be phased down in the spring of 1970. The Ice 

 Reconnaissance Detachment deployed to Argentia 

 on 17 March, then redeployed to the Canadian 

 Forces Base, Summerside, Prince Edward Island, 

 on 30 April. Though this base was 500 miles to 

 the west of the iceberg area, operations were 

 conducted smoothly due to the excellent support 

 provided by the Canadian Forces and by remain- 

 ing overnight at St. John's, Newfoundland, when 

 good weather had been forecast for several suc- 

 cessive days. 



A Side-Looking Airborne Radar (SLAR) unit 

 (model AN/DPD-2) was evaluated commencing 

 with the 1971 Season. It was hoped that SLAR 

 would provide an all-weather detection device. 

 Unfortunately, this was not the result, in this 

 case mainly clue to problems associated with the 

 obsolescence of this particular unit. The evalua- 

 tion concluded at the end of the 1973 Season. 



The 1972 and 1973 Seasons were the first times 

 since 1951 that a surface patrol had to be used to 

 supplement aircraft due to the heavy ice condi- 

 tions. 



The 1973 Season saw the first use of the Inertial 

 Navigation System (INS) in the reconnaissance 

 aircraft. The system has been a most welcome 

 addition, providing better accuracy for iceberg 

 plotting. 



St. John's, Newfoundland, became the base of 

 operations for the 1974 Season. This move from 

 Summerside resulted in a drastic reduction of 

 enroute time to the area, with a corresponding 

 increase in on-scene time. 



An ART unit was evaluated in the latter part 

 of the 1974 Season. The information provided 

 showed great promise for real-time temperature 

 data for iceberg deterioration and possibly for 

 identifying the features of the Labrador and 

 North Atlantic Currents. 



In 1975 a newer SLAR model was evaluated. 

 Though the final analysis of the data is not yet 

 available, the conclusion probably will be that 

 SLAR will enhance Ice Patrol but is not the final 

 answer to its problems. 



Objective and Conduct of Aerial Reconnais- 

 sance 



The primary objective of International Ice 

 Patrol is to guard the southeastern, southern, and 

 southwestern limits of ice in the vicinity of the 

 Grand Banks so that shipping might be advised 



of the extent of that dangerous area. In addi- 

 tion, the Ice Patrol has the purpose of maintain- 

 ing a detailed, up-to-date picture of the ice 

 situation in the Grand Banks region. 



An ice patrol flight is normally between 1,000 

 to 1,500 miles long (approximately 6 to 8 hours 

 of flight time) and the track is carefully laid out 

 so that a maximum area can be searched for the 

 miles flown. Two or three experienced ice ob- 

 servers accompany each flight. To insure the 

 intended search area is actually covered and for 

 accurate iceberg positioning, precise piloting and 

 navigation is demanded of the aircrew. Search 

 altitudes are usually between 1,000 and 1,500 feet 

 and every effort is made to stay beneath the over- 

 cast and provide the observers with maximum 

 visibility. The desired altitude provides an ex- 

 cellent range of sight, while still enabling many 

 individual surface features to be discerned. While 

 flights are usually made in good or fair weather, 

 the prevalence of fog in the spring and summer 

 months occasionally requires that a flight be made 

 in marginal or poor visibility where the aircraft 

 must seek out its targets by radar and then de- 

 scend to gain visual identification of either ship 

 or berg. 



The problem of identifying targets during 

 marginal or poor visibility has plagued the Ice 

 Patrol for many years. The usual 25 mile flight 

 track spacing is a compromise between maximum 

 area coverage and maximum probability of de- 

 tection. To obtain 100 percent visual coverage, 

 an observer must have 12.5 miles of visibility on 

 each side. When this visibility is not obtained, 

 which unfortunately is fairly frequent, reliance 

 is shifted to radar. From the altitudes flown, 

 smaller bergs can usually be picked up by radar 

 at about 10 miles. These radar targets can then 

 be identified by diverting from the planned track, 

 unless ceiling and visibility prohibit. With ceil- 

 ings frequently below 500 feet, inability to iden- 

 tify a radar target as an iceberg or a vessel 

 becomes a serious handicap. An iceberg cannot 

 be ascertained from a moving ship on the aircraft 

 radar scope due to the speed of the aircraft which 

 masks the greatly lesser surface vessel's motion. 

 Small bergs and growlers are not normally de- 

 tected by radar if the range exceeds 10 miles or 

 if sea conditions are moderate to rough. When 

 sea conditions are severe, larger bergs may also 

 be missed. 



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