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32 Table 19. Typical sequence for the first collection. Time Tester 1 Tester 2 T = - 5 Minutes Weigh and record initial weight Weigh and record initial weight Verify wind direction and adjust Verify wind direction and adjust T = -3 Minutes stand stand T = -2 minutes Place two covered plates on stand Place two covered plates on stand T=0 Remove Covers Remove Covers T= 2 minutes Rotate Pans T= 4 minutes Rotate Pans T= 6 minutes Rotate Pans T= 8 minutes Rotate Pans Cover pans and bring in for Cover pans and bring in for T= 10 minutes measurement measurement Ten minutes elapsed between the end of the second collec- Description of Data and tion and the start of the third collection. Methodology Used to Process The typical sequence for the third collection period is detailed in Table 21. The data collected for the holdover time variance across an airfield task and its processing are described in this section. A similar sequence was used for subsequent measure- ments. Tests Conducted Personnel Tests were conducted over two winter seasons, 200708 and 200809, at nine different pairs of collection sites. For most of the initial testing in the winter of 200708, four APS personnel were required for testing. For the YUL tests, two personnel operated the mobile unit in the remote Tests Conducted in the Winter of 200708 location and two remained at the APS test site. However Tests conducted during the winter of 200708 included for the second winter of testing, the test technicians were nine snowstorm events from February 1, 2008 to March 13, more experienced and only two personnel were needed to 2008. These tests were all conducted at Montreal-Trudeau operate the two mobile units used for testing at YMX, DEN, Airport, at various locations. A total of 126 tests were con- and SYR. ducted. Of these, the data from 18 tests was excluded from analysis. The principal reasons for excluding data were cases where the measured precipitation rate exceeded 50 g/dm2/h, Data Forms and cases where there was a considerable amount of blowing One general data form was used to record precipitation snow at one of the test sites. After exclusion of this data, 108 collection. This data form is shown in Figure 6. tests remained, and this set of tests was subjected to analysis. Table 20. Typical sequence for the second collection. Time Tester 1 Tester 2 Place pans back on stand. Verify Place pans back on stand. Verify T = 18 minutes wind direction and adjust stand 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 Cover pans and bring in for Cover pans and bring in for T= 30 minutes measurement measurement

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33 Table 21. Typical sequence for the third collection. Time Tester 1 Tester 2 Place pans back on stand. Verify Place pans back on stand. Verify T = 38 minutes wind direction and adjust stand 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 Cover pans and bring in for Cover pans and bring in for T= 50 minutes measurement measurement Figure 6. Implementation of holdover time determination systems data form.

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34 Table 22. Test site locations for Winter 200708--Montreal-Trudeau Airport. Separation Distance Number of Number of Site 1 Location Site 2 Location Events Tests (ft) (m) Chemin St Franois APS Test Site 45 28' 33" N 45 28' 6" N 4,167 1,270 1 18 73 45' 12" W 73 44' 28" W Marshall Rd APS Test Site Snow Dump 45 28' 6" N 4,232 1,290 3 40 4 27' 28" N 73 44' 28" W 73 44' 14" W Ch. Cote Vertu APS Test Site 45 28' 40" N 45 28' 6" N 5,052 1,540 1 9 73 43' 33" W 73 44' 28" W Chemin St Franois Ch. Cote Vertu 45 28' 33" N 45 28' 40" N 7,017 2,139 2 15 73 45' 12" W 73 43' 33" W Marshall Rd Chemin St Franois Snow Dump 45 28' 33" N 7,933 2,418 1 16 46 27' 28" N 73 45' 12" W 73 44' 14" W APS Office APS Test Site Parking Lot 45 28' 6" N 13,390 4,081 1 10 45 28' 60" N 73 44' 28" W 73 41' 36" W As described, each test set consisted of data collected simul- sites. Six different pairs of sites were used for testing, with sep- taneously at two separate sites. At each site, precipitation was aration distances as shown in Table 22. measured simultaneously on four rate pans. Thus, each test The test site locations and separation distances are shown set comprised a total of eight data points. in Figure 7. Figure 8 shows that the longest distance between Different testing sites were used during the course of the departure points was 13,991 ft (4,265 m). Figure 9 shows dis- test season to produce data for various distances between test tances from a central site to runway departure points. One MONTREAL APS Office Parking Lot et Fe 90 ,3 Ch. Cote Vertu 13 et 7 Fe 7,01 et Fe Ch. St. Francois 2 4,1 05 67 5, Fee 7, t 93 APS Test Site 3 Fe 4,2 et 32 Fe et Marshall Rd. Snow Dump Figure 7. Site locations: Montreal Trudeau International Airport (YUL).

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35 Figure 8. Longest active distance at Montreal Trudeau International Airport (YUL). Figure 9. Distances from APS test site to departure runways at Montreal Trudeau International Airport (YUL).

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36 Table 23. Test site locations for Winter 200809. Separation Distance Number Number of Airport Site 1 Location Site 2 Location of Events Tests (ft) (m) Montreal-Mirabel Cargo C Ch. Charles International Parking Lot Parking Lot 28,500 8687 2 41 Airport 45 40' 46" N 45 41' 27" N (YMX) 74 02' 53" W 73 56' 17" W Syracuse Tuskegee Rd South Bay Rd. 1 Hancock 9 Parking Lot Parking Lot (non-lake-effect) International 8,300 2530 43 06' 19" N 43 07' 01" N 1 Airport 76 06' 56" W 76 08 '33" W 32 (lake-effect) (SYR) st Denver E. 71 Ave Trussville St. International Parking Lot Parking Lot 52 27,800 8473 2 Airport 39 54' 26" N 39 54' 01" N (DEN) 104 40' 13" W 104 40' 12" W test site of each pair was located close to the airport central conducted at three different airports as shown in Table 23. A deicing facility (CDF), thus the noted distances are a good in- total of 135 tests were conducted. Of these, the data from one dication of typical distances from a centrally located HOTDS test was removed due to a measurement error and excluded to runway departure points at YUL airport. from the analysis. The selected site pairs generated separation distances that Testing at SYR offered the opportunity to study lake-effect provided a good reflection of the airport geography. snowfall. Precipitation rates were recorded during one such event. Figure 10 shows the site locations at SYR. Figures 11 and 12 show the locations of the two test sites at Tests Conducted in the Winter of 200809 YMX and DEN, respectively. The long separation distances Tests conducted during 200809 included six snowstorm between runway departure points are apparent from these events from December 9, 2008 to April 4, 2009. Tests were images. Syracuse (SYR) Test Locations South Bay Rd. Parking Lot 8,3 00 Fe et Tuskegee Rd. Parking Lot Figure 10. Site locations: Syracuse Hancock International Airport (SYR).

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37 Mirabel (YMX) Test Locations Cargo C Parking Lot 28,500 Feet Ch. Charles Parking Lot Figure 11. Site locations: Mirabel International Airport (YMX). Denver (DEN) Test Locations Trussville St. Parking Lot 28,500 Feet E. 71St Ave. Parking Lot Figure 12. Site locations: Denver International Airport (DEN).