Even if the area of responsibility was smaller 

 and more aircraft were available for ice observ- 

 ing to enable complete coverage, weather would 

 rarely cooperate. One of the most important 

 portions of the area is the Tail of the Banks, an 

 area of complex oceanographic conditions, where 

 the cold water of the Labrador Current meets 

 the warm water of the Gulf Stream. This area 

 is frequently plagued by dense fog which nor- 

 mally renders ice observation by aircraft ineffec- 

 tive for weeks at a time during the crucial periods 

 of April, May, and June when icebergs can 

 normally be expected at the Tail of the Banks. 



During light seasons when ice is restricted to 

 the northern Grand Banks, or when only a small 

 number of bergs are menacing the Tail of the 

 Banks, guarding the ice limits and ice observation 

 can be effectively accomplished by aircraft alone. 

 During years when many icebergs survive to the 

 Tail of the Banks, aircraft alone cannot properly 

 do the job. The Ice Patrol surface vessel may 

 then be required. Extended periods of poor fly- 

 ing weather may compound the heavy iceberg 

 threat, or by itself necessitate a surface patrol 

 vessel. 



Only twice since 1959 has a surface patrol been 

 initiated. The 1972 Season was the heaviest on 

 record, with an estimated 1587 icebergs drifting 

 south of 48°N, and the longest, 29 February to 

 4 September, a total of 189 days. The 1973 

 Season found an estimated 847 icebergs drift 

 south of 48°N and equalled the 1972 Season in 

 length, 24 January to 31 July. 



The mission of the surface patrol is to provide 

 an on the scene guard over the southernmost or 

 more hazardous ice wdien trans-atlantic shipping 

 is, or is about to be, menaced. 



A surface vessel can search but a small portion 

 of the area necessary to determine the ice limits. 

 However, an aircraft on a day with good visi- 

 bility will determine a large portion of the limits 

 and observe the ice within these limits. Within 

 a day or two after determination of the ice limits 

 by aerial observation, ice conditions, and conse- 

 quently ice limits, may have drastically changed. 

 From the initial reported positions, Ice Patrol 

 Headquarters will be drifting the icebergs using 

 a computer drift model which considers wind and 

 sea current conditions. Another effective ice ob- 

 servation flight may not be possible for days, 

 during which time, the Ice Patrol vessel can 



search out the most dangerous areas and locate, 

 observe, and guard the most dangerous icebergs, 

 warning ships accordingly. 



Thus, when large numbers of icebergs threaten 

 and the aircraft and Ice Patrol vessel are both 

 required, they complement each other in carrying 

 out the mission of the International Ice Patrol. 

 Since virtually all ice observation functions are 

 accomplished now by aircraft, it is possible to 

 confine surface patrols exclusively to known or 

 suspected ice-inhabitated regions. 



This combined air-surface procedure obviates 

 the necessity for long and costly surface vessel 

 searches that were characteristic of the years 

 prior to 1946. 



The Future 



For the foreseeable future, aerial ice surveil- 

 lance will remain the primary tool of Com- 

 mander, International Ice Patrol, supplemented 

 by a surface patrol when conditions warrant. 

 The conduct of the flights will most likely remain 

 as at present. 



The advantages of aircraft over the surface 

 vessel are impressive, namely increased area cov- 

 erage in a greatly reduced amount of time. One 

 disadvantage of aircraft replacing the surface 

 vessel has been, as stated in the bulletin for the 

 Season of 1964, a loss of continuous monitoring 

 of specific icebergs that the cutters used to main- 

 tain. With aerial reconnaissance, an iceberg may 

 be resighted only after a lapse of many days. 

 Even then its identity may not be known with 

 certainty. If iceberg dynamics are to be totally 

 understood, surveillance of icebergs must be con- 

 tinuous. Weather often precludes this with 

 aerial reconnaissance. Thus, there exists a press- 

 ing need for an all-weather remote sensor for Ice 

 Patrol, capable of locating and enabling positive 

 identification of targets. 



By following this partial history of the Ice 

 Patrol, it is apparent that the Ice Patrol is deeply 

 engaged in research toward the goal of providing 

 the best product available, at the lowest cost. 

 To this end, Commander, International Ice Pa- 

 trol is researching for the immediate future 

 utilization of an operational all-weather system. 

 Perhaps a package similar to the U.S. Coast 

 Guard Airborne Oil Surveillance System 

 (AOSS) or a present SLAR model will provide 

 the all-weather detection capabilities desired. 



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