V. ICE RECONNAISSANCE 
The Hydrographic Office conducted an aerial ice reconnaissance program in the 
Ross Sea area during the Antarctic resupply period of Operation DEEP FREEZE 61. 
The objective of this program was to provide ice data to Commander, U.S. Naval 
Support Force, Antarctica, in support of ship movements and, at the same time, to 
acquire a history of ice conditions upon which future ice prediction techniques could 
be formulated. 
Aerial ice reconnaissance was conducted on a non-interference basis and ideal 
observing conditions seldom were available. A total of thirty-one flights were 
participated in by Hydrographic Office ice observers, nineteen of which were U.S. 
Air Force logistics flights between Christchurch, New Zealand, and NAF McMurdo. 
These flights were at an altitude of about 9,000 feet and on a direct track between 
check points. Ice observations were limited to certain areas; some details of floe 
size, relief, and ice age were difficult to estimate owing to high flight altitude. 
In addition to the long-range flights, ice reconnaissance was conducted on 
twelve local flights in the McMurdo Sound area. Surface ice observations were made 
by ice observers assigned to GLACIER and EASTWIND. Results of ice reconnaissance 
observations are shown in Figures 54 through 81. 
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