The National Academies Press

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From page 28... ... However, at airports with large surface area, such as Denver International Airport, the distances from a central location at the airport to a departure runway may exceed 16,000 ft. No data for similar distances were collected in 2007–08, and it was therefore decided to conduct additional testing to verify whether airports with large surface areas would require additional HOTDS installations to provide reliable data. Read the entire page →
From page 29... ... was selected as the primary location for the preliminary test program as efficiencies were obtained by conducting research at the airport where the APS test site is located. The test procedure for data collection was developed, tested, and reﬁned at this primary location. Read the entire page →
From page 30... ... The positioning of the snow-catch pan on the test stand was such that the longer dimension axis of the pan is parallel with the longer dimension axis of the test plate. A typical serving pan commonly found in the restaurant industry proved to be an adequate snow-catching pan. Read the entire page →
From page 31... ... Test stand. Figure 5. Read the entire page →
From page 32... ... Verify wind direction and adjust stand T = 20 minutes Remove Covers Remove Covers T= 22 minutes Rotate Pans T= 24 minutes Rotate Pans T= 26 minutes Rotate Pans T= 28 minutes Rotate Pans T= 30 minutes Cover pans and bring in for measurement Cover pans and bring in for measurement Read the entire page →
From page 33... ... Verify wind direction and adjust stand T = 40 minutes Remove Covers Remove Covers T= 42 minutes Rotate Pans T= 44 minutes Rotate Pans T= 46 minutes Rotate Pans T= 48 minutes Rotate Pans T= 50 minutes Cover pans and bring in for measurement Cover pans and bring in for measurement Table 21. Typical sequence for the third collection. Read the entire page →
From page 34... ... Cote Vertu 45º 28' 40" N 73º 43' 33" W APS Test Site 45º 28' 6" N 73º 44' 28" W 5,052 1,540 1 9 Chemin St François 45º 28' 33" N 73º 45' 12" W Ch. Cote Vertu 45º 28' 40" N 73º 43' 33" W 7,017 2,139 2 15 Chemin St François 45º 28' 33" N 73º 45' 12" W Marshall Rd Snow Dump 46º 27' 28" N 73º 44' 14" W 7,933 2,418 1 16 APS Office Parking Lot 45º 28' 60" N 73º 41' 36" W APS Test Site 45º 28' 6" N 73º 44' 28" W 13,390 4,081 1 10 Ch. Read the entire page →
From page 35... ... Distances from APS test site to departure runways at Montreal Trudeau International Airport (YUL) Read the entire page →
From page 36... ... Parking Lot 43º 07' 01" N 76º 08 '33" W 8,300 2530 1 (lake-effect) 32 Denver International Airport (DEN) Read the entire page →
From page 37... ... 71St Ave. Parking Lot Denver (DEN) Read the entire page →
From page 38... ... Table 25 excerpts the details of tests that were conducted for Event #1 on February 1st, 2008 at YUL airport with a separation distance of 4,232 ft. Following is a brief description of the column headings used in the test log: • Set no.: Sequential number given to the test set. Read the entire page →
From page 39... ... SITE B: APS Test Facility (45º 28' 6" N 73º 44' 28" W) Table 25. Read the entire page →
From page 40... ... 40 R2 = 0.98 0 10 20 30 40 50 60 0 10 20 30 40 50 60 Rate Site 1 R at e Si te 2 Short Distance (4,167 to 5,052 ft.) Scatter Plot 67 Points Figure 13. Read the entire page →
From page 41... ... The initial treatment of the data thus required calculation of precipitation rates, followed by calculation of fluid holdover times for a variety of fluids. Subsequently, the calculated ﬂuid holdover times for each precipitation data point were examined statistically to determine which test sets had differences that could be ascribed to random effects and which had real differences in holdover times generated by each of the two sites. Read the entire page →
From page 42... ... This analysis has taken the perspective of evaluating the risk when holdover times would actually be generated, and thus only those test sets are examined. Calculation of Fluid Holdover Times Holdover time guidelines, which are published annually, provide pilots with tables of the protection times provided by de/anti-icing ﬂuids in winter conditions. Read the entire page →
From page 43... ... For those test sets, a different statistical approach using separate variances t-test is applied. The F-test was applied to the HOTs for each test set in the following manner: • Calculate F-value, which is the ratio of the statistical variance of the two sets of HOTs, with the highest in the numerator; • Retrieve the appropriate F-value from an F-distribution table calculated for a 0.05 signiﬁcance level. Read the entire page →
From page 44... ... c) Holdover time determinations shall be inhibited in snow conditions exceeding 50 g/dm2/h. Read the entire page →
From page 45... ... Site 1 Site 2 Difference Difference as % of Lowest Site # % Test sets concluded as coming from same population 95 39% Test sets forced to equality by 120 minute rule 37 15% Test sets where difference is <20% 69 29% 221 28500 -9 17.2 47.7 39.6 8.1 20.5% 237 28500 -6 13.2 55.9 67.5 11.6 20.7% 95 7933 0.4 16.3 103.7 85.6 18.0 21.1% 312 27800 -10 6.0 113.8 93.9 19.8 21.1% 248 8300 -3.3 15.9 67.9 55.5 12.4 22.3% 65 4232 -3.2 11.0 93.1 76.1 17.0 22.4% 254 8300 -4 5.0 98.0 120.0 22.0 22.4% 233 28500 -6 10.0 70.0 86.6 16.6 23.7% 276 8300 -5.6 7.1 96.0 118.8 22.8 23.7% 304 27800 -10 12.3 50.5 62.6 12.2 24.1% 235 28500 -6 10.9 65.1 80.9 15.8 24.3% 258 8300 -4 9.3 103.2 82.6 20.6 25.0% 231 28500 -8 5.9 120.0 95.6 24.4 25.6% 275 8300 -6 8.0 83.7 105.6 21.8 26.1% difference range from 20 to <30% 306 27800 -10 10.4 72.9 57.8 15.2 26.2% 293 27800 -10 13.7 57.7 45.3 12.3 27.2% 218 28500 -10 23.7 36.2 28.4 7.8 27.4% 203 28500 -14 7.9 83.4 65.4 18.0 27.5% 242 8300 -3.3 14.4 75.8 59.0 16.8 28.5% 299 27800 -10 14.1 44.3 56.9 12.7 28.6% 251 8300 -3.3 8.4 93.1 120.0 26.9 28.9% 294 27800 -10 10.6 72.3 56.0 16.3 29.0% 210 28500 -12 13.2 56.6 43.8 12.8 29.2% 241 28500 -6 7.5 114.3 88.3 25.9 29.4% 228 28500 -8 11.6 72.4 55.8 16.5 29.6% 25 10% 300 27800 -10 12.3 64.6 49.7 14.9 30.1% 201 28500 -14 7.2 68.4 89.1 20.7 30.3% 230 28500 -8 7.0 85.2 111.6 26.4 30.9% 290 27800 -10 9.2 82.7 63.0 19.7 31.2% 107 7933 -3.9 24.4 35.8 47.0 11.3 31.5% 30 4232 -4.8 8.8 107.7 80.1 27.5 34.4% difference range from 30 to <50% 317 27800 -10 8.1 68.6 94.4 25.7 37.5% 246 8300 -3.3 22.9 53.0 38.5 14.5 37.7% 229 28500 -8 9.6 62.8 90.2 27.4 43.6% 9 4% 308 27800 -10 9.0 60.7 91.7 31.0 51.0% 240 28500 -6 7.8 120.0 77.0 43.0 55.8% 259 8300 -5 6.3 76.8 120.0 43.2 56.2% 226 28500 -9 7.4 72.2 117.3 45.0 62.3% 249 8300 -3 12.3 62.1 104.7 42.6 68.7% difference range >50% 253 8300 -4 9.4 69.4 120.0 50.6 72.9% 252 8300 -4 21.0 100.4 30.6 69.8 227.8% 7 3% Total tests analyzed 242 • 39% of 242 test sets had no signiﬁcant difference in HOTs between sites; • 15% of all test sets were forced to equality by the 120-minute rule; • 29% had between-site holdover time differences less than 20%; • 10% had between-site holdover time differences from 20 to 30%; • 4% had between-site holdover time differences from 30 to 50%; and • 3% had between-site holdover time differences greater than 50%. Read the entire page →
From page 46... ... SAE Type I Fluid Clariant MP IV 2012 100/0 Octagon MaxFlo 100/0 Kilfrost ABC-S 75/25 Kilfrost ABC-S 50/50 No Statistical Difference 94 39% 95 39% 95 39% 95 39% 17 40% Forced to Equality by 120 Minute Rule 0 0% 26 11% 37 15% 15 6% 1 2% < 20 % 110 45% 88 36% 69 29% 88 36% 12 29% 20 to 30 % 13 5% 21 9% 25 10% 27 11% 4 10% 30 to 50 % 14 6% 7 3% 9 4% 10 4% 2 5% Test Sets where Dif. in Endurance Time as % of Lowest Site is: > 50 % 11 5% 5 2% 7 3% 7 3% 6 14% Total Test Sets Analyzed 242 100% 242 100% 242 100% 242 100% 42 100% Read the entire page →
From page 47... ... Summary of between-site difference in fluid holdover time -- CAR exemption case. SAE Type I Fluid Clariant MP IV 2012 100/0 Octagon MaxFlo 100/0 Kilfrost ABC-S 75/25 Kilfrost ABC-S 50/50 No Statistical Difference 69 36% 69 36% 69 36% 69 36% 9 31% Forced to Equality by 120 Minute Rule 0 0% 10 5% 11 6% 0 0% 0 0% < 20% 94 49% 81 42% 73 38% 82 43% 11 38% 20 to 30% 19 10% 15 8% 13 7% 18 9% 2 7% 30 to 50% 7 4% 13 7% 18 9% 17 9% 5 17% Test Sets where Dif. Read the entire page →
From page 48... ... 48 Table 31. Relationship of between-site differences and distance -- all data 2007 to 2008. Read the entire page →
From page 49... ... This examination shows that a relationship does exist between site-separation distance and size of between-site holdover time differences. Examination of Lake-Effect Snowfall on HOT Differences The impact of lake-effect snowfall was examined by looking at the lake-effect snowfall data in isolation and comparing it to other data collected within the same site-separation range. Read the entire page →
From page 50... ... ABC-S 50/50 Holdover Times in Snow - Measured Rates (no lake-effect data due temp restriction for 50/50) Number of tests where difference between sites is Number of tests where difference between sites is Distance Range (ft) Read the entire page →
From page 51... ... Comparison of HOTDS Results to Current Operational Practices A brief comparison was made of HOT guideline times that were in effect during the testing versus HOT times as generated by HOTDS systems using the precipitation measurements at the two test sites. This analysis is based on the "base case" and does not consider the CARs exemption criteria. Read the entire page →
From page 52... ... from the two test sites is shown in Table 36. HOTDS Implementation Strategy and Timeline The examination of HOT generated from METAR indications showed that there is a genuine possibility that very different values can result from the two alternative ways of applying METAR forecasts. Read the entire page →
From page 53... ... The conclusions and recommendations resulting from this task are presented in this section. Conclusions Test Methodology The approach to collecting test data was effective, and the data provided a suitable base for comparing HOTs generated from two separate test sites at an airport. Read the entire page →
From page 54... ... In some cases, the METAR visibility and snow visibility charts led to no HOT availability, while the test data produced operationally valuable holdover times. The lower HOT from the two test sites generally was longer than the HOT value derived from either alternative using METAR reports. Read the entire page →
From page 55... ... 2. Bendickson, S., Regression Coefficients Used To Develop Aircraft Ground Deicing Holdover Time Tables: Winter 2007–08, APS Aviation Inc., Transportation Development Centre, Montreal, December 2007, TP14782E. Read the entire page →

From page 28...

... However, at airports with large surface area, such as Denver International Airport, the distances from a central location at the airport to a departure runway may exceed 16,000 ft. No data for similar distances were collected in 2007–08, and it was therefore decided to conduct additional testing to verify whether airports with large surface areas would require additional HOTDS installations to provide reliable data.