200 



FEB. MAR. APR. MAY JUNE JULY 



Figure 1. — Distribution of plane hours, 1950. 



out 25 miles apart and the area covered was estimated as 2,211,000 

 square miles. Very seldom did it happen that visibility was good 

 enough to completely search the area of any flight. It was estimated 

 that the actual area covered by aerial reconnaissance for this season 

 was approximately 1,700,000 square miles. The guiding principle in 

 planning flights was to cover the Grand Banks area from south to 

 north, repeating the procedure every 2 to 3 days. Weather in the 

 Grand Banks area was l^ad for aerial reconnaissance about 70 percent 

 of the time because of fog, low stratus, and storms, and a systematic 

 search of the area every 2 to 3 days was seldom accomplished in 

 practice. Flights were made 2 days in succession on 19 occasions this 

 season. The intervals in days between flights aside from these 19 

 occasions varied from 1 to 8 days. These intervals with the corre- 

 sponding frequency of occurrence are as follows: 



Intervals: 



1 



2 



3 



4 



5 



pTequency 



7 

 .5 

 10 

 4 

 1 

 1 



