although ships were getting through with icebreaker assistance 

 throughout the winter. Sea ice persisted along Cape Breton until 

 mid-May. Detailed monthly ice conditions appear in a later section. 



Notes 



1. The monthly accumulative totals are tabulated for 1900-45. 



2. The totals for 1946-64 are based mainly upon aircraft reconnaissance and are probably more accurate 

 than prior estimtes. 



3. For the years 1946-64, 64 percent of the bergs drifted south of 48° N. during April and May, 94 percent 

 during March- June and 99 percent during the 6-month period February- July. 



4. The annual average from 1946-64 is about 40 percent less than the 1900-64 average. Whether the 

 1946-64 average represents a cycUc trend or the estimates made before use of aircraft were over exaggerated 

 is open to speculation. 



AERIAL ICE RECONNAISSANCE 



The ice limits in the vicinity of the Grand Banks were guarded and 

 ice information was collected by planned aerial ice reconnaissance 

 performed by two Lockheed Hercules (HC-130 B) aircraft of the 

 U.S. Coast Guard Air Station, Argentia. After 2 years experience 

 with this aircraft, it can be stated that the Hercules aircraft has 

 proven to be more reliable and has a greater capability than previous 

 aircraft used. The main advantage of the Hercules is its increased 

 speed allowing more coverage per flight hour. Navigation by the 

 Doppler system with Loran A as a backup was an improvement over 

 the previous year. Forty-two flights totaling 295.8 hours were made 

 during the ice season. An average of two flights weekly were made. 



