 5 53 42 16. Use of anti-icing fluid dilutions 26 42 32 17. Use of infrared deicing technology 32 47 21 18. Use of weather forecasting products for deicing process 0 37 63

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11 Economic savings to the airport or air carrier due to the 6. Operational Efficiency: This criterion examines the optimization technology or procedure; operational efficiencies that are expected to result from Source reduction of glycol due to the optimization tech- the new technology or procedure; this would include nology or procedure; airport throughput, passenger and aircraft delays and/or Reduction in environmental impact due to the optimization enhancements; and technology or procedure; 7. Safety: This criterion examines the level of risk to imple- Reduction in environmental costs due to the optimization ment the new technology or procedure. While any new technology or procedure; technology would not be considered if it posed a safety Effects of technology or procedure on airport infrastructure; concern, certain technologies and procedures have more Adherence to regulatory requirements; associated risk than others. Reduction in aircraft fuel burn due to the implementation of the optimization technology or procedure; Weighting of Analytical Criteria. In order to assign a Improvement in airport throughput due to the optimization weight to each criterion, the focus group participants were technology or procedure; asked to compare the criteria to one another using a structured Readiness for implementation of the optimization tech- approach, and to determine which of any two criteria was con- nology or procedure; sidered more important. This process involved making 21 com- Ability to combine the optimization technology or pro- parative decisions, as shown in Table 5. The detailed responses cedure with others; from the focus group in this decision process are provided in Effect of the optimization technology or procedure on Appendix G. recycling procedures presently used by airport operators; For each of the 21 questions, a score of 1 was given to the Impact on de/anti-icing fluid holdover time of the opti- criterion that had more favorable responses, and a score of mization technology or procedure; and 0 was given to the criterion that had less favorable responses. Applicability of the new technologies and procedures to In 15 of the 21 questions, there was a clear decision from the the end user. survey participants as to which criterion was more impor- tant; the 6 questions that had a closer response result were Identification of Analytical Criteria. Seven criteria were for the criteria that were of lesser importance. In summary, identified as being important for evaluating the 18 optimization the criteria weights determined from this decision process technologies and procedures. The criteria are considered to be are provided in Table 6. mutually exclusive and collectively exhaustive, meaning that all Table 6 shows that a "1" was added to the score for each the important parameters needed to make decisions for evalu- criterion. This was done to ensure that each criterion selected ating new technologies and procedures have been included and or considered important was assigned a weight; otherwise the that there is no "double counting." The seven criteria are: weight of the lowest-ranking criterion would have been zero percent. The results of the focus group survey indicate that 1. Capital Cost: This criterion is simply the capital costs Safety is the most important criterion, followed by Opera- needed to implement the technology or procedure; tional Efficiency. These results were not unexpected. 2. Operating Cost: This criterion includes the operating The survey participants were asked to provide any addi- costs that would result from the implementation of the tional criteria that they felt should be considered and that had technology or procedure, and this would include costs not been included. There were two responses to this question; such as heating, maintenance, management/personnel, in both cases the comments provided were already consid- fluid costs, etc.; ered within the original criteria. 3. Training: This criterion considers the need and difficulty to provide training to deicing crews or pilots when imple- Evaluation of Optimization Technologies menting the new technology or procedure; and Procedures 4. Environmental Impact: This criterion considers environ- mental impacts from implementation of the new technology The individual items in the final list of 18 technologies or procedure, mostly from de/anti-icing fluid reductions, and procedures were next ranked according to their relative but also aircraft fuel burn reductions, and personnel health importance for each criterion. The most important received and safety; the score of 18, progressively reducing to the least impor- 5. Maturity: This criterion examines the level of maturity and tant, which received the score of one (1). The total value of readiness of the technology or procedure; for example, reg- each criterion is 171. In some cases, it was impossible to dis- ulatory approval is considered, as is the sustainability of tinguish between certain items, in which case the score for operations using the new technology or procedure; those items was averaged among them, always respecting

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12 Table 5. Focus group comparative decisions on analytical criteria. Criterion 1 Criterion 2 Capital cost Operating cost X Capital cost Environmental impact X Capital cost Operational efficiency X Capital cost Maturity X Capital cost Training X Capital cost Safety X Operating cost Environmental impact X Operating cost Operational efficiency X Operating cost X Maturity Operating cost X Training Operating cost Safety X Environmental impact Operational efficiency X Environmental impact X Maturity Environmental impact X Training Environmental impact Safety X Operational efficiency X Maturity Operational efficiency X Training Operational efficiency Safety X Maturity Training X Maturity Safety X Training Safety X the total value in each column of 171. The values in each were rated equally, and were ranked at the top of the list. As cell were then converted to percentages based on the total five items were involved, in total they were assigned the sum column value of 171. of values from 14 to 18, for an average value of 16. The evaluation process relative to each of the seven criteria Item 2, Deicing-only fluid buffer reduction, Item 3, First-step is described in the following sections. deicing fluid buffer reduction, and Item 15, Use of 10C Type I buffer, all involved blending of Type I fluid according to the Capital Cost. Ranking against Capital Cost assigns the ambient temperature. The most effective way to achieve this greatest importance to those items bearing the least capital cost. is through use of an on-board fluid blending system on the In Table 7, Items 1, 4, 7, 10, and 14 were all assessed as hav- deicing vehicle. The capital cost, therefore, is the same for all ing no capital cost associated with them. Consequently they these cases. As there were three items involved, in total they Table 6. Focus group criteria weights. Decision Criteria Score+1 Weight % Scores Capital Cost 0 1 3.6% Operating Cost 3 4 14.3% Environmental Impact 4 5 17.9% Operational Efficiency 5 6 21.4% Maturity 1 2 7.1% Training 2 3 10.7% Safety 6 7 25.0% TOTAL 21 28 100%

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13 Table 7. Ranking of technologies and procedures by capital cost. Capital Capital Item # Optimization Technology or Procedure Cost Cost Rank % 10 Spot deicing for frost 16.0 9.4% 14 Type III fluids 16.0 9.4% Blowers and/or other mechanical means to remove dry 1 16.0 9.4% contamination 7 Non-glycol freeze point depressant fluids 16.0 9.4% 4 Fluids applied before the start of precipitation to prevent bonding 16.0 9.4% 15 Use of 10C Type I buffer 12.0 7.0% 2 Deicing-only fluid buffer reduction 12.0 7.0% 3 First-step deicing fluid buffer reduction 12.0 7.0% 5 Forced air used to remove contamination 10.0 5.8% 16 Use of anti-icing fluid dilutions 9.0 5.3% 11 Spray-and-go deicing 8.0 4.7% 18 Use of weather forecasting products for deicing process 7.0 4.1% 12 Tempered steam as a non-glycol gate deicing or pre-deicing tool 6.0 3.5% 6 Implementation of holdover time determination systems 5.0 2.9% Remote ice detection sensors to scan aircraft critical surfaces 9 4.0 2.3% before departure runway 13 Threshold deicing 3.0 1.8% Point detection sensors to indicate fluid condition and 8 2.0 1.2% contamination on aircraft surfaces 17 Use of infrared deicing technology 1.0 0.6% TOTAL 171.0 100.0% were assigned the sum of values from 11 to 13, for an average Operating Cost. The ranking for Operating Cost is shown value of 12. in Table 8. The impact on operating costs, in some cases, is The following items were viewed as having different levels expected to be an overall reduction. In other cases, an increase of capital cost and were ranked accordingly. The required in operating costs would be expected. Ranking against oper- capital costs were: ating cost assigns the greatest importance to those items having the least negative impact. There were no equivalent Item 5, Forced air used to remove contamination: cost to levels of cost between items, and each approach was given replace deicers or retrofit current deicers with forced air its own ranking. systems; The operational benefit associated with Item 10, Spot Item 16, Use of Anti-icing fluid dilutions: cost for fluid deicing for frost, is a reduction in deicing costs (fluid and blenders and additional fluid tanks for various blends; and manpower). An expected reduction in aircraft operating times, Item 11, Spray-and-go deicing: cost to modify taxiway to which implies important savings in maintenance costs, crew enable deicer movement around aircraft and cost to capture costs, fuel burn, and disrupted passenger costs is claimed in the spent fluid. Operational Efficiency criterion. The remaining items all require significant capital invest- Item 10, Item 14, and Item 16 all involve a reduction ment for the purchase and implementation of the technology in de/anti-icing fluid costs, with no additional operational or procedure. expenditure.

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14 Table 8. Ranking of technologies and procedures by operating cost. Operating Operating Item # Optimization Technology or Procedure Cost Cost % Rank 10 Spot deicing for frost 18.0 10.5% 16 Use of anti-icing fluid dilutions 17.0 9.9% 14 Type III fluids 16.0 9.4% 15 Use of 10C Type I buffer 15.0 8.8% 6 Implementation of holdover time determination systems 14.0 8.2% 5 Forced air used to remove contamination 13.0 7.6% 12 Tempered steam as a non-glycol gate deicing or pre-deicing tool 12.0 7.0% Blowers and/or other mechanical means to remove dry 1 11.0 6.4% contamination 11 Spray-and-go deicing 10.0 5.8% 2 Deicing-only fluid buffer reduction 9.0 5.3% 3 First-step deicing fluid buffer reduction 8.0 4.7% 4 Fluids applied before the start of precipitation to prevent bonding 7.0 4.1% 7 Non-glycol freeze point depressant fluids 6.0 3.5% Remote ice detection sensors to scan aircraft critical surfaces before 9 5.0 2.9% departure runway 18 Use of weather forecasting products for deicing process 4.0 2.3% Point detection sensors to indicate fluid condition and contamination 8 3.0 1.8% on aircraft surfaces 17 Use of infrared deicing technology 2.0 1.2% 13 Threshold deicing 1.0 0.6% TOTAL 171.0 100.0% Item 6, Implementation of holdover time determination sys- Training. The ranking for Training is shown in Table 9. tems, supports better decision making, leading to avoidance Ranking against training assigns the greatest value to those of deicing activities when not needed, and use of fluid types items having the least need for training. more appropriate to the weather condition. In Table 9, Items 4, 7, 14, and 16 were seen to require equiv- Item 5, Forced air used to remove contamination, and Item 12, alent levels of training. An average rank value of 16.5 was Tempered Steam as a non-glycol gate deicing or pre-deicing tool, applied to all four items. are similar in that they can be used to remove most of the Thereafter, the extent of the training requirement grew contamination before the actual deicing operation, thereby according to the increase in complexity of the procedure or reducing the amount of de/anti-icing fluid expended. Item 1, technology. Blowers and/or other mechanical means to remove dry contami- nation, is similar, but it applies only to smaller amounts of Environmental Impact. The ranking for Environmental snow and not to other types of contamination. Impact is included in Table 10. In most cases, the ranking was Item 2, Deicing-only fluid buffer reduction, would reduce the based primarily on the reduction in the quantity of glycol amount of glycol expended, as would Item 3, First-step deicing expended. In other cases, additional environmental impacts fluid buffer reduction. In both cases the reduction in cost is less are considered. One such case is Item 10, Spot deicing for frost, than simply using a fluid strength equivalent to the 10C which can result in a substantial reduction in aircraft fuel buffer rather than the standard mixes (neat, 75/25, 50/50). burn and its associated impact on the environment.

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15 Table 9. Ranking of technologies and procedures by training. Item # Optimization Technology or Procedure Training Training Rank % 16 Use of anti-icing fluid dilutions 16.5 9.6% 14 Type III fluids 16.5 9.6% 7 Non-glycol freeze point depressant fluids 16.5 9.6% 4 Fluids applied before the start of precipitation to prevent bonding 16.5 9.6% 10 Spot deicing for frost 14.0 8.2% 13 Threshold deicing 13.0 7.6% 11 Spray-and-go deicing 12.0 7.0% 5 Forced air used to remove contamination 11.0 6.4% 1 Blowers and/or other mechanical means to remove dry contamination 10.0 5.8% 15 Use of 10C Type I buffer 9.0 5.3% 2 Deicing-only fluid buffer reduction 8.0 4.7% 3 First-step deicing fluid buffer reduction 7.0 4.1% 12 Tempered steam as a non-glycol gate deicing or pre-deicing tool 6.0 3.5% 17 Use of infrared deicing technology 5.0 2.9% Remote ice detection sensors to scan aircraft critical surfaces before 9 4.0 2.3% departure runway Point detection sensors to indicate fluid condition and contamination on 8 3.0 1.8% aircraft surfaces 6 Implementation of holdover time determination systems 2.0 1.2% 18 Use of weather forecasting products for deicing process 1.0 0.6% TOTAL 171.0 100.0% Item 13, Threshold deicing, and Item 11, Spray-and-go regulatory, government, or guidance material was required. deicing, provide an opportunity to reduce the amount of A subjective rating of "Yes," "No," "N/A" or "Pending" was fluid (especially Type IV fluid) sprayed. Additionally, these then assigned to each selected technology or procedure. The approaches remove the problem of fluid dripping from air- results of this comparison are presented in Table 11. craft surfaces while taxiing to the departure runway. The optimization technologies or procedures with a "Yes" Other approaches reduce the quantity of de/anti-icing fluid rating are deemed to be currently covered by existing regula- sprayed by removing contamination prior to proceeding to tory guidance documents. Those with a "Pending" rating are deicing, or by reducing the glycol content in the fluid by using being addressed by pending regulatory guidance from a a lower fluid strength. regulator, but not by guidance from the FAA, nor have they Items 8 and 9, which pertain to remote or point ice detection been addressed in deicing documentation from the SAE at sensors, might actually increase the impact on environment by this time. However it appears that most of the technical leading to more returns for repeated deicing. challenges of the optimization technology or procedure with a "Pending" rating have been met, and regulatory Maturity. A total of 22 regulatory, government, and guidance is being considered. Those with a "No" rating industry documents, guidance material, and standards were have not been addressed by appropriate guidance docu- reviewed by APS personnel during the literature review. These ments from the regulators or addressed as an acceptable documents were compared to the 18 identified optimization practice by the SAE or the AEA. Typically these "No" rated technologies and procedures to determine if the selected technologies and procedures are undergoing development optimization technologies and procedures were covered by or require further evaluations by the authorities before an appropriate guidance or standards material or if additional endorsement is given.

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16 Table 10. Ranking of technologies and procedures by environmental impact. Environmental Environmental Item # Optimization Technology or Procedure Impact Rank Impact % 10 Spot deicing for frost 18.0 10.5% 13 Threshold deicing 17.0 9.9% 11 Spray-and-go deicing 16.0 9.4% 7 Non-glycol freeze point depressant fluids 15.0 8.8% Tempered steam as a non-glycol gate deicing or 12 14.0 8.2% pre-deicing tool 5 Forced air used to remove contamination 13.0 7.6% Blowers and/or other mechanical means to remove dry 1 12.0 7.0% contamination 16 Use of anti-icing fluid dilutions 11.0 6.4% 17 Use of infrared deicing technology 10.0 5.8% 15 Use of 10C Type I buffer 9.0 5.3% 6 Implementation of holdover time determination systems 8.0 4.7% 2 Deicing-only fluid buffer reduction 7.0 4.1% 14 Type III fluids 6.0 3.5% 3 First-step deicing fluid buffer reduction 5.0 2.9% Fluids applied before the start of precipitation to prevent 4 4.0 2.3% bonding 18 Use of weather forecasting products for deicing process 3.0 1.8% Remote ice detection sensors to scan aircraft critical 9 2.0 1.2% surfaces before departure runway Point detection sensors to indicate fluid condition and 8 1.0 0.6% contamination on aircraft surfaces TOTAL 171.0 100.0% The ranking of technologies and procedures by Maturity is Operational Efficiency. The ranking of technologies and provided in Table 12. When considering Maturity, technolo- procedures by Operational Efficiency is provided in Table 13. gies or procedures that are ready for implementation were Some approaches, such as Item 10, Spot deicing for frost, offer given the highest-ranking value. Readiness includes availabil- additional benefits in the form of reduced delays and aircraft ity of the equipment needed to do the job, as well as regulatory operating times. This leads to important savings in aircraft approvals. This criterion is important from the perspective of maintenance and fuel costs, crew costs, and passenger disrup- enabling "Quick hit" technologies and procedures. tion costs. In the evaluation, six items were assessed as being ready for Item 11, Spray-and-go deicing, and Item 13, Threshold deic- implementation and were assigned an average ranking value ing, should provide greatly improved operational efficiencies. of 15.5, as shown in Table 12. Eliminating the need to deice (Item 6, Implementation of Item 11, Spray-and-go deicing, and Item 13, Threshold deic- holdover time determination systems) or reducing the time to ing, were seen as having no deicing regulatory constraints, but deice (use of forced air, tempered steam and blowers, or needing local approvals and investments. mechanical means to reduce the amount of contamination at The use of reduced fluid buffers (Items 2 and 3) will the deicing stage) will also lead to operational efficiencies. require new regulatory approvals. Item 14, Type III fluids, may require investigation as to whether the approach leads to Safety. The ranking of technologies and procedures by fluid dry-out on aircraft control surface drives. Item 6, Imple- Safety is provided in Table 14. The ranking of items against mentation of holdover time determination systems, will require safety was found to be the most challenging. None of the regulatory approval, as will the use of ice detectors. approaches were perceived to be unsafe, otherwise they would