resulting in much Jighter than normal ice years. Ice Patrol records 

 strongly indicate this may be true. During the first 25 years of Ice 

 Patrol bergs were a frequent occurrence at the Tail of the Banks, 

 and sea ice often survived to the Tail of the Banks. During the 

 past 25 years bergs have infrequently reached the Tail and sea ice 

 there has been a rarity. Nevertheless, in the years that lie ahead, we 

 can expect a return to heavier ice seasons and greater increase in ice- 

 bergs in the main shipping lanes near the Tail of the Banks. Unless 

 ice observing capability by aircraft is greatly improved, it will prob- 

 ably be necessai-y to employ the Ice Patrol Vessel more frequently in 

 the future to help guard the ice limits and to help observe the ice 

 conditions. 



The use of aircraft for ice observing has resulted in a considerably 

 more effective International Ice Patrol. The iceberg limits can more 

 closely be guarded and ice conditions observed and studied more effec- 

 tively. Normally one successful flight on a given day can determine 

 the probable limits of icebergs in the vicinity of the Grand Banks. 

 However, there are situations when two flights may be necessary to 

 insure proper coverage. Flights are normally planned to determine 

 the limits of ice and to observe as much of the ice conditions within 

 those limits as practicable. Flights are planned mainly on the basis of 

 the estimated ice conditions at the time of flight. Starting with the 

 last observed ice conditions and including ice reports, the movement of 

 ice is forecast twice daily taking into account drift due to geostrophic 

 current and drift due to wind. Deterioration of ice is also forecast. 

 A reasonable safety factor is used to allow for greater drift than fore- 

 cast, especially in areas of the Labrador Current. Nevertheless, bergs 

 will, on occasion, drift unnoticed outside the forecast or even so-called 

 observed ice limits. There is a natural inclination toward caution in 

 flight planning to reasonably insure that there are no icebergs outside 

 the forecast ice limits. However, there is a practicable limit to the 

 amount of caution that can be exercised. The aircraft is limited in 

 the amount of coverage it can reasonably handle. Furthermore, over- 

 caution might result in failure to determine the iceberg limits and to 

 observe the ice conditions. The number of aircraft and personnel are 

 limited and the entire Grand Banks and vicinity could not possibly be 

 thoroughly searched in 1 day wnth available facilities even if weather 

 permitted. Those who have planned Ice Patrol flights over the years 

 know only too well that rarely if ever can there be complete assurance 

 that no dangerous ice lies outside the area of flight coverage. So the 

 flight is planned to cover the probable ice limits with an added safety 

 factor which will still permit determination of the ice conditions. 

 Then one hopes and prays that no dangerous ice exists outside the area 

 of coverage. Most of the time the prayer is answered. Sometimes it 

 is not. How often the prayer isn't answered will never be known. 



93 



