operating locations reduced the transit time to 

 reach the selected search areas. Occasional 

 poor terminal weather conditions (fog) at St. 

 Johns reduced the number of potential avail- 

 able reconnaissance days. A high percent of 

 the poorterminal conditions days also directly 

 reflected poor weather in the search areas. 



During the visual reconnaissance pe- 

 riod, weather, both at the search area and the 

 terminal, was a primary factor in iceberg re- 

 connaissance flight planning. Fog is prevalent 

 on the Grand Banks during the period of about 

 mid-April through early July. The aircraft gen- 

 erally flew their patrols at an altitude of about 

 1000 feet with a track spacing of 25 nautical 

 miles. If the terminal weather conditions were 

 acceptable for takeoff and return, a flight was 

 planned for an area of the boundary of all 

 known ice wheretheweatherwasgood. Good 

 weather on scene was defined as having vis- 

 ibility forecast for over at least 50 percent of 

 the planned search area. From 1 960 to 1 982, 

 an average of about one flight was conducted 

 every 4.5 days during the season. Non-flying 

 days were due to bad weather and aircraft 

 mechanical problems. Occasional flights to 

 the interior of the limits were also conducted. 

 Occasionally fights to the same area on con- 

 secutive days would be flown to evaluate 

 radar targets detected on the previous day's 

 flight. 



During the years 1960 to 1968, the 

 percent of the area flown that was able to be 

 effectively searched visually (where cloud cover 

 was less than five tenths) was published in the 

 annual Ice Patrol Bulletins. On an average, 

 only 70 percent of the area flown was able to 

 be searched visually. This means icebergs 

 possibly existed undetected within the search 

 area. 



During the early and mid-1970s. Ice 

 Patrol mostly used preset flight plans to cover 

 specific sections of the operations area. Infor- 

 mation about these preset flight plans can be 

 determined by reviewing the flight plans pub- 

 lished in the Ice Patrol Bulletins forthat period. 

 If needed, a nonstandard flight would be flown. 



In 1960, the only electronic method of 

 navigation available to the Ice Patrol aircraft 

 was LORAN-A. In 1964, Doppler navigation 



equipment was installed on the aircraft. The 

 LORAN-A coverage of the Ice Patrol opera- 

 tions area was limited and Doppler improved 

 the navigation accuracy. In 1973, an Inertial 

 Navigation System (INS) was installed on the 

 Ice Patrol aircraft. INS is presently the primary 

 navigation system on the aircraft used by Ice 

 Patrol. This system did not require the receipt 

 of an external signal and greatly improved the 

 navigational capabilities of the aircraft. The 

 cumulative error for the INS over an Ice Patrol 

 patrol is on the orderof 1 nautical miles. Each 

 improvement in the navigation capability of the 

 patrol aircraft meant the aircraft could fly the 

 planned patrol area more accurately with less 

 gaps in the area coverage caused by naviga- 

 tional errors. The improvements also meant 

 the iceberg position reports were more accu- 

 rate. 



Ice Patrol Reconnaissance 

 (1983-Present) 



1 983 saw the introduction of the APS- 

 135 Side Looking Airborne Radar (SLAR) 

 aboard the assigned HC-130 H model aircraft 

 as the primary iceberg detection tool, supple- 

 menting the human eye. This instrument had 

 a profound effect on Ice Patrol's reconnais- 

 sance operations. The SLAR provided a near 

 all weather target detection capability. It also 

 changed our reconnaissance strategy, includ- 

 ing aircraft deployment scheduling. 



Beginning as early as 1957, the Inter- 

 national Ice Patrol had began evaluating a 

 variety of SLARs. Although a variety of testing 

 and evaluation was conducted, no SLAR was 

 used on a continuous, operational basis prior 

 to 1983. Ice Patrol used the results of the 

 limited SLAR research flights as input into the 

 drift prediction model, however these targets 

 were not differentiated from visual sightings. 

 These research flights did not contribute sig- 

 nificantly to the number of sightings. 



In 1 983, SLAR became an integral part 

 of Ice Patrol's routine reconnaissance opera- 

 tions. The SLAR equipped aircraft conduct 

 patrols at 6000-8000 feet. The flights are 

 flown with a 25 nautical mile track spacing. 

 The SLAR range used is 27 nautical miles (50 

 kilometers). This SLAR range combined with 

 the track spacing allows for about 200 percent 



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