Techniques of Preseason Aerial Iceberg 

 Observation 



The precise technique used in iceberg observa- 

 tion has varied somewhat from year to year, al- 

 though generally it is simple and straightfor- 

 ward. In the HC130B Hercules aircraft the ice 

 observers usually sit on stools behind the pilot 

 and copilot where they can see the doppler navi- 

 gational instruments. One of the ice observers has 

 a chart of the area on a portable plotting board. 

 As the aircraft flies along on its planned tracks, 

 which are normally 25 to 30 miles apart, the ice 

 observers count icebergs as they pass abeam out 

 as far as approximately 15 miles. At the end of 

 a convenient interval, 5 or 10 miles, the number 

 of icebergs counted is plotted on the chart. If the 

 concentration of icebergs is not too large the 

 counts are broken down into small, medium, and 

 large icebergs. Another technique is to record the 

 individual icebergs or groups of icebergs as they 

 pass abeam. In large concentrations this tech- 

 nique requires a third man just to handle the 

 plotting. A third technique is for the observer 

 to pick out mentally an area marked by a few 

 "landmark" icebergs, count the icebergs in that 

 area, record the count in the corresponding area 

 of the chart, and then shift his attention to a 

 new area. In low visibility radar is used to obtain 

 counts by methods identical to those described 

 above for visual use. 



On one occasion, in September 1968, a visual 

 statistical sampling technique was used in place 

 of actual counts covering the entire area. This 

 technique was used along the coast and offshore 

 from 30 to 60 miles between latitudes 77-30N and 

 75-30N because there were too many icebergs to 

 count individually. From comparisons with the 

 1949 photographic survey it appears to the author 

 that the statistical method is fairly reliable if 

 the following 3 conditions are met: (1) iceberg 

 concentrations are between about 10 and 200 ice- 

 bergs per hundred square miles, (2) the results 

 are not extrapolated from more than 20 miles oft' 

 the aircraft track, and (3) the results are not 

 extrapolated to fjords, small bays, or glacier 

 fronts. In using the statistical technique the ice 

 observers made one minute counts of icebergs 

 abeam the aircraft within 7 miles every 3 min- 

 utes. The ratio of iceberg concentration beyond 

 7 miles to that within was also estimated. The 

 miles to go to the next turn point was noted on 

 the doppler navigational readout at the end of 



each 1 minute count. In the analysis of the data 

 tlie areas in which counts were made were plotted 

 on a chart, and then the data were interpolated 

 or extrapolated for other areas using the concen- 

 tration factors. 



All of the iceberg surveys since 1963, with the 

 exception of the glacier front surveys, have been 

 visual surveys, supplemented where necessary by 

 radar information. Due to the relative scarcity of 

 shipping in Baffin Bay all radar targets can be 

 presumed to be icebergs. In areas away from the 

 West Greenland coast, probably 90 to 95% of the 

 area of Baffin Bay, visual/radar iceberg observa- 

 tion appears to be adequate for the purpose of 

 determining the general iceberg distribution and 

 approximate count. However, there is a definite 

 psychological tendency for iceberg observers, as 

 they progress northward into Baffin Bay, to dis- 

 regard an increasing number of smaller size ice- 

 bergs because they tend to appear as mere growl- 

 ers or berg bits in the presence of the greater 

 number of very large icebergs found farther 

 north. 



The problem of accurate counts within a few 

 miles of the "West Greenland coast is much more 

 complicated. Here there are icebergs wliich may 

 be aground more or less permanently; there are 

 icebergs which may be trapped within a fjord due 

 to a shallow sill; there are icebergs out of sight 

 from Baffin Bay tens of miles up a narrow twist- 

 ing fjord; there are icebergs so densely concen- 

 trated along the front of a glacier that it is im- 

 possible to tell from the air where the icebergs 

 stop and the glacier begins ; and there are swarms 

 of smaller pieces of ice within the fjords or just 

 outside them which defy consistency in deciding 

 whether they should or should not be included 

 in the count. Visual estimates of the number of 

 icebergs in this area can easily be off by 100% 

 or even more when made from even slow flying 

 aircraft. It is interesting to compare the com- 

 ments of iceberg observers regarding this area. 

 In a 1949 report it was stated that "Especially 

 in the fjords and along the glacier fronts, the 

 photograph was so full of ice that it staggered 

 the imagination to distinguish bergs from growl- 

 ers or brash." Using a similar expression a 1968 

 report notes that "Concentrations of icebergs in 

 some areas in the vicinity of the Greenland coast 

 were so dense that they completely staggered 

 human ability to count the individual icebergs." 

 An iceberg observer once commented orally that 



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