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

Chapter: Chapter 2 - Promising De/Anti-Icing Source Reduction Practices

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Suggested Citation:"Chapter 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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 2 - Promising De/Anti-Icing Source Reduction Practices." 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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3Introduction Aviation regulations prohibit the takeoff of aircraft when snow, ice or frost is adhering to wings, tails, control surfaces, propellers, engine intakes and other critical surfaces of the aircraft. This rule forms the basis of the “Clean Aircraft Con- cept.” To this end, the aviation industry has developed ground de/anti-icing procedures and technologies to maintain the safety of winter flight operations. Aircraft deicing consists of the removal of ice, snow, and frost from aircraft surfaces; anti- icing uses a protective agent to avoid any further accumula- tion of ice or snow following deicing and prior to takeoff. The technologies most prominently used for aircraft ground de/anti-icing are glycol-based, freeze point depressant fluids. Aircraft ground de/anti-icing is critical to flight safety because ice accumulation on critical aircraft surfaces can have a detrimental impact on aerodynamic performance and can possibly result in engine loss or damage due to ice ingestion. Aircraft ground de/anti-icing became the subject of concerted industry attention approximately 15 years ago due to the occurrence of several fatal icing-related aircraft accidents. Of particular importance to North American regulators were the crashes that occurred in Dryden, Ontario and La Guardia, New York in 1989 and 1992, respectively. Both accidents resulted in the loss of lives and ultimately stimulated extensive Transport Canada (TC) and FAA involvement in aircraft de/anti-icing research and development. Despite dramatic improvements in recent years in the qual- ity of aircraft de/anti-icing fluids, fluid delivery equipment, fluid recovery equipment, industry procedures, and ground/ flight crew training, the negative aspects of the use of glycol for aircraft ground de/anti-icing are still prominent. These negative aspects include, but are not limited to: • High costs associated with the use of glycol; • Environmental concerns (toxicity, biodegradability); • Aircraft delays and airport throughput issues in deicing events; • Increase in fuel burn due to live deicing operations; • Glycol mitigation; and • Occupational hazards. The negative aspects of glycol aircraft de/anti-icing fluids and their direct impacts were once dismissed by the industry as the necessary evil to ensure safe winter operations. This sit- uation is changing rapidly, however. Environmental protec- tion agencies and regulators worldwide are exerting increasing pressure on airports and operators to be accountable, and the high costs associated with the use of glycol have made many airlines examine the current way of doing business. Objective The objective of ACRP Project 10-01 was to identify proce- dures and technologies that optimize the use of ADAFs, thus reducing their environmental impact while assuring safe air- craft operations in deicing and anti-icing conditions. The proj- ect produced (1) a description of the application of currently available procedures and technologies to optimize ADAF use; (2) the results of an experiment to validate the effectiveness of several promising procedures and technologies; (3) a plan for implementation of these promising procedures and technolo- gies; and (4) recommendations for further study. Organization ACRP Project 10-01 was performed in two phases. Phase I has three work elements: 1. A thorough literature review and information collection on current aircraft ground de/anti-icing optimization procedures and technologies. 2. An analysis of data developed in work element #1 to iden- tify specific procedures and technologies for further eval- uation in Phase II of ACRP Project 10-01. C H A P T E R 2 Promising De/Anti-Icing Source Reduction Practices

3. Preparation of an interim report summarizing the results of Task 1, a comprehensive discussion of each of the pro- cedures and technologies recommended for further eval- uation, and an outline of an experimental plan. Phase II has these work elements: 1. Design of the experimental plan to validate the feasibility and effectiveness of procedures and technologies approved by ACRP in Phase I and conduct of the experiments. 2. Identification of additional opportunities for further research. 3. Preparation of this final report summarizing the results and recommendations of the research. Research Approach This section describes the approach and methodologies employed in Phase I. Literature Review and Data Examination APS performed a literature review to identify technologies and procedures that could potentially optimize the use of aircraft de/anti-icing fluids and, thus, reduce environmental impact while maintaining or even enhancing the safety of air- craft operations in de/anti-icing conditions. The literature review consisted of: • Aircraft ground deicing technical reports, produced on behalf of the Transportation Development Centre (TDC) of TC, the FAA, and aviation industry product manufacturers; • Regulatory, government and industry documentation, guidance material, and standards; and • Aircraft ground deicing patents. Aircraft Ground Deicing Technical Reports Thirty-seven aircraft ground deicing technical reports were reviewed. In the initial step, the reports were grouped into these areas of interest to facilitate the presentation of report review findings: • Deicing Procedures—Fluid Freeze Point Buffer Require- ments; • Aircraft Anti-Icing Fluid Characteristics; • Ice Detection Sensors; • Alternative Deicing Approaches: – Hot Water; – Forced Air Systems; – Warm Fuel; – Mobile Infrared System; and – Tempered Steam. • Aircraft De/Anti-Icing Fluid Research; • Aircraft De/Anti-Icing Fluid Testing; • Application of Holdover Time Guidelines; • Holdover Time Determination Systems; • Aerodynamic Penalties of Clean or Partially Expended De/ Anti-icing Fluid; and • Aircraft Ground Deicing Exploratory Research. Subsequent to the classification exercise, a thorough review of each technical report was performed to examine and identify potential technologies and procedures for use in de/anti-icing optimization. Particular attention was paid to identify potential quick hits—optimization technologies and procedures that are ready to implement now or that are already in use, but could be improved upon readily. For each technical report reviewed, the optimization tech- nology or procedure was listed along with a list of the positive and negative attributes of the optimization technology or pro- cedure and general comments from the review. A summary of the review of each of the 37 technical reports is provided in Appendix A. A complete listing of all literature reviewed is given at the end of this chapter. Regulatory, Government and Industry Documentation, Guidance Material, and Standards Twenty-two regulatory, government, and industry docu- ments were reviewed. The preponderance of these documents were from the FAA, and addressed many of the activities associated with aircraft icing to include ground icing, ground deicing programs, in-flight icing, aircraft ice protection and use of infrared deicing facilities. Similar ground deicing docu- ments were reviewed from TC and from the Association of European Airlines (AEA). One document from the U.S. Environmental Protection Agency (EPA), entitled Preliminary Data Summary—Airport Deicing Operations (Revised), was reviewed. Other documents reviewed were those used by foreign air carriers and included documentation from the Joint Aviation Authorities (JAA), International Organization for Standardization (ISO), International Civil Aviation Orga- nization (ICAO) and New Zealand Civil Aviation Authority. Also, the Society of Automotive Engineers (SAE) document Aerospace Recommended Practice (ARP) 4737, Aircraft Deicing/Anti-icing Methods with Fluids, which serves as the industry standard for methodologies on aircraft deicing, was reviewed. In the Bibliography of Chapter 2, the regulatory, government and industry documentation, guidance material, and standards reviewed were grouped in the following manner: • U.S. Federal Aviation Administration (FAA); • U.S. Environmental Protection Agency (EPA); 4

• Transport Canada (TC); • Society of Automotive Engineers (SAE); • Association of European Airlines (AEA); and • Other. A summary of the document was prepared, including an assessment of the positive and negative aspects of the docu- mentation. A summary of the review of each of the 22 regula- tory, government and industry documents has been provided in Appendix B. In addition to performing a general review, each document was assigned a rating relative to current aircraft ground deicing practices. The ratings varied from high to very low. Those doc- uments that were updated in a timely manner (usually yearly or whenever significant changes in ground deicing practices or requirements occurred) were assigned a high rating, whereas those documents that were seriously outdated or were not specifically directed at ground deicing issues, were assigned rat- ings from medium to very low, depending upon the relevance of their information content. The document ratings appear in Appendix C. Aircraft Ground Deicing Patents A general review of aircraft ground deicing-related patents was performed to identify potential deicing optimization technologies and procedures for future study. Patent-related information was gathered from two Internet websites: • http://www.freepatentsonline.com; and • http://www.braindex.com/patent_pdf/. A search for aircraft ground deicing-related patents pro- duced over 400 U.S. patents and applications. An abstract of each of the 400 patents was reviewed, and 52 hard-copy ver- sions of the patents (in Adobe Acrobat PDF) were downloaded for more extensive review. An abstract of each of the 52 patents reviewed in detail is provided in Appendix D. Most of the patents reviewed applied to de/anti-icing fluid formulation, de/anti-icing vehicle configuration, ice detection sensors, deicing sprayers, onboard deicing systems, and non- glycol deicing technologies. Only a few potential technolo- gies and procedures were identified for further examination from the patent review. These included the use of non-glycol de/anti-icing fluid formulations and the use of laser technol- ogy for deicing aircraft. Focus Group Survey A focus group was organized to gain industry insights and feedback on current and future aircraft de/anti-icing fluid opti- mization practices. The methodology employed to assemble the focus group and conduct the survey are summarized herein. A copy of the survey, list of survey respondents, and detailed sur- vey results are provided in Appendixes E, F, and G respectively. Focus Group The focus group was assembled from two sources: key con- tacts in the aviation industry and ACRP Project 10-01 panel members. Industry contacts were selected for inclusion in the focus group based on their knowledge, experience, and decision- making authority related to aircraft ground operations in win- ter conditions, specifically de/anti-icing fluid usage. A concerted effort was made to include individuals representing various interests in the industry including: de/anti-icing fluid manufac- turers, deicing equipment manufacturers, air carriers (of vari- ous sizes), airframe manufacturers, deicing service providers, airport authorities and regulators. While most individuals selected were based in North America, several Europeans were also included in the focus group. ACRP Project 10-01 panel members were included in the focus group to allow panel members to share their experience and knowledge. Survey A survey was developed to gather information from the focus group. A copy of the survey is included in Appendix E. Survey Administration and Response The survey was provided to the focus group via email and the responses organized in a database. In total, the survey was sent to 37 individuals, including 24 industry contacts and 13 ACRP Project 10-01 panel mem- bers. Nineteen individuals submitted completed surveys, and one individual provided general comments. The overall response rate was 54% (20 of 37). The response rates by inclusion source and interest group are shown in Tables 1 and 2, respectively. At least one response was received from each interest group. A complete list of focus group members who completed the survey is included in Appendix F. Survey Results The detailed survey results are provided in Appendix G. The application of survey results is discussed in the following section. Binary Decision Analysis Model The Binary Decision Analysis Model was used in the deter- mination of which technologies and procedures should be 5

recommended for future study. This model, used for ranking of alternatives, is a systematic formalized procedure for solv- ing complex decision problems. Following the compilation of potential de/anti-icing opti- mization technologies and procedures, a list of analytical crite- ria for evaluating the usefulness of the selected technologies and procedures was developed. The Binary Decision Analysis Model was then employed to assign a weight to each of the analyti- cal criteria. This process compared each combination of two criteria and determined which of the two was more important. The more important criterion of each pair is then given the value of one, and the other is given a value of zero. At the com- pletion of the exercise, the values are totaled for each criterion, and a percentage is calculated based on the total number of pairs possible. This exercise with seven selected criteria produced 21 pairs for comparison. An initial, internal weighting of the analytical criteria was made to select technologies and procedures for further research. This selection was later reinforced by criteria weights deter- mined by the focus group as part of the survey described earlier. Findings and Applications Aircraft De/Anti-Icing Optimization Technologies and Procedures The objective of the literature review was to develop a list of potential means for optimizing the use of de/anti-icing flu- ids, thus reducing environmental impact while maintaining or enhancing aircraft safety. The nature of the potential improvements generally included: • Procedures that may already be instituted by certain oper- ators, but which would offer value if applied on a wider scale (example: spot deicing for frost); • Procedures that could be instituted, already having regula- tory approval (example: application of dilutions of Type IV fluids versus full strength); • Procedures that would require regulatory approval (exam- ple: reduced fluid freeze-point buffer for first-step deicing fluid and hot water deicing); and • Application of new technologies (either proven or in development). Preliminary List of De/Anti-Icing Optimization Technologies and Procedures The review of technical reports; regulatory, government, and industry documentation; and applicable patents pro- duced the following list of 34 potential de/anti-icing opti- mization technologies and procedures: 1. Reduction of fluid buffer for deicing-only conditions. 2. Introduction of larger negative freeze-point buffer for first-step deicing fluid, enabling use of hot water for deic- ing at ambient temperatures lower than 26.6°F (−3°C). 6 Inclusion Source Persons in Focus Group Responses Received Response Rate APS Contacts 24 14 58% ACRP Panel Members 13 6 46% Total 37 20 54% Table 1. Survey response rate by inclusion source. Interest Group Persons in Focus Group Responses Received Response Rate Air Carriers 10 6 60% Airframe Manufacturers 1 1 100% Airport Authorities 4 1 25% Deicing Equipment Manufacturers 1 1 100% Deicing Service Providers 4 2 50% Fluid Manufacturers 3 2 67% Regulators 7 5 71% Other 7 2 29% Total 37 20 54% Table 2. Survey response rate by interest group.

3. Use of heated Type II and IV fluids as an overspray to support the use of a more dilute first-step deicing fluid. 4. Reduction of fluid buffer for fluids applied before the start of precipitation, to prevent bonding of frozen pre- cipitation to the aircraft surface. 5. Development of means of determining de/anti-icing fluid failure (adherence to surface) as opposed to identifying failure by visual indications. 6. Use of Allied Signal Contaminant/Fluid Integrity Mea- suring System (C/FIMS) to indicate fluid condition and contamination on aircraft surfaces. 7. Use remote ice detection sensors to scan aircraft critical surfaces just before entering the departure runway. 8. Use of the Intertechnique Ice Detection Evaluation System (IDES) system to detect ice adherence and fluid condition on aircraft surfaces. 9. Use of warmed fuel to protect wings against precipitation and frost contamination. 10. Use of a mobile infrared system to deice aircraft. 11. Use of Type III fluids as a replacement for Type I fluid in one-step de/anti-icing operations. 12. Development and publication of holdover time guidelines for heated Type III fluid. 13. Documentation of guidelines to ensure that adequate quality control checks are conducted on the fluids and on deicing procedures. 14. Implementation and monitoring of quality control checks and operational deicing procedures at airports. 15. Determination of optimum spray equipment and tech- nique to reduce the shearing effect associated with spraying Type II/IV fluid. 16. Implementation of National Center for Atmospheric Research (NCAR) Hotplate at airports to provide pilots with real-time snow intensity information. 17. Development of a simulation model to evaluate wing exposure to wind and snow catch associated with the use of different runways. 18. Reduction of delays at the deicing pad following comple- tion of the anti-icing application through documentation of best practices. 19. Protection of holdover time as opposed to noise abatement when assigning departure runways during deicing events. 20. Protection of holdover time as opposed to noise abate- ment when assigning departure runways during snow- storm events. 21. Implementation of D-Ice A/S all weather holdover time determination system at airports to provide pilots with deicing decision support. 22. Use of onboard or ground-based lasers to deice aircraft. 23. Use of Tempered Steam as a non-glycol gate deicing or pre-deicing tool. 24. Use of Tempered Steam as an engine deicing tool. 25. Development and implementation of non-glycol or reduced glycol de/anti-icing fluids. 26. Use of ice-phobic or hydrophobic coatings to protect aircraft surfaces from adhering contamination. 27. Use of weather forecasting tools for better identification and planning of deicing-related events. 28. Use of forced air assist for applying de/anti-icing fluids. 29. Use of infrared deicing technology. 30. Use of spray-and-go deicing procedures. 31. Use of threshold deicing procedures. 32. Use of spot deicing for frost. 33. Increased use of anti-icing fluid dilutions. 34. Use of snow/leaf blowers to remove dry contamination. Elimination of Items with Low Potential for Success Following the development of the preliminary list of poten- tial de/anti-icing optimization technologies and procedures in the previous section, an analysis was performed to identify those technologies and procedures offering the greatest promise. This evaluation resulted in the elimination of a number of items because of technical, operational, or environmental short- comings, as described in Table 3. In addition to the items in Table 3, several items of simi- lar nature were combined under generic titles. For example, Item 6 from the preliminary list, Use of Allied Signal Conta- minant/Fluid Integrity System (C/FIMS) to indicate fluid con- dition and contamination on aircraft surfaces and Item 8, Use of the Intertechnique Ice Detection Evaluation System (IDES) system to detect ice adherence and fluid condition on aircraft surfaces, were combined under the title, Point detection sen- sors to indicate fluid condition and contamination on aircraft surfaces. This reduced the number of technologies and proce- dures for further review, as well as eliminated commercial and competitive issues related to technologies of similar nature. Development of Final List of Technologies and Procedures Following the activities described in the previous section, the following final list of 18 de/anti-icing optimization tech- nologies and procedures in alphabetical order was developed: 1. Blowers and/or other mechanical means to remove dry contamination: leaf blowers, brooms, scrapers, etc., to remove dry contamination prior to de/anti-icing opera- tion (if applicable); 2. Deicing-only fluid buffer reduction: “Deicing-only” conditions exist when an aircraft is not exposed to a period of active precipitation (i.e., overnight precipitation that has ceased by the time of departure). The fluid freeze- 7

point buffer could be reduced further in these conditions to limit glycol dispensed; 3. First-step deicing fluid buffer reduction: Current indus- try regulations allow for Type I fluid to be sprayed at a −5.4°F (−3°C) buffer (freeze point 5.4°F or 3°C above ambient temperature) when used as a first-step deicing fluid (hot water can also be employed down to 26.6°F). Testing has indicated that this buffer could be further reduced; 4. Fluids applied before the start of precipitation to prevent bonding: Pre-treating of aircraft surfaces with de/anti- icing fluid to protect surfaces against the adherence of ice (for example, this procedure would be useful prior to a freezing rain event); 5. Forced air used to remove contamination: Forced air has been employed effectively by the industry for several years to blow off dry contamination prior to de/anti-icing; 6. Implementation of holdover time determination sys- tems: Airport systems, such as D-Ice A/S Deicing Infor- mation System and NCAR Checktime, which measure meteorological parameters at airport sites for use in scientific computations to enhance the accuracy of fluid holdover times, thus facilitating better de/anti-icing fluid selection; 8 # Item from Preliminary List Reason for Elimination 3 Use of heated Type II and IV fluids as an overspray to support the use of a more dilute first-step deicing fluid May require development of additional set of holdover time values for heated fluids 5 Development of means of determining de/anti-icing fluid failure (adhere to surface) as opposed to identifying failure by visual indications Doesn't offer significant environmental enhancement 9 Use of warmed fuel to protect wings against precipitation and frost contamination Doesn't offer significant environmental or operational enhancement 12 Development and publication of holdover time guidelines for heated Type III fluid Doesn't offer significant environmental enhancement 13 Documentation of guidelines to ensure that adequate quality control checks are conducted on the fluids and on deicing procedures Doesn't offer significant environmental enhancement 14 Implementation and monitoring of quality control checks and operational deicing procedures at airports Doesn't offer significant environmental enhancement 15 Determination of optimum spray equipment and technique to reduce the shearing effect associated with spraying Type II/IV fluid Doesn't offer significant environmental enhancement 17 Development of a simulation model to evaluate wing exposure to wind and snow catch associated with the use of different runways Doesn't offer significant environmental enhancement 18 Reduction of delays at the deicing pad following completion of the anti-icing application through documentation of best practices Doesn't offer significant environmental enhancement 19 Protection of holdover time as opposed to noise abatement when assigning departure runways during deicing events Little flexibility is available in the process of assigning runways during deicing conditions 20 Protection of holdover time as opposed to noise abatement when assigning departure runways during snowstorm events Little chance of success and limited environmental enhancement 22 Use of onboard or ground-based lasers to deice aircraft Technological and implementation challenges 26 Use of ice-phobic or hydrophobic coatings to protect aircraft surfaces from adhering contamination Technological and operational challenges Table 3. Elimination of Items from the preliminary list.

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

10 De/Anti-Icing Optimization Technology and Procedures Not Useful (%) Somewhat Useful (%) Very Useful (%) 1. Blowers and/or other mechanical means to remove dry contamination 5 58 37 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 bonding 6 56 39 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 contamination on aircraft surfaces 17 61 22 9. Remote ice detection sensors to scan aircraft critical surfaces before departure runway 0 58 42 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- deicing tool 11 26 63 13. Threshold deicing 5 42 53 18. Use of weather forecasting products for deicing process 0 37 63 14. Type III fluids 32 53 16 15. Use of 10°C 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 Table 4. Focus group results pertaining to usefulness of the selected technologies and procedures.

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

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

were assigned the sum of values from 11 to 13, for an average value of 12. The following items were viewed as having different levels of capital cost and were ranked accordingly. The required capital costs were: • Item 5, Forced air used to remove contamination: cost to replace deicers or retrofit current deicers with forced air systems; • Item 16, Use of Anti-icing fluid dilutions: cost for fluid blenders and additional fluid tanks for various blends; and • Item 11, Spray-and-go deicing: cost to modify taxiway to enable deicer movement around aircraft and cost to capture spent fluid. The remaining items all require significant capital invest- ment for the purchase and implementation of the technology or procedure. Operating Cost. The ranking for Operating Cost is shown in Table 8. The impact on operating costs, in some cases, is expected to be an overall reduction. In other cases, an increase in operating costs would be expected. Ranking against oper- ating cost assigns the greatest importance to those items having the least negative impact. There were no equivalent levels of cost between items, and each approach was given its own ranking. The operational benefit associated with Item 10, Spot deicing for frost, is a reduction in deicing costs (fluid and manpower). An expected reduction in aircraft operating times, which implies important savings in maintenance costs, crew costs, fuel burn, and disrupted passenger costs is claimed in the Operational Efficiency criterion. Item 10, Item 14, and Item 16 all involve a reduction in de/anti-icing fluid costs, with no additional operational expenditure. 13 Item # Optimization Technology or Procedure Capital Cost Rank Capital Cost % 10 Spot deicing for frost 16.0 9.4% 14 Type III fluids 16.0 9.4% 1 Blowers and/or other mechanical means to remove dry contamination 16.0 9.4% 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 10°C 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% 9 Remote ice detection sensors to scan aircraft critical surfaces before departure runway 4.0 2.3% 13 Threshold deicing 3.0 1.8% 8 Point detection sensors to indicate fluid condition and contamination on aircraft surfaces 2.0 1.2% 17 Use of infrared deicing technology 1.0 0.6% TOTAL 171.0 100.0% Table 7. Ranking of technologies and procedures by capital cost.

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

Item # Optimization Technology or Procedure TrainingRank Training % 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 10°C 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% 9 Remote ice detection sensors to scan aircraft critical surfaces before departure runway 4.0 2.3% 8 Point detection sensors to indicate fluid condition and contamination on aircraft surfaces 3.0 1.8% 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 deicing, provide an opportunity to reduce the amount of fluid (especially Type IV fluid) sprayed. Additionally, these approaches remove the problem of fluid dripping from air- craft surfaces while taxiing to the departure runway. Other approaches reduce the quantity of de/anti-icing fluid sprayed by removing contamination prior to proceeding to deicing, or by reducing the glycol content in the fluid by using a lower fluid strength. Items 8 and 9, which pertain to remote or point ice detection sensors, might actually increase the impact on environment by leading to more returns for repeated deicing. Maturity. A total of 22 regulatory, government, and industry documents, guidance material, and standards were reviewed by APS personnel during the literature review. These documents were compared to the 18 identified optimization technologies and procedures to determine if the selected optimization technologies and procedures were covered by appropriate guidance or standards material or if additional regulatory, government, or guidance material was required. A subjective rating of “Yes,” “No,” “N/A” or “Pending” was then assigned to each selected technology or procedure. The results of this comparison are presented in Table 11. The optimization technologies or procedures with a “Yes” rating are deemed to be currently covered by existing regula- tory guidance documents. Those with a “Pending” rating are being addressed by pending regulatory guidance from a regulator, but not by guidance from the FAA, nor have they been addressed in deicing documentation from the SAE at this time. However it appears that most of the technical challenges of the optimization technology or procedure with a “Pending” rating have been met, and regulatory guidance is being considered. Those with a “No” rating have not been addressed by appropriate guidance docu- ments from the regulators or addressed as an acceptable practice by the SAE or the AEA. Typically these “No” rated technologies and procedures are undergoing development or require further evaluations by the authorities before an endorsement is given. 15 Table 9. Ranking of technologies and procedures by training.

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

not have been included in the analysis. A decision process was finally agreed upon wherein each item was first assessed whether it potentially improved safety, was safety neutral, or involved a risk of decreasing the level of safety below the cur- rent level (in relation to that item only and while still main- taining a satisfactory level of safety). Six items were identified as potentially improving safety (each given an average score of 15.5), nine were safety neutral (each given an average score of 8), and three were identified as potentially decreasing safety (each given an average score of 2). Overall Ranking of Optimization Technologies and Procedures Once the list of optimization technologies and procedures had been ranked for each criterion, the complete matrix of item scores was assembled, as shown in Table 15. The poten- tial items for optimization are sorted by score percentage, with the most promising approaches at the top of the list. Table 15 is a matrix where each cell presents an overall per- centage score. Each cell then has been given a score calculated by multiplying the criterion weights for the approaches within each criterion. This representation allows a direct comparison between various cells, identifying the criterion and the approaches that give the greatest weight. Sensitivity Analysis As described in the previous sections, the ranked list of opti- mization technologies and procedures was developed based upon the focus group weighting of criteria. Prior to request- ing inputs from the focus group, an internal exercise was per- formed to weigh the criteria in a similar fashion to the focus group. A team of experts at the research agency independently developed the criterion weights shown in Table 16. The weights in Table 16 are slightly different from the weights determined by the focus group. Application of the weights in Table 16 to the technology and procedure 17 Item # Optimization Technology or Procedure Rating 1 Blowers & mechanical means to remove dry contamination Yes 2 Deicing-only fluid buffer reduction No 3 First-step deicing fluid buffer reduction No 4 Fluids applied before the start of precipitation to prevent bonding Yes 5 Forced air to remove contamination Yes 6 Implementation of holdover time determination systems Pending 7 Non-glycol freeze point depressant fluids No 8 Point detection sensors to indicate fluid condition and contamination on aircraft surfaces No 9 Remote ice detection sensors to scan aircraft critical surfaces before departure runway No 10 Spot deicing for frost Yes 11 Spray-and-go deicing Yes 12 Tempered Steam as a non-glycol gate deicing or pre-deicing tool Pending 13 Threshold deicing Yes 14 Type III fluids Yes 15 Use of 10°C Type I BUFFER Yes 16 Use of anti-icing fluid dilutions Yes 17 Use of Infrared deicing technology Yes 18 Use of weather forecasting products for deicing process N/A Table 11. Maturity of technologies and procedures versus guidance material.

18 Item # Optimization Technology or Procedure Maturity Rank Maturity % 10 Spot deicing for frost 15.5 9.1% 5 Forced air used to remove contamination 15.5 9.1% 16 Use of anti-icing fluid dilutions 15.5 9.1% 15 Use of 10°C Type I buffer 15.5 9.1% 1 Blowers and/or other mechanical means to remove dry contamination 15.5 9.1% 4 Fluids applied before the start of precipitation to prevent bonding 15.5 9.1% 11 Spray-and-go deicing 11.5 6.7% 13 Threshold deicing 11.5 6.7% 2 Deicing-only fluid buffer reduction 10.0 5.8% 14 Type III fluids 9.0 5.3% 17 Use of infrared deicing technology 7.5 4.4% 3 First-step deicing fluid buffer reduction 7.5 4.4% 6 Implementation of holdover time determination systems 6.0 3.5% 18 Use of weather forecasting products for deicing process 5.0 2.9% 12 Tempered steam as a non-glycol gate deicing or pre-deicing tool 4.0 2.3% 7 Non-glycol freeze point depressant fluids 3.0 1.8% 8 Remote ice detection sensors to scan aircraft critical surfaces before departure runway 2.0 1.2% 9 Point detection sensors to indicate fluid condition and contamination on aircraft surfaces 1.0 0.6% TOTAL 171.0 100.0% Table 12. Ranking of technologies and procedures by maturity.

19 Item # Optimization Technology or Procedure Operational Efficiency Rank Operational Efficiency % 10 Spot deicing for frost 18.0 10.5 11 Spray-and-go deicing 17.0 9.9 13 Threshold deicing 16.0 9.4 6 Implementation of holdover time determination systems 15.0 8.8 12 Tempered steam as a non-glycol gate deicing or pre-deicing tool 14.0 8.2 5 Forced air used to remove contamination 13.0 7.6 1 Blowers and/or other mechanical means to remove dry contamination 12.0 7.0 14 Type III fluids 11.0 6.4 18 Use of weather forecasting products for deicing process 10.0 5.8 4 Fluids applied before the start of precipitation to prevent bonding 9.0 5.3 15 Use of 10°C Type I buffer 8.0 4.7 16 Use of anti-icing fluid dilutions 7.0 4.1 7 Non-glycol freeze point depressant fluids 6.0 3.5 2 Deicing-only fluid buffer reduction 5.0 2.9 3 First-step deicing fluid buffer reduction 4.0 2.3 17 Use of infrared deicing technology 3.0 1.8 8 Remote ice detection sensors to scan aircraft critical surfaces before departure runway 2.0 1.2 9 Point detection sensors to indicate fluid condition and contamination on aircraft surfaces 1.0 0.6 TOTAL 171.0 100.0% Table 13. Ranking of technologies and procedures by operational efficiency.

20 Item # Optimization Technology or Procedure Safety Rank Safety % 11 Spray-and-go deicing 15.5 9.1 13 Threshold deicing 15.5 9.1 6 Implementation of holdover time determination systems 15.5 9.1 18 Use of weather forecasting products for deicing process 15.5 9.1 8 Remote ice detection sensors to scan aircraft critical surfaces before departure runway 15.5 9.1 9 Point detection sensors to indicate fluid condition and contamination on aircraft surfaces 15.5 9.1 10 Spot deicing for frost 8.0 4.7 5 Forced air used to remove contamination 8.0 4.7 16 Use of anti-icing fluid dilutions 8.0 4.7 14 Type III fluids 8.0 4.7 12 Tempered steam as a non-glycol gate deicing or pre-deicing tool 8.0 4.7 15 Use of 10°C Type I buffer 8.0 4.7 7 Non-glycol freeze point depressant fluids 8.0 4.7 4 Fluids applied before the start of precipitation to prevent bonding 8.0 4.7 17 Use of infrared deicing technology 8.0 4.7 1 Blowers and/or other mechanical means to remove dry contamination 2.0 1.2 2 Deicing-only fluid buffer reduction 2.0 1.2 3 First-step deicing fluid buffer reduction 2.0 1.2 TOTAL 171.0 100.0% Table 14. Ranking of technologies and procedures by safety.

21 # Optimization Technolog y or Procedure Capital Cost Score (% ) Operating Cost Score (% ) Environmental Impact Score (% ) Operational Efficienc y Score (% ) Maturity Score (% ) Training Score (% ) Safet y Score (% ) Score (% ) 10 Spot deicing for frost 0.3 1.5 1.9 2.3 0.6 0.9 1.2 8.7 11 Spray -and-go deicing 0.2 0.8 1.7 2.1 0.5 0.8 2.3 8.3 13 Threshold deicing 0.1 0.1 1.8 2.0 0.5 0.8 2.3 7.5 5 Forced air used to remov e contamination 0.2 1.1 1.4 1.6 0.6 0.7 1.2 6.8 6 Implementation of holdov er time determina tion sy ste ms 0.1 1.2 0.8 1.9 0.3 0.1 2.3 6.6 16 Use of anti-icing fluid dilutions 0.2 1.4 1.1 0.9 0.6 1.0 1.2 6.5 14 Ty pe III fluids 0.3 1.3 0.6 1.4 0.4 1.0 1.2 6.3 12 Tempered steam as a non-gly col gate deicing or pre-deicing tool 0.1 1.0 1.5 1.8 0.2 0.4 1.2 6.1 15 Use of 10°C Ty pe I buffer 0.3 1.3 0.9 1.0 0.6 0.6 1.2 5.8 1 Blow ers and/or other mechanical means to remov e dry contamina tion 0.3 0.9 1.3 1.5 0.6 0.6 0.3 5.6 7 Non-gly col freeze point depressant fluids 0.3 0.5 1.6 0.8 0.1 1.0 1.2 5.5 4 Fluids applied before the start of precipitation to prev ent bonding 0.3 0.6 0.4 1.1 0.6 1.0 1.2 5.3 18 Use of w eather forecasting products for deicing process 0.1 0.3 0.3 1.3 0.2 0.1 2.3 4.6 2 Deicing-only flu id buffer reduction 0.3 0.8 0.7 0.6 0.4 0.5 0.3 3.6 9 Remote ice detection sensors to scan aircraft critical surfaces before departure runw ay 0.1 0.4 0.2 0.3 0.1 0.3 2.3 3.6 17 Use of infrared deicing technology 0.0 0.2 1.0 0.4 0.3 0.3 1.2 3.4 8 Point detection sensors to indicate fluid condition and contamination on aircraft surfaces 0.0 0.3 0.1 0.1 0.0 0.2 2.3 3.0 3 First-step deicing fluid buffer reduction 0.3 0.7 0.5 0.5 0.3 0.4 0.3 3.0 TOT AL 3.6% 14.3% 17.9% 21.4% 7.1% 10.7% 25.0% 100.0% Table 15. Overall ranking of technologies and procedures.

evaluation analytical process provided the ranking shown in Table 17. Table 17 demonstrates that the overall ranking of the opti- mization technologies or procedures does not change signif- icantly with the different sets (research agency and focus group) of criterion weights. Conclusions and Recommendations Conclusions Aircraft ground deicing technical reports; manufacturer product reports; regulatory, government, and industry doc- umentation; guidance material and standards; and deicing- related patents and applications were reviewed to identify technologies and procedures that could potentially optimize the use of current de/anti-icing methodologies, most pre- dominantly glycol-based fluids. The review produced a list of 34 potential technologies and procedures. Many of the potential technologies and procedures were deemed to possess technical or operational deficien- cies, or were deemed to not offer an adequate environmental or operational enhancement over the current status quo, and were eliminated from further evaluation. Additional technolo- gies and procedures of similar nature were merged under generic titles to eliminate commercial or competitive issues. This process of elimination and merger produced a final list of 18 proposed technologies and procedures for further review. A series of seven analytical criteria (capital cost, operating cost, environmental impact, training, maturity, operational effi- ciency, safety) was developed and defined to assist in the evalu- ation of the 18 technologies and procedures for future study. A ranking (1 to 18) of each of the technologies and procedures was then performed for each analytical criterion, to identify the comparative strengths and weaknesses of each proposed item. A focus group of industry experts was surveyed for inputs on the usefulness of the 18 proposed technologies, as well as on the weighting of the analytical criteria employed for analyzing and ranking of the technologies and procedures for future study. This exercise produced a final ranking of the de/anti-icing opti- mization technologies and procedures for future study. The final list was comprised of numerous “quick hit” approaches (ones that are currently in use but could be readily improved upon), as well as many approaches requiring greater levels of research. Recommendations for Further Study The research performed in Phase I identified and ranked 18 potential de/anti-icing optimization technologies and pro- cedures for further study. The top 10 ranked de/anti-icing optimization technologies and procedures were selected from this list. This eliminated the bottom eight ranked technolo- gies and procedures: • Item 2, Deicing-only fluid buffer reduction; • Item 3, First-step deicing fluid buffer reduction; • Item 4, Fluids applied before the start of precipitation to prevent bonding; • Item 7, Non-glycol freeze point depressant fluids; • Item 8, Point detection sensors to indicate fluid condition and contamination on aircraft surfaces; • Item 9, Remote ice detection sensors to scan aircraft critical surfaces before departure runway; • Item 17, Use of infrared deicing technology; and • Item 18, Use of weather forecasting products for deicing process. The remaining technologies and procedures were then grouped into two categories: 22 Criteri a Decision Scores Score+1 Weight % Capital Cost 3 4 14. 3 Operating Cost 2 3 10. 7 Environmental Impact 1 2 7. 1 Operational Efficiency 4 5 17. 9 Maturity 5 6 21. 4 Training 0 1 3. 6 Safety 6 7 25. 0 TOTAL 21 28 100.0% Table 16. APS criteria weights.

• Mature Technologies and Procedures (quick hits): These technologies and procedures include those that could be supported and advanced by efforts such as production of cost benefit analysis, a lesser level of research in some cases, and development of industry information aids. In general, these items have reached a level of maturity that enables rapid application and implementation. The effort associ- ated with this group would be directed toward developing supporting material to influence decision-makers for field operations to implement approaches that are appropriate to their own operation. • Research and Development Technologies and Proce- dures: The technologies and procedures included in this group are those that are not yet fully developed. They offer strong potential for optimizing the use of glycol and have been identified as desirable in the focus group survey. The effort associated with this group would be directed toward supporting and advancing the research and development process required to bring these items to the implementa- tion stage. The results of the categorization are shown in Table 18. Recommendations for Phase II The top two quick hit procedures and the top two research technologies from Table 18 were recommended for further development and evaluation in Phase II of the project: 1. Implementation of Holdover Time Determination Systems (research); 2. Spot Deicing for Frost (quick hit); 23 # Optimization Technology or Procedure Focus Group Final Score (%) APS Final Score (%) Focus Group Rank APS Rank 10 Spot deicing for frost 8.7 8.5 1 1 11 Spray-and-go deicing 8.3 7.7 2 2 13 Threshold deicing 7.5 6.7 3 4 5 Forced air used to remove contamination 6.8 6.9 4 3 6 Implementation of holdover time determination systems 6.6 6.3 5 9 16 Use of anti-icing fluid dilutions 6.5 6.5 6 5 14 Type III fluids 6.3 6.4 7 7 12 Tempered steam as a non-glycol gate deicing or pre-deicing tool 6.1 5.1 8 11 15 Use of 10°C Type I buffer 5.8 6.5 9 6 1 Blowers and/or other mechanical means to remove dry contamination 5.6 6.2 10 10 7 Non-glycol freeze point depressant fluids 5.5 4.9 11 12 4 Fluids applied before the start of precipitation to prevent bonding 5.3 6.3 12 8 18 Use of weather forecasting products for deicing process 4.6 4.9 13 13 2 Deicing-only fluid buffer reduction 3.6% 4.1% 14 14 9 Remote ice detection sensors to scan aircraft critical surfaces before departure runway 3.6 3.5 15 15 17 Use of infrared deicing technology 3.4 3.2 16 17 8 Point detection sensors to indicate fluid condition and contamination on aircraft surfaces 3.0 3.0 17 18 3 First-step deicing fluid buffer reduction 3.0 3.5 18 16 Table 17. Comparison of focus group and APS ranking of technologies and procedures.

3. Spray-and-Go Deicing (quick hit); and 4. Tempered Steam as a Non-Glycol Gate Deicing or Pre- Deicing Tool (research). After review of these recommendations, ACRP selected Technologies 1 and 2 for comprehensive evaluation in Phase II of the project. The results of these evaluations are described in detail in Chapter 3 and 4 respectively. Bibliography Aircraft Ground Deicing Technical Reports Subject Matter: Deicing Procedures—Fluid Freeze Point Buffer Dawson, P., Examination of the Role of Fluid Freeze Point Buffers, APS Aviation Inc., Montreal, Canada, Transporta- tion Development Centre report TP 13129E (1997). Dawson, P., Aircraft Deicing Fluid Freeze Point Buffer Require- ments: Deicing Only and First Step of Two-Step Deicing, APS Aviation Inc., Montreal, Canada, Transportation Develop- ment Centre report TP 13315E (1998). Dawson, P., Aircraft Deicing Fluid Freeze Point Buffer Require- ments for Deicing-Only Conditions, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 13478E (1999). Subject Matter: Fluid Characteristics—Characteristics of Air- craft Anti-Icing Fluids Subjected to Precipitation Chaput, M. et al, Characteristics of Aircraft Anti-Icing Fluids Subjected to Precipitation, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 13317E (1998). Hunt, M., Chaput, M. et al, Characteristics of Aircraft Anti- Icing Fluids Subjected to Precipitation, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 13484E (2001). Moc, N., Adhesion of Aircraft Anti-Icing Fluids on Aluminum Surfaces, APS Aviation Inc., Montreal, Canada, Trans- portation Development Centre report TP 14149E (not yet published) (2004). Moc, N., Adhesion of Aircraft Anti-Icing Fluids on Aluminum Surfaces: Phase II, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 14377E (not yet published) (2004) Subject Matter: Ice Detection Sensors Bendickson, S., A Sensor for Detecting Anti-Icing Fluid Failure: Phase I, APS Aviation Inc., Montreal, Canada, Trans- portation Development Centre report TP 14382E (not yet published) (2004). Bendickson, S., A Sensor for Detecting Anti-Icing Fluid Failure: Phase II, APS Aviation Inc., Montreal, Canada, Transporta- tion Development Centre report TP 14446E (not yet pub- lished) (2005). Dawson, P. and Peters, A., Feasibility of Use of Ice Detection Sensors of End-of-Runway Wing Checks, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 13481E (1999). Dawson, P. and Hunt, M., Ice Detection Sensor Capabilities for End-of-Runway Wing Checks: Phase 2 Evaluation, APS Avi- 24 Rank Optimization Technology or Procedure Item # Type of Activity 1 Spot deicing for frost 10 Quick Hit 2 Spray-and-go deicing 11 Quick Hit 3 Threshold deicing 13 Quick Hit 4 Forced air used to remove contamination 5 Quick Hit 5 Implementation of holdover time determination systems 6 Research 6 Use of anti-icing fluid dilutions 16 Quick Hit 7 Type III fluids 14 Quick Hit 8 Tempered steam as a non-glycol gate deicing or pre-deicing tool 12 Research 9 Use of 10°C Type I buffer 15 Quick Hit 10 Blowers and/or other mechanical means to remove dry contamination 1 Quick Hit Table 18. Top 10 ranking de/anti-icing technologies and procedures.

ation Inc., Montreal, Canada, Transportation Development Centre report TP 13662E (2000). Weisser, Carl F., Final Report Operational Evaluation for the Two Sensor Contaminant/Fluid Integrity Measuring System (C/FIMS) Midway Airlines F-100 Aircraft, Allied Signal Aerospace, Etobicoke, Canada, Transportation Develop- ment Centre report TP 12979E (1997). Weisser, Carl F., Operational Evaluation for the Four Sensor Contaminant/Fluid Integrity Measuring System (C/FIMS) Midway Airlines F-100 Aircraft, Allied Signal Aerospace, Etobicoke, Canada, Transportation Development Centre report TP 13254E (1997). Subject Matter: Hot Water Deicing Dawson, P., Hot Water Deicing Trials for the 1994–95 Winter, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 12653E (1995). Dawson, P., and Hanna, M., Hot Water Deicing of Aircraft, APS Aviation Inc., Montreal, Canada, Transportation Develop- ment Centre report TP 13483E (1999). Dawson, P., and Hanna, M., APS Hot Water Deicing of Air- craft: Phase 2, APS Aviation Inc., Montreal, Canada, Trans- portation Development Centre report TP 13663E (2000). Subject Matter: Forced Air Deicing Bendickson, S., A Protocol for Testing Fluids Applied with Forced Air Systems, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 14380E (not yet published) (2004). Bendickson, S., Evaluation of Type IV Fluids Using FedEx Forced Air Assist Equipment, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 14445E (not yet published) (2005). Dawson, P., Endurance Times of Fluids Applied with Forced Air Systems, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 14153E (2003). Subject Matter: Alternative Deicing Approaches Dawson, P. and Hanna, M., APS Evaluation of Warm Fuel as an Alternative Approach to Deicing, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 13482E (1999). Ruggi, E., and Pole, C., APS Deicing with a Mobile Infra-Red System, APS Aviation Inc., Montreal, Canada, Transporta- tion Development Centre report TP 13489E (2005). Posteraro, D. and Chaput, M., Evaluation of the Chinook Tempered Steam Deicing Technology for Aircraft Deicing Applications, APS Aviation Inc., Montreal, Canada (not yet published) (2007). Subject Matter: Aircraft De/Anti-Icing Fluid Research Chaput, M., A Potential Solution for De/Anti-Icing of Commuter Aircraft, APS Aviation Inc., Montreal, Canada, Transporta- tion Development Centre report TP 14152E (2003). Chaput, M., APS Development of Holdover Time Guidelines for Type III Fluids, APS Aviation Inc., Montreal, Canada, Trans- portation Development Centre report TP 14379E (2004). Subject Matter: Aircraft De/Anti-Icing Fluid Testing Chebil, S. and Alwaid, A., Influence of Application Procedure on Anti-icing Fluid Viscosity, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 13996E (2002). Dawson, P., SAE Type I Fluid Endurance Time Test Protocol, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 13827E (2003). Moc, N., Effect of Heat on Endurance Times of Anti-icing Fluids, APS Aviation Inc., Montreal, Canada, Transportation Devel- opment Centre report TP 14447E (not yet published) (2005). Youssef, D., Dawson, P., Effect of Heat on Endurance Times of Anti-icing Fluids (Research 2005–2007), APS Aviation Inc., Montreal, Canada, Transportation Development Centre report (not yet published) (2007). Subject Matter: Application of Fluid Holdover Time Guidelines Bendickson, S., Relationship Between Visibility and Snow- fall Intensity, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 14151E (2003). Subject Matter: Holdover Time Determination Systems Chaput, M., Technical Assessment of the Dan-Ice Detection and Information System, APS Aviation Inc., Montreal, Canada (2004). Chaput, M., Operational Assessment of the Dan-Ice Detection and Information System (DIIS) Winter 2003–04, APS Avia- tion Inc., Montreal, Canada (2004). Chaput, M., and Ruggi, M., Continued Technical Assessment of the Dan-Ice Information System, APS Aviation Inc., Montreal, Canada (2006). Ruggi, M. and Moc, N., Evaluation of a Real-Time Snow Pre- cipitation Gauge for Aircraft Deicing Operations, APS Avia- tion Inc., Montreal, Canada, Transportation Development Centre report TP 14150E (2003). Ruggi, M. and Moc, N., Evaluation of a Real-Time Snow Pre- cipitation Gauge for Aircraft Deicing Operations (2003–04), APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 14150E (2004). 25

Subject Matter: Aerodynamic Penalties of Clean or Partially Expended De/Anti-icing Fluid Chaput, M. and Campbell, R., Aircraft Takeoff Test Program for Winter 2001–02: Testing to Evaluate the Aerodynamic Penalties of Clean or Partially Expended De/Anti-Icing Fluid, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 13995E (2002). Subject Matter: Aircraft Ground Deicing Exploratory Research Bendickson, S., Chebil, S., Moc, N. and Vepsa, K., Aircraft Ground Icing General and Exploratory Research Activities for the 2003–04 Winter, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 14381E Winter (not yet published) (2004). Chebil, S., Mayodon, M., Dawson, P., Aircraft Ground Icing Exploratory Research for the 2002–03 Winter, APS Aviation Inc., Montreal, Canada, Transportation Development Centre report TP 14154E (not yet published) (2003). Regulatory, Government and Industry Documentation, Guidance Material and Standards U.S. Federal Aviation Administration (FAA) U.S., Federal Aviation Administration AFS-2508, FAR Part 135 Icing Limitations, Advisory Circular (AC) 135-9, U.S. Federal Aviation Administration, Washington, DC (5/30/ 1981). U.S. Federal Aviation Administration AWS-100, Hazards Fol- lowing Ground Deicing and Ground Operations in Condi- tions Conducive to Aircraft Icing, Advisory Circular (AC) 20-117, Federal Aviation Administration, Washington, DC (reissued 3/29/1988). U.S. Federal Aviation Administration AFS-400, Pilot Guide— Large Aircraft Ground Deicing, Advisory Circular (AC) 120-58, U.S. Federal Aviation Administration, Washing- ton, DC, (9/30/1992). U.S. Federal Aviation Administration AFS-2507, Ground Deicing and Anti-Icing—Training and Checking, Advisory Circular (AC) 135-16, U.S. Federal Aviation Administra- tion, Washington, DC (12/12/1994). U.S. Federal Aviation Administration AFS-200, Pilot Guide— Small Aircraft Ground Deicing, Advisory Circular (AC) 135-17, U.S. Federal Aviation Administration, Washing- ton, DC (12/14/1994). U.S. Federal Aviation Administration AFS-220, Pilot Guide— Flight in Icing Conditions, Advisory Circular (AC) 91-74, U.S. Federal Aviation Administration, Washington, DC (12/12/2002). U.S. Federal Aviation Administration AFS-22010, Aircraft Deicing and Anti-icing Program, Advisory Circular (AC) 120-60B, U.S. Federal Aviation Administration, Washing- ton, DC (12/05/2004). U.S. Federal Aviation Administration AFS-2209, Ground De- icing Using Infrared Energy, Advisory Circular (AC) 120-89, U.S. Federal Aviation Administration, Washington, DC (12/13/2005). U.S. Federal Aviation Administration AIR-120, Aircraft Ice Protection, Advisory Circular (AC) 20-73A, Federal Avia- tion Administration, Washington, DC (10/16/2006). U.S. Federal Aviation Administration AFS-20011, Approved Deicing Program Updates, Winter 2006–07, FAA N8000.329, U.S. Federal Aviation Administration, Washington, DC (10/27/2006). U.S. Federal Aviation Administration ACE-1006, Certification of Part 23 Airplanes for Flight in Icing Conditions, Advisory Circular (AC) 23-1419-2D, U.S. Federal Aviation Admin- istration, Washington, DC (4/19/2007). U.S. Environmental Protection Agency (EPA) Barash, S., J. Covington, and C. Tamulonis, EPA—821-R-00- 016: Preliminary Data Summary Airport Deicing Operations, U.S. Environmental Protection Agency, Office of Water, (2000). Transport Canada (TC) Transport Canada, Holdover Time (HOT) Guidelines 2006–2007, Transport Canada, Ottawa, Canada (July 2006). Transport Canada, Ingold, D., Guidelines for Aircraft Ground Operations and Holdover Time Guidelines for Winter 2006– 2007, Commercial and Business Aviation Advisory Circular (CBAAC) 0025R3, Transport Canada, Commercial and Business Aviation, Ottawa, Canada (July 21, 2006). Transport Canada, Ingold, D., Guidelines for Aircraft Ground Icing Operations, Transport Canada, Ottawa, Canada, Transport Canada document TP 14052E (April 17, 2007). Society of Automotive Engineers (SAE) SAE G-12 Methods Subcommittee, SAE Aerospace Recom- mended Practice (ARP) 4737G Aircraft Deicing/Anti-Icing Methods With Fluids, SAE Aerospace Inc., Warrendale, PA (November 2005). Association of European Airlines (AEA) Association of European Airlines Deicing/Anti-icing Work- ing, Recommendations for Deicing/Anti-Icing of Aircraft on 26

the Ground 21st Edition, Association of European Airlines (AEA), Brussels, Belgium (September 2006). Association of European Airlines Deicing/Anti-icing Work- ing, Fieandt, J., AEA Training Recommendations and Back- ground Information for Deicing/Anti-icing of Aircraft on the Ground 3rd Edition, Association of European Airlines (AEA), Brussels, Belgium (September 2006). Other International Civil Aviation Organization (ICAO)/Interna- tional Air Transport Association (IATA) Safety Committee, Manual of Aircraft Ground Deicing/Anti-icing Operations, Second Edition, International Civil Aviation Organization, Montreal, Canada, Document 9640 (2000). Joint Aviation Authorities (JAA), Ice and Other Contaminants (Ground Procedures), Joint Aviation Requirements (JAR) OPS 1.345, Joint Aviation Authorities, Hoopdorp, Nether- lands (1/3/1998). New Zealand Civil Aviation Authority, New Zealand Air- craft Icing Handbook, 1st Edition, New Zealand Civil Aviation Authority, Wellington, New Zealand (June 14, 2000). International Organization for Standardization (ISO) Tech- nical Committee 20/SC-9 with Association of European Airlines (AEA) and the SAE G-12 Aircraft Ground Deic- ing Committee Technical Specialists, ISO 11076 Aircraft— Ground Based Deicing/Anti-icing Methods with Fluids, ISO Copyright Office, Geneva, Switzerland (November 15, 2006). 27

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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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