this search pattern was cuiit* efficient for tlie purix)se of detecting 

 ice on days with <jood visibility. Wlien poor visibility occurred, such 

 that 15 naile visual sightings of bergs was pi'ecluded, this spacing ap- 

 peared to be the optimum for a radar search and permitted sufficient 

 reserve in flight hours to divert the aircraft from the pattern in order 

 to identify radar targets. A trained aerial ice observer was assigned 

 to each ice reconnaissance flight. Loran A was the primary positive 

 method of air navigation. Airljorne doppler sensor system was used 

 to navigate all flight plans, and w'hen possible, corrected by Loran A 

 or other available means. The use of doppler radar visual readout 

 presentations provided the ice observer continuous track and cross 

 track information greatly assisting, and increasing the accuracy, in 

 positioning bergs. Maneuvei's off the prescribed tracks, once extremely 

 difficult to plot, could now be readily plotted. Radar aided the ob- 

 server in locating ice, especially when A'isibility conditions were mini- 

 mal. A passi\'e microwave radiometer, with the frecpiency selected for 

 optimum ice emmissivity, is planned for installation for the 1966 ice 

 season. It is hoped that this device will permit positive ice identifica- 

 tion during periods of extremely poor visibility. 



As in past years, the prevalence of fog in the Grand Banks area 

 hampered the effectiveness and the systematic scheduling of ice re- 

 connaissance flights. Weather reports from shipping and weather 

 forecasts made by the United States Fleet Weather Central at Argen- 

 tia were extremely helpful in avoiding the scheduling of flights during 

 periods of low visibility in the search areas. When periods of low 

 visibility continued for a number of days and it appeared, due to pre- 

 vious observed ice conditions, that a dangerous situation might de- 

 velop in the steamer tracks, ice reconnaissance flights were flown de- 

 pending solely on radar to detect targets. As a highly qualified 

 radar operator can, under certain conditions, evaluate the radar target 

 denoting it as a ship or iceberg, attempts were made to identify all 

 radar targets. All luiidentified targets were listed as possible bergs. 



Flight statistics for the season are presented in Table 2 : Aerial 

 Ice Reconnaissance Statistics — 1965 Season. 



Table 2. Aerial ice reconnaissance statistics — 1 965 season 



' Days on wliich possible to search visually at least 50 percent of scouting area with 25 mile spacing between 

 legs of flight plan. 

 2 Ratio CXIOO) of area actually searched visually to area planned to be searched. 



