440 



Yearbook^ of Agriculture 1949 



NUMBER AND TYPE OF PLANE, THEIR ASSIGNED FLYING SPEEDS, SWATH WIDTHS, AND 

 SPRAY-LOAD CAPACITY, AND MAXIMUM FLYING HEIGHT ABOVE TREETOPS 



Type of plane 



Height 



Spray Spray above 



Planes Speed load Swath Delivery treetops 



Miles Gallons 



per per 



and went through a training period, as 

 planned. 



The flying contractors arrived on 

 May 19. 



Insecticide was on hand. Test flights 

 were made on May 19 and 20 to check 

 spray apparatus and to establish swath 

 widths for the various types of planes 

 flying at specified speeds and heights 

 above treetops. 



Flying-weather controls were estab- 

 lished as follows: 



( 1 ) Planes would fly only on weath- 

 er clearance by the Bureau of Entomol- 

 ogy and Plant Quarantine leader. They 

 would stop flying on order when wind 

 velocity reached 8 miles an hour or on 

 their own judgment when thermal ac- 

 tivity caused dangerous air turbulence. 



(2) Spraying would stop an hour 

 before rain and not resume until foli- 

 age was dry. 



Assigned flying speeds, swath widths, 

 and maximum flying height above tree- 

 tops are shown in the table above, with 

 the number and type of planes used and 

 their spray-load capacity. 



This was dangerous flying. Only 

 skilled pilots familiar with the tricky 

 air currents of rough, mountainous ter- 

 rain, flying at low altitude, could lay 

 down spray in narrow parallel swaths 

 while following ground-level features 

 as guides. There would be no time or 

 clearance to parachute from a crippled 

 plane under such conditions. Great 

 credit is due the flying contractors for 

 their meticulous preparation and con- 

 stant care of equipment and to the 



esprit de corps of the flying groups, 

 from ground crews to the contractors. 

 They were determined to make the job 

 a success. Only three accidents oc- 

 curred out of more than 2,100 indi- 

 vidual flights; one man got a broken 

 nose and another a cracked ankle bone. 



All-out spraying commenced on May 

 22. From then on the objective of both 

 the contractors and the Federal agen- 

 cies was to utilize every hour of flying 

 weather and complete the job by June 

 30 or before. On 2 or 3 days the spray 

 coverage was as high as 25,000 acres. 



The pattern of flying was worked out 

 during the first few days. With the help 

 of aerial photographs, forest maps, and 

 reconnaissance flights, the area was 

 divided into flying units of 1,000 to 

 3,000 acres. Topographic features usu- 

 ally provided the boundaries. Units 

 were assigned to individual pilots. 

 Usually the pilot responsible for a unit 

 would make dry runs over the area 

 and plan his flight pattern before spray- 

 ing. Then he would make the spray- 

 application runs until the unit was 

 completed. This was the only practical 

 method of obtaining efficient applica- 

 tion of spray in this rugged area. The 

 acreage of each unit was checked 

 against volume of spray used, which 

 gave a relatively simple alternative 

 method of checking application. Most 

 of the spraying was done from about 

 3:30 a. m. to 9 a. m., when the air 

 was calm and cool. Only a few times 

 was spraying continued after 9 a. m. 

 Seldom could spraying be done dur- 



