88 



actual proper patroling of even the critical western and southern parts 

 of its 13,200 square sea miles a continual problem. 



During heavy ice periods about the only times when the area inside 

 of this triangle should be left are w^hen bergs that must be followed 

 drift west or south of its southern portion. Of course during very 

 light-ice times, which occur near the ends of some seasons, it some- 

 times happens that there is no ice in the critical triangle. Then 

 occasional runs to the north can be made in order to locate the south- 

 ernmost ice limits. Generally speaking, however, throughout the 

 active ice-patrol season, if a high degree of safety from danger of 

 collision with ice is to be maintained during times of low visibility 

 along the B tracks, the western and southern portions of the critical 

 triangle must be constantly and repeatedly searched. The ice found 

 there must be most carefully watched and followed until it either 

 melts or recurves and drifts so far to the north that it no longer 

 menaces the B tracks. 



During most of the ice-patrol season the B tracks just south of the 

 critical triangle are in constant use. That means the route of west- 

 bound traffic to the United States lies right along the southern edge 

 of the critical triangle. These westbound ships are of great assistance 

 in reporting water temperatures and in notifying the patrol of chance 

 bergs that may be crossing the southern part of the triangle for points 

 farther south, with some drift of cold water. The eastbound B tracks 

 are 60 geographical miles south of the westbound ones, and so are 

 considerably safer than the latter, on the general proposition that the 

 farther south of the Tail of the Banks one is in the ocean, in the long 

 run, the fewer bergs will be encountered. The eastbound traffic is 

 doubly protected from liability of meeting unreported ice by the 

 active operations of the westbound ships in cooperating with the 

 patrol. 



Nevertheless, the 60 miles separating the eastbound and westbound 

 traffic streams of the B tracks can be traversed by a berg during cer- 

 tain times of accelerated circulation in a period of about 30 hours. 

 Therefore, especially toward the ends of periods of fog of two or more 

 days' duration, even along the eastbound B tracks, vessels while 

 between 52° W. and 45° W. are subject to a real, though very slight, 

 chance of unexpectedly meeting an unreported iceberg. Because of 

 the much greater danger along the westbound B tracks, however, the 

 ice patrol must at all times exert its utmost efforts to locate all bergs 

 that are approaching the latter lanes from the north. 



Freighters, tankere, and other vessels not carrying passengers are 

 not included in any track agreement and are not expected to adhere 

 to any definite lane. A large number of the bolder vessels of the non- 

 passenger class cross the ocean about where they see fit. The reports 

 from such sources are the main dependence of the patrol for its knowl- 



