transmission time ( 1 600Z or 1 8 1 OZ). This year 

 one ice-chart transmission was late, and 1 1 

 were not transmitted at all. A problem in the 

 line between CAMSLANT and the transmitter 

 antenna in Boston was the primary cause for 

 late and missed ice-chart transmissions. 



Safety Broadcasts 



During the 2004 season. Ice Patrol sent 

 six unscheduled safety broadcasts for icebergs 

 and stationary radar targets near or outside the 

 LAKl. These six safeties reported eight targets: 

 one iceberg inside but near the LAKI, four 

 stationary radar targets outside the LAKI, and 

 three icebergs outside the LAKI. 



Because of two untimely reports of 

 icebergs outside the LAKI — which resulted in 

 two of the season's six safeties — the Limit was 

 inaccurate in four of 184 bulletins. The 

 icebergs in these two reports — made on 

 separate days — were sighted before IIP had 

 created the OOOOZ LAKI, but the reports did not 

 arrive at IIP until after personnel had already 

 released both the OOOOZ and 1200Z bulletins. 

 Therefore, on two days. Ice Patrol unwittingly 

 broadcast inaccurate OOOOZ and 1200Z LAKIs. 

 In both cases, however, personnel immediately 

 sent a safety upon receipt of the ice report. The 

 end result was 98% LAKI accuracy in 2004 

 (Figure 6). 



Historical Perspective 



To compare ice seasons, IIP uses two 

 measurements developed by various authors 

 (Alfultis, 1987; Trivers, 1994; Marko et al., 

 1994). Ice Patrol determines season severity 

 based on season length (Figure 7) and the 

 number of icebergs south of 48°N (Figure 8). 

 This second measurement includes both 

 icebergs sighted south of 48°N and those that 

 were sighted north of 48°N but that BAPS 

 eventually drifted south of 48°N. Of the two 

 measurements, IIP focuses more on the number 

 of icebergs south of 48°N because it 



94% 96% 98% 



LAKI Accuracy 



Figure 6. LAKI accuracy. 



emphasizes the degree of a season's iceberg 

 danger to transatlantic shipping. 



The 2004 season lasted 92 days and saw 

 262 individual icebergs south of 48°N. 

 Compared to the past four years, 2004 was light 

 both in terms of season length and number of 

 icebergs south of 48°N. Furthermore, the 2004 

 statistics accord with Trivers's (1994) 

 definition of a light season, which he 

 determined lasts less than 105 days and has 

 fewer than 300 icebergs south of 48°N. 



Canadian Support 



As they do every year, the Canadian 

 Government generously supported IIP during 

 the 2004 season. The Canadian Ice Service 

 conducted ice reconnaissance using a SLAR- 

 equipped Dash-7 airplane and shared its 



Figure 7. Length of ice season since 2000. The 20- 

 year (1985-2004) mean is 142. 



