Statistics for the 1957 surface vessel patrol are given in table 1. The 

 data presented for the CGC Evergreen are for the employment of this 

 vessel for patrol duty only and not for oceanographic duties. The results 

 of the Current surveys and scientific program are given in a later section 

 of this report. 



Table 1.— Surface Ice Patrol Statistics for the 1957 Ice Season 



AERIAL ICE OBSERVATION 



During the 1957 ice season, 105 ice observation flights were made. 

 The average length and duration of these flights was 1,048 miles and 7.2 

 hours, respectively. The maximum flight length was 1,325 miles. Prior 

 to the ice season, 17 flights were made to detect the first encroachment 

 of ice into the Grand Banks area and to enable Commander, Inter- 

 national Ice Patrol to decide when to commence broadcast of ice warnings 

 to shipping. Six postseason flights were made to guard against any 

 stray berg entering the shipping lanes undetected. 



The United States Coast Guard Air Detachment at Argentia had 

 available three PB1G (B-17) type aircraft for ice reconnaissance. These 

 aircraft were all equipped with radar to enable location of ice during 

 periods of low visibility. However, visual identification of radar targets 

 was necessary to distinguish between berg and nonberg radar targets 

 which meant that the plane was obliged to divert from its intended 

 track to identify radar targets beyond the range of visibility. 



The search pattern normally consisted of a system of parallel lines 

 spaced at 20- to 30-mile intervals, depending on visibility conditions. 



Flights were usually scheduled only on days and in areas where good 

 visibility conditions were forecast. 



