Aerial Applicator’s 

 Manual

A national Pesticide applicator certification study Guide

Aerial Applicator’s Manual

A National Pesticide Applicator 

Certification Study Guide

Written By

Patrick J. O’Connor-Marer, PhD

Published by the 

National Association of State Departments 

of Agriculture Research Foundation
ii

This publication was developed under 

Cooperative Agreement No. X8-83235401 

awarded by the U.S. Environmental Protection 

Agency to the National Association of State 

Departments of Agriculture Research Foundation. 

EPA made comments and suggestions on the 

document intended to improve the scientific 

analysis and technical accuracy of the document. 

However, the views expressed in this document 

are those of its authors and EPA does not 

endorse any products or commercial services 

mentioned in this publication.
acknowledgments iii

This manual was produced thanks to the support of the National Association 

of State Departments of Agriculture Research Foundation and the U.S. 

Environmental Protection Agency, Office of Pesticide Programs. The following 

people generously gave their time and contributed their expertise by serving on a 

Technical Advisory Committee and reviewing and contributing to the manual.

Ron Cline, Central Valley Helicopters, Ellensburg, Washington

Adolfo Gallo, California Department of Pesticide Regulation, Sacramento, California 

Paul Liemandt, Minnesota Department of Agriculture, Pesticides, St. Paul, Minnesota 

Drew Martin, Purdue University, West Lafayette, Indiana

Glenn Martin, Helicopter Applicators Inc., Gettysburg, Pennsylvania 

Scott Schertz, Schertz Aerial Service Inc., Hudson, Illinois

Russell Stocker, Bob’s Flying Service, Davis, California

Dennie Stokes, Stokes Flying Service, Parkin, Arkansas 

Dale Thomas, Thomas Helicopters, Inc., Gooding, Idaho

Mike Thompson, Arkansas State Plant Board, Little Rock, Arkansas 

Michael Weaver, Virginia Tech, Blacksburg, Virginia 

Robert Wolf, Kansas State University, Manhatttan, Kansas 

The following individuals served as ad hoc members of the Technical Advisory 

Committee and contributed valuable information and made meetings with the 

committee possible.

Kenneth Degg, National Agricultural Aviation Association, Hillsboro, Illinois 

Richard Herrett, National Association of State Deptartments of Agriculture, Washington, DC

Carol Parker, U.S. Environmental Protection Agency, Washington, DC

Carolyn Schroeder, U.S. Environmental Protection Agency, Washington, DC

Mike Walsh, U.S. Environmental Protection Agency, Washington, DC 

Several individuals and organizations generously provided photographs used in this 

manual.

Dennis Gardisser, WRK of Arkansas, Lonoke, AR

Tom Hoffmann, Washington State Department of Agriculture, Moses Lake, WA

Glenn Martin, Helicopter Applicators Inc., Gettysburg, Pennsylvania

John Mateski, Western Helicopter Services, Newberg, OR 

Dale Thomas, Thomas Helicopters, Inc., Gooding, Idaho

Michael Weaver, Virginia Tech, Blacksburg, Virginia

Robert Wolf, Kansas State University, Manhattan, Kansas

California Agricultural Aircraft Association

Minnesota Department of Agriculture

U.S. Department of Agriculture, Agricultural Research Service, Image Library

A special thank you to the following people who provided careful reviews, helpful 

suggestions, and additional information.

Scott Bretthauer, University of Illinois, Urbana, Illinois

Joseph Spitzmueller, Minnesota Department of Agriculture, St. Paul, Minnesota

Acknowledgments
iv
iv CONTENTS v

Contents

acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

CONTEnts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

The National Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Scope of this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

 How to Use this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

 Detailed Content Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

CHAPTER 1 Laws and Regulations for the Aerial

Applicator Pilot . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Requirements for Pilot Certification . . . . . . . . . . . . . . . . . . . . . . . . 10

EPA Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

The Pesticide Label . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

CHAPTER 2 Operation and Application Safety . . . . . . . 17

Aircraft and Pesticide Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

 Evaluating Aerial Application Operation Security . . . . . . . . . . . . . . 18 

 Timely Coordination with Authorities . . . . . . . . . . . . . . . . . . . . . . 19 

Protecting People and the Environment . . . . . . . . . . . . . . . . . . . . . 19

 Employee Training . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

 Employee Habits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Application Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

 The Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

 Understanding the Work Order . . . . . . . . . . . . . . . . . . . . . . . . . . 23

 Scouting the Target Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

 Understanding Pesticide Label Restrictions . . . . . . . . . . . . . . . . . . 25

 Resolving Conflicts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

 Reviewing and Documenting the Application . . . . . . . . . . . . . . . . . 27

Planning for Emergencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

 Emergency Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

 Flight Hazards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

 Plans in Case of Aircraft Crash . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

 Application Equipment Malfunction . . . . . . . . . . . . . . . . . . . . . . . 29

 Ground Crew Emergencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

 Overspray, Drift, and Other Misapplication . . . . . . . . . . . . . . . . . . 29

 Spray or Dust Contacting Bystanders or Vehicles . . . . . . . . . . . . . . . 30
vi contents

Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

CHAPTER 3 PREVENTING PESTICIDE DRIFT . . . . . . . . . . . . . . 33

Factors that Contribute to Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

 Classification of Droplet Size . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

 Spray Mixture Physical Properties . . . . . . . . . . . . . . . . . . . . . . . 36

 External Factors Affecting Droplet Size and Drift . . . . . . . . . . . . . . 37

Minimizing Off-Target Drift . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

 Application Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

 Smoke Generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

CHAPTER 4 Aerial Pesticide Dispersal Systems . . . . . . 43

Dispersal System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

 Equipment and Component Factors . . . . . . . . . . . . . . . . . . . . . . 44

Liquid Dispersal System Components . . . . . . . . . . . . . . . . . . . . . . . 44

Spray Pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

 Pesticide Tanks and Hoppers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

 Filters and Screens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

 Pipes, Hoses, and Fittings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

 Spray Booms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

 Flow Meters, Valves, and Pressure Gauges . . . . . . . . . . . . . . . . . . . 48

 Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

 Nozzle Anti-Drip Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

 GPS Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

 Computers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

 Flow Volume Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

 Mapping Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Positioning Booms and Nozzles . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Nozzle Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

 Pattern Testing a Spray Boom . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

 Spraying System Operating Pressure . . . . . . . . . . . . . . . . . . . . . . . 57

Dry Material Spreaders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

 Ram-Air Spreader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

 Centrifugal Spreader . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

CHAPTER 5 Calibrating Aerial Application Equipment 63

Why You Need to Calibrate Equipment . . . . . . . . . . . . . . . . . . . . . 64

Improper Application Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Equipment Calibration Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

 Calibrating Liquid Sprayers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

 Calculating Sprayer Flow Volume per Mile (Rotary-Wing Aircraft) . . . 67

 Calculating Sprayer Flow Volume per Mile (Fixed-Wing Aircraft) . . . 68

 Calculating Acres Treated per Minute . . . . . . . . . . . . . . . . . . . . . . 69

 Determining Gallons per Acre . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

 Determining the Amount of Pesticide to Put Into the Tank . . . . . . . . . 70

 Calculating the Area of a Rectangular or Square Application Site . . . . 71
contents vii

 Calculating the Area of a Triangular Application Site . . . . . . . . . . . . 72

 Calculating the Area of a Circular Application Site . . . . . . . . . . . . . . 73

 Calculating the Area of an Irregularly-Shaped Application Site . . . . . . 74

 Calibrating Granule Applicators . . . . . . . . . . . . . . . . . . . . . . . . . . 75

 Computing Granule Application Rate per Acre . . . . . . . . . . . . . . . . 76

Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

CHAPTER 6 Making an Aerial Pesticide Application . . 81

Ferrying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Checking the Application Site . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

What to Watch for During an Application . . . . . . . . . . . . . . . . . . . . 83

 Monitor Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

 Importance of Onsite Ground Crew During an Application . . . . . . . 84

 Pilot Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

 Ground Crew Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Application Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

 Application Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

 Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

 Obstructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

Flight Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

 The Turnaround . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

 Applying Granules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Factors Influencing the Aircraft . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

 Estimating Density Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

 Density Altitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

 Operation S.A.F.E. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

Review Question Answers . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Appendix 1: Pesticide Regulatory Agency Contact 

Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Appendix 2: FAA Requirements for Agricultural 

Aircraft Operators . . . . . . . . . . . . . . . . . . . . 101

Appendix 3: Heat Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Appendix 4: Steps to Follow in Cleaning Up a

Pesticide Spill . . . . . . . . . . . . . . . . . . . . . . . . . . 107

Appendix 5: Global Positioning Systems . . . . . . . . . . . . 108

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
viii
introduction

Introduction

Applying pesticides by air is an 

important part of many agricultural 

pest management activities. If you are 

a pilot and plan to engage in this type 

of work, you must become proficient 

in making safe, legal, accurate, and 

effective pesticide applications from 

an aircraft. However, before you begin 

applying federal restricted-use pesticides for hire, you have to demonstrate 

your skills and knowledge through a 

certification process administered by a 

pesticide regulatory agency.

Pesticide regulatory agencies 

within states, tribes, and territories, as 

well as federal departments or agencies, 

are responsible for certifying pilots who 

intend to apply restricted-use pesticides 

to agricultural crops from aircraft. 

This federally-mandated certification 

process applies to pilots who make 

applications of restricted-use pesticides 

for hire and those who work for commercial pest control operators. State, 

tribal, and territorial pesticide regulatory agencies may require certification 

of pilots who apply other pesticides as 

well. Many state pesticide regulatory 

agencies in the U.S. have adopted the 

National Aerial Pesticide Applicator 

Pilot Certification Examination as their 

tool for pilot certification.

In addition to the National Aerial 

Pesticide Applicator Pilot Certification 

Examination, state pesticide regulatory 

agencies may require pilots to pass 

a core examination and possibly one 

or more category-specific examinations (agriculture, forest, right-of-way, 

aquatic, etc.) as part of their certification process. Check with the 

pesticide regulatory agency in whose 

jurisdiction you will be working for 

complete certification requirements. 

(See Appendix 1 for pesticide regulatory agency contact information). 

Requirements may differ from one 

jurisdiction to another, and you may 

need to participate in separate certification processes for each jurisdiction. 

In addition to the aerial applicator pilot 

certification requirements, Chapter 1 

of this book covers the general standards set by Federal regulations for 

certifying all commercial pesticide 

applicator pilots and aerial pest control 

operators who apply federal restricteduse pesticides for hire.

1

Robert Wolf—Kansas State University
2 introduction

A team of experienced pilots and business owners who are actively engaged 

in aerial application of pesticides 

participated with an examination specialist to develop the National Aerial 

Pesticide Applicator Pilot Certification 

Examination. This committee identified the essential knowledge and skills 

each entry-level pilot applicator needs 

to competently, safely, and legally 

perform all aspects of aerial pesticide 

application.

The committee developed a 

Detailed Content Outline, included 

on pages 3 through 7, which serves 

as the blueprint for all examination 

questions and for this study manual. 

Before taking the examination, review 

this document so you understand the 

scope of knowledge and skills expected 

of you as you apply pesticides from an 

aircraft. The examination tests you on 

this knowledge and required skills.

The NATIONAL Examination

This manual focuses on how to 

apply pesticides properly and safely 

from an aircraft. It includes all the 

content found on the National Aerial 

Pesticide Applicator Pilot Certification 

Examination and consists of the following six chapters:

1 — Laws and Regulations for the Aerial 

Applicator Pilot

2 — Operation and Application Safety

3 — Preventing Pesticide Drift

4 — Aerial Pesticide Dispersal Systems

5 — Calibrating Aerial Application 

Equipment

6 — Making an Aerial Pesticide 

Application

Also included in this manual is a 

glossary of terms, an index, and several 

appendices that provide additional 

information that may prove useful as 

you prepare for the examination.

How to Use this Manual

Since this is a study manual, the 

end of each chapter has a number of 

review questions to help test your 

understanding of the information you 

just read. These review questions are 

similar to the types of questions on 

the actual examination so they will 

help you become familiar with the 

examination style and process. Each 

chapter begins with a set of objectives 

corresponding to certain skills and 

knowledge expected of you as an aerial 

pesticide applicator pilot.

scope of this manual

John Mateski—Newberg, OR
introduction 3

Read a chapter and then test 

your understanding of the material 

presented by answering the review 

questions. Check your answers to 

these questions by turning to page 97. 

If you miss some questions, go back 

and review sections of the chapter 

that covers that information. Repeat 

this process for each of the chapters. 

Information of special interest is organized into sidebars throughout the 

manual. You may find this information 

helpful in your work as an aerial application pilot.

DETAILED CONTENT OUTLINE

for

Licensed/Certified Aerial Applicator pilots

I. OPERATIONS

A. Federal and State Regulation Compliance

 1. Maintain requirements for a commercial pilot’s certification for aerial application 

(e.g., biennial flight review, medical)

 2. Comply with all FAA regulations

 3. Recognize an area that may be construed as congested by the FAA

 4. Plan flight patterns to avoid passes over residences, schools, communities, field 

workers, or animals

 5. Comply with state regulations regarding aerial pesticide applications

 6. Operate according to government regulations while applying good judgment 

during each application

 7. Maintain aircraft according to generally-accepted maintenance practices

 8. Tailor application plans to the job situation and locale while addressing 

requirements of regulatory agencies

 9. Obtain the required FAA Part 137 knowledge and skills endorsement from 

the business owner/operator

 10. For agricultural operations, communicate with the business owner/operator and 

grower:

 a. regarding job scheduling, rescheduling, and special considerations to meet 

Worker Protection Standard regulations

 b. ensuring they have proper documentation (label) regarding the application as 

required by the Worker Protection Standard regulations

 11. Ensure proper notification is given, including required field posting, before 

starting an application

B. Field Operations

 1. Secure aircraft so it cannot be accessed or flown by unauthorized personnel

 2. Ensure:

 a. ground-support crew members can implement their job responsibilities
4 introduction

 b. the area to be treated is clear

 c. unplanned conditions have not arisen at the time of an application

 3. Resist pressure to apply a product that presents unacceptable risk for the pilot, 

aircraft, public, surrounding crops, or wildlife

 4. Refuse jobs that are unsafe or illegal

 5. Participate in pre-application planning sessions and in post-application 

debriefings

 6. Document special precautions required to protect sensitive areas or situations

II. COMMUNICATIONS

A. Mixer/Loader Supervision

 1. Review responsibilities of the mixing-loading crew at the base and satellite 

locations

 2. Ensure the proper product is loaded into the aircraft for each application

 3. Perform minor in-field repairs on ground-support equipment

 4. React in a positive and helpful way in an emergency situation (e.g., broken 

loading hose)

B. Pilot and Ground Crew

 1. Use radio transceivers to communicate with the ground crew

 2. Communicate information on work order changes in the field directly between 

the customer/field men and the business owner/operator or crew leader

 3. Contact appropriate personnel when uncertain about any aspect of an application

 4. Practice procedures and contingency plans to ensure necessary communications 

are detailed, quick, and accurate

 5. Develop a strategy to notify a pilot when an aircraft should not be flown because 

of maintenance problems

III. APPLICATION SAFETY

A. Emergency Planning

 1. Anticipate types of accidents or incidents that can happen during the course of 

an aerial application or loading operation

 2. Devise a contingency plan for evacuating the aircraft in case of emergency

 3. Review pilot and ground crew procedures for an aircraft crash

B. Pre- and Post-Flight Preparations

 1. Check aircraft fuel and oil levels

 2. Seek local advice regarding topography and sensitive areas when an application 

will occur in an unfamiliar location

 3. Review an application job order to determine whether the job can be 

accomplished safely and adequately with reasonable precautions and work 

procedures

 4. Inspect flight suits, safety harnesses, and flight helmets for proper operating 

condition

 5. Wear a proper aviation flight helmet
introduction 5

 6. Check the operation of seat restraints

 7. Inspect:

 a. the fire extinguisher

 b. dispersal equipment (e.g., nozzles, hoses, connections) for signs of leakage and 

mechanical damage

 8. Develop a procedure to ensure contaminates are not carried on clothes into the 

cockpit

 9. Maintain maps and aerial photos if available and mark any obstacles, hazards, and 

sensitive areas

 10. Survey a field before treatment noting sensitive situations including

	 	 	 	• field crews 	 	 • domestic animals and wildlife

	 	 	 	• traffic or individuals	 • aquatic areas

	 	 	 	• crops in the vicinity	 • private residences

 11. Check each field for in-flight hazards (e.g., towers, power lines, guy wires, 

irrigation pipes, and vent pipes) before each application begins

 12. Report equipment deficiencies to the business owner/operator

 13. Ensure known equipment deficiencies have been addressed

 14. Protect employees from chemical exposure while changing nozzles and spray 

equipment configurations

C. Scheduling

 1. Implement work schedules that provide adequate rest periods

 2. Perform the most difficult and sensitive jobs when rested

 3. Help the business owner/operator plan equipment overhaul activities prior to 

periods of high demand

D. Pesticide Label

 1. Comply with label requirements and restrictions for aerial application of 

pesticides including:

 a. spray volumes (Gallons per Acre — GPA)

 b. buffers and no-spray zones

 c. weather conditions specific to wind and inversions

 2. Interpret labels that do not include a reference to aerial use

IV. DISPERSAL EQUIPMENT

A. Selection 

 1. Inspect dispersal system components for proper operating condition including 

hopper/tank, pump, filters, pipes, and fittings

 2. Select proper nozzles for desirable coverage and drift minimization

 3. Describe:

 a. major components of an aerial application liquid dispersal system

 b. desirable features of pesticide hoppers and tanks

 c. primary ways pumps are powered, and requirements for location and output 

capacity 
6 introduction

 d. features, advantages, and disadvantages of a fan-driven pump

 e. desirable features of pipes and fittings in an aerial dispersal system

 4. List primary types of spray patterns produced by hydraulic nozzles

 5. Describe:

 a. features of filters and screens

 b. hollow cone and flat fan patterns

 6. Determine the number of nozzles for required sprayer output using 

manufacturer’s specified nozzle flow volume chart, aircraft speed, and 

swath width

B. Position

 1. Describe where:

 a. filters/screens should be located in the system

 b. pressure gauges should be positioned

 2. Ensure

 a. booms and nozzles are positioned to release spray into a laminar airflow

 b. nozzles are placed to compensate for uneven dispersal from uneven 

airflow from:

	 	 	 	• wing tip vortices 	• high or low helicopter rotor speeds

	 	 	 	• aircraft propeller turbulence

 3. Drop nozzles to either side of, or below, airflow obstructions (e.g., landing gear, 

oil coolers, boom hangers, pumps and swath markers) to minimize distortion of 

the spray pattern

 4. Place nozzles:

 a. in the air stream to produce the appropriate droplet size consistent with 

boom pressure to give acceptable performance for each job while adhering to 

label restrictions

 b. along the boom to produce a uniform deposition on the target when the 

aircraft is flown at the normal spraying airspeed and altitude

 5. Check swath pattern uniformity for each nozzle configuration used for 

various flows

C. Maintenance

 1. Check dispersal system pressure gauge accuracy

 2. Maintain appropriate dispersal system filter cleaning schedule

 3. Check nozzles for excessive wear

 4. Correct leaking nozzles, fittings, and diaphragms on the ground during loading 

by cleaning or replacing parts as often as needed

 5. Keep:

 a. spray system connections and fittings tight and in good repair to minimize 

leaks

 b. the boom suck-back valve adjusted and in working order to ensure a positive 

shut-off and safeguard against leaking nozzles
introduction 7

D. Performance Measurement and Adjustment

 1. Change nozzle tips and orifices as required for various flows

 2. Calculate required and actual flow volumes, and actual output

 3. Verify flow volume using fixed timing, open timing, known distance, or a 

flow meter

 4. Adjust and calibrate: 

 a. the aircraft dispersal system prior to use on a job

 b. after any modification is made to the aircraft or dispersal system

V. APPLICATION CONSIDERATIONS

A. Site-Specific Meteorological Criteria

 1. Recognize application limits imposed by weather

 2. Determine wind velocity, direction, and air density at the job site

 3. Identify climatic conditions that:

 a. can affect aircraft engine power, take-off distance, and climb rate

 b. promote spray droplet evaporation

 4. Anticipate air temperature and humidity effects on 

spray droplet size

 5. Describe conditions associated with:

 a. thermals 

 b. a temperature inversion

B. Minimizing Off-Target Product Movement

 1. Assess risks of off-target movement 

 2. Refer to USDA Agricultural Research Service spreadsheet information and nozzle 

manufacturer fact sheets to facilitate nozzle selection and spray droplet size

 3. Select proper nozzles, operating pressure, orientation, and placement to 

minimize spray drift

 4. Relate: 

 a. volume-median-diameter (VMD) and relative span to desired deposition

 b. physical properties of a product to on-target deposition

 5. Using a smoke generator, determine if the spray has a potential to drift 

 6. Evaluate vertical and horizontal smoke plumes to assess wind direction, speed, 

and concentration

 7. Identify positive air movement away from critical areas

 8. Relate dispersal equipment configurations to airflow around the aircraft

 9. Select techniques (e.g., boom shut-offs, cross-wind applications, buffer zones) 

that minimize product movement out of the treatment area

 10. Apply product to headlands and edges of fields when drift potential is minimal 

 11. Document special equipment configurations or flight patterns used to reduce 

off-target movement
8 introduction

Glenn Martin—Gettysburg, PA

C. Making the Application

 1. Select a flight altitude that minimizes streaking and off-target movement

 2. Choose a flight pattern that provides the best performance and safety level for 

job conditions and operation mode

 3. Engage and disengage spray precisely when entering and exiting a 

predetermined swath pattern

 4. Utilize swath marking tools (e.g., GPS, flags)

 5. Continuously evaluate an application to ensure uniform dispersal

 6. Document the product(s) applied and application conditions
Laws and Regulations for the Aerial Applicator pilot

Laws and Regulations for

the Aerial Applicator Pilot

As an aerial pesticide applicator 

pilot, you must abide by all regulatory 

requirements and restrictions that 

pertain to pesticide handling and aerial 

pesticide application. Only under an 

extreme emergency, where the public 

or environment may be in danger, can 

you vary from any legal flight and aircraft handling requirements. Federal, 

state, tribal, territorial, and sometimes 

local laws and regulations address the 

handling and application of pesticides 

in the United States. These laws and 

regulations help:

•  Provide for the proper, safe, and

efficient uses of pesticides essential 

for the production of food and 

fiber and protecting public health 

and safety.

Studying this chapter will help you to:

	 • Understand why you must comply with federal, state, and local

regulations regarding aerial pesticide applications while using good 

judgment, best management, and safety practices during each

application.

	 • Understand the requirements for applying for a private or

commercial pilot certification for aerial application of pesticides and

how to maintain a valid certificate.

	 • Know the requirements and processes for maintaining an aircraft

according to applicable regulations, safety practices, and aircraft

manufacturer guidelines and recommendations.

	 • Tailor aerial pesticide applications to the job situation and locale

while following the requirements of regulatory agencies.

	 • Recognize congested areas and the importance of planning flight

patterns that avoid passes over residences, schools, communities,

field workers, and animals.

	 • Comply with label requirements and restrictions for aerial

application of pesticides and interpreting labels that do not include

specific use directions for aerial use.

9

CHAPTER 1

LEARNING OBJECTIVES
10 CHAPTER 1

•  Protect the environment by prohibiting, regulating, or controlling 

certain pesticide uses.

•  Assure agricultural and pest

control workers of safe working 

conditions where pesticides are 

present.

•  Assure that aerial agricultural

pest control is performed by 

qualified, competent, and 

responsible individuals.

•  Assure users that pesticides are

appropriate for the use designated by the label.

•  Require that pesticide and

service containers are properly 

labeled.

•  Encourage the development

and implementation of pest 

management systems that stress 

the incorporation of biological 

and cultural pest control techniques with selective pesticide 

uses when necessary to achieve 

acceptable levels of control 

with the least possible harm to 

nontarget organisms and the 

environment.

Federal regulations applicable to the certification of people 

who apply pesticides and to pesticide 

handling and application are part of 

the Federal Insecticide, Fungicide, and 

Rodenticide Act (FIFRA). The U.S.

Environmental Protection Agency

(EPA) and state, tribal, and territorial

pesticide regulatory agencies enforce 

the provisions of FIFRA. EPA regulations focus on applicator (pilot) job

knowledge including pesticide handling and protecting people and the 

environment. State licensing, use, 

storage, handling, and disposal regulations, as well as tribal, territorial, 

and local regulations, often further 

regulate application procedures and 

pesticide uses in order to protect 

people and vulnerable sensitive areas 

or organisms.

The U.S. Federal Aviation

Administration (FAA) certifies

agricultural aircraft operations and 

enforces Federal Aviation Regulations

(FARS) pertaining to aircraft operation. FARS Section 14, part 137 of

the Code of Federal Regulations specifically addresses agricultural aircraft 

operations. An agricultural aircraft

operation is a business that operates 

aircraft for the purpose of:

•  Dispensing any economic poison.

•  Dispensing any other substance

intended for plant nourishment, 

soil treatment, propagation of 

plant life, or pest control.

•  Engaging in dispensing activities

directly affecting agriculture, 

horticulture, or forest preservation.

FAA regulations concern such

areas as aircraft operation, aircraft 

inspection and maintenance, ferrying routes, operation altitude, 

pilot licensing, and medical exams. 

Appendix 2 provides a summary of

the FAA agricultural aircraft operator

certification requirements and process.

Applicants for aerial applicator pilot 

certification must hold and maintain a 

commercial pilot’s license and have a 

current Class II Medical Certificate. If 

you work as a pilot-in-command for an 

agricultural aircraft operator, you also 

need an endorsement letter from that 

operator or a person designated by that 

operator. The aircraft you fly must be 

equipped with approved and properly 

labeled seat belts and shoulder harnesses for each pilot station.

EPA Requirements

State-administered EPA pesticide

applicator certification determines the 

competency of individual pilots who 

will be applying pesticides. You must 

demonstrate your knowledge of general 

aspects of pesticide handling and application as well as your knowledge of the 

specialized area or areas of application 

where you intend to work, e.g., agricultural crops, forests, rights-of-way, 

public health pest control.

REQUIREMENTS FOR PILOT CERTIFICATION
Laws and Regulations for the Aerial Applicator pilot

Determination of Competency

State pesticide regulatory agencies 

use written examinations to determine 

your competency in using and handling 

pesticides. State competency standards 

must, at a minimum, conform to federal 

regulations. To prepare for examinations 

testing your knowledge of general aspects 

of pesticide handling and application, 

obtain a copy of the National Pesticide

Applicator Certification Core Manual

published by the National Association

of State Departments of Agriculture

Research Foundation, Washington,

DC. You can download PDF versions

of manual chapters at http://www.nasda.

org/StaticContent/workersafety/. The 

manual covers the general standards 

listed below. States may also have additional study materials available to assist 

in preparing for the exam.

General Standards for All Certified 

Commercial Applicators

To become a certified commercial 

applicator, you must demonstrate 

practical knowledge of the principles 

and practices of pest control and safe 

pesticide use and handling. General 

standards of competency include the 

following categories. 

Label and Labeling Comprehension. 

You must know the format and 

terminology of pesticide labels and 

labeling, including:

•  Understanding instructions,

warnings, terms, symbols, and 

other information commonly 

appearing on pesticide labels.

•  Recognizing product classification:

“general-use” or “restricted-use.”

•  Adhering to the requirement to

use pesticides consistent with their 

label instructions.

Safety Factors. Regulations require you

to understand:

•  Pesticide toxicity and hazards to

people.

•  Symptoms of pesticide poisoning.

•  The usual pesticide exposure

routes.

•  Types and causes of common pesticide accidents.

•  The precautions necessary to

guard against injury to applicators

and other individuals in or near 

treated areas.

•  The need for and proper use of protective clothing and equipment.

•  First aid and other procedures

to follow in case of a pesticide 

accident.

•  Proper identification, storage,

transport, handling, mixing procedures, and disposal methods 

for pesticides and used pesticide 

containers, including precautions 

to prevent children from having 

access to pesticides and pesticide 

containers.

Environment. You must recognize 

how the following factors possibly 

influence the environmental fate of 

pesticides:

•  Weather and other climatic conditions.

•  Types of terrain, soil, or other

substrate.

•  Drainage patterns.

•  Presence of fish, wildlife, and

other non-target organisms.

Pests. For effective pest control, you 

need to be able to identify relevant 

pests and recognize the common 

characteristics of pest organisms and 

their damage symptoms and signs. You 

must also understand pest development 

and biology relevant to identification 

and control.

Pesticides. Your knowledge of pesticides must include:

•  Knowing the general types of

pesticides.

•  Being familiar with various types

of formulations.

•  Understanding compatibility,

synergism, persistence, and 

animal and plant toxicity of the 

formulations.

11
CHAPTER 1

•  Recognizing hazards and residues

associated with use.

• Being aware of factors that

influence effectiveness or lead to 

such problems as pesticide resistance.

•  Knowing the proper procedures

for diluting pesticide concentrates.

Equipment. You must demonstrate 

your familiarity with types of 

application and mixing equipment and 

know the advantages and limitations 

of each. You must be proficient in 

calibrating and maintaining pesticide 

application equipment. 

Application Techniques. Regulations

require you to demonstrate proper 

application methods for various 

formulations of pesticides, their 

solutions, and choose the correct 

application technique to use in a given 

situation. You must demonstrate how 

to prevent drift and pesticide loss into 

the environment. 

Laws and Regulations. You must 

also demonstrate your knowledge 

of applicable state and federal laws 

and regulations. States may require 

certification (examinations) in additional categories over and above the 

general standards. These additional 

categories align with various pesticide 

uses, such as agricultural pest control, 

rights-of-way vegetation control, 

vector control, or forest pest control.

The pesticide container label and 

associated labeling are important legal 

documents that contain directions 

and restrictions you must follow when 

making an aerial application. Some labels 

refer to other documents, such as endangered species area protection maps or 

the Worker Protection Standard provisions of the Code of Federal Regulations

applicable to agricultural operations (40

CFR part 170). These and other documents referred to on pesticide labels 

become part of the pesticide labeling.

Some labels and associated labeling 

contain information specifically 

applicable to aerial application. Other 

labels and associated labeling contain 

information pertaining to any type of 

application method and do not provide 

specific instructions or precautions for 

aerial application. Certain pesticide 

labels prohibit the aerial application of 

the labeled material, so you must never 

apply these materials by air, even when 

mixed with other pesticides approved 

for aerial application.

Labels having specific aerial application information are usually easier to 

interpret than those that only provide 

general information. Examples of

the PESTicide label

12

The use of 80-degree or 110-degree flat-fan nozzles is highly recommended for optimum spray coverage and canopy penetration. To

achieve uniform spray coverage, use nozzles and pressure that deliver MEDIUM spray droplets as indicated in nozzle manufacturer's

catalogs and in accordance with ASAE standard S-572. Use screens that are 50 mesh or larger.

AERIAL APPLICATION

Herbicide should be applied in a minimum of 5 gallons of water per broadcast acre. Weed infestations should be treated before they

become competitive with the crop.

To achieve uniform spray coverage, use nozzles and pressure that deliver MEDIUM spray droplets as indicated in nozzle manufacturer's

catalogs and in accordance with ASAE standard S-572. DO NOT use raindrop nozzles.

Aerial applications with this product should be made at a maximum height of 10 feet above the crop with low drift nozzles at a

maximum pressure of 40 psi. Avoid application under conditions where uniform coverage cannot be obtained or where excessive

spray drift may occur.

Flagmen and loaders should avoid inhalation of spray mist and prolonged contact with skin.

See the SPRAY DRIFT MANAGEMENT section of this label for additional information on proper application of herbicide.

MIXING INSTRUCTIONS

Herbicide must be applied with clean and properly calibrated equipment. Prior to adding herbicide to the spray tank, ensure that

the spray tank, filters, and nozzles have been thoroughly cleaned. In-line strainers and nozzle screens should be 50 mesh or coarser.
Laws and Regulations for the Aerial Applicator pilot

aerial-specific information covered in 

labels may include:

•  Statements that refer to or allow

aerial application.

•  Specific use directions, such as for

rate and dilution that apply directly 

to aerial applications without interpretation or calculations.

•  Allowable weather conditions for

applications.

•  Restrictions pertaining to spray

volume and dilution.

•  Droplet size information based on

ASABE S-572.1 (see Page 37) Spray

Nozzle Classification by Droplet

Spectra.

•  Drift management requirements.

•  Off-target and especially sensitive

area precautions.

• Buffer zone requirements.

Manufacturers must register pesticide products with the EPA before

anyone can buy or use them. The EPA

registers specific products, not generic 

pesticide materials. This registration 

procedure protects people and the environment from ineffective or harmful 

chemicals. The registration procedure 

includes an evaluation of each chemical 

and establishes how the EPA classifies

the material at the federal level. This 

evaluation determines whether the EPA

classifies a pesticide as restricted-use 

or general-use. Only certified pesticide 

applicators can buy, use, or supervise the 

use of a federal restricted-use pesticide 

(RUP). States may also have specific registration and labeling requirements and 

may restrict the use of other products 

not classified as restricted-use by the 

EPA.

Regulations set the format for

pesticide labels and prescribe what 

information they contain. Some pesticide containers are too small, however, 

to have all this information printed on 

them. In these cases, the EPA requires

registrants or manufacturers to attach 

additional labeling. On metal and plastic 

containers, registrants or manufactures 

put such packets into plastic sleeves 

glued to the sides of the containers. 

Paper packages usually have label directions inserted under the bottom flaps of 

the package.

States or local regulatory agencies 

may impose additional restrictions 

or prohibitions on aerial applications 

that may or may not be included on 

the pesticide label. For example, local 

regulations may be more restrictive 

on requirements such as buffer areas, 

no-spray zones, and dilution rates. 

Always follow the requirements that

are most restrictive in the location 

where you are making an application. 

For example, local agencies might 

prohibit aerial applications regardless 

of label use directions, or they might 

prohibit fixed-wing applications under 

certain circumstances and require that 

only rotary-winged aircraft make aerial 

applications in these situations.

Professional Aerial Applicator’s Support System (PAASS)

A pesticide drift mitigation and education project initiated in 1996 by the National 

Agricultural Aviation Association (NAAA). PAASS is an industry-based collaborative 

educational effort that focuses on outreach to pilots and operators of aerial 

applicator businesses. The program’s primary goals are to reduce the number of 

pesticide agricultural aviation accidents, improve pilot safety, and reduce pesticide 

drift incidents by fostering professionally-sound decision-making.

The PAASS interactive program improves critical decision-making skills sensitive to environmental factors. The agricultural aviation industry regards the PAASS 

program as the single relevant recurring training source for modern agricultural 

aviation pilots. Many companies providing insurance to agricultural aviators require 

pilots to participate in this training as a condition of insurability.

Statistics show that aerial application accidents and drift incidents have notably 

declined since the PAASS program first began.

13
14 CHAPTER 1
Laws and Regulations for the Aerial Applicator pilot 15

1. Pesticide laws and regulations help to:

A. Encourage pesticide use.

B. Protect the environment.

C. Avoid dependence on alternative pest control

methods.

D. Prevent pests from developing control

resistance.

2. Knowing the proper procedures for diluting 

pesticide concentrates is: 

A. An FAA requirement.

B. The requirement of local pesticide 

regulatory agencies.

C. Part of the federal Worker Protection

Standard provisions.

D. An EPA general standard for certified

applicators.

3. The format of pesticide labels is established by:

A. Pesticide manufacturer guidelines.

B. Federal regulations.

C. State laws.

D. ASABE professional standards. 

4. Knowing how to properly handle, mix, store, 

and dispose of pesticides is a requirement 

of the:

A. Environmental Protection Agency (EPA).

B. Occupational Safety and Health 

Administration (OSHA).

C. United States Department of Agriculture

(USDA).

D. Federal Aviation Administration (FAA).

5. One purpose of federal pesticide regulations is to:

A. Require public notification about pesticide

applications.

B. Provide health benefits to agricultural workers.

C. Establish safety standards for pesticide

application equipment.

D. Prevent agricultural workers from handling

pesticides or working in pesticide-treated areas.

6. State pesticide regulatory agencies generally 

have the responsibility for:

A. Certifying commercial pesticide applicators.

B. Determining the personal protective

equipment required on pesticide labels.

C. Developing material safety data sheets

(MSDS).

D. Identifying endangered species.

7. In addition to the actual pesticide label, 

which of the following is part of the pesticide 

labeling?

A. Any product sales brochures.

B. The job work order.

C. Worker Protection Standard provisions.

D. The Material Safety Data Sheet.

8. Which of the following is one of the requirements for pesticide applicator certification?

A. Knowing how to use appropriate application

methods for various pesticide formulations.

B. Demonstrating safe aircraft operation.

C. Following recommended aircraft inspection 

and maintenance schedules.

D. Making applications at altitudes specified 

in regulations.

CHAPTER 1: Laws and Regulations for the

Aerial Applicator Pilot

 Review Questions
16 CHAPTER 1

9. From the choices below, what pesticide use 

information found on a product label would be 

specific to an aerial application?

A. PPE requirements.

B. ASABE droplet size requirements.

C. Field posting requirements.

D. Restricted-entry interval requirements.

10. Having a current Class II Medical Certificate 

is a requirement of the for all 

pilots making aerial pesticide applications.

A. U.S. Environmental Protection Agency

(EPA).

B. State Lead Agency (SLA).

C. Federal Aviation Agency (FAA).

D. National Transportation Safety Board

(NTSB).

REVIEW QUESTION ANSWERS ON PAGE 97
Operation and Application Safety 17

Operation and Application

Safety

Safety awareness and practices in all 

as-pects of an aerial pesticide application operation protects employees, 

the public, and the environment. 

Your operation needs procedures to 

secure the aircraft, ground equipment, 

and pesticide materials when not in 

use to prevent unauthorized access. 

Unauthorized access can range from 

individuals wanting to damage or 

burglarize property to crimes of 

opportunity, such as unplanned acts of 

vandalism. There is also the possibility 

that people are unaware of the hazards 

associated with a pesticide application 

operation while inadvertently gaining 

access to the facility. An example would 

be children who might be curious 

about and attracted to aircraft or 

other pesticide use equipment, thereby 

trespassing to inspect the equipment 

when company personnel are not at 

the facility. In addition to securing 

the facility, you can protect people and 

This chapter will assist you to:

	 • Understand the importance of preventing security threats to the

operations and reducing hazards to the public from unauthorized or

illegal access to the aircraft, pesticide materials, and equipment.

	 • Understand the importance of protecting people and the

environment from hazards associated with aerial application of

pesticides.

	 • Know steps to make pesticide applications that are safe for you and

the ground operations crew.

	 • Understand what precautions to take to protect sensitive areas while

making pesticide applications from an aircraft.

	 • Recognize the importance of good communications with the ground

operations crew and others before, during, and after making

pesticide applications.

	 • Prepare for emergencies, including knowing proper first-aid

procedures for pesticide exposure and related illnesses or injuries,

and heat-related illnesses.

CHAPTER 2

LEARNING OBJECTIVES
18 CHAPTER 2

the environment by carefully planning 

each function of the application operation to avoid accidents and hazards. 

Provide safety training to ground crew 

members so they know how to handle 

pesticides properly and work carefully 

around aircraft and other associated 

equipment.

Make sure each person involved in 

the application operation is well rested, 

alert, and not under the influence of 

alcohol or drugs. Develop reliable 

methods of communication between 

you, the customers, and ground operations. In case an accident or mishap 

should occur, take immediate steps to 

reduce damage and injury, including 

performing proper first aid and decontamination procedures for pesticide 

exposure.

Aircraft and pesticide security

Progressive and conscientious operations that handle pesticides work to 

actively manage risks to ensure the safety 

of their employees, their customers, and 

their communities. They focus on safely 

operating aircraft and mixing-loading 

equipment. To achieve these goals, they 

use preventative maintenance, up-to-date 

operating procedures, and well-trained 

staff. Because of heightened concerns 

about terrorism and sabotage, the operation must also pay more attention to the 

security of aerial application equipment, 

facility sites, and pesticide storage areas. 

All aerial application operations need 

some measure of site security in place to 

minimize crime, prevent unauthorized 

access, and protect company assets.

While many of the steps you take 

to ensure an effective security program 

seem routine, they are important to 

the health and safety of the aerial 

application operation staff and the surrounding community. Without effective 

security procedures, the business risks 

being vulnerable to both internal and 

external threats, which can pose hazards 

to you and the employees, sensitive 

business information, the facilities and 

equipment, and stored pesticides.

Evaluating Aerial 

Application Operation 

Security

There are several important 

security needs and critical control points 

for an aerial application operation.

Securing Facilities, Storage Areas, 

and Surrounding Property

One of the most fundamental 

security needs is keeping intruders 

out of areas used for pesticide storage. 

Elements of an effective security plan 

can range from basic fencing, lighting, 

and locks, to intrusion detection systems 

and cameras. Inventory management 

policies help limit the amount of pesticides stored on site, reducing the risks of 

accidental or intentional release or theft. 

Securing Pesticide Application 

Aircraft, Vehicles, and Equipment

The operation you work for needs 

appropriate security protections to 

prevent intruder access to equipment 

used for mixing, loading, and applying 

pesticides. Accepted methods to prevent 

unauthorized flying of aircraft include 

installing hidden electrical system shutoff switches, parking disabled trucks or 

other equipment in front and back of 

aircraft, removing batteries from aircraft, using devices that lock propellers 

or rotors, and disabling engines in 

unused aircraft. Use similar methods to 

prevent intruders from operating ground 

vehicles, such as trucks, tractors, forklifts, and other motorized equipment. 

Always park the aircraft in a secure 

place when it is not in use. In addition, 

establish methods to know at all times 

the location and status of all equipment 

used in the operation. Routinely update 

equipment records.

Security awareness is particularly 

important for large-scale pesticide 

application equipment, like aircraft. The 

Federal Bureau of Investigations (FBI) 

requests that aerial operators be vigilant 

to any suspicious activity relative to the 

use, training in, or acquisition of dangerous pesticide chemicals or airborne 

application of these materials. This 

includes threats, unusual purchases, 
Operation and Application Safety 19

suspicious behavior by employees or 

customers, and unusual contacts with 

the public. If you observe any suspicious behavior, irregular circumstances, 

or unusual requests for information, 

immediately report this to a local law 

enforcement agency and the FBI.

Employees

Effective hiring and labor relations 

policies are important to obtain and 

retain good employees who will support 

and follow the operation’s safety precautions. The hiring process should ensure 

that pesticide handlers have all requisite 

training necessary to handle pesticides 

safely. Background checks of employees 

who will have access to secure areas, particularly those areas where pesticides are 

stored, can be an important employee 

selection tool.

Emergency Response

Effective emergency response procedures help to ensure that the operation 

manager and employees understand 

how to respond and whom to contact 

in the case of an emergency. Aside from 

accidents, such plans need to consider 

vandalism, burglary, arson and bomb 

threats that target the operation, and 

potential widespread terrorist activity 

that involves the equipment or pesticides.

Timely Coordination with 

Authorities

If a breach of security or suspicious 

activity does occur, immediately contact 

the local police or sheriff’s department. 

The U.S. Department of Homeland 

Security requests that operations also 

report security breaches, threats, or 

suspicious behavior to the local FBI 

field office. Information on the location 

of the nearest FBI office is available at 

http://www.fbi.gov.

Minnesota Department of Agriculture

The aerial application operation you 

work for depends on your piloting 

skills as well as competent ground crew 

members who safely and responsibly 

carry out their duties. Proper training 

and enforcing safety practices within 

the operation help reduce hazards to 

ground crew members working around 

equipment and aircraft. In addition, a 

well-developed safety program provides 

the structure to protect the public and 

nontarget areas from pesticide exposure. 

Providing training, assuring good 

employee habits, checking areas before 

an application, and resisting pressure to 

make unsafe or illegal applications are 

important components of the operation 

that protect people, areas surrounding 

treatment sites, and the environment.

Employee Training

States have Occupational Safety 

and Health Administration (OSHA) 

regulations that require employers 

to train employees on how to safely 

operate equipment and avoid hazards 

associated with their work. The EPA 

Worker Protection Standard (WPS) 

mandates specific training requirements 

for employees who handle pesticides in 

agricultural operations. According to 

this regulation, a pesticide handler in 

an aerial application operation is any 

employee who:

•  Mixes, loads, transfers, or applies

pesticides.

•  Maintains, services, repairs, cleans,

or handles equipment that may 

contain residues or that has been 

used in pesticide mixing or application activities.

•  Works with opened pesticide containers, including emptied but not 

rinsed containers.

protecting people and the environment
20 CHAPTER 2

•  Flags during aerial applications.

The Worker Protection Standard 

requires that employers in agricultural 

operations provide training to pesticide 

handlers working in their operations. 

Employers must either provide the 

training themselves or arrange for 

someone else to provide it. 

The Training Program

The WPS requires that a pesticide 

handler training program address the following topics as they apply to the specific 

pesticide materials employees handle:

•  Understanding the format and

meaning of information, such as 

precautionary statements about 

human health hazards, contained 

in the labeling of the pesticide 

products.

•  Understanding the health hazards

associated with pesticides handled 

by employees, including acute and 

chronic effects, delayed effects, and 

sensitization, as identified in pesticide product labeling.

•  Knowing the routes by which pesticides can enter the body.

•  Recognizing how exposure occurs

and being familiar with signs and 

symptoms of exposure-related 

injury or illness.

•  Knowing specific emergency firstaid procedures for overexposure 

to the pesticides that employees 

handle.

•  Knowing how to obtain emergency

medical care when a pesticide injury 

or illness occurs.

•  Knowing routine and emergency

decontamination procedures, 

including spill clean up and the 

need to thoroughly shower with 

soap and warm water after the pesticide handling exposure period.

•  Understanding the pesticide label

requirements for using personal 

protective equipment (PPE), recognizing its limitations, knowing how 

to use and clean it properly, and 

knowing how and when to repair or 

replace it.

•  Knowing how to prevent, recognize, and provide first aid for 

heat-related illness.

•  Understanding safety requirements and procedures for pesticide 

handling, including the use of engineering controls (such as closed 

mixing systems and enclosed cabs), 

and proper ways to transport, 

store, and dispose of pesticides and 

properly rinsed containers.

•  Recognizing how drift and runoff

cause environmental damage and 

hazards to wildlife.

•  Understanding why it is unsafe to

take pesticides or pesticide containers home.

•  Knowing what isrequired to handle

pesticides safely.

California Agricultural Aircraft Association

California Agricultural Aircraft Association
Operation and Application Safety 21

•  Knowing the employee’s rights,

including the right:

w To personally receive information about pesticides to which 

he or she may be exposed.

w For his or her physician or 

employee representative to 

receive information about pesticides to which he or she may be 

exposed.

w To be protected against retaliatory action due to the exercise 

of any of his or her rights.

Other Important Topics

Training must include the following 

general pesticide handling procedures 

that apply to all pesticide products:

•  Understanding the importance of

wearing clean work clothing daily.

•  Knowing how to properly and safely

handle, open, and lift containers.

•  Knowing how to properly pour

pesticides out of containers.

•  Knowing how to operate mixing

and application equipment.

•  Knowing procedures for triple

rinsing containers.

•  Knowing how to legally recycle or

dispose of empty containers.

•  Knowing how to confine spray to

the target area.

•  Knowing how to avoid contaminating people, animals, waterways, 

and other non-target objects and 

areas.

•  Knowing how and where to

properly and safely store containers 

that hold pesticides or have been 

emptied but not rinsed.

•  Understanding and following procedures to prevent unauthorized 

access when containers cannot be 

locked up or otherwise secured.

•  Understanding the importance of

washing hands thoroughly before 

eating, smoking, drinking, or using 

the restroom.

Consult with your state pesticide 

regulatory agency to see if there are any 

additional training requirements for 

pesticide handlers. 

Federal WPS regulations require 

pesticide handlers receive training 

every five years at a minimum. States 

may require more frequent training. 

Training must take place before any 

pesticide handling activities. Employees 

who are certified as pesticide applicators are exempt from this training 

requirement.

Employee Habits

Every aerial pesticide application 

requires alertness and attention to 

detail. Before and during work periods, 

you and the ground crew members 

should never use alcohol or any drugs 

or medications that impair judgment or 

decrease mental alertness. Employees 

who wear personal protective equipment 

must also take steps to avoid heatrelated illnesses.

Avoiding Use of Alcohol and Drugs

A lcohol, drugs, and certain 

over-the-counter and prescription 
22 CHAPTER 2

medications cause drowsiness, impair 

judgment, and often influence the 

ability to handle or apply pesticides 

safely. These substances may also alter 

the toxicity of pesticides in case of 

exposure. Make your physician aware 

of your occupation handling pesticides 

so that is considered when prescribing 

medications. Do not use alcohol or 

drugs before, during, or immediately 

after handling pesticides, or before or 

during flight operations.

Staying Alert

Physical and mental alertness 

requires that you and the ground 

crew get sufficient sleep before an 

application operation and avoid other 

activities prior to the operation that 

cause fatigue. In addition, stress from 

work or personal activities distracts and 

interferes with alertness. Therefore, 

individuals experiencing high levels of 

stress should not participate in aerial 

application operations.

Preventing Dehydration and 

Heat-Related Illness

Drink ing insuff icient water 

coupled with wearing personal protective equipment during hot weather 

may lead to heat-related illness that 

may mimic certain types of pesticide 

poisoning. Symptoms of heat illness 

include tiredness, weakness, headache, 

sweating, nausea, dizziness, and 

fainting. Severe heat illness can cause 

a person to act confused, get angry 

easily, or behave strangely. Along 

with training on recognizing pesticide 

illness, WPS regulations require that 

pesticide handlers receive training on 

recognizing, avoiding, and treating 

heat stress. Appendix 3 describes 

useful methods to avoid and treat heat 

stress.

application safety

Aerial application safety processes and 

procedures involve the highly important 

components of the aircraft, the pesticide 

dispersal system installed on the aircraft, 

and ground equipment used to mix pesticides and load them into the aircraft.

Each pesticide application you 

make is possibly unique for you because 

of differences between application site 

locations, obstacles, non-target areas, 

weather, pesticide materials, crops 

or target areas, and other variables. 

Therefore, you and the ground crew 

must begin by clearly understanding 

the work order and the pesticide label. 

Arrange to scout the target site and 

surrounding areas so you can plan the 

application before scheduling it. Review 

the pesticide label to understand application restrictions and precautions and 

to prepare for emergencies or other 

problems. Some pesticide materials may 

have local application restrictions such 

as time of use, height of application, prohibitions due to nearby sensitive crops, 

and requirements for buffer zones. 

Check with state or local pesticide regulatory agencies if you need information 

about additional restrictions.

The Equipment

As a pilot, you must understand the 

importance of, and legal requirements 

for, scheduled inspections, servicing, 

and maintenance of the aircraft you fly. 

Take responsibility to assure the aircraft 

meets these requirements. This includes 

a preflight fuel and oil check, taking 

responsibility for proper fueling of the 

aircraft, and inspecting the aircraft 

for maintenance items each time you 

Glenn Martin—Gettysburg, PA stop the operation for the day or for a 
Operation and Application Safety 23

rest break. In addition, any aircraft you 

operate over congested areas must have 

had, within the preceding 100 hours of 

time in service, a 100-hour or annual 

inspection by an authorized person, 

or been inspected under a progressive 

inspection system. Congested areas 

include populated areas where chances 

of personal injury or property damage 

are greater if the aircraft should crash or 

if you must dump the pesticide load.

Have the aircraft’s application 

equipment inspected and maintained 

regularly to assure that it functions 

properly and accurately and does not 

have leaks or other problems. When 

something malfunctions, repair it 

immediately. Make a daily inspection 

of the aircraft’s application equipment, 

the same as you do for the aircraft. After 

winter storage of the aircraft’s dispersal 

system, carefully inspect it for wear and 

leaks. Make sure all hoses are in good 

condition and tighten all fittings. Look 

for seepage around the pump housing 

that indicates a leaking gasket or loose 

connections.

Also, establish an inspection and 

maintenance program for ground 

equipment used for mixing and loading 

pesticide materials into the aircraft, as 

well as ground vehicles used to transport 

people, pesticides, and equipment. Keep

all associated equipment in good repair. 

Any breakdown in this equipment will 

delay the pesticide application, wreak 

havoc with scheduling, and could be 

costly to the business and customers.

Keep on hand spare parts and supplies, such as nozzles, hoses, fittings, 

drive belts, fuel, lubricants, and other 

components that are critical to the operation. Replace spare parts and supplies 

used during a breakdown so you always 

are ready for future operations.

Understanding the Work 

Order 

Review the work order carefully to 

be certain you can make the application 

safely, correctly, and legally, according 

to the label and state and federal regulations. You should be able to perform 

the requested work with reasonable 

precaution and within the expectations 

of normal work procedures for both 

yourself and the ground crew. Take 

into account the following factors when 

evaluating a work order. 

Features and Limitations of the 

Aircraft

The aircraft must be operationally 

ready to perform the aerial pesticide 

application. Be sure that the operator 

you work for has a procedure in place to 

prevent use of an unsafe aircraft or faulty 

dispersal equipment and to notify you 

in situations when you or others should 

not fly the aircraft due to maintenance 

issues or mechanical malfunctions. 

This includes involving the company’s 

job scheduler in all company procedures for grounding an aircraft. Take 

responsibility for notifying the operator 

of problems that may affect the safety 

or efficient operation of the aircraft or 

involve your safety equipment. This 

includes:

•  Developing a way to communicate

details of the problem to the person 

in charge.

•  Establishing a timeline in which

the problem needs to be corrected.

•  Verifying that the problem is corrected before putting the aircraft or 

equipment back into service.

The aircraft must be capable of 

safely delivering the appropriate amount 

of pesticide to the target site. It must:

•  Have the power and performance capabilities for the routine 

maneuvers needed to carry out the 

application, as well as being able to 

perform emergency maneuvers.

•  Have a maximum load capacity

that will accommodate the weight 

of the pesticide and, if needed, be 

able to handle takeoffs and landings 

from short, rough, or temporary 

airstrips.

•  Be properly equipped to discharge

the recommended amount of pesticide product per unit (acre) of 

target site area.

•  Be able to produce and deliver spray

droplets that provide an effective 

application and have low spray drift 

potential at the intended location.
24 CHAPTER 2

Pilot Qualifications and Limitations

Your competence, alertness, 

and capacity for timely and accurate 

judgment largely determine the safety 

of the operation and the quality of the 

application. In addition, your attitude 

about making safe and legal applications 

goes a long way in positively influencing 

others to accept and follow the safety 

procedures. You must be:

•  Aware of your personal limitations

in operating the aircraft and be 

fully aware of the features and limitations of the aircraft.

•  Capable of executing emergency

maneuvers appropriate to common 

emergency situations that you 

might experience.

•  Capable of safely maneuvering

the aircraft under normal flight 

conditions when it is loaded to its 

maximum legal weight.

•  Able to determine the best direction

in which to apply the pesticide to 

reduce its off-target movement.

•  Capable of immediate and clear

communication exchanges with 

on-site ground crew members and 

others.

•  Sufficiently rested to accomplish

the job safely.

•  Able to establish and follow realistic

task deadlines and work patterns.

•  Knowledgeable of weather factors

and their influence on aerial application work.

•  Able to correctly interpret and

follow the pesticide label directions 

and work order and observe any 

state regulations regarding aircraft 

setup or product restrictions.

•  Familiar with each pesticide

product label to know first-aid 

measures in the event of accidental 

overexposure, special precautions 

required for aerial application, and 

registered crops or sites.

•  Able to recognize different types

of crops from the air in order to 

ensure the correct site is treated.

•  Able to delineate boundaries of

adjacent nontarget areas.

Take the following measures to 

reduce the potential for spray droplets to 

drift off the application site:

•  Use a nozzle type, size, pressure,

and orientation that maintains the 

desired droplet spectrum.

•  Ensure that positive shut-off valves

are working properly.

•  Achieve good field-end coverage on

initial spray runs (crossing the ends 

of fields that are bordered by trees 

or other obstacles usually means 

flying higher and increasing the 

chance of drift).

•  Maintain applications at the appropriate height for the aircraft type 

and speed.

•  Use a boom length that does not

exceed 75% of the wingspan of 

Robert Wolf—Kansas State University

California Agricultural Aircraft Association
Operation and Application Safety 25

fixed-wing aircraft or the rotor 

diameter of rotary-wing aircraft 

in order to reduce drift caused by 

wing tip and rotor vortices.

•  Consult the pesticide label for recommendations on boom type and 

setup requirements.

Scouting the Target Site

Each application site may contain 

unique obstacles and hazards. Before 

committing to make an application, 

someone from the operation should 

visit the target site to identify obstacles, 

hazards, and sensitive areas. Do this by 

ground, by air, or both. Afterwards, 

coordinate visual observations with 

maps and photographs of the area. 

Should the application site and surroundings be unfamiliar, seek more 

information regarding weather patterns, topography, and sensitive areas 

from the property operator and other 

people familiar with the area. During 

scouting, collect information about the:

•  Location of the site and the size and

shape of the area to be treated.

•  Types of crops adjacent to the

application site.

•  Proximity of the site to adjacent

fields and other areas where field 

workers may be present.

•  General local weather conditions.

•  Proximity of the site to areas used

or inhabited by people, including 

residences, parks, schools, playgrounds, shopping centers, 

businesses, roadways, adjacent 

fields, work crews, and other 

areas.

•  Proximity of the site to environmentally sensitive areas such as 

lakes, streams, ponds, irrigation 

canals, riparian zones, wildlife 

habitats, sensitive plants, nearby 

crops, and organic farms.

•  Proximity of the site to farms,

ranches, or other businesses 

with livestock or other domestic 

animals, such as dairies, feedlots, 

swine operations, dog kennels, and 

horse stables.

•  Proximity of the site to honey bee

hives and other commercial pollinating insects.

•  Safety hazards such as power lines,

guy wires, vent pipes, antennas, 

towers, trees, and other obstacles 

adjacent to the site and within the 

site itself.

•  Current cultural practices taking

place at the site and other adjacent 

agricultural areas.

•  Possible limitations to the operation, such as ground crew access 

to the site.

Charting all sensitive areas and 

obstacles will prove useful during the 

operation and for future reference. 

Established aerial pest control operators 

often have a collection of maps and 

aerial photographs that identify hazards 

and sensitive areas. Be sure to keep these 

up-to-date. Prior to the actual application, make a final check to confirm 

there are no recent changes that would 

put you, other people, the property, or 

the surrounding areas at risk. 

Understanding Pesticide 

Label Restrictions

Review the pesticide label to understand the legal requirements and use 

restrictions for that material and designations of which type of aircraft is or is 

not acceptable. If the recommendation 

or work order calls for a tank mix of two 

USDA—ARS Image Library
26 CHAPTER 2

or more pesticide products, review the 

labels of all the products to ensure you 

can combine them legally and that there 

are no compatibility issues. Follow the 

directions of each label having the most 

restrictive requirements for application, 

mixing, personal protective equipment, 

and other factors. You must understand 

the pesticide label.

Application Instructions

Confirm that there are no prohibitions to applying any of the prescribed 

materials by air. Check to see if there 

are restrictions such as buffer areas, 

spray material dilution parameters, air 

temperature requirements during application, and time of day spraying.

Personal Protective Equipment 

Requirements

Understand the PPE requirements 

on the label or labels and have available 

the most restrictive PPE required for 

handlers and you when you are outside 

of the aircraft cockpit. Make sure your 

flight suit, safety harness, and flight 

helmet are in good condition. Remove 

pesticide PPE before entering the aircraft cockpit.

First Aid and Decontamination 

Requirements

Read the label or labels for instructions on what type of first aid and 

decontamination procedures to follow 

in case of pesticide exposure.

Sensitive Crop Restrictions

Review all label precautions 

regarding applying the material onto or 

near sensitive crops or other plants.

Notification and Posting Requirements

Understand the responsibilities for 

informing people about hazards prior to 

making an application and any requirements for preventing entry by workers 

or people from the surrounding areas. 

Pesticide labels may require oral notification, field posting, or both. According 

to the Worker Protection Standard, 

agricultural employers are responsible 

for this notification and, when required, 

posting. However, aerial operations 

often post fields as a service to their 

clients. Never begin an application 

until the grower, property manager, or 

you meet the notification and posting 

requirements.

Honey Bee and Other Pollinating 

Insect Restrictions

Check the labels to see if the 

materials you are applying are harmful 

to foraging honey bees and other pollinating insects. If the label has such 

warnings or restrictions, adjust the 

application time to coincide with times 

these insects are most predictably not in 

the field you are treating.

Environmental Hazards

Check for precautions relating 

to environmentally sensitive areas, 

protecting natural enemies and beneficial insects, and other environmental 

hazards.

Cleaning Application Equipment

After each use, clean and decontaminate application equipment. Even 

some very small quantities of residues 

remaining in a tank can contaminate subsequent pesticide mixtures 

resulting in crop damage. Other times 

residues may affect tank mix compatibility or the toxicity of a subsequent 

product. Be particularly careful and 

clean between herbicides. Some herbicide labels bear explicit instructions 

on tank cleaning; make sure you follow 

their instructions and use their prescribed cleaning materials. 

Rinse the inside of the tank with 

water. If necessary, decontaminate it 

by using an appropriate tank cleaning 

material; common cleaners are 

ammonia or commercial tank cleaning 

product (e.g., 1 quart of household 

ammonia to each 25 gallons of water). 

Buy commercial pesticide tank cleaning 

and neutralizing compounds from 

chemical suppliers and farm equipment 

dealers. Be sure to check the pesticide 

label for any precautions regarding 

the use and disposal of cleaning and 

decontaminating chemicals. Follow the 

directions for the amount of cleaner to 

use for your spray tank. Be sure to run 

pumps and agitators, and flush all hoses 

and booms. Wear appropriate PPE and 

eye protection.

PREVENTING 

ENVIRONMENTAL

HAZARDS

P. O’Connor-Marer—Roseville, CA
Operation and Application Safety 27

Pesticide residue on the outside of 

application equipment can be hazardous 

to people who must operate or repair 

this equipment. Wash the outside of 

spray equipment with water, using a 

small amount of detergent if necessary. 

Clean equipment in an area where you 

can contain runoff. Otherwise, clean 

the equipment at the application site.

Resolving Conflicts

If the work order appears to be in 

conflict with any of the previously-listed 

factors, or if you or others have any 

safety concerns, delay the application 

until you and the property manager 

agree on modifications that resolve the 

conflicts and concerns. Resist pressure 

to perform an aerial application that 

presents high levels of risk. Also, refuse 

any job that is clearly illegal or not in 

compliance with any of the pesticide 

labels. Never apply a material for pest 

control that the EPA has not registered 

as a pesticide. This includes household 

and other products whose labels do not 

have EPA Registration numbers, such 

as soaps, spices, and vinegars.

Reviewing and 

Documenting the 

Application

After completing an application, 

especially a challenging one, spend time 

with the ground crew to identify parts 

of the operation that went especially 

well and things you could improve when 

working in another similar situation. 

Examine possibilities of better planning, 

better communication, making different 

adjustments to the equipment, using 

different equipment, becoming more 

familiar with the target site, or changing 

other aspects of the application process. 

A debriefing such as this will take a little 

time, but will improve efficiency and 

fine-tune future operations.

Record Keeping

Keep records of every application.

Federal regulations require keeping 

records of certain information when you 

make applications of federally restricteduse pesticides, and some states require 

keeping records of all agricultural pesticide 

applications—restricted- and generaluse (www.pesticidestewardship.org). 

To comply with federal record keeping 

when you make an application of federally restricted-use pesticides, you must 

have a record of the:

•  Date (month, day, and year) of the

application.

•  Brand or product name of the pesticide material applied.

•  EPA registration number.

•  Total quantity of pesticide product

used.

•  Location where you made the

application.

•  Size of the treated area.

•  Name and certification number of

the applicator.

Regulations require the operator 

to provide this information to the 

grower or property manager for whom 

you made the application within 30 days 

of the application. Federal regulations 

require the operator to keep copies of 

these records for a minimum of two 

years; state requirements may differ.

In addition to meeting federal and 

state requirements, application records 

are useful and important information 

for future reference and should questions or problems show up after an 

application. Consider including in the 

application records some or all of the 

following additional or more detailed 

information about the application. 

This documentation will serve in your 

defense in case of possible legal action 

due to crop damage or off-target 

movement of the pesticide:

•  Description of the application

site, including type of site or crop 

treated. 

•  Proximity of the treated area to

roads, structures, other crops, field 

workers, hazards, and sensitive 

sites.

•  Recent or ongoing cultural practices (such as irrigation) at the 

application site.

•  The date and time the application

started and the time the application 

finished.
28 CHAPTER 2

•  Weather conditions at the time

of application—air stability, temperature, humidity, wind speed, 

and wind direction recorded in 

degrees using a compass. 

•  Any changes in weather conditions occurring during the 

application.

•  Names and amounts of all pesticides and adjuvants applied, and 

the dilution rate.

•  Application equipment configuration, including nozzle type, size, 

spacing, pressure, and orientation.

•  Application pattern and directions

in which you flew the swaths.

•  Application speed and height.

•  Precautions taken to protect sensitive areas.

•  Location of the mixing-loading

site.

•  Routes taken for ferrying between

the loading site and target area.

•  Names of ground crew members

and people present at the site 

during the application.

•  Observations made by you, the

ground crew, or others that may 

have had any influence on the 

operation.

Save all electronic files from an 

application, including flight data and 

the as-applied map files from the GPS

system. These files serve as documentation for much of the information 

included in your records.

planning for emergencies

A very important part of the application 

planning includes being prepared for any 

emergency that might occur during the 

operation. Having a written emergency 

response plan, and sharing and discussing this plan with the ground crew, 

helps everyone know how to respond 

and reduces the possibility of injury 

or death. Emergency planning must 

include providing ground crew members 

at the loading zone and satellite strips 

with emergency telephone numbers. 

Equip the aircraft and loading areas with 

first-aid kits and ensure the aircraft has a 

working and properly-labeled fire extinguisher. Have a complete spill cleanup 

kit at the loading area. Develop a plan 

of action for ground crew members to 

follow in case your aircraft is overdue at 

the loading site or home base.

Train everyone in emergency 

response by actually play acting on how 

to deal with different emergency situations. Practicing also helps to point out 

deficiencies in the emergency response 

plan so you and the ground crew can 

correct them. 

Emergency Information

Locate the nearest medical facility 

to the application site and provide each 

crewmember with instructions on 

how to get there. A good strategy is to 

discuss the type of operation and its 

hazards with staff of nearby medical 

facilities to prepare them in advance for 

possible pesticide emergencies. Train 

all members of the ground crew how 

to direct emergency responders to the 

application or mixing-loading site. Equip 

members of the application operation 

with cell phones or radios to call for 

emergency help or to arrange transport 

of an injured person to a medical facility. 

Provide them with telephone numbers 

of the local hospital, fire department, 

police or sheriff’s department, and 

local Flight Standards District Office 

(FSDO). These numbers may change 

when using different landing areas, so 

prepare lists for each specific location.

Flight Hazards

Whenever possible, have a ground 

crew member present at the application 

site who is able to communicate with you 

during the entire operation. This person 

can warn you of hazards and notify you 

of problems on the ground that require 

stopping or delaying the application. 

The ground crew member should communicate with anyone on the ground 
Operation and Application Safety 29

who might be at risk during the application, and take action to warn them or 

escort them from the area. Provide this 

ground crew member with a map that 

shows the hazards and sensitive areas 

within the application site and in surrounding areas.

Plans in Case of Aircraft 

Crash

Make emergency plans for catastrophic events such as aircraft engine or 

landing gear failure leading to a forced 

landing or crash. This requires training 

every member of the ground crew to 

respond immediately, act promptly, stay 

calm, and focus on helping you. Should 

a crash occur, switch off the aircraft’s 

batteries and shut off its fuel line. If you 

are uninjured yet unable to open the 

cockpit door, break open a window and 

exit the aircraft as quickly as possible. 

Instruct ground crew to get to the crash 

site immediately with a fire extinguisher 

and to communicate the exact location 

of the site to emergency responders and 

others by cell phone or radio.

Application Equipment 

Malfunction

Application equipment malfunction could include ruptured hoses 

or lines, a tank leak, pump failure, nozzle 

and check valve leaks, or electronic controller failure. Any of these problems 

risk contaminating areas outside of the 

target area and may require a load jettison before the aircraft can return to 

an airport for repairs. Prepare for this 

type of emergency by locating possible places to jettison the load or to set 

down the aircraft. Any route you take 

with an aircraft having a pesticide leak 

should be over areas not occupied by 

people or animals. To protect the public 

when experiencing any emergency of 

this type, FAA regulations permit you 

to deviate from required flight patterns 

and other restrictions.

Ground Crew Emergencies

Ground crew emergencies include

leaks and spills of concentrated pesticides or diluted spray materials as well as 

splashes or spills that contaminate one 

or more of the ground crew members. 

It could also be a fire involving 

pesticide materials. These serious 

problems require immediate action to 

protect people and the environment. 

Regulations require that pesticide labels 

be at the use site, which includes the 

area you are spraying, in addition to 

the mixing-loading site. There is an 

exemption to this requirement for aerial 

applications as long as you maintain 

radio contact with the ground crew and 

any flaggers. Labels serve as references 

for emergency personnel responding 

to accidents involving spills and they 

provide first-aid information in case of 

pesticide exposure.

The ground crew must first take 

steps to prevent any human exposure and 

then immediately control, contain, and 

clean up spills or leaks to prevent further 

contamination of the mixing-loading 

area. Preparations for a leak or spill 

emergency includes training and practicing cleanup procedures and having 

an adequately equipped spill cleanup kit 

at the mixing-loading site at all times. 

Train handlers performing the mixingloading jobs on proper ways to clean up a 

spill (see Appendix 4). Provide them with 

a cell phone or radio to summon help for 

major spills or in case of a pesticide fire 

or other emergency. Keep instruction

sheets at the mixing-loading site for 

cleaning up spills, dealing with pesticide 

fires, and situations requiring assistance 

from fire fighters or emergency medical 

technicians.

Train handlers how to follow the 

first-aid information on the pesticide 

label if someone involved in mixingloading activities gets exposed to a 

pesticide. Be sure there is sufficient 

clean water for emergency eye washing 

and decontamination of the entire 

body. Have soap and single use towels 

available at the mixing-loading site 

along with changes of clothing for each 

crew member.

Overspray, Drift, and 

Other Misapplication 

As the applicator, you assume 

responsibility for any pesticide misapplication. Overspray, off-target 

movement, and other types of misapplication may damage surrounding 
30 CHAPTER 2

crops, residential plantings, landscapes, 

and other property, as well as cause 

environmental contamination. These 

are all violations of pesticide labels as 

well as many state pesticide control laws. 

Train ground crews to be alert during 

an application and quickly communicate 

with you if they spot any potential for 

such problems. Considerable financial 

liability and legal consequences may 

result from any damage caused by misapplication. 

Spray or Dust Contacting 

Bystanders or Vehicles

It is illegal to apply any 

pesticide in a manner that exposes 

people, livestock, vehicles, and 

other objects to the spray or dust. 

Unfortunately, farm workers, joggers, 

trespassers, and others may not recognize the hazard of entering an area 

until an aircraft making an application 

flies over them. Weather patterns, 

especially wind direction, can also 

change rapidly, causing pesticide from 

the application to move off site and 

possibly onto workers or other people 

nearby. For example, you might plan 

and begin an application based on 

the wind blowing away from nearby 

areas where people are present. 

However, during the application the 

wind direction could change and 

blow towards these areas. Therefore, 

develop a plan that includes communication between you and the ground 

crew to delay or stop the application 

if anyone spots people nearby, and 

only make applications if no one is in 

adjacent areas where they might be 

subject to exposure. Inspect the application site and adjoining areas before 

beginning an application to confirm 

no one is around the site.

In the emergency plan, include 

instructions to follow if spray contacts bystanders. This should involve 

decontamination methods and procedures for obtaining medical care for 

exposure victims.

Operational problems can result from 

poor communications or sketchy information about jobs the ground crew 

performs. It is risky to assume that 

ground crew employees already possess 

all the vital information they need to 

carry out their jobs safely. Job delays, 

having to return for forgotten materials, 

treating the wrong fields, or spraying 

improper pesticide types, formulations, 

or concentrations are examples of mistakes that may occur when ground crew 

employees are operating with incomplete information.

Involve the supervisor and ground 

crew in:

•  Developing maps of all areas to be

treated and charting all hazards, 

adjacent crops, and environmental 

sensitive areas.

•  Scouting all new areas and keeping

maps up to date so you can identify 

new obstacles or changes in conditions promptly.

•  Developing a system for accepting

or transmitting information 

between you and the ground crew 

on work order changes in the field.

•  Filling out mix sheets and determining the order of mixing spray 

batches.

•  Ensuring that mixer/loaders are

trained in calculating tank batches, 

pesticide handling procedures, and 

the use and care of personal protective equipment. 

Provide the ground crew with 

essential site-specific job information 

and make sure they have a checklist 

outlining the steps to take to comply 

with applicable regulations and company 

policies. Develop and complete an upto-date Standard Operating Procedures 

(SOP) for ground crew members to 

use and make sure it is available at the 

loading site. This is especially useful 

when communication with you is 

impaired and ground crew members disagree or are uncertain about procedures 

such as mixing batches of pesticide spray.

communications
Operation and Application Safety 31

1. The type of first aid given to a pesticide 

exposure victim depends on the:

A. Type of exposure.

B. Age of the victim.

C. Training of the person administering first 

aid.

D. Work situation where the person received 

the exposure.

2. If a person shows signs of pesticide poisoning, 

he or she should:

A. Stop working for the day.

B. Receive immediate medical attention.

C. Be assigned to another job not involving 

pesticides.

D. Be scheduled for a blood test.

3. If a person spills liquid pesticide onto his or 

her arm, the amount of exposure and injury 

can often be reduced by:

A. Wiping arm with antibacterial wipes.

B. Wiping the liquid off the person’s arm.

C. Covering the exposed area with a damp 

cloth.

D. Washing the exposed area with soap and 

water.

4. During an application operation, pilots must 

wear the label-required personal protective 

equipment for pesticide handlers:

A. Only while making an aerial application.

B. Anytime they are in the aircraft cockpit.

C. While making nozzle adjustments.

D. Only when mixing and loading.

5. First-aid instructions to use for pesticide 

exposure is found on:

A. Pesticide labels.

B. OSHA’s Emergency Response website.

C. Supplemental labeling.

D. Manufacturer literature.

6. An up-to-date Standard Operating Procedures 

(SOP) document is useful to ground crew 

members especially when:

A. The communication channel with the pilot 

is lost.

B. The pilot begins applying the pesticide in a 

manner inconsistent with the work order.

C. Trying to determine the best time for 

applying the pesticide.

D. The pilot applies the pesticide to a site not 

listed on the label.

7. For protection of the surrounding community, 

a good reason for securing pesticide application aircraft and other equipment when not in 

use is to:

A. Prevent weather damage to the equipment.

B. Protect employees from pesticide exposure.

C. Prevent intruder access to the equipment.

D. Comply with regulatory agency mandates.

CHAPTER 2: Operation and Application Safety

 Review Questions
32 CHAPTER 2

8. At a minimum, the training that ground crews 

must receive as pesticide handlers is required 

to be performed:

A. At the beginning of each operation.

B. Annually, before performing handling 

activities.

C. Every two years, before performing 

handling activities.

D. Every five years, before performing 

handling activities.

9. Chances of pesticide exposure greatly 

increases if a pesticide handler fails to:

A. Read the Statement of Practical Treatment 

on the pesticide label.

B. Take frequent breaks during handling 

activities.

C. Drink adequate water during handling 

activities.

D. Wear the required personal protective 

equipment.

10. Good communication with the ground crew 

before and during an application operation 

may result in:

A. Greater chances of accidents.

B. Inability for the ground crew to perform their 

tasks properly.

C. Fewer job delays.

D. Improper spray mixes.

REVIEW QUESTION ANSWERS ON PAGE 97
Preventing Pesticide Drift 33

Preventing Pesticide Drift

Pesticides are essential tools in managing pests in a particular location, 

but confining the pesticide to the 

intended target during application is 

an important responsibility. Reducing 

drift and off-target pesticide movement 

is necessary when you make any type of 

pesticide application because, if not controlled, this off-target movement can 

contribute significantly to the pesticide 

load in the environment. However, you 

must take steps to control drift of the 

pesticide material away from the target 

area during an application.

Off-target movement of pesticides 

is the condition where pesticides or pesticide residues leave the application site 

at any time and in any manner other 

than during a pesticide application. 

Often the physical and chemical characteristics of the pesticide contribute to 

or reduce the chances that the material 

may move offsite after an application. 

For example, pesticides that break down 

quickly after you have applied them will 

be less likely to move off the application 

site than pesticides that are highly persistent in the environment.

Pesticides and pesticide residues 

can move off the application site in 

several ways after they are applied. 

These include:

•  Post-application volatilization into

the atmosphere of the pesticide 

that adhered to treated surfaces, 

the crop plants, the soil in between 

the plants, or bare ground—pesticides with high volatility are more 

likely move off the application site 

than pesticides with low volatility.

•  Leaching through the soil at the

application site and moving into 

surface or ground water after 

application—pesticides with low 

solubility in water will not leach as 

much as those that are very soluble 

in water.

This chapter will assist you to:

	 • Understand what off-target pesticide movement is and knowing the

difference between drift and off-target pesticide movement.

	 • Recognize the way droplet size contributes to drift or reduces drift

potential.

	 • Recognize the factors and conditions that contribute to drift and

off-target pesticide movement.

	 • Learn how to minimize drift and off-target pesticide movement.

CHAPTER 3

LEARNING OBJECTIVES
34 CHAPTER 3

•  Rainfall or irrigation water

washing residues off the application 

site into surface waters after application—pesticides that have a high 

absorption potential are less likely 

to wash off plant surfaces.

•  Blowing off the site attached to

soil particles or dead plant material 

after application.

•  Leaving the application site as

residues on harvested crops.

•  Being carried off the application site

on vehicles, equipment, animals, 

and people.

•  Being carried off the application site

as fine droplets in an inversion cloud.

The National Coalition on Drift 

Minimization (NCODM) defines spray 

drift to be “the movement of pesticide 

through the air at the time of pesticide 

application or soon thereafter from 

the target site to any non- or off-target 

site, excluding pesticide movements 

by erosion, migration, volatility, or 

windblown soil particles after application.” Pesticide drift includes pesticide 

droplets, vapors, or dust particles that 

move off the application site after leaving 

the dispersal system but before adhering 

to the intended treatment site during 

a pesticide application. This includes 

vapor or droplets that concentrate in an 

inversion layer during an application.

During any application, a certain 

percentage of the spray droplets will 

drift. If this drift is confined to the 

treatment site so that it is part of the 

pesticide application, there is generally 

little hazard to the surrounding areas

that are not part of the application. 

Pesticide drift, however, increases 

the hazard to people and other living

organisms outside of the treatment site. 

The following information pertains to 

recognizing the causes of pesticide drift

and ways to reduce this problem.

factors that contribute to drift

The spray droplets and the percentage 

of droplets within a certain size range

are the key factors affecting off-target 

drift. You can control some of these 

factors when making aerial applications.

The unit of measure for the 

diameter of a spray droplet is a micron 

(also referred to as a micrometer). The

mathematical symbol for a micron 

or micrometer is μ. One micron is 

1/25,000 or 0.00003937 of an inch. 

To illustrate the relative size of one

micron, a single sheet of paper is about 

100 microns thick.

The longer a spray droplet remains 

airborne or suspended in the air, the 

greater the chance it will drift from the 

application site. A small spray droplet is 

more susceptible to drift than a larger 

droplet because the small droplet is 

lighter and therefore remains airborne 

much longer. For example, while it 

takes approximately 4 minutes for a 

COMPARISON OF DROPLET FALL RATES

DROPLET DIAMETER 20

microns

100

microns

240

microns

400

microns

TIME TO FALL 10 FEET 4 minutes 11 seconds 5 seconds 2 seconds
Preventing Pesticide Drift 35

20-micron droplet to fall a vertical distance of 10 feet, it takes only 2 seconds 

for a 400-micron droplet to travel the 

same distance.

There is a rapid decrease in 

the drift potential of droplets larger 

than about 200 microns. Conversely, 

research has proven that droplets 

smaller than 200 microns are very 

prone to drift. People who study drift 

classify droplets that are 150 to 200 

microns or smaller as driftable fines. In 

wind speeds ranging from 1 to 9 mph, 

droplets that are 200 microns or larger 

have an insignificant drift potential. 

For example, the theoretical distance 

that spray droplets move laterally while 

falling from 10 feet above the ground 

in air moving at 3 mph would be only 

about 8 feet for 400-micron droplets. 

However, this distance increases to 

about 1,000 feet for 20-micron droplets. 

Higher velocity winds increase the 

drift potential of all droplets.

Droplets below 50 microns in 

diameter remain suspended in the air 

indefinitely or until they evaporate. 

Droplets of this size have no benefit

to a pest control program, other than 

certain vector control operations, 

because they are never likely to reach 

target surfaces. Avoid using nozzles or

nozzle orientations and configurations

that produce droplets in this size range

because there is no way to assure that 

these droplets will remain on or near 

the application site.

Classification of Droplet 

Size

All nozzles produce a range of

droplet sizes, known as the droplet-size 

spectrum. This means that even when 

you use a nozzle having a large orifice

that mainly produces large droplets, 

some percentage of the droplets in the 

spray are going to be small enough to 

be prone to drift.

A common classification method 

used to describe the droplet-size

spectrum produced by a nozzle is the

volume median diameter (VMD). This

means that half of the total spray volume 

of that nozzle consists of spray droplets

smaller than the VMD numerical

value, while the other half is larger 

than the VMD numerical value. For

instance, a nozzle with a VMD of 400

microns sprays out half its total volume 

in droplets having a diameter greater 

than 400 microns and the other half in 

droplets having a diameter smaller than 

400 microns. However, this does not 

20 microns

8 ft

LATERAL MOVEMENT OF DIFFERENT SIZE DROPLETS

50 microns

100 microns

150 microns

10 ft

400 microns

WIND SPEED = 3 MPH

22 ft 45 ft 178 ft 1056 ft

LESS

THAN 400 μ

GREATER

THAN 400 μ

Volume Median Diameter = 400 Microns
36 CHAPTER 3

tell you how much of the spray volume 

is made up of droplets that are smaller 

than 200 microns.

Another way of classifying the 

droplet sizes produced by a nozzle is to

identify the percentage of the total spray 

volume that contains droplets smaller 

or larger than a specific diameter, 

usually 200 microns. This directly 

addresses those droplets at risk for drift. 

For instance, a nozzle may produce

2 percent of its total spray volume in 

droplets smaller than 200 microns in 

diameter. This means that only a small 

portion of the droplets produced by this 

nozzle are at risk for drift. This type

of description, however, tells nothing 

about the size of the remaining droplets

produced, which is the information you 

need to determine the type of coverage 

you can expect.

The most useful way to describe the 

droplet sizes produced by a nozzle is to

use droplet-size categories based on the

entire droplet-size spectrum of a nozzle,

rather than just the VMD or a specific

size droplet by percentage of volume.

This spray-classification system is the 

American Society of Agricultural and 

Biological Engineers (ASABE) standard

S-572.1: Spray Nozzle Classification 

by Droplet Spectra. This classification 

system has eight categories: extra fine, 

very fine, fine, medium, coarse, very 

coarse, extra coarse, and ultra coarse 

(see chart on next page). Using these

categories, you can select a nozzle,

orifice size, and operating pressure

that produces the label-recommended 

droplet-size spectrum.

All pesticide labels will eventually 

contain nozzle specifications and/or the

required droplet-size spectrum. The

chart on page 37 shows the standard 

droplet size categories and color coding.

Consult the pesticide label for 

specific instructions when selecting 

nozzles. Using the droplet-size

spectrum categories, determine which 

nozzle to use to reduce drift and provide

adequate coverage in a particular 

application operation. By selecting the

appropriate category based on the type 

and use of a pesticide, you get acceptable 

results while keeping the risk of drift to 

a minimum.

Spray Mixture Physical 

Properties

Three key physical properties of a 

spray mixture have a significant effect 

on droplet size in aerial applications.

Dynamic Surface Tension

Surface tension is the force that 

keeps a droplet together. When the 

fluid that makes up the droplet contains adjuvants or other substances the 

normal surface tension changes, but it 

takes a certain amount of time for the 

molecules in the adjuvants to move to 

the surface of the droplets. Therefore, 

the surface tension of spray droplets can 

change after the droplets are formed, 

causing a larger droplet to split into 

smaller droplets.

Extensional Viscosity

When the pump forces spray 

liquid through a nozzle orifice, it

stretches to a certain point before 

breaking off to form a droplet. The 

amount of stretching or “stringiness” 

is the extensional viscosity. Pressure 

in the system, which regulates the 

ejection speed of the liquid, affects the 

extensional viscosity. Higher pressure 

lowers this viscosity, therefore producing smaller droplets.

SHEAR

VISCOSITY

EXTENSIONAL VISCOSITY

DYNAMIC SURFACE TENSION
Preventing Pesticide Drift 37

Shear Viscosity

Shear viscosity is a liquid’s resistance 

to flow. Some liquids are thicker and 

therefore resist flow or flow more slowly 

than less thick, or less viscous, liquids. 

Spray drift control adjuvants, when 

added to the spray mixture, may help 

reduce the number of driftable droplets 

under certain conditions. However, 

reports indicate that some types of drift 

control agents lose their effectiveness 

when circulated through a sprayer pump. 

Studies show that some materials sold 

as drift control adjuvants actually do 

not perform as such. Spray drift control 

adjuvants are a specific class of chemical 

adjuvants, so do not confuse these with 

other adjuvants such as surfactants, 

wetting agents, spreaders, and stickers. 

These other adjuvants, and formulations containing alcohol or certain water 

miscible solvents, tend to reduce the 

dynamic surface tension of spray droplets, 

resulting in smaller droplet sizes.

External Factors Affecting 

Droplet Size and Drift

Certain factors remain beyond 

your control. These external factors 

include weather such as humidity, rain, 

extremely high or low temperatures, 

wind, or conditions leading to an 

inversion layer. 

Effects of Evaporation on 

Droplet Size

Once exposed to the atmosphere, 

individual spray droplets will generally begin to evaporate. Evaporation

removes water or other carriers, making 

the spray droplet smaller than it was 

when it left the nozzle. As the droplet

becomes smaller, it becomes more prone 

to drift. Conditions that contribute to 

evaporation include:

• Air temperature–evaporation is more 

rapid as temperature increases.

Extra Fine

Very fine

Fine

Medium

Coarse

Very Coarse

Extra Coarse

Ultra Coarse

XF 

VF 

F 

M 

C 

VC 

XC 

UC 

PURPLE

RED

ORANGE

YELLOW

BLUE

GREEN

WHITE

BLACK

Droplet Spectrum 

Category Symbol Color Code 

This standard defines droplet spectrum categories

for the classification of spray nozzles relative to the

specified reference fan nozzle. The purpose of this

classification is to provide the nozzle user with droplet

size information primarily to indicate off-site spray drift

potential and secondarily for application efficacy.

Refer to product labels for specific guidelines on a

droplet spectra category required for a given application situation.

Nozzle manufacturers provide information necessary

to place nozzle types into a droplet spectrum category

based at least on orifice size and pressure. The color

code is an industry standard.

ASABE STANDARD S-572.1

Spray Droplet Spectrum Categories

EFFECTS OF EVAPORATION ON

DROPLET SIZE
38 CHAPTER 3

•  Humidity—evaporation is more 

rapid as humidity decreases.

•  Air movement—evaporation is more 

rapid as air movement increases.

•  Distance from discharge to the 

target—the further the droplet has 

to fall the more time is available for 

evaporation.

•  Spray carrier—water will evaporate 

faster than oil carriers.

The optimum time to make an 

aerial application when evaporation of 

spray droplets is a concern is during the 

coolest part of the day. Early morning is

usually ideal because it is generally more 

humid at this time and wind speeds 

are often low. However, temperature 

inversion conditions may be greater 

during early mornings. Avoid making 

applications during hot, dry periods of 

the day. Keep the application height 

between 8 and 12 feet from the target to 

shorten the distance that spray droplets 

must fall. To minimize the risk of drift

caused by evaporation, small droplet 

sprays require lower application heights.

Co-Distillation

Pesticides can also move offsite 

through a process called co-distillation. 

This phenomenon occurs when the pesticide contacts very hot surfaces, usually 

soil with no vegetation. Pesticides, even 

those that are not highly volatile, leave 

the soil surface with water molecules 

during rapid evaporation that occurs 

immediately after irrigation. Fog also 

is able to pick up pesticides from the 

application site and carry them offsite.

Effect of Wind and Thermals on 

Drift and Off-Target Movement

Air movement from wind or 

thermals is a major contributing factor 

to off-target pesticide drift. Wind 

carries lighter and smaller droplets 

away from the target site where they 

accumulate until they saturate a given 

volume of air with the pesticide. As 

winds become stronger, the air traps 

more and more larger droplets and may 

move them away from the target before 

they return to the ground.

Upward air movement caused by

thermals also entraps and moves small 

droplets, increasing the probability that 

they will drift away from the application 

site. Thermals occur as the ground 

heats up, usually in the afternoon, and 

especially after cool night temperatures. 

This causes air near the ground to rise, 

since warm air is lighter (molecules are

further apart) than cool air.

Temperature Inversions

Differing air temperatures in 

stratified layers of the atmosphere 

are responsible for the inversion phenomenon that can exacerbate the 

problem of off-target pesticide drift. 

Inversions occur when an upper layer of 

air is warmer than the air below it. This 

warm air cap may start at 20 to 100 or 

more feet above the ground and block 

the cooler air below it, preventing vertical air movement.

Over a wide area, it may be possible to identify the presence of an 

inversion condition by checking with 

the National Weather Service. In 

some areas, during certain times of 

the year, temperature inversions occur 

regularly. One method for detecting 

a temperature inversion in a localized

area is to observe a column of smoke 

rising into the air. Sometimes, dust 

from agricultural operations may 

serve the same purpose. If the rising 

smoke column or dust cloud flattens 

and begins moving sideways or collects in one area above the ground, an 

inversion condition probably exists.

Do not make applications during 

an inversion condition because 

the inversion layer traps fine spray 

WARM AIR

COOL AIR

0 ft

10 ft

20 ft

30 ft

Temperature inversion
Preventing Pesticide Drift 39

droplets and pesticide vapors. These 

become concentrated, similar to smoke 

particles in the smoke column. Rather 

than dispersing somewhat evenly 

throughout the atmosphere over a 

relatively large area, the pesticide often 

moves as a concentrated cloud away 

from the treatment site. Afterwards, 

the concentrated pesticide cloud will 

return to the ground and may cause 

problems for people, non-treated 

crops, and other living organisms.

An inversion condition can occur 

when the air is calm with very little 

air mixing. This condition makes it 

possible for the cloud of spray droplets 

or vapor to move slowly downwind. 

Temperature inversions generally begin 

before sunset and remain into early 

morning or near bodies of water.

Drift research shows that nozzles and

other spray components can produce 

large spray droplets that have less of 

a tendency to drift. However, when 

improperly used, wind shear effects on 

nozzles result in drift-prone smaller

droplets. Appropriate airspeed and 

proper nozzle orientation are the two

factors that reduce wind shear effects. 

You need to find a balance between the 

aircraft’s minimum airspeed needed for 

covering the desired acreage in a given 

period and the maximum airspeed 

before wind shear impacts the size of

spray droplets. 

In addition to selecting proper 

nozzles and finding the balance

between proper airspeed to minimize

atomization of large droplets, the other

challenge you face is to find a balance 

between drift reduction provided by 

large droplets and good coverage associated with smaller droplets. 

Research conducted by pesticide 

manufacturers, the pesticide application 

industry, universities, and state and 

federal regulatory agencies demonstrate that you can minimize off-target

pesticide drift during any application 

operation by: 

•  Selecting nozzle types with orifice

sizes that produce large droplets—

wider spray angles typically 

produce finer sprays.

•  Using a nozzle orientation straight

back in relation to the aircraft’s 

level flight line so that the discharged spray is least affected by 

wind shear across the nozzle face,

therefore maintaining the rated 

desired droplet size (some research

is showing that a slight angle of 

about 5 degrees allows the spray 

to be directed downward without 

affecting droplet size).

•  Confining boom length to no more

than 75 percent of the wingspan of 

a fixed-wing aircraft or the rotor 

diameter on rotary-wing aircraft, 

to reduce drift caused by wing tip 

and rotor vortices.

•  Increasing system pressure when

flying at faster speeds to reduce 

the amount of smaller droplets.

0 degrees—

largest droplets

TRAVEL DIRECTION

45 degrees—

smaller droplets

90 degrees—

smallest droplets

minimizing off-target drift
40 CHAPTER 3

•  Making sure the positive shut-off

and suck-back systems are working 

properly.

•  Accurately calibrating application

equipment, including using a 

system pressure that is appropriate 

to the airspeed of the aircraft for 

maintaining a droplet size that

results in optimal spray coverage.

•  Using spray drift control adjuvants

when appropriate to increase spray 

droplet size.

Spray droplets are normally finer 

at greater flight speeds, especially when 

using wide-angle fan nozzles or a nozzle

orientation that is not straight back in 

relation to the level flight of the aircraft. 

However, for applications using straight 

stream or narrow angle (20 to 40°) flat

fannozzlespointedbackward,increasing

the spray pressure can actually result in 

a coarser spray if the exit velocity from 

the nozzle becomes closer to the speed

of the aircraft. Doing this reduces the 

air shear effect.

Application Techniques

Some application techniques for 

reducing off-target pesticide drift 

during an aerial application include:

•  Leaving untreated buffer zones

one, two, or more swath passes 

wide within the treated site or 

field, along the downwind edges so 

that any pesticide that drifts will 

stay on the treated site; treat these 

buffer zones later, when the wind

direction reverses into the field.

•  Getting good field-end coverage on

initial spray runs; end passes made 

to fields that are bordered by trees 

or other obstacles usually means 

flying higher, which increases the 

chance of drift.

•  Flying at the optimum airspeed

that will, when combined with 

pump output pressure, help to 

maintain larger droplets.

•  Keepi ng application height

between 8 and 12 feet above the 

target crop.

•  Avoiding applications during

weather conditions that promote 

off-target drift, such as high winds 

or inversion conditions.

 Smoke Generators

You use smoke generators on the 

aircraft to visualize air movement at

the application site. You can also use it 

to identify inversion conditions below 

the application height. The smoke 

generator injects oil into the aircraft’s 

exhaust system, which burns to produce 

smoke. You control the oil injector with 

a switch inside the cockpit.

When you activate the smoke 

generator, you can watch the smoke 

movement to estimate the off-site 

movement potential for spray you are 

applying. Although of limited effectiveness, you can also use the smoke 

to locate the position of the previous 

pass to estimate where to begin the 

next pass. However, due to possible 

movement of the smoke in air currents, 

this method is less reliable for swath 

marking.

Smoke generators are a common 

part of the onboard equipment found 

on most agricultural aircraft. One 

reason for this is that GPS systems have

eliminated the need for human flaggers 

at the application site to position the 

aircraft for each swath. However, a 

flagger typically also provided you 

with information about wind speed 

and direction. Since off-target pesticide drift is a major concern during 

aerial applications, a smoke generator 

provides a better visual picture of wind 

direction and relative wind speed at the 

time of spray release. Using a smoke

generator before beginning the first 

pass of an application allows you to 

make immediate local wind condition 

evaluations without depending on 

someone on the ground.
Preventing Pesticide Drift 41

1. Managing off-target pesticide drift during an 

aerial application is:

A. The ground crew’s responsibility.

B. The property owner’s responsibility.

C. The pilot’s responsibility.

D. A requirement of a pilot’s FAA licensing.

2. Off-target pesticide drift is the offsite 

movement of the pesticide that occurs:

A. Any time after an application.

B. At the time of pesticide application or soon 

thereafter.

C. As residues on objects moving from the 

application site.

D. Several hours to several days after an 

application.

3. The color code for a nozzle that produces 

spray droplets in the extra fine category is:

A. Black.

B. Red.

C. Purple.

D. Orange.

4. Generally, the optimum time for making an 

aerial application of a liquid when droplet 

evaporation is a concern is:

A. Early morning.

B. Mid morning.

C. Early afternoon.

D. Late afternoon.

5. Which of the following factors has NO effect on 

off-target pesticide drift?

A. Nozzle orientation.

B. Spray pressure.

C. Constant 3 mph wind.

D. Physical properties of the spray mixture.

6. Wider-angle spray nozzles usually produce 

 droplets than narrower spray 

nozzles.

A. Coarser.

B. More uniform.

C. Less uniform.

D. Finer.

7. The most effective boom lengths for reducing 

the amount of drift are:

A. 90% of the wingspan or the rotor span.

B. 75% of the wingspan or the rotor span.

C. 65% of the wingspan or the rotor span.

D. 50% of the wingspan or the rotor span.

8. Aside from external factors, the most important factors affecting off-target drift are:

A. Physical properties of the spray mixture.

B. Extremely high or low temperatures.

C. The size of the spray droplets and the

percentage of droplets within a certain size

range.

D. Conditions leading to a temperature 

inversion layer.

CHAPTER 3: Preventing Pesticide Drift

 Review Questions
42 CHAPTER 3

9. Driftable fines are droplets in the size range of:

A. Larger than 500 microns.

B. 300 to 500 microns.

C. 200 to 300 microns.

D. 50 to 200 microns.

10. The droplet size at which spray drift becomes 

a concern is:

A. 50 microns and below.

B. 100 microns and below.

C. 200 microns and below.

D. 300 microns and below.

REVIEW QUESTION ANSWERS ON PAGE 97
Aerial Pesticide Dispersal Systems 43

Aerial Pesticide Dispersal Systems

Accurate metering and application of 

pesticides are the key purpose of all 

aircraft dispersal systems. Dispersal 

equipment has to deliver the labeled 

rate of a liquid or dry pesticide formulation uniformly and accurately.

Pesticide materials and the dispersal system add considerable weight, 

requiring aircraft that can safely lift, 

transport, and make applications 

when fully loaded. Fixed-wing aircraft 

used for pesticide application are fast, 

maneuverable, and carry heavier loads 

than rotary-wing craft. A limitation of 

a fixed-wing aircraft is the need for a 

designated landing area, which may not 

always be close to the application site. 

Rotary-wing aircraft used for pesticide 

application are more maneuverable 

but slower than fixed-wing aircraft, 

and can operate over a range of speeds 

and in almost any area since they do 

not require a runway for takeoff or 

landing. This allows ground crews to 

perform loading operations at or near 

the application site. 

This chapter will assist you to:

	 • Understand the desirable requirements of an aircraft pesticide

dispersal system for liquid and dry pesticide formulations.

	 • Become familiar with the components of an aircraft pesticide

dispersal system for liquid and dry pesticide formulations.

	 • Understand the importance of inspecting, servicing, and maintaining

dispersal systems.

	 • Become familiar with spray nozzles and how to correctly position

them on spray booms.

	 • Know how to test dispersal systems for appropriate spray patterns.

	 • Understand the features of, and how to change the settings on, dry

material spreaders.

CHAPTER 4

LEARNING OBJECTIVES

dispersal system requirements

The main function of a dispersal 

system is to allow you to apply an 

accurate and uniform amount of pesticide material over the application site 

as efficiently as possible. Liquid dispersal systems include a pump, a tank or 

hopper, hoses and/or metal lines, control 

valves with suck-back features, a pressure 
44 CHAPTER 4

gauge, filters, one or more booms, and 

nozzles. Pumps in these systems may 

be electric or hydraulic motor powered, 

wind-driven, or directly powered from 

the aircraft engine.

Equipment and 

Component Factors 

Consider several factors for dispersal equipment and components used 

for aerial application of pesticides. They 

must be durable. 

Corrosion Resistant

Many pesticide materials are corrosive, so only use corrosion resistant 

components in the dispersal system. 

Stainless steel, fiberglass, polyethylene, 

and polypropylene are non-corrosive, 

while steel, iron, and aluminum will 

corrode. In addition, acidic liquids may 

react with steel or iron to produce highly 

explosive hydrogen gas. Even though 

application components are corrosion 

resistant, the rest of the aircraft may not 

be, so regularly clean, inspect, maintain, 

and protect these parts.

Leak Proof

Make sure all components of the 

aircraft’s pesticide dispersal system can 

resist leaks during the rigors of takeoffs, 

landings, and flight. This includes tanks, 

pumps, agitators, bearings and seals, 

hoses, and hose fittings. The presence 

of pesticide residues on the belly of the 

aircraft could be an indicator of a leaking 

hose or connection somewhere in the 

system. Leaks endanger you and can 

damage parts of the aircraft. In addition, 

leaks can expose workers to pesticide 

materials, contaminate places and objects 

used by people, and render runways, 

hangars, and other areas unusable until 

decontaminated. Leaks may also cause 

damage to crops and other plantings 

outside of the treatment area.

Allow You to Make Accurate 

Volume Measurements

The dispersal equipment has to 

include a way to measure accurate 

volumes of pesticide materials in order 

for you to apply the correct amount to 

the treated area.

Able to Produce Uniform Flow 

Volumes

The dispersal system should 

provide a uniform flow of the pesticide 

through the nozzles for even distribution of liquid sprays over treatment 

areas. Systems that adjust the flow 

volume according to the application 

air speed (referred to as flow control) 

provide the greatest application volume 

uniformity, but can affect droplet size.

liquid dispersal system components

Important qualities of liquid dispersal 

systems include being dependable and 

durable, as well as being uncomplicated 

to service and repair. Descriptions of 

major dispersal system components 

follow.

Spray Pumps

The spray pump maintains the 

pressure in the system to ensure a 

uniform flow volume and proper atomization by the nozzles. The pump also 

may power the tank agitation system 

HYDRAULIC POWERED PUMP

Tom Hoffmann—Washington State Department of Agriculture M. J. Weaver—Virginia Tech

Fan Driven PUMP
Aerial Pesticide Dispersal Systems 45

that keeps the pesticide mixture in 

suspension. On fixed-wing aircraft, 

the most common power source for 

the pump is a fan mounted under the 

aircraft, below the tank. The aircraft’s 

propeller slipstream drives this fan. 

Some fan-driven pumps have variable 

pitch blades so you can change the 

pump speed, and thus output, for different application requirements. Ultra 

low volume (ULV) applications may 

require modifications to the pumping 

system to make it suitable for such low 

output.

Other types of power sources for 

aircraft spray pumps include the aircraft’s hydraulic system or an electric 

motor that drives the pump. 

Pumps need enough power and 

capacity to meet the system’s nozzle 

pressure, flow volume, and tank agitation requirements. The pump needs 

some extra capacity to make up for 

pressure loss due to friction in the lines 

and to operate nozzle anti-drip check 

valves. If you use a pump with too little 

capacity, you need to reduce the swath 

width to get adequate uniform coverage. 

However, this wastes time and fuel.

The centrifugal pumps commonly 

used on aircraft produce high volumes 

of spray material (up to 200 gallons per 

minute or more, depending on the size 

of the pump) at low pressure, usually 

ranging between 10 and 70 pounds per 

square inch (psi). Centrifugal pumps 

made from aluminum with bronze or 

steel internal parts are most common. 

Centrifugal pumps have a high range 

of applications, including spraying 

abrasive wettable powders and flowable 

formulations, because there is no close 

contact between moving parts. These 

pumps usually require operating speeds 

between 1,000 and 5,000 revolutions 

per minute (rpm).

Pesticide Tanks and 

Hoppers

Tanks and hoppers have to be corrosion resistant, and most tanks used in 

aircraft are fiberglass. Other materials 

used for tanks and hoppers include 

stainless steel, high-density polypropylene, or polyethylene. Stainless steel 

tanks or hoppers generally are more 

durable than plastic 

or fiberglass, but they 

are heavier, therefore 

adding additional 

weight to the aircraft. Overall, tanks 

and hoppers made of 

stainless steel require 

less maintenance 

and can withstand 

rougher handling 

than those made of 

plastic or fiberglass. 

A l t h o u g h m o s t 

popular because of 

less weight, a disadvantage of fiberglass 

is that it absorbs pesticide liquids if its 

surface is scratched or abraded, possibly contaminating future tank loads. 

However, scratches, small cracks, or 

punctures in fiberglass are easy to 

repair, while cracks or punctures in 

polypropylene and polyethylene tanks 

are difficult to fix.

Most tanks serve a dual use: they 

hold liquids for spraying and are hoppers 

for dry materials such as granular pesticides, fertilizers, and seeds. Tanks have 

top openings for filling, but it is easier 

to pump liquids through a pipe that has 

a quick coupling disconnect protruding 

through the side of the aircraft fuselage.

A gauge or visual level that shows 

the amount of material in the tank or 

hopper is necessary. This gauge has to 

be conveniently located so it is visible 

from the cockpit.

Interior baffles in tanks limit the 

sloshing of liquid during flight and 

dampen the effect of load shift on the 

aircraft’s stability. In case of an emergency when a load must be dumped in 

a matter of seconds, the tank needs a 

large valve or port at the bottom that 

you can open quickly. Tank vents are 

necessary and these should accommodate a large enough passage of air 

to prevent a vacuum that would slow or 

stop the normal flow of liquid through 

the nozzles or bottom port. Adequate 

ventilation of the tank also prevents the 

buildup of hazardous fumes, explosive 

gases, or dusts that could damage the 

aircraft and even endanger your life. 

On fixed-wing aircraft, mounting 

the tank or hopper in front of the 

cockpit and as close as possible to the 

M. J. Weaver—Virginia Tech

EXTERNAL SPRAY TANK WITH QUICK 

COUPLING DISCONNECT
46 CHAPTER 4

aircraft’s center of 

gravity reduces the 

effect on the aircraft’s 

t rim as t he tan k 

empties. Small rotarywing aircraft have 

either a pair of tanks, 

with one mounted 

on each side of the 

fuselage, or a single 

bel ly t a n k . W it h 

two tanks, a pipe or 

hose connects them 

and allows the pump 

to draw the spray 

mixture equally from 

both, keeping the 

aircraft balanced. Larger rotary-wing 

aircraft have a tank mounted on the 

inside. Tank or hopper size depends on 

the load capacity of the aircraft.

Tank Agitation

Many pesticide formulations, such 

as emulsifiable concentrates, wettable 

powders, and flowables, require agitation of the liquid mixture in the spray 

tank to maintain uniformity. Without 

agitation, the pesticide product may 

settle out from the water with which 

it is mixed. A common method of tank 

agitation is the recirculation of all or 

part of the pump output back into the 

tank (hydraulic agitation). A valve that 

diverts the flow from the spray boom 

back into the tank or hopper usually 

does this. Commonly, this boom valve 

provides a low negative pressure, or 

suck-back, to the boom when in the 

closed position. In another type of 

agitator, some external source powers 

a propeller mounted inside the tank 

(mechanical agitation). Mechanical 

agitation is not common on aircraft 

because the power required robs engine 

performance and adds extra weight.

Keep agitators running during 

ferrying to the worksite and during 

turnarounds. When the pump has sufficient capacity, some of the pump output 

recirculates back into the tank during 

spraying as well. Recirculated material 

enters near the bottom of the tank to 

prevent settling of the spray mixture.

If you apply dusts or powders, be 

aware that fine dry materials (60-mesh 

and above) in the aircraft hopper may 

also require mechanical agitation to 

prevent packing or caking on the top 

surface of the material during flight. 

This occurrence, known as bridging, 

creates voids under this top layer and 

leads to uneven flow of the dry material 

from the hopper.

Filters and Screens

Filters and screens protect the 

dispersal system from damage and keep 

nozzles from clogging. Clogged filters 

result in uneven applications. Screens 

require daily cleaning during spray 

operations and additional cleaning 

any time flow volume or change in 

system pressure indicates clogging. 

Filter screens range in size from 10 to 

200 mesh. A 10-mesh size denotes 10 

openings per inch, therefore the larger 

the mesh number the finer the screen.

Nozzle Screens

Generally, agricultural aircraft do 

not use nozzle screens because aerial 

applications call for larger nozzle 

orifice sizes than ground applications 

do. However, certain types of nozzles 

and nozzles with smaller orifice sizes 

require screens or slotted strainers. The 

nozzle orifice size and the type of liquid 

you are spraying also determine the size 

of the nozzle screen.

Line Screens

When using a centrifugal pump, 

place a line screen on the output side 

of the pump, in the line between the 

pump and the spray boom. For other 

types of pumps, locate the line screen 

on the suction side of the pump to help 

prevent damage from sand or other 

foreign particles, which can also cause 

nozzle check valves to leak.

Never store the dispersal system at 

the end of a season without thoroughly 

flushing out the booms. This reduces 

the likelihood of material accumulating on the inside surfaces of booms 

downstream from the line screen. This 

material can flake off later and clog 

nozzles or nozzle screens.

Pipes, Hoses, and Fittings

Main piping and fittings should be 

of a large diameter (up to 3 inches) to 

California Agricultural Aircraft Association
Aerial Pesticide Dispersal Systems 47

be able to apply high volumes of liquids. 

Smaller diameter pipes and fittings 

(approximately 1 to 1-1⁄2 inch) work for 

low-volume applications. Smaller piping 

is compatible with rotary-wing aircraft 

because their slower speed makes it 

possible to use lower flow volumes. 

Whatever the size, piping must be able 

to handle the maximum pump volume.

Hoses used in the dispersal system 

need to be large enough to carry the 

desired flow and must resist corrosion. 

Hoses are less likely to blow off if ends 

of the connecting tubes are beaded or 

flared. Using double clamps on hose 

connections also helps to keep them 

secure. Position hoses in such a way 

as to avoid sharp bends. Replace hoses 

if they swell, develop surface cracks, 

or otherwise show wear. Sometimes, 

hoses may not show external signs of 

wear or fatigue but they become brittle 

and hard after extended exposure to 

sunlight, high temperatures, vibration, 

and the various pesticides and other 

chemicals used in the system. Even 

when they look serviceable, hoses used 

beyond their life expectancy may fail 

without warning. Therefore, regularly 

replace hoses even if they look intact 

and free of defects or wear. 

A positive shut-off valve, installed 

in the hose or line that delivers spray 

material to the nozzles, eliminates 

dripping when you shut off the spray. 

The most effective positive shut-off 

valve is one that incorporates a suckback feature so that the pump applies a 

slight negative pressure to the liquid in 

the boom. The negative pressure aids 

the nozzle check valves in preventing 

any dripping. The system pressure 

gauge will register this slight negative 

pressure. If nozzles are not equipped 

with check valves, you may need to 

increase the negative pressure. Keep the 

negative pressure low enough so that it 

does not remove all the liquid from the 

spray boom, otherwise there will be too 

long of a delay as the boom refills when 

starting a new spray pass.

Spray Booms

The spray boom is the structure 

that supports nozzles along the 

wingspan or rotor span of the aircraft 

and usually carries liquid spray to 

the nozzles. It may be round, airfoil 

shaped, or streamlined. Streamlined 

booms create the least amount of turbulence, followed by airfoil booms and 

then round booms. To place nozzles in 

cleaner airflow on fixed wing aircraft, 

position the booms behind and below 

the trailing edge of the wings. For some 

configurations, use drop pipes from 

the boom to keep nozzles in clean air. 

Research shows that this lower position 

is likely to give a better deposition 

pattern. Securely attach spray booms to 

the aircraft to prevent bouncing. Make 

sure booms are durable enough to 

Tom Hoffmann—Washington State Department of Agriculture
48 CHAPTER 4

handle the output pressure of the pump. 

Some booms have separate right and left 

sections. Using a control valve, you can 

direct spray to either or both of these 

sections, making it easier to regulate 

spray placement in sensitive areas.

Operators of rotary-wing aircraft 

sometimes use special boom and nozzle 

combinations because of their ability to 

produce large, uniformly sized droplets 

at slower speeds. Operators use this 

type of boom most often for applying 

herbicides to rights-of-ways. Droplets 

form as the spray exits multiple 

needlelike nozzle tubes on the boom. 

The airstream pulls droplets into the 

air behind the boom.

Ef fect ive spray booms are 

approximately 75 percent as long as 

the wingspan for fixed-wing aircraft 

or the diameter of the main rotor blade 

of rotary-wing aircraft. If booms are 

longer than this, wing tip or main rotor 

vortices capture a large amount of the 

output from nozzles at the boom tips, 

causing distortions in the spray pattern 

and contributing to drift.

Position the boom and nozzles so 

that the spray will not strike any part of 

the aircraft or boom attachments. If the 

spray does strike structural parts of the 

aircraft, it will likely:

•  Collect and fall off in large drops.

•  Distort the spray pattern.

•  Waste material.

•  Corrode aircraft surfaces.

Having removable caps on the 

ends of a boom is useful for periodic 

flushing of sediment buildup inside the 

boom. However, a boom with end caps 

prevents positioning nozzles at or near 

the boom ends. Trapped pressurized 

air in this space between the boom 

ends and the outermost nozzles causes 

the spray to continue flowing for a 

short while even after you close the 

spray valve. To eliminate this problem, 

install air bleed lines to each end of the 

boom. Attach the other ends of these 

bleed lines to one of the nozzles near 

the ends of the boom, making sure 

these nozzles only receive spray fluid 

from the bleed lines. 

Flow Meters, Valves, and 

Pressure Gauges

The spraying system should 

include the following components to 

improve application ability. 

Flow Meters

An accurate flow meter monitors 

the discharge volume of liquid from 

the pump through the nozzles. The 

flow meter alerts you to changes in 

the spraying system such as clogged 

nozzles, leaks, and pump malfunction.

Valves

Valves in the system start, stop, 

prevent dripping, and direct and regulate the flow of the liquid. Some valves 

have control levers that you manually 

move to turn on or shut off the spray. 

M. J. Weaver—Virginia Tech

HELICOPTER SPRAY BOOM
Aerial Pesticide Dispersal Systems 49

Check valves are spring loaded and 

have a diaphragm, a ball, or needle and 

seat that starts or stops the liquid flow 

depending on whether the pressure in 

the system exceeds a preset minimum 

pressure. Electronic flow volume controllers employ motorized ball valves to 

regulate the amount of flow.

Inspect valves in the dispersal 

system frequently to confirm they are 

working correctly and are not leaking. 

Sediments or debris in the plumbing of 

the system may prevent some valves from 

shutting off completely or may restrict 

the flow of liquid passing through them. 

Make sure all nozzle check valves have 

the same size outlet diameter to provide 

uniform flow volumes along the length 

of the boom.

Pressure Gauges

Use a pressure gauge as another 

tool to monitor the spraying system. 

A pressure gauge helps you determine 

the correct pump speed or spray valve 

opening in order to achieve the proper 

nozzle output, droplet size, and spray 

pattern. You can use the pressure 

gauge to monitor and maintain system 

pressure during application should the 

electronic flow control system in the 

aircraft stop working. A pressure change 

in the system during spraying indicates 

potential problems. For instance, clogged 

nozzles or filter screens could increase 

pressure. A drop in pressure might 

indicate a broken nozzle, a disconnected 

line, another type of leak, or pump 

malfunction. When a pressure change 

occurs, inspect the system to determine 

the cause and make necessary repairs. 

To assure precise readings of pressure at 

the nozzles, connect the pressure gauge 

sensor line to the spray boom.

The pressure gauge in the aircraft 

needs periodic checking. When connected to the same pressure source, 

compare readings from the aircraft’s 

gauge to another gauge known to be 

accurate.

Nozzles

Nozzles provide the primary 

means of controlling three factors that 

affect any application and possible offtarget movement of the pesticide: the 

application volume, droplet size, and 

spray pattern. It is important for nozzles 

to operate within the range of pressures 

and flow volumes prescribed by their 

manufacturers. Therefore, be sure that 

the spraying system is compatible with 

the specified pressure and flow volume 

ranges for the nozzles you use and the 

aircraft’s speed. Manufacturers produce 

many types of nozzles for various liquid 

pesticide application situations.

The application volume influences 

the type of nozzle used in an aerial 

application. Aerial application volumes 

fall into three categories:

•  Conventional (5 to 15 or more

gallons per acre).

•  Low volume (LV) (0.5 to 5 gallons

per acre).

•  Ultra low volume (ULV) (less than

0.5 gallons per acre).

Traditionally, amounts less than 

8 gallons per acre were the norm for 

conventional volume aerial applications. 

Pilots made these types of applications 

with cone pattern nozzles. However, 

aerial spray drift studies indicate that 

spray output from cone pattern nozzles 

are likely to emit drift-prone droplets 

unless configured to produce coarser 

droplets. Many pilots now make conventional applications using straight 

stream nozzles, variable orifice flood 

nozzles, or flat fan nozzles.

Application volumes in the low 

volume (LV) range are often suitable 

M. J. Weaver—Virginia Tech

BOOM-MOUNTED PRESSURE GAUGE
50 CHAPTER 4

for certain situations, such as applying 

particular fungicides. You may use flat 

fan or variable orifice flood nozzles set 

to a suitable deflection angle, based on 

orifice size, pressure, and aircraft speed, 

for LV applications. Drift studies show 

that properly installed straight-stream 

or variable orifice flood nozzles reduce 

the amount of small droplets that are 

prone to drift.

When using vegetable oil carriers, 

or when you apply concentrates in forest 

or public health pest control, such as 

mosquito abatement spraying, ULV 

application volumes may be around one 

to a few ounces per acre. Rotary atomizers work well for ULV applications as 

well as LV applications.

Straight Stream Nozzles

Straight stream nozzles oriented 

straight back often produce the largest 

droplets and the lowest drift compared 

to other nozzle types. These nozzles 

provide a way to produce large droplets 

at higher airspeeds when you match 

the flow volume of the stream from 

the nozzle with the airspeed. However, 

at very high speeds the large droplets 

produced by straight stream nozzles can 

shatter and create driftable fines.

Fan-Pattern Nozzles

 Spray drift studies indicate that 

nozzles that emit fan-shaped spray patterns typically produce fewer small, 

drift-prone spray droplets than do conepattern nozzles. 

Flat fan and even flat fan nozzle tips 

produce flat, fan-shaped spray patterns. 

Flat fan patterns have the highest deposition in the center of the pattern and 

deposition tapers off towards the edges. 

Even flat fan nozzle 

patterns are uniform 

across the whole width 

of the nozzle pattern. 

The exact angle of the 

fan-shaped pattern 

produced by these 

nozzle tips depends 

on nozzle design, 

spray pressure, and 

characteristics of the 

pesticide spray mix. 

Nozzle tips designed to produce fanshaped patterns have angles of 25, 40, 65, 

80, or 110 degrees. In general, fan nozzle 

tips that produce wide angles generate 

more drift-prone spray droplets. For 

this reason, fan nozzle tips designed to 

emit no more than an 80-degree spray 

pattern are better suited for aerial spray 

applications. Typically, 40-degree flat 

fans are recommended for the higher 

speeds associated with fixed winged 

aircraft and 80 degree flat fans are recommended for slower speeds associated 

with rotary wing aircraft. Compared to 

standard flat fan nozzles, even flat fan 

nozzles have little effect on the spray 

distribution applied by an aircraft. The 

more critical consideration when using 

flat fan nozzles on an aerial boom is 

that the nozzle tip produces a narrow 

spray angle.

Variable Flow Rate Flat Fan Nozzles

Typically, nozzle orifice sizes 

are fixed and the only way to increase 

or decrease nozzle flow volume and 

maintain a desired spray droplet size 

range at a certain spray pressure is to 

change the size of the nozzle orifice. 

With standard nozzles, slightly 

increasing or decreasing the spray 

pressure allows minor adjustments in 

nozzle flow volume, but this adversely 

affects the optimum spray pattern. 

Variable flow rate nozzles overcome 

this problem because the nozzle orifice 

size is flexible and enlarges or gets 

smaller as the system pressure increases 

or decreases. This maintains greater 

integrity of the droplet size spectrum 

and spray pattern as system pressure 

changes. The advantages of variable 

flow rate nozzles include:

•  The ability to change application

volume on the fly by increasing or 

decreasing system pressure instead 

of replacing nozzle orifices.

•  Better spray droplet uniformity

that is less affected by system 

pressure changes.

•  A more uniform application

volume and spray pattern even 

when application airspeed varies.

Variable Orifice Flood Nozzles

A variable orifice flood nozzle disperses liquid in a flood type wide-angle 

FLAT FAN

NOZZLE

EVEN FAN

NOZZLE
Aerial Pesticide Dispersal Systems 51

flat fan pattern or a straight stream. 

The nozzle body has two manual 

adjustments, one for orifice size and 

the other for deflection angle. Four 

orifices can be selected, plus an “off” 

position. The orifice size and pressure 

determine the nozzle flow volume. 

Spray from the selected orifice hits an 

adjustable deflector that you adjust to 

produce fine, medium, or coarse spray 

droplets. There are two common types 

of variable orifice flood nozzles. One 

has deflection angles of 30, 55, and 90 

degrees and the other has a straight 

stream setting and deflection angles of 

5 and 30 degrees. Slower aircraft typically require larger deflection angles 

than faster aircraft.

Rotary Atomizers

A rotary atomizer consists of 

a screen mesh cylinder that rotates 

around the nozzle orifice. Its own fan or 

an electric or hydraulic motor powers 

this rotating cylinder. The higher airspeed of fixed-wing aircraft favors the 

use of fan-driven rotary atomizers. 

Most fan-drive units have adjustable fan 

blade pitch so you can 

achieve the optimum 

c y l i nder r ot at ion 

relative to the aircraft’s 

speed. The slower 

speeds of rotary-wing 

aircraft require motor 

driven cylinders.

Spray droplets that 

emerge from the screen 

mesh cylinder are 

relatively uniform in 

size. Rotary atomizer 

nozzles deliver a wide 

range of application 

volumes. Because they have relatively

large metering orifices, their nozzles 

do not clog as easily as conventional 

nozzles when applying low-volume 

sprays containing a high concentration 

of chemicals in suspension. Uniformity 

also depends on droplet size and nozzle 

spacing. The number of nozzles you 

need is based on how wide a swath 

you intend to cover. Typically, a single 

rotary atomizer can generate a swath of 

10 to 15 feet.

Hollow-Cone Pattern Nozzles

Hollow-cone pattern nozzles 

include the disc-core type and the 

whirl-chamber type. Recent spray drift 

research indicates that using hollowcone nozzles on an aerial spray boom 

yields a disproportionate amount of very 

fine, drift-prone droplets. Because cone

nozzles emit spray in a conical pattern, 

the effect of wind shear is greater than 

its effect on straight stream or flat fan 

spray nozzles.

The orifice of a hollow-cone 

nozzle is located in a disc that fits into 

the nozzle body. Discs are available in 

various orifice sizes to accommodate 

application needs. Located behind the 

disc is a core, or spinner plate, that 

puts a high rotational spin on the liquid 

passing through the orifice. The size of 

the disc-core combination determines 

the gallons per minute (gpm) rating of 

the nozzle at a given pressure.

A whirl chamber nozzle consists 

of a specialized nozzle body and nozzle 

Glenn Martin—Gettysburg, PA cap. When liquid enters the nozzle 

VARIABLE ORIFICE FLOOD NOZZLE

Glenn Martin—Gettysburg, PA
52 CHAPTER 4

body, the interior structure causes the 

liquid to whirl rapidly before exiting 

as a cone-shaped spray pattern. Whirl 

chamber nozzles are relatively free 

from clogging problems.

Nozzle Anti-Drip Devices

Equip all the nozzles on the spray 

boom with check valves to prevent 

dripping when you shut the spray 

off. These valves have spring-loaded 

diaphragms, needles, or steel balls 

that stop the nozzle flow when spray 

pressure drops below a certain preset 

amount, usually about 7 psi. Use antidrip check valves in combination with 

shut-off valves that have the suck-back 

feature. In systems where suck-back is 

unavailable, use a stronger spring so 

the nozzles seal shut when pressure 

drops to about 15 psi. Never switch on 

and off an electric motor driven pump 

in a rotary-wing aircraft to start or 

stop spraying. Using the boom valve 

to start and stop the spray and leaving 

the pump running allows the suckback feature to work properly and 

provides hydraulic agitation for the 

spray tank.

Inspect and frequently clean check 

valves to assure they work properly and 

are not leaking. Replace diaphragms 

when they show wear. You can flush 

needle and seat types of anti-drip check 

valves without disassembling the nozzle 

by pulling on the needle, which typically clears the valve of debris and stops 

the leak.

Electronic equipment such as global 

positioning systems, flow volume 

controllers, and mapping systems are 

important components of aircraft 

dispersal systems. This equipment 

increases precision application, reduces 

error and drift, and prevents waste of 

pesticide materials. These systems also 

provide permanent records of various 

aspects of the application for site 

mapping, customer billing, and environmental and regulatory reporting.

GPS Systems

Operators choose differential 

global positioning systems (DGPS) for 

their aircraft because they provide the 

high degree of precision needed for 

aerial application. The amount and kind 

of navigational information available 

for aircraft-mounted DGPS equipment 

depends on the features incorporated 

into the systems. As with other navigational devices, an FAA-certified aircraft 

maintenance technician must install, 

test, and repair DGPS equipment 

and components. See Appendix 5 for 

descriptions of types of global positioning systems and how they operate 

and are managed.

Before purchasing mobile DGPS

hardware and software for an appliHOLLOW CONE SOLID CONE

SPRING LOADED

DIAPHRAGM

NOZZLE FILTER

NOZZLE ORIFICE

electronics
Aerial Pesticide Dispersal Systems 53

cation aircraft, find out if the equipment 

processes signals for the type of DGPS 

service that is available in the area where 

the aircraft operates. In addition, learn 

what kinds of DGPS peripheral devices, 

such as light bars and flow controllers, 

the equipment accommodates.

An aircraft fitted with basic DGPS 

components provides you with the 

ability to perform DGPS-aided precision aerial swathing. A basic DGPS 

includes a:

•  DGPS mobile receiver.

•  GPS antenna.

•  Light bar.

•  Computer processor (CPU )—in

some units, the CPU and light bar 

are combined into one unit.

Using the GPS Light Bar

The GPS light bar is a linear array 

of light emitting diodes (LEDs) that 

produce a visual representation of the 

position of the aircraft in relation to the 

swath you are spraying. It allows you 

to easily visualize off-track errors and 

quickly make flight path corrections.

The onboard DGPS receiver continuously sends about 5 updated signals 

per second to the light bar. These signals 

activate specific LEDs, with the center 

of the light bar indicating the aircraft 

is lined up with the swath centerline. 

The other LEDs on the left and right of 

center represent a certain distance away 

from the swath centerline. This distance 

is usually 2 feet per LED, but can be set 

to as little as 6 inches per LED.

After completing a pass, advance 

the GPS setting to the next swath. 

When the aircraft is exactly over the 

centerline of that swath, the center-most 

LEDs of the light bar illuminate. If the 

path of the aircraft shifts to the left of 

the swath centerline, the illuminated 

sector of the light bar shifts towards the 

right. You correct the flight course by 

steering toward the illuminated LEDs. 

You restore the correct flight path when 

only the center most LEDs glow.

Once you line up the aircraft with 

the next swath centerline, use traditional landmark navigation to begin and 

perform the spray pass by selecting a 

distant visual object and flying toward it. 

Occasionally check the light bar during 

the spray pass to fine-tune your course.

Computers

The advantages of DGPS computer 

systems include mapping, waypoint 

navigation, and spray operation record 

keeping. The computer provides 

options for you to select a desired 

application pattern, such as racetrack. 

The computer then uses the GPS positioning data to continuously calculate 

and display the aircraft’s location with 

respect to the target site and application 

pattern. This eliminates the need for 

flagging or marking devices or human 

flaggers.

The computer system records the 

precise in-field location of each spray 

swath. For jobs requiring multiple spray 

loads, its mapping system guides you to 

where to begin applying the next load. 

Throughout the spray operation, the 

computer system collects data and constructs records.

Flow Volume Controllers

Manufacturers of DGPS computer systems offer software programs 

and computer hardware interfaces that 

provide precision spray boom operations. The aircraft DGPS computer 

combines continuously updated ground 

speed data with the spray swath width 

and sends correction signals to the 

flow volume controller. The controller 

regulates boom output by increasing or 

decreasing pressure and/or flow volume 

so that it maintains a preset application 

M. J. Weaver—Virginia Tech

GPS INSTALLATION
54 CHAPTER 4

volume per acre. More sophisticated 

units even control output on individual nozzles. Flow volume controller 

systems include means for measuring, 

computing, and recording:

•  Total liquid volume.

•  Liquid pressure.

•  Liquid flow volume.

•  Total spray time.

•  Relative humidity.

With this equipment, you can 

deliver the spray uniformly for the 

duration of the job in progress even 

when travel speed of the aircraft varies. 

You use feedback data from the flow 

volume controller to construct an 

on-site record of the output performance of the spray boom.

Mapping Systems

Producing maps of the targeted area 

is one of the features of the global positioning systems in many aircraft. These 

systems enable you to define boundaries, 

mark hazards, and produce as-applied 

maps that document your work. These 

maps are useful references for future 

applications. In addition, during an 

application, the on-screen map in the 

aircraft shows you where you turned 

the spray on and off. This gives you the 

accuracy to separate an area of the same 

field and fly it in a different direction to 

help you protect sensitive areas.

positioning booms and nozzles

Improper positioning of nozzles along 

the spray boom negates the advantages 

derived from pilot skill, advanced 

electronics, other application aids, and 

modern nozzle engineering and manufacturing technology. Determining 

the proper position for each spray 

nozzle helps achieve uniform spray 

deposition. Be sure nozzles are in the

aircraft’s laminar airflow where there 

is undisturbed air. Adjust the spacing 

of the nozzles along the boom to compensate for uneven spray deposition 

caused by air movement over aircraft 

surfaces. After positioning the nozzles 

according to accepted application 

industry standards, evaluate the setup 

by conducting pattern testing of 

the dispersal system. Do this before 

making any pesticide applications. 

Nozzle Adjustments

There are several factors to consider 

when adjusting nozzle positions.

Prop Wash Displacement

On fixed-wing aircraft, propeller 

rotation produces a spiral slipstream 

about the fuselage. This spiral slipstream 

moves spray particles from right to left 

under the aircraft. The result is a reduced 

application volume under the right wing 

and a higher application volume under 

the left wing. This problem is most 

evident on aircraft fitted with spray 

booms that have a symmetrical nozzle 

arrangement. The conventional correction for prop wash displacement is 

to add nozzles to the right side of the 

boom and remove noz-zles from the left 

side of the boom. You usually determine 

the correct number and location of the 

nozzles by trial and error, preferably 

PROP WASH DISPLACEMENT 

PROP WASH OVERCOMPENSATION 

WING TIP VORTEX 
Aerial Pesticide Dispersal Systems 55

while conducting pattern testing, not 

during pesticide application. Generally, 

the nozzles that need alteration are 

those positioned within 3 to 6 feet of the 

fuselage.

Prop Wash Overcompensation

The emphasis on spray pattern 

distortion due to prop wash has 

prompted some pilots to overcompensate for propeller-induced effects. 

You can often correct a pronounced 

spray peak developing on the left of the 

fuselage by turning off one or more 

nozzles mounted within 3 to 6 feet of 

the right side of the fuselage. Conduct 

pattern testing to assure you have not 

overcompensated.

Wing Tip and Rotor Vortex

Wing tip and rotor vortexes 

usually produce spray patterns with 

high peaks at its edges. This pattern 

can occur on either fixed- or rotarywing aircraft. The vortex captures 

and propels upward the spray emitted 

from the outermost nozzles on booms 

that extend to the full wing or rotor 

span. Spray droplets so captured do 

not contribute to the effective swath 

width, but are a significant source 

of spray drift. In almost every case, 

you can overcome a wing tip or rotor 

vortex induced spray pattern problem 

by keeping the spray boom length at 

75 percent of the wingspan for fixedwing aircraft or the rotor diameter of 

rotary-wing aircraft.

Rotor Distortion

Rotary-wing aircraft may display a 

spray pattern having a low application 

volume in the middle of the swath and 

heavier patterns at each end of the spray 

boom. Normally, you can correct this 

by adding nozzles under the aircraft 

between the skids.

Pattern Testing a Spray 

Boom

When evaluating the spray pattern 

and determining the effective swath 

of an aircraft, the application height, 

power setting, spray pressure, and 

nozzle location should duplicate field 

conditions. The best time for spray 

pattern testing is early in the morning 

before the sun heats the ground and 

causes thermal turbulence or convective 

instability. During testing, fly the aircraft directly into the wind. Conduct 

pattern test flights only when ambient 

wind speed is less than 10 mph.

One method for spray pattern 

testing consists of a detector (fluorometer) that reads the intensity of 

fluorescent dye deposited onto a string 

or tape positioned across a test site. A 

computer converts the fluorescence 

to data points and displays these in a 

graphical spray pattern representation. 

Dale Thomas—Gooding, ID
56 CHAPTER 4

Use this graph to assess nozzle positioning along the boom, determine 

spray deposition uniformity, and 

measure the effective swath width. You 

need to know the effective swath width 

to program a DGPS guidance system. 

If computerized pattern testing 

equipment is not available, you can 

determine the spray pattern by other 

means. The Course Layout figure (next 

page) depicts a suitable test layout for 

spray pattern evaluation. Determine the 

wind direction and place several flags, 

visible to you from the aircraft, about 

100 feet apart along the centerline 

of the direction of travel. Staple and 

sequentially number squares of water 

sensitive paper to small blocks of wood 

along an 80- to 100-foot line that runs 

perpendicular to the line of travel. You 

can substitute plain white cards for the 

water sensitive paper if you add dye to 

the spray tank to visualize the droplets.

When flying a spray pattern test, 

make sure that the nozzle tips, filter 

screens, and check valves are clean. Put 

about 30 gallons of water into the spray 

tank. Before takeoff, operate the pump

and briefly engage the boom to check 

for leaks.

After takeoff, purge the boom and 

make sure that water from the system 

reaches the end nozzles. Align the aircraft with the centerline flags on a spray 

run that duplicates an actual field application. Operate the boom for at least 

100 yards both before and after passing 

over the line of water sensitive paper 

or cards. To minimize control surface 

induced air disturbance, maintain 

straight and level flight during spray 

boom operation—this will help assure

a representative pattern. After the pass, 

have a ground crew member collect the 

sprayed cards in the order the ground 

crew laid them out. Put new cards on 

the wood blocks and repeat the test to 

make sure the run was representative of 

typical spray deposition.

Visual evaluation of treated cards 

reveals common problems with spray 

uniformity and swath width. Especially 

look for:

•  A region of light spray droplet

density in the vicinity of the flight 

centerline.

•  Uneven spray droplet densities

toward the wing tips, indicating 

prop or rotor distortion (see previous section).

•  Light spray droplet density corresponding to boom hangars or 

other structures that interrupt 

airflow.

Correct uneven patterns by repositioning nozzles on the spray boom. 

Conduct a new pattern test to verify 

that you have improved the pattern.

With a proper nozzle setup, you 

will notice that the number of spray 

droplets per card is reasonably constant for some distance on each side 

of the centerline path and then they 

gradually diminish until no spray is 

California Agricultural Aircraft Association

PATTERN TESTING
Aerial Pesticide Dispersal Systems 57

evident. The typical pattern forms a 

trapezoidal shape. The effective swath 

is the distance between the midpoints 

on the sloping ends of the pattern. 

Each midpoint corresponds to a spray 

deposition that is approximately onehalf the average amount of spray 

deposited in the more uniform portion 

of the spray pattern. In an actual application, this midpoint is the border 

between adjacent swaths.

Spraying System 

Operating Pressure 

Drift reduction requires directing 

nozzles straight back and setting the 

spraying system operating pressure to 

match the speed of the aircraft with the 

exit speed of the pesticide liquid from 

the nozzles. A pressure of 40 to 60 psi 

may produce larger droplets due to less 

wind shear and minimizes the production of droplet sizes prone to drift. 

Drift prone droplets are those that are 

smaller than 200 microns in diameter. 

When it is necessary to increase 

the output volume of the nozzles, 

you can make very small changes by 

increasing or decreasing the system 

operating pressure, often by changing 

the pump speed. Electronic spray 

volume controllers increase or decrease 

system pressure to change the output 

volume of the system when there are 

slight changes in the aircraft’s speed. 

This produces an application that is 

more even than if the pressure remains 

constant as the aircraft’s speed varies. 

However, this adjustment has limitations because, in order to double the 

spray output, you must quadruple the 

spray pressure. This will have a major 

impact on droplet size. In most cases, 

the best way to make significant changes 

in boom output volume is by changing 

nozzle tip size, nozzle orifice size, or by 

changing the number of nozzles in use. 

Typically, you should change the spray 

system pressure only to make minor 

changes (alterations of 10 percent or 

less) in boom output.

COURSE LAYOUT FOR PATTERN TESTING

Center line

100 Sampling

width Spaced on 

2 centers 

Spaced on 

5 centers 

Wind

40

Spaced on 

5 centers 

20

DRY MATERIAL SPREADERS

On fixed-wing aircraft, ram-air 

spreaders disperse dry formulations, 

such as granules or pellets. You would 

use these spreaders also for applications 
58 CHAPTER 4

of fertilizers and seeds. On rotary-wing 

aircraft, you typically use a centrifugal 

spreader to apply dry formulations.

Ram-Air Spreader 

A fixed-wing aircraft fitted with a 

properly configured ram-air spreader 

can apply dry formulation pesticides 

very uniformly. However, setup and 

operation may be more complex than 

that required for applying liquid pesticide products. General limitations 

imposed by ram-air spreaders include 

higher engine power requirements and 

high aerodynamic drag, which affect 

aircraft performance and maneuverability. 

Ram-air spreaders are comparatively simple, versatile, and reasonably 

priced. You would typically attach a 

ram-air spreader beneath the fuselage 

in such a way that you can remove it 

easily to restore the liquid spraying 

capability of the aircraft. The hopper 

is the same one used to hold liquid pesticide sprays.

An unsatisfactory distribution 

pattern of dry materials results from 

most ram-air devices if you attempt to 

apply more than 250 pounds per acre 

of material or increase the feed rate to 

more than 35 pounds per second.

Feed Rate

In a ram-air spreader, the dry pesticide product drops from the hopper 

into a ducted airstream, where the 

airflow ejects it rearward and laterally. 

A metering gate situated between the 

hopper floor and the spreader throat 

governs the feed rate of pesticide 

granules or pellets. The spreader has 

either a hinged metering gate or a 

sliding hatch between the hopper and 

the spreader.

When using a spreader equipped 

with a hinged metering gate, you use 

a cable or rod to rotate the trailing 

margin of the gate downward to open it 

to whatever setting you want. Material 

escapes from the hopper by flowing 

over the lowered edge of the gate. 

Usually, hinged metering gates require 

more frequent calibration adjustment 

than do sliding hatch types. Some 

hinged metering gate units are capable 

of dispensing liquid materials.

Sliding hatch styles of hopper 

metering gates generally are easier to 

adjust, especially for low application 

rates. However, these units tend to 

be more prone to wear than hinged 

metering gates.

The hopper metering gate must 

provide even feed of the pellets or 

granules across its opening; otherwise, 

the aircraft will produce an uneven 

swath pattern. It is unreasonable to 

expect any combination of ram-air 

spreader adjustments to compensate 

entirely for swath pattern problems 

caused by improper gate adjustment.

Substantially increasing the 

hopper-to-spreader feed rate beyond 

its design maximum is a poor strategy 

for increasing application rate. If you 

meter too much dry pesticide product 

into the spreader, ducting becomes 

choked and less air is able to flow 

through the unit. Increasing the 

amount of dry pesticide entering the 

spreader requires more air to propel 

the material through the spreader. 

Spreader Vanes

The air channel of a typical 

ram-air spreader consists of from 5 to 

13 laterally adjacent, curved ducts. The 

partitions that form the walls of these 

ducts are the spreader vanes. Each 

spreader vane typically has adjustable 

sections located at its front and rear. 

These adjustable sections allow for 

lateral repositioning of the inlet and 

exit portions of a given vane within the 

spreader body. Vane adjustment allows 

you to fine tune a ram-air spreader to 

a particular aircraft’s airflow and slipstream characteristics.

In a ram-air spreader, the material 

metered from the hopper f lows 

through the ducts as a thin, sheetRAM-AIR SPREADER 
Aerial Pesticide Dispersal Systems 59

like layer of particles. Air entering 

the spreader inlet forces the product 

rearward, where it flows along the 

internal upper surface (ceiling) of the 

spreader. Spreading of this particle 

layer is the main job of the spreader 

vanes. When functioning correctly, 

the vanes prevent air and particles 

from moving from one duct to another. 

The top of each vane, including 

the movable sections, must be in close 

contact with the top of the internal 

surface of the spreader. If any air gap 

occurs between vane and duct ceiling, 

both air and particles can move from 

one duct to another during spreader 

operation. This will seriously affect 

the even distribution of the pesticide.

Adjusting the inlet vane positions 

helps to make the swath uniform. 

Airframe-induced influences are known 

to affect ram-air spreader performance, 

but that can often be compensated for 

by spreader inlet vane adjustment.

•  Aircraft oil-cooler-induced

turbulence.

•  Speed ring effects.

•  Propwash effects.

•  Turbulence caused by a flagging

device air deflector.

The propwash effect displaces 

material released near the right of the 

fuselage towards the left side of the 

fuselage. This results in a non-uniform 

swath where distribution of granules or 

pellets on the right side is sparse and it 

is too heavy on the left side. To correct 

a propwash-induced problem, configure 

a ram-air spreader to discharge more 

material from its right side than from its 

left. Do this by moving the spreader’s 

inlet vanes toward the left, making the 

left discharge ports smaller than the 

right side discharge ports. 

Shifting inlet vanes too far laterally 

causes problems, however. As you shift 

an inlet vane laterally, the airstream 

attack angle (angle of incidence) of the 

duct wall increases. When the duct wall 

angle of incidence becomes too great, 

static air pressure increases inside the 

duct and impairs the hopper-to-duct 

flow rate. This causes an undesired 

reduction of spreader output. Lateral 

repositioning of an inlet vane should 

never exceed a 15-degree angle of incidence as measured in relation to the 

path of forward flight.

Altering the spreader’s exit configuration requires repositioning the 

adjustable rear portion of one or more 

spreader vanes if the equipment is set 

up for this type of adjustment. Rear 

vane section adjustments provide a way 

to fine-tune overall swath pattern uniformity. This is because the position of 

the rear section of a vane mainly influences the exit direction of the particles 

passing through that duct.

Alignment of the rear section of 

a vane should, as much as possible, 

smoothly follow the arc formed by the 

vane’s rigid internal curvature. For 

rear vane adjustment, the key concepts are smooth, non-obstructive, 

non-impeding, exit airflow changes. 

Generally, you only need to make small 

adjustments. Over-adjustment usually 

causes particles moving through the 

duct to slow down, resulting in too 

much material in one part of the swath.

Spreader Mounting

The best possible mounting configuration of a ram-air spreader is the one 

that causes the least turbulence. Having 

the smoothest airflow into, around, and 

out of the spreader improves spreader 

performance and provides good application results. 

Relative to an aircraft’s roll axis, 

a correctly mounted spreader hangs 

beneath the fuselage and is level with the 

fuselage from side-to-side and parallel 

to the long axis of the fuselage. Spreader 

mounting differs from airframe orientation only in pitch. The attack angle of 

a ram-air spreader directly influences 

the amount of airflow entering the 

spreader inlet. Set the spreader attack 

angle by establishing the pitch of the 

spreader body during mounting.

The forward mounting points 

of ram-air spreaders are usually nonadjustable. Therefore, change the attack 

angle by changing the distance between 

the aircraft fuselage and the rear part of 

the spreader. In general, the lower skin 

of the spreader is the reference surface 

for measuring spreader attack angle. 

The attack angle of the lower surface 
60 CHAPTER 4

should be approximately 1 to 3 degrees 

less than the attack angle of the lower 

surface of the aircraft wing. When a 

spreader attack angle is either too great 

or too small, the likely result is:

•  Increased turbulence and drag.

•  Increased deposition of the pesticide material on the tail gear of 

the aircraft.

•  A non-uniform swath pattern.

•  Swath narrowing due to lowered

exit speeds of particles.

Application Rate and Swath

Up to the point of its maximum 

material handling capability, changing 

the application rate of a spreader automatically changes its effective swath 

width. Increasing hopper feed to the 

spreader will cause a decrease in swath 

width because the particle stream 

exiting a spreader duct becomes heavier 

and less prone to being broken apart. 

For high application rates such as jobs 

requiring more than 250 pounds of 

pesticide product per acre, the best 

strategy is to reduce the per-pass application rate, configure the spreader for 

a reduced swath width, and fly more 

passes per site. 

Centrifugal Spreader 

The centrifugal spreader used by 

rotary-wing aircraft is a self-contained 

unit having its own hopper. The rotarywing aircraft carries the entire unit 

beneath the aircraft, suspended on a 

cable. The unit meters material from 

the hopper onto a spinning disc that distributes the pesticide, seed, or fertilizer. 

A hydraulic motor or gasoline engine 

usually drives the spinner. You control 

the motor via a hydraulic control cable 

or by an electrically activated solenoid. 

Typically, an operation would have two 

self-contained units so you can spread 

with one while the ground crew fills 

the other. Another method involves 

using a bag suspended from a boom 

that the ground crew fills while the 

pilot makes an application to the field 

with the spreader. When the hopper 

needs refilling, the pilot positions the 

unit under the bag and a ground crew 

member releases the contents of the bag 

into the hopper. The refilling operation 

takes only a matter of seconds while the 

helicopter hovers above.

USDA ARS Image Library
Aerial Pesticide Dispersal Systems 61

1. Aircraft suitable for aerial application of 

pesticides must be:

A. Registered with the U.S. EPA.

B. Constructed entirely of corrosion resistant 

materials.

C. Equipped with DGPS navigational 

equipment.

D. Able to lift, transport, and disperse 

pesticides safely.

2. One of the reasons for an adequate vent in the 

aircraft pesticide tank is to:

A. Release excess pressure.

B. Allow the pump to function efficiently.

C. Prevent a vacuum from altering the normal 

flow of liquid.

D. Keep the pesticide mixture uniform.

3. The purpose of baffles inside a liquid spray 

tank is to:

A. Assure even mixing of the spray material.

B. Prevent extreme pressure changes in the 

system.

C. Reduce sloshing of the liquid during flight.

D. Eliminate foaming of the spray mixture.

4. Hydraulic agitation of the mixture in the 

aircraft spray tank requires:

A. An external power source.

B. Sufficient pump output capacity.

C. Baffles mounted inside the tank.

D. Proper tank ventilation.

5. A proper functioning positive cutoff valve with a 

suck-back feature will supply 

pressure to the boom and nozzles when the spray 

flow is stopped.

A. High negative.

B. Low negative.

C. High positive.

D. Low positive.

6. The purpose of bleed valves at the ends of the 

spray boom is to:

A. Prevent spray from continuing to flow from 

nozzles after the spray valve is closed.

B. Prevent pressure from building up from 

trapped air when the spray valve is opened.

C. Make cleaning the inside of the spray boom 

easier.

D. Reduce internal corrosion of the spray 

boom.

7. To accommodate for the influence of prop 

wash on spray pattern, it is necessary to:

A. Regulate the output flow to the nozzles.

B. Adjust the speed of the aircraft.

C. Reposition the nozzles on the spray boom.

D. Decrease the pump speed.

CHAPTER 4: Aerial Pesticide Dispersal Systems

 Review Questions
62 CHAPTER 4

8. The advantage of an electronic sprayer volume 

controller is that it:

A. Maintains the same spray output as airspeed 

changes.

B. Reduces or increases the spray output as 

airspeed changes.

C. Maintains the same spray output as altitude 

changes.

D. Reduces or increases the spray output as 

altitude changes.

9. Ram-air spreaders can:

A. Compromise fixed wing aircraft 

performance.

B. Improve fixed wing aircraft performance.

C. Reduce aerodynamic drag on the aircraft.

D. Reduce the aircraft’s power requirements.

10. The purpose of adjusting ram-air spreader 

vanes is to:

A. Improve the performance of the aircraft.

B. Reduce the aerodynamic drag on the 

aircraft.

C. Improve the granule distribution pattern.

D. Change the swath width of the granule 

application.

REVIEW QUESTION ANSWERS ON PAGE 97
Calibrating Aerial Application Equipment 63

Calibrating Aerial Application

Equipment

Pesticide registrants, manufacturers, 

and regulatory agencies use extensive 

research to establish proper application 

volumes and to develop safety precautions that you must legally follow 

when making a pesticide application. 

Registrants place this mandatory 

information on the pesticide labeling. 

On occasion, regulatory agencies 

identify a reason to evaluate a product’s 

existing labeling directions, usually 

because of human safety concerns. As 

a result, they may impose regulations 

that supersede the product’s current 

labeling. This may involve changing 

application volumes or imposing additional safety requirements.

In order to make a legal, safe, 

and effective aerial application, you 

are responsible for applying pesticide 

products uniformly and at the proper 

volume per unit of area. Pesticide 

product labels or local regulations 

prescribe maximum volumes, so 

exceeding these volumes violates 

federal and state laws. 

The success of each aerial pesticide 

application depends on accurate calibration. The term calibration refers to 

setting up and adjusting the application 

equipment to ensure that you dilute and 

apply the pesticide active ingredient 

Reading this chapter will help you understand:

	 • Why you need to calibrate dispersal equipment.

	 • How to calibrate liquid and dry dispersal equipment.

	 • How to make adjustments to the application equipment’s dispersal

volume or rate.

CHAPTER 5

LEARNING OBJECTIVES

USDA ARS Image Library

CALIBRATION PREVENTS 

SERIOUS PROBLEMS
64 CHAPTER 5

according to regulations. This chapter 

discusses the steps to take to calibrate, 

test, and adjust a fixed- or rotary-wing 

aircraft’s pesticide dispersal system. 

Sidebar graphics are included to detail 

useful calculations.

Once you calibrate the aircraft’s 

dispersal system, check and test the 

equipment periodically to be sure the 

calibration remains accurate. Heavy 

workloads as well as applying abrasive 

pesticide formulations contribute to 

nozzles and other equipment becoming 

maladjusted or worn.

Technological advances such 

as DGPS systems and electronic 

controllers make aerial pesticide 

application more precise. These tools 

reduce calibration errors and automatically adjust the spraying system 

to accommodate for changes in pump 

output, nozzle wear, and variations in 

application speed. The best resources 

for setting up and adjusting these 

systems are their operation manuals. 

Therefore, this chapter does not cover 

calibrating or adjusting electronic 

devices.

why you need to calibrate equipment

The main reason for calibration is to 

figure out how much pesticide to put 

into the tank or hopper of the aircraft 

so you can apply the work order recommended volume to the target site when 

you operate the aircraft at a determined speed and altitude. Accurate 

calibration is necessary for:

•  Assuring compliance with the

requirements in labeling, law, or 

regulation.

•  Effective pest control.

•  Protecting human health, the

environment, and treated crops or 

surfaces.

•  Preventing waste of resources.

•  Controlling the volume of water

(for liquid applications) applied to 

a given area.

Improper Application Rate

Applicators are legally liable for 

injuries or damage caused by improper 

pesticide application. Several problems 

are associated with applying a pesticide 

at a volume higher than the maximum 

legal rate.

Illegal Residues

Applying higher than legal 

volumes of a pesticide may result in 

residues on crop plants that exceed the 

legal tolerance level. If over-application 

results in illegal residues on plant surfaces, regulators have the authority to 

confiscate and destroy an entire crop 

to protect consumers.

Impact on Effective Pest Control

Pesticide registrants and/or manufacturers of pesticides spend millions 

of dollars researching ways to use their 

products correctly and effectively. This 

research includes determining the right 

amount of pesticide to apply to control 

target pests. Using less than the labeled 

rate is legal, but may result in inadequate control, wasting time and money. 

Application volumes that are too low 

also may lead to problems such as pest 

resistance and resurgence. Higher than 

label rates are illegal and waste pesticides. Using too much pesticide may 

adversely affect natural enemies of the 

pest being controlled. 

APHID PEST
Calibrating Aerial Application Equipment 65

Human Health Concerns

Pesticides applied at higher than 

label rates could endanger the health 

of pesticide handlers, field workers, 

yourself, and other people working in or 

visiting an area where you applied them. 

Environmental Concerns

Pesticide concentrations higher 

than label directions may cause serious 

environmental problems. Calibrating

equipment to maintain application 

volumes within label requirements 

reduces the potential for contaminating 

surface water, ground water, and the air.

Impact on Treated Plant Surfaces

Certain pesticides are phytotoxic

(injurious to plants) and damage treated 

plant surfaces when used at higher than 

label-prescribed rates. Manufacturers 

evaluate these potential problems while 

testing their products so they can 

determine safe concentrations. 

Soil Contamination

Using too much pesticide increases 

the chance of building up excessive 

residues in the soil. A buildup of certain 

pesticides sometimes seriously limits 

the types of future crops that farmers 

can grow in the treated area.

Wasting Resources

Using the improper amount of pesticide wastes time and adds unnecessary 

costs to the application.

equipment calibration methods

Pesticide materials are expensive, and 

the fuel, labor, and equipment wear and 

tear required to make extra applications 

are costly.

If you apply pesticides improperly, 

you are subject to criminal and civil 

enforcement actions that may result 

in loss of your pilot certificate, paying 

fines and penalties, serving imprisonment time, and the costs and lost 

time dealing with lawsuits.

Properly calibrating aerial application equipment is necessary to ensure 

uniform distribution of the pesticide 

materials and it helps prevent pesticide 

related problems. The following sections 

discuss different calibration techniques 

for liquid application equipment and 

granular application equipment.

Calibrating Liquid Sprayers

Calibrating liquid sprayers involves

determining how much area each 

tank of spray covers when the aircraft 

travels at a known speed and the system 

operates at a known pressure. You begin 

by matching the desired application 

volume and droplet size category with 

the number of nozzles, nozzle orifice 

size, application airspeed, and swath 

width. Use nozzle specifications from 

the manufacturer to select nozzles 

that, as closely as possible, produce the 

desired spray output and droplet size for 

the product you intend to apply. Arrange 

nozzles on the boom in such a way as to 

produce the desired deposition pattern 

when applying the material from the 

application height selected. Keep the 

application height constant during each 

swath run to obtain uniform coverage. 

Avoid adjusting application height to 

either change the swath width or spray 

pattern uniformity. Instead, replace 

nozzles to correct swath width and 

pattern uniformity.

Once the aircraft is properly set up, 

measure the following four factors:

•  Tank capacity.

•  Application airspeed.

•  Flow volume.

•  Effective spray swath width.

Spray pressure is a component of 

the flow volume because as the pressure 

increases or decreases the flow volume 

increases or decreases as well. Spray 

pressure must never exceed the recommendations of the nozzle manufacturer.

Check liquid spraying equipment

frequently when applying abrasive pesticides, such as wettable powders, because 

these materials cause wear in pumps 

and nozzles. Pump wear decreases the 

amount and pressure of fluid output, 
66 CHAPTER 5

while nozzle wear increases the volume 

of output. Alone or in combination, 

these two occurrences usually lower 

the output pressure and may produce a 

poor spray pattern.

Tank Capacity

You need to know exactly how 

much liquid you can put into the aircraft’s spray tank in order to determine 

how much area you can spray with 

each load. This requires measuring the 

capacity of the spray tanks, usually one 

time only. If you modify the tank, or 

remove or add components inside the 

tank, you will have to re-measure its 

capacity. Never rely on tank size ratings 

provided by the manufacturer because 

these may be approximate volumes, 

they may not take into account fittings 

installed inside the tank, and they do 

not account for the attitude of the aircraft while it is on the ground.

Position the fixed- or rotary-wing 

aircraft on a level surface and make sure 

there is no liquid in the system. Drain 

the system if necessary, then close any 

open valves to prevent water leaks. Start 

adding measured amounts of clean 

water. Keep the pump running to circulate the liquid. Using a flow meter, 

bring the water level to the maximum 

operating fill point. This is the level 

to which you will always fill the tank 

whenever applying a full load. Once 

you determine the actual capacity of 

the tank or tanks, paint or engrave this 

amount onto a prominent place near the 

tank for permanent reference.

While filling the tank, also 

calibrate the tank sight gauge, or make 

marks on the tank as you add measured 

volumes of water. Once you calibrate 

the sight gauge or tank, it is easy to see 

how much liquid is in the tank when it 

is not entirely full. Always return the 

aircraft to a level surface when reading 

the sight gauge or tank marks. The sight 

gauge readings while the aircraft is in 

flight will differ from readings taken 

when the aircraft is on the ground due 

to flight attitude.

Application Airspeed

Measure airspeed under actual 

working conditions, with the aircraft 

spray tank about half full of water (to 

get the best average for weight considerations), and flying at the same altitude 

as an actual spray application. If the aircraft spraying system is equipped with 

a flow volume controller, the controller 

will calculate the proper flow volume 

and make adjustments if airspeed 

changes. For it to make these adjustments, you must enter the application 

volume and the size of the effective 

swath width into the unit.

Flow Volume

If the aircraft is not equipped 

with a flow volume controller, measure 

the actual output of the system when 

nozzles are new, then periodically 

thereafter to accommodate for nozzle 

wear. Manufacturers provide charts 

showing the estimated output of given 

nozzle sizes at specified spray pressures. 

Manufacturer charts are most accurate 

when using new nozzles—used nozzles 

may have different output volumes 

because of wear. Even new nozzles may

have slight variations in actual output. 

Additionally, the pressure gauge in the 

aircraft may not be accurate, which 

further adds error to the output estimate 

determined from manufacturer charts. 

These charts express flow volume in 

gallons per minute, which you can then 

convert to gallons per linear mile at the 

prescribed swath width.

Rotary-wing Aircraft. Rotary-wing aircraft usually have electric or hydraulic 

powered pumps, so the aircraft does not 

need to be in flight to measure nozzle 

output. To find out the combined flow 

volume for all nozzles on a helicopter 

spray boom, collect liquid from each 

nozzle over a known time (such as 30 

seconds) and add together these amounts. 

Use a calibrated container that measures 

liquid ounces. Once you determine the 

total amount of output, convert the 

ounce measurement into gallons and 

then determine the gallons per minute 

and mile outputs (see Sidebar 1).

Fixed-wing Aircraft. Most fixed-wing 

aircraft use fan driven spray pumps, so 

the aircraft must be airborne or have 

the engine running at high speed while 

on the ground. Due to the air blast 

from the propeller, you cannot collect 

spray from the nozzles. Therefore, find 
Calibrating Aerial Application Equipment 67

the output of the sprayer over time by 

measuring how much water you use 

during several test flights. Each time

you fill the tank, make a run operating 

the sprayer for a timed period.

Start by moving the aircraft to a 

level surface and fill the tank to a known 

amount with clean water. Fill the tank

to a level that you can duplicate when 

refilling. Check for leaks around tank

seals, hoses, and hose fittings. Be sure all 

nozzles are clean and operating properly 

or the results will be inaccurate.

Take off and fly to an area where 

you can release the spray water. Operate 

the sprayer at its normal operating 

speed and pressure. Open the valve to 

the spray boom, starting a stopwatch 

at the same time. Continue to run the

sprayer for several minutes, and then 

close the valve. Record the elapsed 

time, return to the ground, and park 

the aircraft at the same spot where you 

originally filled the tank. 

Attach a flow meter to a lowpressure filling hose and refill the tank 

to the original level. Record the gallons 

of water used; this volume is the amount 

of liquid sprayed during the timed run. 

Determine the gallons per minute 

output of the sprayer and convert the 

result to gallons per mile as shown in 

Sidebar 2. For more accuracy, repeat

this process two more times to get an 

average of sprayer output.

Swath Width

A crucial step in the calibration 

of an aircraft liquid dispersal system 

involves determining the effective 

A helicopter spray boom is equipped with 30 nozzles. Liquid has been collected from each nozzle for 30 seconds. When combined, the total amount 

of liquid collected is 600 ounces.

Convert the 600 ounces per 30 seconds into gallons per minute.

Next, convert the total ounces per minute into gallons per minute.

In this example, the helicopter discharges 9.375 gallons of liquid per minute. 

This result can be converted to gallons per mile by dividing the airspeed in 

miles per hour by 60 minutes per hour and then dividing the result into the 

gallons per minute.

Assume the helicopter is traveling at 50 miles per hour.

 

calculating sprayer flow volume per mile

(Rotary-Wing Aircraft)

Sidebar 1

= 1200 ounces/minute

= ounces/minute total ounces collected × 60 seconds/minute

 seconds of collection time

600 ounces collected × 60 seconds/minute

30 seconds

= 9.375 gallons/minute 1200 ounces/minute

 128 ounces/gallon

 = 0.833 miles/minute 50 MPH

60 minutes/hour

0.833 miles/minute = 11.25 gallons/mile 9.375 gallons/minute
68 CHAPTER 5

swath width. Although the actual swath 

width may be wider, the effective swath 

width includes overlaps made with each 

pass to achieve a more even application. 

Measure the amount of overlap leading 

to the effective swath width produced 

by an aircraft by pattern testing. 

Whenever you alter the spray boom in 

any way or change application height, 

you must repeat this pattern test and 

recalculate the effective swath width. 

Application height affects the effective 

spray swath, so the application height 

used during pattern testing must be 

the same as the height flown during an 

actual application.

Application Height

Application height describes the 

distance between the nozzle tips and 

the target, be it the plant canopy or 

open ground at the target site. The 

effective swath width usually increases 

as the application height increases due 

to air movement. However, there are 

limits to how high you can go and get 

a wider swath. Spray drift management 

studies indicate that application height 

can affect the amount of off-target 

drift of the spray, depending on the 

spray droplet size. Therefore, minimizing off-target drift risk requires 

lower application heights. The greater 

the application height, the more time 

it takes for spray droplets to reach the 

target and so they are subjected to 

evaporation and other forces that create 

off-target drift. High temperatures and 

low humidity will increase the evaporation rate.

An application height of 8 to 10 

feet is usually the maximum suitable 

for applying spray droplets that have 

less tendency to drift. For application

heights greater than 8 to 10 feet, you 

need larger spray droplets to reduce 

drift. The pesticide label usually 

provides application height limits or 

a range of application heights for a 

particular product. Flying too low can

cause additional drift issues because 

of air turbulence hitting the ground 

(ground effect).

Determining the Acres per Minute 

Treated

To calculate the number of acres 

treated in one minute, use the airspeed 

For this example, the aircraft’s spray tank is filled with water to its top

mark. After takeoff and leveling off, the pilot made four runs at 120 MPH 

and opened the spray valve for 30 seconds for each run. After landing, the 

aircraft was returned to the same location where the tank was originally 

filled. Using a flow meter attached to a water hose, the tank was refilled to 

the top mark. It took 36 gallons of water to refill the tank.

Calculate the gallons per minute output of the sprayer.

Convert the gallons per minute into gallons per mile.

calculating sprayer flow volume per mile

(Fixed-Wing Aircraft)

Sidebar 2

120 miles/hour

60 minutes/hour = 2 miles/minute

18 gallons/minute

2 miles/minute = 9 gallons/mile

= 18 gallons/minute 2 minutes

36 gallons
Calibrating Aerial Application Equipment 69

and the effective swath width measurements in the calculations shown in 

Sidebar 3.

Determining the Application 

Volume per Acre

In the “Flow Volume” section, the

fixed-wing aircraft example calculation 

(Sidebar 2) showed that a boom with 

50 nozzles was discharging 18 gallons 

per minute. At 120 miles per hour, this 

amounts to 9 gallons per mile. Sidebars 

3 and 4 illustrate how to convert the 

gallons per mile to gallons per acre.

Determining the Amount of 

Pesticide to Put into the Tank

The label or job order prescribes 

how much pesticide to apply per acre. 

Be sure to confirm that the job order 

does not exceed the legal rate given 

on the label. You may have to adjust 

nozzle output or modify the application pattern to achieve this desired 

volume. For example, you may have to

make more than one pass over a swath 

to apply the total number of gallons of 

spray or pounds of granules per acre as 

required by the label or job order application rate.

To prevent waste of pesticide 

material, you must accurately know the 

size of the area to be treated. Then, mix 

only the amount of pesticide needed. 

Multiply the total acres in the application site by the application volume 

to find out how much pesticide will be 

required for the complete job.

Use tank volume and the gallons 

per minute figure to calculate how much 

time it will take for you to spray out all 

the liquid in the tank. Once you know 

this time, you can calculate the total 

area covered with each tank of material. 

The result will be the actual acres of 

treatment site that you can spray with 

Convert the airspeed from miles per hour to feet per minute using this formula.

Assume for this example that the aircraft travels at 120 miles per hour. 

Convert this speed to feet per minute.

Next, multiply the effective spray swath width by the feet per minute airspeed to 

determine the area, in square feet, covered in one minute. The effective swath width 

has been determined to be 50 feet and the travel speed is 10,560 feet per minute.

Convert this area into acres by dividing the square feet/minute 

by 43,560 square feet/acre.

calculating acres treated

per minute

Sidebar 3

MPH × 5,280 feet/mile

 60 minutes/hour = feet/minute

 120 MPH × 5,280 feet/mile = 633,600 feet/hour

feet/minute × effective swath width = square feet/minute

10,560 feet/minute × 50 feet = 528,000 square feet/minute

633,600 feet/hour = 10,560 feet/minute 60 minutes/hour

528,000 square feet/minute

43,560 square feet/acre = 12.1 acres/minute
70 CHAPTER 5

A spray boom having 50 nozzles discharges 18 gallons of spray per minute. 

Using the calculations from Sidebar 3, this aircraft covers 12.1 acres per 

minute.

Divide the gallons per minute by the acres per minute to get gallons per acre.

Therefore, the aircraft in this example will be spraying 1.49 gallons of 

liquid per acre when traveling at 120 miles per hour and spraying a 50 foot 

effective swath width.

determining gallons per acre

Sidebar 4

18 gallons/minute

12.1 acres/minute = 1.49 gallons/acre

A fixed wing aircraft is equipped a with spray tank with a total measured 

capacity of 300 gallons. The aircraft spraying system will discharge 18 

gallons per minute when flown at 120 miles per hour. 

Divide the tank capacity by the gallons per minute to determine how many 

minutes it will take to spray 300 gallons, the tank’s capacity.

Next, calculate the number of acres that can be sprayed with one tankful of liquid. To 

do this, multiply the minutes per tank figure by the acres per minute figure computed 

in Sidebar 3.

In this example, the aircraft can treat 201.7 acres with one tank of spray 

mixture. Assume the job order prescribes 2 pints of pesticide per acre. 

Knowing that one tank can cover 201.7 acres, the total amount of pesticide 

to put into the tank can be calculated. 

Multiply the pints per acre by the acres per tank and divide this by 8 pints per 

gallon to determine the gallons of pesticide to put into the tank.

These calculations show that 50.5 gallons of pesticide must be mixed with 

249.5 gallons of water to fill the tank with 300 gallons of spray mixture.

determining the amount of pesticide

to put into the tank

Sidebar 5

= 16.7 minutes/tank 300 gallons/tank

 18 gallons/minute

16.7 minutes/tank × 12.1 acres/minute = 202 acres/tank

2 pints/acre × 202 acres/tank

8 pints/gallon = 50.5 gallons/tank
Calibrating Aerial Application Equipment 71

one tank of pesticide mixture. Knowing 

this value and the recommended rate of 

application (units of pesticide per acre 

of treatment area) makes it possible to 

determine how much pesticide to mix 

with water in the aircraft’s tank. See 

the calculations for this in Sidebar 5. 

You also need to calculate the area to be 

treated (Sidebars 6-9).

Changing Sprayer Output

Once calibrated, you have determined the output volume of the aircraft’s 

spraying system for a specific speed, 

altitude, and pump pressure. However, 

there may be times during an operation 

when you may need to change the 

output volume slightly. These include:

•  Accommodating variations in

foliage density.

•  Different plant spacing within the

same field.

•  Special requirements of the

treatment area such as obstacles or 

sensitive areas.

•  Compensating for nozzle or pump

wear.

You can make the adjustments 

discussed below, either alone or in 

combination, to effectively increase or 

decrease sprayer output, but only within 

a limited range.

Changing Speed. Typically, you should 

not adjust application speed in a fixedwing aircraft to change the application 

volume. However, the simplest way to 

adjust the volume of spray (and amount 

of pesticide) you are applying in a 

To calculate the area of a rectangular (or square) site, you must know the:

•  Length of the longest side (in feet)

•  Width of one adjacent side (in feet)

A rectangular field is 800 feet long and 250 feet wide. To find the area of the field 

(in square feet), multiply the length times the width.

Convert the 200,000 square feet to acres by dividing by the number of square feet in 

one acre (43,560 square feet).

Calculating the Area of a Rectangular

or Square Application Site

Sidebar 6

800 feet × 250 feet = 200,000 square feet

200,000 square feet

43,560 square feet per acre = 4.59 acres

length

width
72 CHAPTER 5

To calculate the area of a triangular site, you must know two dimensions, 

making sure both of these dimensions are in feet.

•  The length of the longest side of the triangle (its base).

•  The width of the triangle at its widest point (its height).

The longest side (base) of a triangular field measures 650 feet. The distance 

between this side and the point where the two other sides meet (height) is 300 feet.

Divide the 97,500 square feet by 43,560 square feet per acre to find 

the number of acres in this triangular site.

Calculating the Area of a Triangular

Application Site

Sidebar 7

(base × height)

2 area of a triangle =

base

650 feet × 300 feet 

2 = 97,500 square feet

97,500 square feet 

43,560 square feet per acre = 2.24 acres height
Calibrating Aerial Application Equipment 73

Calculating the Area of a Circular Application Site

Sidebar 8

diameter

radius

To calculate the area of a circular site, you must know two values.

•  The radius of the circle in feet (see diagram below)

•  The value of the constant pi (often indicated by the Greek letter π) which is 

approximately 3.14

The radius is the length of the straight-line distance from the center of a circle to any given place 

on the circle’s edge. The radius is equal to one half of the diameter. A diameter is the length 

of the longest possible straight-line distance across a circle, passing through the center of the 

circle. Pi is a ratio of the circumference of a circle to its diameter. It is used to determine areas or 

volumes that involve circles, spheres, and other curved objects. 

The area of any circle is determined by multiplying pi (π) times the square of the radius of the circle, where 

the square of the radius means multiplying the length of the radius by itself. Use this formula.

area = π × r2

where r is the radius and π = 3.14

Before making any calculations, make sure the length of the radius (or the diameter) is known in 

feet. If only the diameter is known, divide this by 2 to get the radius.

The diameter of the circular field is 400 feet. This means that the radius is 200 feet. To calculate the area, 

multiply π (3.14) times the square of the radius (200 feet × 200 feet).

area = 3.14 × (200 feet × 200 feet) = 125,600 square feet

To convert this area to acres, divide the 125,600 square feet by 43,560 square feet per acre.

125,600 square feet

43,560 square feet per acre = 2.88 acres
74 CHAPTER 5

Calculating the Area of an

Irregularly-Shaped Application Site

Sidebar 9

Many sites are not perfect circles, rectangles, or triangles. Often, agricultural sites have curved 

corners, have a bulge along one or more sides, or, have a notched area because an obstacle does not 

allow cultivation or spraying. This can make an accurate area calculation difficult. Here are some 

guidelines on how to proceed.

•  First, sketch a general map of the site. This is a key step, yet, in most cases, you do not need many

measurements to make a good general map. The main purpose of the map is to let you clearly identify 

the number and kinds of shapes that together make up the site. 

•  Next, identify the kinds and number of shapes such as triangles, circles, and rectangles that together

form the irregular shape. Return to the field and place marker stakes to identify the boundaries of each 

identified shape or subsection. Record the location of each marker stake on a map.

•  Take in-field measurements to determine the dimensions of each regularly shaped subsection. Record

these measurements on the map.

•  Calculate the area (in square feet) of each regularly-shaped subsection, following the procedures for

calculating the areas of a rectangles, circles, and triangles.

•  Finally, add together the square feet calculations from all the subsections. This will give you the total

size, in square feet, of the irregularly shaped site. This square foot measurement can then be converted 

to acres.

In the example shown here, based on the general map of the site, three regularly shaped subsections 

(Triangle A, Triangle B, and Rectangle C) can be identified and measured. Then add together the

three areas.

A

B

C
Calibrating Aerial Application Equipment 75

rotary-wing aircraft is to change the 

speed. A slower speed results in more 

material applied, while increasing the 

speed reduces the application volume. 

Changing the travel speed eliminates

the need for altering the concentration of chemicals in the spray tank 

if there is a valid reason for increasing 

or decreasing the application volume. 

However, there are limits to the amount 

of speed change that you can make. 

Increasing speed too much is a problem 

because it increases the wind shear 

effect on spray droplet sizes, producing 

smaller spray droplets. In addition, 

faster speeds may reduce the application 

volume so much that it results in poor 

coverage and ineffective pest control. 

Flying too slow may possibly result

in over-application by exceeding the 

maximum label rate. At the very least, it 

would increase the amount of pesticide 

applied, causing runoff and waste, and 

increasing application time and cost.

Changing Output Pressure. As nozzles 

begin to wear, the spray volume will 

increase from the orifice getting larger. 

However, when a pump begins to wear, 

it becomes less efficient as it moves less 

volume of spray because of the increase 

in space between the moving parts that 

normally force the liquid through the 

system. As a result, the nozzle output 

drops off. Adjusting the pump speed 

to increase or decrease output pressure 

will change the spray volume slightly. 

Increasing pressure increases the output, 

while decreasing pressure lowers it. In 

order to double the output volume, you 

must increase the pressure by a factor 

of four. This is usually beyond the 

capabilities of the spraying system and 

a pressure increase negatively affects 

the droplet size spectrum. The working 

pressure range of the sprayer pump also 

limits this adjustment.

Changing Nozzle Orifice Size. The 

most effective way to change the output 

volume of the aircraft spraying system 

is to install different sized orifices on 

nozzles. Larger orifice sizes increase 

volume, while smaller ones reduce spray 

output. Changing orifice sizes usually

alters the pressure of the system and 

requires an adjustment of the pressure 

regulator or pump speed. Be aware that 

changes in orifice size will also change 

the droplet size and spray pattern and 

will affect drift potential. A major 

factor in reducing drift is to reduce 

the amount of small fines prone to 

off-target drift. Considerations must

include the effect of airspeed on droplet 

atomization as well as the effect of air 

shear across the nozzle face. Use tables 

from nozzle manufacturer web sites or 

manufacturer literature as guides for 

estimating output of different nozzle 

and orifice size combinations. When 

you change nozzle orifices, remeasure 

the output volume.

Calibrating Granule 

Applicators

The techniques for calibrating 

granule applicators are similar in many 

ways to those used for liquids. However, 

granules vary in size and shape from 

one pesticide to the next, influencing 

their flow rate from the applicator 

hopper and spreader. Temperature 

and humidity may also inf luence 

granule flow. Due to their lower drift 

potentials, you generally can apply 

pesticides formulated as granules from 

greater application heights than what 

is suitable for liquids. Usually, higher 

granule application heights produce 

more uniform deposition patterns.

Before beginning to calibrate 

a granule applicator, be sure that it 

is clean and all parts are working 

properly. Measure three variables when 

calibrating a granule applicator:

•  Application airspeed.

•  Output rate.

•  Swath width.

Application Airspeed

Always measure airspeed under 

actual working conditions with the 

aircraft loaded to normal operational 

weight and flying at the altitude that 

you will use when making a granule 

application.

Output Rate

To determine the rate of output, 

follow the manufacturer’s guidelines 
76 CHAPTER 5

and set the ram-air spreader gate or 

centrifugal spreader gate to the desired 

rate per acre. Place a series of at least 

13 collection pans at 5-feet intervals in 

a straight line on the ground. Set these 

out perpendicular to the flight line. The 

footprint shape of the collection pans is 

unimportant, but the pans should be 

approximately 4 inches deep and have 

an area of at least 1 square foot. All of 

the collection pans must be exactly the 

same size. Pad the bottom of each pan 

with a thin foam layer to help prevent 

any granules from bouncing out.

Swath Width

Fly a swath test along a centerline

oriented at a right angle to the line of 

collection pans. If ambient wind speed 

is greater than a sustained 8 mph, 

orient the line of pans at a right angle 

to the prevailing wind and fly directly 

into the wind.

After the swath test flight, use 

a small graduated cylinder to collect 

and measure granule volume in each 

individual pan, progressing from left 

to right. Record each pan’s volume on 

a graph in the exact order of collection. 

Plotting these volumes as a graph lets 

you visualize the distribution of your 

granule application across the swath. 

Finally, combine the granules from

all the pans into another container, 

then weigh and record this weight. 

Calculate the total area of the 13 pans.

For example, if each pan is exactly one

square foot, the total area would be 13 

square feet. Sidebar 10 shows how to 

calculate the granule application rate 

per acre.

The distribution shown in the 

figure on the next page is an idealized 

plotting of the amounts caught in 

13 pans laid out 5-feet apart across a 

60-foot swath. Another pass centered 

30 feet to the right of the first pass 

produces a 50% overlap of the swaths 

and results in an even distribution of 

granules. This represents an effective 

swath width of 30 feet.

Examination of this figure shows

that at point A, six units (these could 

be pounds, ounces, or any other unit 

of weight) were collected in the pan. 

At point B, the first swath applied five 

units in the pan and the second swath 

added one more for a total of six. At 

point C, each swath applied three units

for six units in the pan.

The pattern shown at the bottom 

of the next page is a more typical trapezoidal pattern generated by granular 

spreaders. The effective swath width 

of a pattern having this shape is determined by adding the distances AD 

and BC together and dividing by 2, as

shown on the next page. 

Once you determine the effective 

swath width, you can estimate the 

The weight of the granules collected in all 13 pans totals 2 ounces. 

Compute the pounds of granules being applied per acre as follows:

Convert ounces per acre to pounds per acre by dividing by 16 ounces per pound:

Computing granule application rate per acre

Sidebar 10

43,560 square feet/acre × 2 ounces 

 13 square feet = 6,701.54 ounces/acre

6,701.54 ounces/acre 

 16 ounces/pound = 418.85 pounds/acre
Calibrating Aerial Application Equipment 77

amount of granules, in pounds per 

acre. The example above is not an ideal 

method of calibrating a granule applicator because of the large difference in 

weight between the granules caught in 

the pans and those deposited onto the 

actual application swath. Unfortunately, 

it is often impossible to calibrate dry 

materials accurately unless you are 

using the actual materials. Spreading 

pesticide granules onto an area not designated for the application of a pesticide 

is dangerous and irresponsible. If possible, obtain blank granules (granules 

of the same size, shape, and weight as 

the pesticide product, but without the 

pesticide active ingredient) from the 

manufacturer to use for calibration. If 

this is not possible, the only alternative 

is to rely on the equipment manufacturer recommendations for setting and 

adjusting the ram-air spreader gate or 

VOLUME DISTRIBUTION OF GRANULES

60 feet

A B

C

30 feet

7

6

5

4

3

2

1

0

TYPICAL GRANULE APPLICATION PATTERN

APPLICATION RATE

A D

B C

If distance AD (the distance between the two end pans containing zero 

granules) is 60 feet, and distance BC (the distance where granule catch per

pan is relatively constant) is 30 feet, calculate the effective swath width.

In this situation, application passes should be made 45 feet apart.

60 feet + 30 feet

2

effective swath width = = 45 feet
78 CHAPTER 5

centrifugal spreader gate to the desired 

rate per acre. This setting should 

result in accurate initial application 

rates. You can fine-tune this rate to be 

even more precise by calculating the 

amount of pesticide that you applied 

to a known area and comparing that to 

the desired rate.
Calibrating Aerial Application Equipment 79

1. The purpose of calibration is to:

A. Determine the capacity of the spray tank(s).

B. Prevent off-target pesticide drift.

C. Apply the correct amount of pesticide.

D. Protect the environment.

2. Applying a pesticide at a rate that is higher 

than the pesticide label rate is:

A. Necessary.

B. Careless.

C. Illegal.

D. Useful.

3. Increasing airspeed without changing the 

spray output will result in:

A. More pesticide active ingredient applied 

per acre.

B. Less pesticide active ingredient applied 

per acre.

C. An increase in the pesticide flow volume.

D. A decrease in the pesticide flow volume.

4. If 1700 ounces of material is collected from 

nozzles on a helicopter spray boom in 90 

seconds, what is the total flow volume in 

gallons per minute?

A. 4.42

B. 8.85

C. 13.28

D. 17.70

5. An aircraft spraying system has an output volume 

of 8 gallons per minute. How many gallons are 

sprayed per mile when the aircraft travels at 130 

miles per hour?

A. 3.7

B. 4.5

C. 5.8

D. 6.5

6. An effective swath width is the:

A. Total swath made by two passes.

B. Total swath made by a single pass.

C. Width of a single pass that includes portions 

of overlaps from other passes.

D. Distance between the outermost or widest 

points of application across the entire swath.

7. An aircraft sprays 20.2 gallons per minute. How 

many minutes of spraying time are needed to 

spray out 147 gallons of spray mixture?

A. 6.8

B. 7.3

C. 8.5

D. 9.0

8. Given an application rate of 11.3 gallons per 

acre, how many acres can be sprayed with 147 

gallons of spray mixture?

A. 11

B. 12

C. 13

D. 14

CHAPTER 5: Calibrating Aerial Application

Equipment

Review Questions
80 CHAPTER 5

9. If an aircraft treats 14 acres per tank of spray 

mixture, how many pints of pesticide liquid 

should be put into the spray tank to apply at a 

volume of 1.5 pints per acre?

A. 11

B. 15

C. 21

D. 24

10. How many acres are in a rectangular field that 

measures 620 feet by 1280 feet?

A. 16.1

B. 18.2

C. 22.8

D. 28.8

REVIEW QUESTION ANSWERS ON PAGE 97
making an aerial pesticide application 81

Making an Aerial Pesticide

Application

The reasons for following proper 

aerial pesticide application methods 

are to make precise, safe, and legal 

aerial applications consistently and to 

minimize the off-target movement of 

pesticide droplets. Proper application 

methods include knowing how to:

•  Recognize the factors and conditions that contribute to off-target 

pesticide drift and other offsite 

movement, and know how to 

minimize off-target pesticide drift 

and other offsite movement.

•  Safely ferry the aircraft between

home base, the loading site, and 

the application site.

•  Inspect the application site and

surrounding areas for hazards 

before beginning the application.

•  Watch for hazards throughout the

application operation.

•  Fly an effective application pattern

and make safe and efficient turns 

and passes.

•  Recognize the atmospheric factors

that influence the stability and 

maneuverability of the aircraft.

•  Use DGPS or other guidance

systems.

Agricultural aircraft are highly 

visible and noisy, and as a result, some 

people view aerial pesticide applications 

as nuisances or hazards. The sight of an 

aircraft flying low over fields is a serious 

and sometimes anxiety producing 

concern for some. When you make

aerial applications, be aware of these 

concerns and, when necessary, be sure 

to acknowledge them by taking steps to 

foster better communication with the 

public. Notify people in the area about 

a planned application and make efforts 

to mitigate noise in areas where people 

Reading this chapter will help you understand:

	 •	 Safe ferrying techniques.

	 •	 What to check when arriving at the application site.

	 •	 How to recognize and work with weather at the application site.

	 •	 Different types of application patterns.	

	 •	 Special considerations when applying granules.

CHAPTER 6

LEARNING OBJECTIVES
82 CHAPTER 6

live and work during ferrying or application operations.

Preflight, departure, and application checklists are useful tools 

for you, ground crew members, and 

others involved in an aerial application 

operation (see Pages 85 and 86 for pilot 

and ground crew checklists). These 

checklists help anyone involved in the 

operation to organize and manage their 

responsibilities and they help to assure 

that the operation is safe and effective.

For you and the ground crew, the

first and last runs of the day often call 

for extra attention. The first flight of 

the day requires that you and ground 

crew members be alert and mentally 

prepared immediately for the complexities of the operation—with no time to 

bring the operation up to maximum 

performance gradually. Likewise, the 

last flight of the day must not be rushed 

or compromised in any way in order 

to finish quickly—it requires the same 

attention, care, and time as every other 

flight during that day. However, the 

first flight of the day is the best time 

to schedule jobs that are more difficult 

since you and the ground crew are 

more rested. 

When traveling with an empty or full 

aircraft between the loading area and 

the application site, fly at an altitude of 

at least 500 feet above the surface and 

keep at least 500 feet away from people 

or personal property. Make every 

effort to avoid flying over buildings, 

residential areas, parks or playgrounds, 

penned animals, and other areas where 

people or livestock may be present. If

the operation requires many trips back 

into an area, avoid taking the same 

route each time. Instead, vary the flight

route by one-eighth to one-fourth mile 

during each trip to avoid repeated passes 

over the same surroundings. This tactic 

tends to minimize the audio and visual 

impact of the flights, as opposed to 

repeatedly flying the same route and 

subjecting the same people to the same 

level of distraction.

ferrying

Tom Hoffmann—Washington State Department of Agriculture

checking the application site

Upon arrival at an application site, fly 

an initial inspection pass to verify that:

•  Local weather conditions are

suitable for the prescribed aerial 

application work.

•  Agricultural workers, spectators,

trespassers, and others, including 

their vehicles and equipment, are 

not within or immediately adjacent 

to the application area, especially 

down-wind of the site.

•  Livestock are not in the application area or adjacent areas 

where they may come in contact 

with the spray.

•  Crops adjacent to the application

site match those identified on the 

work order—if in doubt, verify 

the type of crop with the grower 

before beginning an application.

•  All members of the ground crew

assigned to this operation are 

present and ready to begin their 

duties.

•  The communication link between

you, the ground crew, and the 

base location is functioning correctly and that you have a working 

backup communication plan in 

case of equipment failure.
making an aerial pesticide application 83

•  The aircraft DGPS system, if

equipped, is properly functioning.

If you note any conditions in the

application site or adjacent areas that the 

pesticide label does not permit or that 

you consider unsafe, and these conditions cannot be resolved quickly, abort 

the operation and return to your home 

base. If the area is clear and conditions

favor an application, circle the field at 

a very low altitude, but high enough to 

clear all obstructions by at least 50 feet. 

Look for utility poles, guy wires, high 

tension power lines and other types 

of utility lines, and other obstructions 

such as trees, buildings, windmills, 

radio antennas, road signs, pipeline 

markers, and fences that are in or near 

the treatment area. Carefully check

around trees that may conceal power 

lines or other obstacles. Look for breaks 

in the normal cultivation or planting 

pattern that may indicate the presence 

of power lines or other hazards. Poles, 

high fences, or other obstructions may 

prevent cultivation of weeds or other 

vegetative growth in these areas, so 

look for vegetative clues indicating the 

presence of obstructions that may otherwise blend into the background.

After circling the field and noting 

obvious hazards, fly just above and to 

one side along power lines and telephone wires and check each pole. Look 

for branch wires, guy wires, and transformers. Transformers usually have 

branch wires leading to a house, shop, 

well, or other structure. A guy wire will 

normally be placed on the opposite side 

of a pole from a branch wire or at the 

pole where a main line makes a turn. 

Branch wires may be obscured or difficult to see, so look for a cross arm 

going in a different direction from the 

main wires. If any structures are near

the treatment area, look for wires that 

provide electrical power and telephone 

service to them.

Considerthe possibility that conditions may have changed since someone 

made previous inspections or aerial 

applications to this particular field. 

For instance, crops in fields adjacent

to the application site may be different 

from those noted on the work order. 

If this is the case, confirm the application site location. Also, new buildings 

or wells may have necessitated new 

power poles, or the utility company 

may have relocated some power lines. 

Sometimes the height of the planted

crop or trees may have changed since 

a previous application. For example,

it may have been possible to fly under 

certain wires in the spring when a crop 

was first planted, but not possible later 

in the year when the crop is taller. In

addition, heat causes wires to expand 

and therefore hang lower to the ground 

during hot summer days.

what to watch for during an application

Conditions at an application site or 

surrounding areas may change during 

the course of an application. For this

reason, be constantly alert and keep in 

contact with someone on the ground at 

the site. 

Monitor Changes

Changes that may affect the safety

or effectiveness of the opeation include 

the following:

Weather

Wind speed may increase or

decrease or the wind direction may 

change, creating hazards of drift or John Mateski—Newberg, OR
84 CHAPTER 6

contamination of sensitive areas. 

Alternatively, wind may stop altogether, 

increasing the chances of a temperature 

inversion condition. The weather may 

worsen and turn to rain, requiring 

postponement or cancellation of 

the application. Some pesticides are

restricted to applications at times when 

temperatures remain below a certain 

level—if the temperature at ground 

level rises above this point, plants may 

suffer damage (phytotoxicity) from the 

spray material. Certain pesticide labels

may have humidity restrictions for 

application.

Hazards

Previously unidentified hazards 

may become apparent to either you or 

the ground crew, requiring that you 

stop or modify the application at that 

site. This might include the discovery 

of livestock in the area or a work crew 

arriving to work in an adjacent field or 

nearby. There may also be communication from the property manager or 

others with concerns about hazards.

Field Workers

Field workers may inadvertently

walk or drive into an area being sprayed 

or people working in adjacent fields 

unaware of the application operation 

could pass through or walk into the 

field under treatment. In both cases,

the operation is required to stop until 

everyone is safely out of the area. This 

emphasizes the importance and usefulness of ground crew members in 

spotting people in the area and helping 

them to leave quickly.

Service People and Others

Various people occasionally have 

reasons to enter fields or pass through 

them as part of their job responsibilities. 

This includes electric meter readers, 

delivery services, people called to make 

repairs on equipment, irrigation district 

personnel, mosquito control district 

personnel, and others. In addition,

some people enjoy walking or running 

through rural property, often without 

the permission of the landowner, and 

may be unaware of the hazards. The 

ground crew can assist in spotting and 

warning anyone attempting to enter the 

application site and escort them out of 

the area for their own safety.

Importance of Onsite 

Ground Crew During an 

Application

Each on-site ground crew member 

needs to be able to communicate 

directly with you, providing sitespecific details of current weather 

conditions, topographical features, 

location and dimensions of groundbased hazards, buffer zone locations, 

and other information about hazards 

or sensitive areas. Duties of an on-site

ground crew member typically include:

•  Acting as a liaison between you

and the property manager to 

ensure aerial application obligations are met.

Carol Ramsay—Washington State University
making an aerial pesticide application 85

PILOT CHECKLIST

Things to consider before, during, and after any application.

•  Inspect the aircraft and all of its safety equipment and your personal

safety equipment for proper operation and usable condition.

•  Be sure the aircraft’s onboard fire extinguisher is in working condition and has a readable inspection tag.

•  Confirm that the correct pesticide material is mixed with the proper

amount of water and put into the aircraft’s spray tank by the ground

crew by rechecking the pesticide label and counting the number of 

empty containers.

•  Wear an approved safety helmet, long-sleeved shirt, long pants, shoes,

socks, and, when out of the cockpit, the other required personal protective equipment specified on the pesticide label or in regulation.

•  If possible, avoid mixing and loading activities to reduce chances of

bringing pesticide residue into the aircraft’s cockpit.

•  Check the field and surrounding area before applying pesticides to

be sure there are no animals, humans, crops, waterways, streams, or 

ponds that might be injured or contaminated either by direct application or drift.

•  Whenever possible, avoid flying through the suspended spray of a

previous pass.

•  Stop the application and return at another time if winds rise or other

adverse weather conditions develop and create a drift hazard; also 

stop the application if the wind is too calm, usually less than 2 mph.

•  Never turn on dispersal equipment or check the flow volume except

while over the area you are treating.

•  Refuse to fly if the customer requires having any pesticide applied in

a manner and at a time that may create a hazard to crops, humans, 

animals, and the surrounding environment.

•  Make sure every application of a pesticide follows a valid label for a

listed crop or site and that the label has no prohibition for application 

by air.

•  Read the label and know the hazardous characteristics of the pesticides.

•  Using a smoke generator or other device, estimate how far and in

what direction some of the chemical may move away from the application site.

•  Never spray over a flagger, other handlers, or anyone else working in

the area.

•  After making an application, if you notice any equipment malfunction

or problems, securely fasten a note in the cockpit to alert other pilots 

and the maintenance crew.

•  Prepare and keep accurate application records.
86 CHAPTER 6

•  Preventing individuals from

entering the site, both immediately prior to and during the 

application operation.

•  Immediately reporting the

presence of unauthorized individuals in the treatment site to 

you and the on-site field crew 

supervisor or leader.

•  Assisting you in pretreatment

target area inspection.

•  Acting as an in-field reference

point for you to identify swath 

boundaries.

•  Providing emergency response and

summoning emergency services in 

case of a crash incident.

Instruct members of the ground crew to take several precautions before,

during, and after any application.

•  Using extreme care when handling pesticides or cleaning the aircraft or other contaminated equipment.

•  Reading the labels of all pesticides being mixed and wearing labelor regulation-required work clothing and personal protective 

equipment.

•  Insuring that the correct pesticides are properly diluted and mixed

before loading into the aircraft’s spray tank.

•  Tightly securing tanks and hoppers so the pesticides will not blow

back over the pilot or the cockpit.

•  Closing and securing the hopper and covering it as soon as loading

is completed.

•  Removing any pesticide spilled around the aircraft tank fill opening.

•  Not standing in runoff water and avoiding splashes.

•  Changing out of work clothing and washing thoroughly at the end

of the work day after handling pesticides, washing the aircraft, or 

cleaning contaminated equipment.

•  Assisting in preparing and keeping application records.

The ground crew should also be familiar with the pilot’s checklist.

GROUND CREW CHECKLIST

APPLICATION METHODS

Use safe flying procedures during all 

phases of the application operation. 

Never take risks for the thrills at the 

expense of good judgment or safety. To 

ensure that the pesticide application 

will be effective, follow label use directions and requirements in the label and 

regulations. Avoid off-target pesticide 

drift or other off-target movement of 

the pesticide material. Adhere to the 

methods discussed in this manual to 

avoid off-target pesticide drift. Visually 

check the spray or granule discharge 

while making applications to spot application problems.

Straight, parallel passes produce

the most uniform spray pattern. Use

a reliable method, such as DGPS, to

mark each swath to ensure uniform 

coverage and to avoid excessive overlap 
making an aerial pesticide application 87

or gaps. Whenever possible, make

passes perpendicular or at a 45 degree 

angle to the wind direction to assist 

in overlap and coverage uniformity. 

Begin treatments on the downwind 

side of the treatment site to minimize 

flying through spray suspended in the 

air from previous swaths. Also, try to 

make application passes parallel to the 

longest dimension of the treated area 

to reduce the number of turnarounds.

To prevent spray from contacting 

sensitive areas, or to avoid flying or 

turning over residences and other 

sensitive areas, you may need to wait 

for more favorable conditions or alter 

the application pattern in relation to 

prevailing wind direction and even 

contrary to logical field layout. For

instance, consider a rectangular field 

having its longest width running east 

and west. Because the wind is from 

the north, it would appear logical to 

make east-west passes. However, on 

the eastern border of the field is a road 

with houses on the other side of this 

road. East-west passes require making 

turns over the road and houses. In this

situation, make shorter, north-south 

passes over the field—even though this 

requires making more turns.

Application Speed

Maintain constant airspeed, 

consistent with the calibration of 

the aircraft, during each pass of 

an application. Variations in speed 

during an application may result in 

uneven coverage unless you are using 

an electronic flow volume controller 

to compensate for speed changes. 

Flying crosswind or 45 degrees to the

crosswind during an application avoids 

the adverse effects of head- and tailwinds on the application volume.

Altitude

Notwithstanding legal requirements in the label, in law, or in 

regulation, the type of pesticide you 

apply usually determines application 

altitude. For example, liquid pesticides

are most effective and off-target drift is 

less of a problem when you make applications 8 to 12 feet above the crop or 

tree canopy. Flying lower will reduce

off target drift because the droplets are 

closer to the ground, however flying 

too low may cause uneven streaking 

due to not allowing enough time for 

the spray pattern to fill in. Flying too

low over bare ground or over short 

crops may produce a ground effect 

that forces air displaced by the aircraft 

to move upward from the ground. 

Ground effect occurs when the aircraft

is less than 3⁄4 the wing or rotor span 

from the ground. This upward moving 

air entraps and lifts some of the spray 

and contributes to off-target pesticide 

movement. Trees and other plants with 

dense foliage may lower the ground 

effect risk.

Application altitude also depends 

on atmospheric conditions. It is

common for an aircraft to fly higher 

in calm conditions and lower when 

the wind is higher. As the aircraft gets 

lower, the induced drag decreases, 

reducing drift. Wing tip vortices,

which will increase drift, are dependent 

on aircraft configuration, speed, and 

weight. Slower and heavier aircraft will

have larger wing tip vortices due to 

increased induced drag.

Keep the application height constant during each application pass to 

maintain the effective swath width 

that you determined during calibration 

of the dispersal equipment. Failure to

do so will result in difficulty obtaining 

uniform coverage.

Obstructions

If you encounter obstructions at

the beginning or end of a swath run, 

turn the spray on or shut it off one or 

two swath-widths from the beginning or 

GROUND EFFECT

CAUSED BY FLYING

TOO LOW
88 CHAPTER 6

end of the field. Then, when you finish 

all parallel swaths, fly one or two swaths 

crosswise to the rest of the application 

direction to finish out the field. Never 

disperse materials while dropping in 

or pulling out of a field because this 

distorts the deposition pattern. Should

this happen, the pesticide will be more 

likely to drift or concentrate in a small 

area. If there are obstructions along the

sides of a field, fly parallel and as close 

to the obstruction as is safe. For safety,

leave an untreated buffer strip adjacent 

to buildings, residences, livestock areas, 

bodies of water, and other sensitive areas.

There are two methods for 

working around trees, poles, or other 

obstructions in the middle of a field. 

One is to treat them in the same 

manner as if they were at the end of the 

field: stop spraying one or two swath 

widths before reaching the obstruction. 

Pull up and fly over the obstruction. 

Then, make a 180-degree turn before 

dropping in to spray, approaching the 

obstacle from the other direction. This 

will allow better control of the aircraft’s

speed and will avoid overshooting the 

other side. Complete the application by

spraying one or two swath widths on 

each side of the obstacle, perpendicular 

to the previous swaths. The second 

method is to stop spraying and pull up 

as you approach the obstacle, make a 

360° turn, fly over the obstacle, drop 

down, and continue spraying.

When a high enough wire crosses

a swath that has trees at one end, fly 

under the wire if possible, and then pull 

up and fly over the trees. This is safer 

than entering the field over trees and 

then passing under the wire.

RACETRACK PATTERN

WIND

DIRECTION

BACK AND FORTH PATTERN

One flight pattern for aerial application 

is the adjacent swath or back and forth 

pattern, applying swaths over the target 

in straight, parallel lines. In areas that

flight patterns
making an aerial pesticide application 89

PROPER TURNAROUND

LET

DOWN

LET

DOWN

ANOTHER

METHOD

PULL UP AND LET DOWN TAKES

PLACE INSIDE FIELD

TURN IS TOO TIGHT

DOES NOT ALLOW TIME

FOR POSITIONING

PULL

UP

PULL

UP

IMPROPER TURNAROUND

are too rugged for uniform altitude and 

speed, follow the contours of the slopes 

during application passes. In hilly

terrain, or where hills or mountains 

confine the application area and do not 

permit contour flying, make all passes 

in one direction, down slope. Upslope

spraying can be dangerous.

Usually, the racetrack pattern is

the most energy-efficient. This pattern 

maximizes application time and lessens 

the time required for turns. It also

allows time for the spray to settle, 

reducing the chance of flying through 

it. This pattern often minimizes pilot 

fatigue. Whether flying a racetrack or

back and forth pattern, it is important 

to start and stop spraying at the right 

time when entering or leaving the field. 

Starting too soon or stopping too late

causes spray to be applied to off target 

areas. Starting too late or stopping too

soon may result in improper coverage 

to field ends.

The Turnaround

When flying back and forth

or racetrack swaths in a fixed-wing 

aircraft, be careful when executing 

turnarounds. This is because a pull up 

followed by a turn renders a low-speed, 

high-drag condition that could lead to 

a stall. Poorly executed turnarounds 

cause a considerable number of aerial 

application accidents. In addition,

poorly executed turnarounds do not 

allow time for proper positioning for 

the next swath and may result in uneven 

applications.

When completing a swath run,

pull up, clear any obstructions, and level 

off before starting a turnaround. After 

pull up, make a wide enough initial turn 

downwind that will provide sufficient 

room for a smooth turn around. Then 

level off for several seconds before completing the turn back into the treatment 

area. This provides ample time for the 

turn, prevents crowding the turn, and 

reduces the chance of a stall spin. Many 

factors affect the number of seconds 

needed in level flight before completing 

the turn, including swath spacing, 

speed and direction of the wind, air 

density, altitude, and the load weight, 

power, and maneuverability of the aircraft. Attentiveness to these factors and 

careful timing during this final stage of 

the turnaround are the keys to avoiding 

the hazards associated with fast or 

intricate maneuvering. Always complete the turnaround before dropping 

in over any obstructions on the next 

swath run approach.
90 CHAPTER 6

Avoid snapping reversal or wing 

over turns. When making a turn by

going upwind first requires more 

space and time to complete the turn. 

Any turning while dispensing a spray 

or granules distorts the distribution 

pattern resulting in uneven application 

of the pesticide. Whenever possible,

avoid making turnarounds over residences and other buildings, penned 

poultry or livestock, livestock watering 

places, ponds, reservoirs, or other 

bodies of water. Avoiding these areas 

mitigates or minimizes nuisance from 

noise or sight of the aircraft.

Applying Granules

Airspeeds of 100 to 120 mph or 

faster (depending on the type of aircraft) for some fixed-wing aircraft, but 

slower for rotary-wing aircraft, are 

recommended when applying granules. 

These speeds maintain good airflow 

through the spreader and obtain proper 

distribution and maximum swath width.

Application Height

The maximum swath width at a 

certain height above the crop varies 

with the density, size, and grading of 

the granule particles. For most materials and aircraft, this is in the range 

of 45 to 70 feet. Effective height is 

determined by the lateral distance the 

spreader throws the heavier particles. 

Flying below this height allows particles

to hit the ground while still traveling in 

the lateral direction. Flying above this

height achieves no increase in swath 

width because particles fall vertically 

after the lateral energy dissipates. 

Do not fly any higher than necessary

because this increases problems with 

swath displacement.

Maintain the flying height, airspeed, and correct ground track as 

constant as possible to obtain uniform 

results. Crosswinds have considerable

effect on offsetting the dispersal 

pattern from the ground track centerline because of the higher-flying 

height required for granules. Heador tailwinds affect ground speed, 

therefore, making adjustments in flow 

volume and/or airspeed can improve 

uniform distribution on alternating 

upwind-downwind passes. An onboard 

DGPS unit linked to a flow controller

simplifies this process by providing 

automatic in-flight regulation of the 

dispersal system output as airspeed 

changes.

CORRECT APPLICATION HEIGHT APPLICATION IS TOO LOW

Factors Influencing the Aircraft

Density altitude as well as local weather 

conditions and load weight can affect 

the stability and maneuverability of an 

aircraft during an application operation. 

Weather conditions such as wind can

affect the stability and handling of the 

aircraft and contribute to uneven swaths 

and off-target pesticide drift.
making an aerial pesticide application 91

The following is a fairly accurate and easy-to-remember general rule for 

determining the density altitude at locations above sea level:

•	 Standard temperature at sea level is 59oF. For elevations above sea level,

subtract 3.5 degrees per thousand feet of elevation from the sea level 

temperature of 59oF.

•	 For each 10oF above standard temperature at any particular elevation,

add 600 feet to the field elevation. For each 10oF below standard temperature, subtract 600 feet.

Here is an example. The elevation at the application site is 2,342 feet.

1.  Divide the elevation by 1,000.

 

 

2. Multiply 2.342 by 3.5. 

3.  Subtract 8.197 from the sea level standard temperature of 59oF.

4.  The standard temperature at the application site is 50.8oF.In this example,

assume that the current temperature at the application site is 97oF.

Subtract the standard temperature at the application site from this.

5.  Divide this difference by 10 degrees (for each 10oF above standard).

6. Multiply 4.62 by 600 (600 feet per 10 degrees).

 

7. Add this correction factor of 2,772 feet to the field elevation of 2,342 

feet at the application site.

The density altitude for the application site when the temperature is 97oF is

5,114 feet. This means that you should handle the aircraft at the application 

site as you would on a standard day at 5,114 feet elevation. 

46.2

10 = 4.62

ESTIMATING DENSITY ALTITUDE

2,342 = 2.342

1,000

2.342 × 3.5 = 8.197

59 - 8.197 = 50.803

97 - 50.8 = 46.2

4.62 × 600 = 2,772

2,772 + 2,342 = 5,114
92 CHAPTER 6

Humidity also affects available 

engine power and aircraft performance 

because higher humidity is an increase 

in water content of air, displacing 

oxygen that is vital for optimum engine 

internal combustion. For example, at

96oF, the water vapor content of the air

can be as much as eight times greater 

than it is at 42oF. High humidity can

reduce the available engine power 

needed for takeoff and climbs as well 

as maneuvers needed for pull-ups and 

turnarounds during applications.

Density Altitude

Density altitude is a condition

where air molecules spread or thin out, 

becoming less dense, changing aircraft 

flight characteristics such as lift and 

maneuverability. In addition, thinner

air means that less oxygen is available 

for optimum engine performance and 

this reduces horsepower unless the 

aircraft has a turbocharged engine. 

Factors that influence the density of

air molecules include pressure (the 

effect of altitude) and temperature. The 

higher the altitude, the less dense air 

becomes because the air molecules are 

further apart, leaving fewer molecules 

to provide lift for the aircraft. Warmer

air temperature also causes air molecules to move further apart, making 

the air less dense as well.

Density altitude, as well as high

air temperatures, affects the stability 

and maneuverability of the aircraft 

for making applications, takeoffs, and 

landings. It also changes stall thresholds

and influences the ability to perform 

maneuvers such as turns and rolls. The 

effects of density altitude can even 

appear in low altitude areas, such as 

near sea level, when the air temperature 

goes above standard (59oF). Takeoff distance, available engine horsepower, and 

climb rate are all adversely affected. For

an aircraft loaded with spray material or 

granules, an increase in density altitude 

results in:

•  Increased takeoff distance.

•  Reduced rate of climb.

•  Increased true airspeed on

approach and landing.

•  Increased landing roll distance.

•  Limited service ceiling of the aircraft while en route.

Density altitude limits the performance capabilities of the aircraft, but is 

not a height reference and should not be 

confused with pressure altitude, indicated altitude, true altitude, or absolute 

altitude.

In high elevation areas, usually

between mid-morning and midaf ter noon, h igh temperat u re s 

sometimes have such an effect on 

density altitude that normally safe 

aerial application operations become 

extremely hazardous. Very high temperatures at lower elevations can also 

affect aircraft performance, making it 

necessary to reduce the weight of the 

pesticide load for safer flight. During

periods of high temperatures, it may be 

safer to make applications during early 

mornings, when temperatures generally 

are lower. However, early mornings are 

typical times for temperature inversion 

conditions in many areas.
making an aerial pesticide application 93

one U.S. Department of Agriculture scientist characterized the growing public

concern over possible effects of spray drift by stating: “Drift control is the key to survival of aerial application in agriculture.”

In response to this concern, members of the National Agricultural Aviation

Association (NAAA), the organization of professional aerial applicators and pilots, 

developed Operation S.A.F.E. The word S.A.F.E., important in any pilot's vocabulary,

is an acronym for Self-Regulating Application and Flight Efficiency.

The intent of Operation S.A.F.E. is to clearly demonstrate that ag aviation recognizes its responsibility to minimize the potential for adverse health and environmental 

effects of agricultural chemical application. The program was approved by the NAAA 

Board of Directors in 1981.

Because the performance of one aerial applicator reflects on all others, participation 

in Operation S.A.F.E. is not limited to NAAA members. Any licensed operator or agricultural aviator is welcome to participate in Operation S.A.F.E. In order to qualify for

the S.A.F.E. emblem, the participant must be a current member of the NAAA.

Operation S.A.F.E. is a comprehensive program of education, professional analysis

of application, and commitment to the principles outlined by the NAAA Board of 

Directors. NAAA is convinced that full implementation of Operation S.A.F.E. offers

substantial advantages to the operator, customers, and the producers of chemicals 

applied by air. These advantages are found in economy of operation and application, as 

well as in increased safety and reduced health and environmental concerns.

The backbone of Operation S.A.F.E. is the Professional Application Analysis

Clinic—the Operation S.A.F.E. Fly-In. Professional application analysis clinics are

a key part of Operation S.A.F.E. Participation in an NAAA-approved swath analysis

equipment, under the direction of an authorized analyst, is essential to qualify for the 

Operation S.A.F.E. emblem. The emblem is affixed to an individual aircraft only when

the aircraft, its pilot, and the operator have each met Operation S.A.F.E. guidelines.

Fly-ins have long been a popular activity among pilots. Their objectives traditionally range from getting together to swap experience and stories to socializing. 

However, among ag pilots, fly-ins 

have long been seen as a learning 

experience, an opportunity to improve 

their own performance and increase 

their professionalism.

The key to the effectiveness—

and acceptance—of aerial application 

is the spray pattern of the aircraft 

itself and the dedication of operators 

to its accuracy. Swath study and

analysis have been a part of aerial 

application since the first plane dusted 

an Ohio catalpa grove in 1921. Since

that time, scientists from land grant 

universities and private corporations, 

and aerial applicators have been active 

in improving the state-of-the-art of 

aerial application. Chemical manufacturers have worked on chemical 

Operation S.A.F.E.

(Self Regulating Application and Flight Efficiency)

(continued on next page) Paul Newby—Bozeman, MT
94 CHAPTER 6

formulations and additives to improve the pilot's ability to put the product on the target.

Today, equipment is available to provide the operator a precise picture of swath 

characteristics, and to provide it quickly. Thus, the Operation S.A.F.E. fly-in becomes a

professional application analysis clinic. The Operation S.A.F.E. clinic gives the operator

and pilot the opportunity to test equipment with a trained analyst to help interpret the 

information and to recommend changes to improve performance. A follow-up test is 

immediately available, so the operator can be certain improvement does exist.

NAAA expects all applicators to remain informed of and comply with all pertinent 

legal requirements. In addition, participating applicators agree to submit voluntarily to

an inspection of their equipment and operating procedures to determine:

•  Compliance with manufacturers’ mixing rates, application recommendations, and

label requirements of agricultural chemicals. 

•  Adequacy of safety procedures in storing and handling agricultural chemicals.

•  Compliance with flight safety procedures.

The NAAA urges every operator and pilot to participate in an Operation S.A.F.E.

clinic yearly. Check with your state ag aviation association to see when a clinic will be

offered in the area. Display the Operation S.A.F.E. sticker and yearly decals on the aircraft with pride. Let customers know that you have taken advantage of this opportunity 

to check equipment and refresh your skills prior to taking on their job. 
making an aerial pesticide application 95

1. The last application flight of the day:

A. Is more relaxed and requires less attention.

B. Is not as important as other flights of the

day.

C. Requires the same attention as every other

flight.

D. Should be to the most challenging field of

that day’s operation.

2. Varying the application speed without changing 

flow volume during an application will:

A. Provide a more even application.

B. Accommodate for wind direction changes.

C. Result in uneven coverage.

D. Increase off-target drift potential.

3. The application pattern that helps to avoid 

flying through spray from a previous swath 

is the:

A. Race track pattern.

B. Back and forth pattern.

C. Alternate swath pattern.

D. Upslope pattern.

4. Ferrying flights must be made at an altitude of 

at least:

A. 8 to 10 feet.

B. 100 feet.

C. 500 feet.

D. 1500 feet.

5. Ferrying flights that pass over areas where people 

live or work should:

A. Follow the same route in each direction for

all trips.

B. Be varied by 1/8 to 1/4 mile for each trip.

C. Follow the same route each time to the field,

but vary the route when returning to base.

D. Follow a different route each time to the

field, but use the same route for each return 

to base.

6. Breaks seen in the normal cultivation patterns 

of a field may alert the pilot to:

A. Changes in soil type.

B. Problems with field cultivation equipment.

C. Hidden hazards.

D. Changes in the needed application volume.

7. Too wide or too narrow overlapping of spray 

passes will result in:

A. Flight hazards.

B. Increased chances of off-target drift.

C. Uneven application patterns.

D. Disabling of the DGPS system.

8. To avoid the adverse effect of headwinds 

or tailwinds on an application volume, you 

should fly:

A. Into the wind.

B. Against the wind at all times.

C. Back and forth, alternating between into the 

wind and against the wind.

D. Crosswind or 45 degrees to the crosswind.

CHAPTER 6: Making an Aerial Pesticide 

Application

Review Questions
96 CHAPTER 6

9. Which of the following would have little 

effect on the safety and effectiveness of 

an application if changes occur during the 

operation?

A. Moving the operation to a different mixingloading location.

B. Wind intensity increases.

C. Delaying the application until field workers

leave the area.

D. Leaving a buffer area adjacent to a sensitive 

area.

10. The problem with flying too low when making 

a granule application is that:

A. Granules are still moving vertically at lower

heights.

B. Granules are still moving horizontally at

lower heights.

C. Even granule dispersal is affected by the 

ground effect at lower heights.

D. Propwash has a greater effect on granules at 

lower heights.

REVIEW QUESTION ANSWERS ON PAGE 97
Review Question answers 97

Review Question Answers

Chapter 1 1. b

2. d

3. b

4. a

5. d

6. a

7. c

8. a

9. b

10. c

Chapter 2 1. a

2. b

3. d

4. c

5. a

6. a

7. c

8. d

9. d

10. c

Chapter 3 1. c

2. b

3. c

4. a

5. c

6. d

7. b

8. c

9. d

10. c

Chapter 4 1. d

2. c

3. c

4. b

5. c

6. b

7. c

8. b

9. a

10. c

Chapter 5 1. c

2. c

3. b

4. b

5. a

6. c

7. b

8. c

9. c

10. b

Chapter 6 1. c

2. c

3. a

4. c

5. b

6. c

7. c

8. d

9. a

10. b
98 appendix 1

Alabama

Plant Protection and Pesticide Management Section 

Alabama Department of Agriculture and Industries 

P.O. Box 3336 

Montgomery, AL 36109-0336

(334) 240-7236

Alaska

Environmental Health 

Alaska Department of Environmental Conservation 

555 Cordova 

Anchorage, AK 99501-2617

(907) 269-1099

Arizona

Environmental Services Division 

Arizona Department of Agriculture 

1688 West Adams Street 

Phoenix, AZ 85007-2617

(602) 542-3575

Arkansas

Arkansas State Plant Board 

P.O. Box 1069 

Little Rock, AR 72203-1069

(501) 225-1598

California

California Department of Pesticide Regulation 

1001 I Street 

P.O. Box 4015 

Sacramento, CA 95812-4015

(916) 445-4000

Canada

Pest Management Regulatory Agency 

Health Canada 

2720 Riverside Drive D765 

Ottawa, ON K1A 0K9 

Canada

(613) 736-3662

Colorado

Division of Plant Industry 

Colorado Department of Agriculture 

700 Kipling Street, Suite 4000 

Lakewood, CO 80215-8000

(303) 239-4138

Connecticut

Waste Engineering and Enforcement Division 

Department of Environmental Protection 

79 Elm Street 

Hartford, CT 06106-5127

(860) 424-3264

Delaware

Delaware Department of Agriculture 

2320 South Dupont Highway 

Dover, DE 19901-5515

(302) 698-4570

District of Columbia

Department of Health

Environmental Health Administration 

Toxic Substance Division

Pesticide Program 

51 N Street NE, 3rd Floor, Room 3003 

Washington, DC 20002

(202) 535-2280

Florida

Department of Agricultural Environmental Services 

Florida Department of Agriculture and 

 Consumer Services 

3125 Conner Blvd - Suite F, Room 130 - C16 

Tallahassee, FL 32399-1650

(850) 488-3731

Georgia

Plant Industry Division 

Georgia Department of Agriculture 

Capitol Square 

Atlanta, GA 30334-4201

(404) 656-1265

Hawaii

Plant Industry Division 

Hawaii Department of Agriculture 

1428 South King Street 

Honolulu, HI 96814-2512

(808) 973-9535

Idaho

Division of Agricultural Resources 

Idaho Department of Agriculture 

P.O. Box 790 

Boise, ID 83701-0790

(208) 332-8531

Illinois

Bureau of Environmental Programs 

Illinois Department of Agriculture 

P.O. Box 19281 

Springfield, IL 62794-9281

(217) 785-2427

Indiana

Indiana State Chemist Office 

175 South University Street 

Purdue University 

West Lafayette, IN 47907-2063

(765) 494-1492

Iowa

Consumer Protection and Industry Services Division 

Iowa Department of Agriculture and 

 Land Stewardship 

Wallace Building, 502 East 9th Street

Des Moines, IA 50319-0051

(515) 281-8610

pesticide regulatory agency

contact information

appendix 1
APPENDIX 1 99

Kansas

Kansas Department of Agriculture 

901 South Kansas Avenue 

Topeka, KS 66612-1281

(785) 296-3556

Kentucky

Division of Consumer and Environmental Protection 

Kentucky Department of Agriculture 

107 Corporate Drive 

Frankfort, KY 40601-1108

(502) 573-0282

Louisiana

Pesticide and Environmental Programs 

Louisiana Department of Agriculture and Forestry 

P.O. Box 3596 

Baton Rouge, LA 70821-3596

(225) 925-3763

Maine

Board of Pesticides Control 

Maine Department of Agriculture 

28 State House Station 

Augusta, ME 04333-0028

(207) 287-2731

Maryland

Office of Plant Industries and Pest Management 

50 Harry S. Truman Parkway 

Annapolis, MD 21401-7080

(410) 841-5870

Massachusetts

Division of Regulatory Services 

Massachusetts Department of Agricultural 

Resources 

251 Causeway Street, Suite 500 

Boston, MA 02114-0009

(617) 626-1771

Michigan

Pesticide and Plant Pest Management Division 

Michigan Department of Agriculture 

P.O. Box 30017 

Lansing, MI 48909-7517

(517) 373-4087

Minnesota

Pesticide and Fertilizer Management Division 

Minnesota Department of Agriculture 

625 Robert Street North 

St. Paul, MN 55155-2538

(651) 201-6615

Mississippi

Bureau of Plant Industry 

Mississippi Department of Agriculture and 

Commerce 

P.O. Box 5207 

Mississippi State, MS 39762-5207

(662) 325-8789

Missouri

Plant Industries Division 

Missouri Department of Agriculture 

P.O. Box 630 

Jefferson City, MO 65102-0630

(573) 751-2462

Montana

Agricultural Sciences Division 

Montana Department of Agriculture 

P.O. Box 200201 

Helena, MT 59620-0201

(406) 444-2944

Nebraska

Nebraska Department of Agriculture

Bureau of Plant Industry 

301 Centennial Mall 

P.O. Box 94756 

Lincoln, NE 68509-4756

(402) 471-2394

Nevada

Division of Plant Industry 

Nevada Department of Agriculture 

350 Capital Hill Avenue 

Reno, NV 89502-2923

(775) 688-1182

New Hampshire

Division of Pesticide Control 

New Hampshire Department of Agriculture, 

Markets, and Food 

P.O. Box 2042 

Concord, NH 03302-2042

(603) 271-3640

New Jersey

Pesticide Control

Coastal and Land Use Enforcement 

New Jersey Department of Environmental 

Protection 

P.O. Box 411 

Trenton, NJ 08625-0411

(609) 984-2011

New Mexico

Division of Agricultural and Environmental Services 

New Mexico Department of Agriculture 

P.O. Box 30005, Department 3AQ 

Las Cruces, NM 88003-8005

(505) 646-2133

New York

Division of Solid and Hazardous Materials 

New York State Department of Environmental 

Conservation 

625 Broadway, 9th Floor 

Albany, NY 122337250

(518) 402-8651

North Carolina

Structural Pest Control and Pesticides Division 

North Carolina Department of Agriculture and 

Consumer Services 

1090 Mail Service Center 

Raleigh, NC 27699-1090

(919) 733-3556

North Dakota

Plant Industries 

North Dakota Department of Agriculture 

600 East Boulevard, 6th Floor 

Bismarck, ND 58505-0020

(701) 328-4756
100 APPENDIX 1

Ohio

Division of Plant Industry 

Ohio Department of Agriculture 

8995 East Main Street 

Reynoldsburg, OH 43068-3399

(614) 728-6383

Oklahoma

Consumer Protection Services Division 

Oklahoma Department of Agriculture, Food, and 

Forestry 

P.O. Box 528804 

Oklahoma City, OK 73152-8804

(405) 522-5879

Oregon

Pesticides Division 

Oregon Department of Agriculture 

635 Capitol Street, NE 

Salem, OR 97301-2532

(503) 986-4635

Pennsylvania

Bureau of Plant Industry 

Pennsylvania Department of Agriculture 

2301 North Cameron Street 

Harrisburg, PA 17110-9408

(717) 772-5217

Puerto Rico

Analysis and Registration of Agricultural Materials 

Puerto Rico Department of Agriculture 

P.O. Box 10163 

Santurce, PR 00908-1163

(787) 796-1710

Rhode Island

Division of Agriculture and Resource Marketing 

Rhode Island Department of Environmental 

Management 

235 Promenade Street 

Providence, RI 02908-5767

(401) 222-2782

South Carolina

Regulatory and Public Service Programs 

Clemson University 

109 B Barre Hall 

Clemson, SC 29634

(864) 656-1234

South Dakota

Office of Agronomy

Division of Agricultural Services 

South Dakota Department of Agriculture 

Foss Building, 523 East Capitol 

Pierre, SD 57501-3182

(605) 773-4432

Tennessee

Tennessee Department of Agriculture 

Division of Regulatory Services 

P.O. Box 40627, Melrose Station 

Nashville, TN 37204-0627

(615) 837-5152

Texas

Texas Department of Agriculture 

Pesticide Programs Division 

P.O. Box 12847 

Austin, TX 78711-2847

(512) 463-7504

Utah

Utah Department of Agriculture and Food 

350 North Redwood Road 

P.O. Box 146500 

Salt Lake City, UT 84114-6500

(801) 538-7180

Vermont

Vermont Agency of Agriculture, Food, and Markets 

116 State Street, Drawer 20 

Montpelier, VT 05620-2901

(802) 828-2431

Virgin Islands

Division of Environmental Protection 

Department of Planning and Natural Resources 

Cyril E. King Airport 

St. Thomas, VI 00802

(340) 774-3320

Virginia

Office of Pesticide Services 

Virginia Department of Agriculture 

 and Consumer Services 

P.O. Box 1163, 102 Governor Street, Room 149 

Richmond, VA 23218-1163

(804) 371-6561

Washington

Pesticide Management Division 

Washington Department of Agriculture 

P.O. Box 42589 

Olympia, WA 98504-2589

(360) 902-2011

West Virginia

Regulatory and Environmental Affairs Division 

West Virginia Department of Agriculture 

1900 Kanawha Boulevard East 

Charleston, WV 25305-0190

(304) 558-2208

Wisconsin

Agriculture Resource Management Division 

Wisconsin Department of Agriculture

Trade and Consumer Protection 

P.O. Box 8911 

Madison, WI 53708-8911

(608) 224-4567

Wyoming

Technical Services 

Wyoming Department of Agriculture 

2219 Carey Avenue 

Cheyenne, WY 82002-0100

(307) 777-6574
APPENDIX 2 101

FAA Requirements for Agricultural

Aircraft Operators

appendix 2

The FAA’s approach for evaluating and 

determining your ability to comply with 

Part 137 and other applicable regulations focuses on three categories: the 

pilot, the aircraft, and the operation. 

You must successfully satisfy each of the 

following five phases in the evaluation 

process to become a certified agricultural aircraft operator: 

•  Pre-application.

•  Formal application.

•  Document compliance.

•  Demonstration and inspection.

•  Certification.

For complete and helpful information on the process to follow to obtain 

an FAA pilot certification for agricultural operations, refer to FAA Advisory 

Circular 137-1A—Certification Process 

for Agricultural Aircraft Operators. 

You may obtain this document and 

application forms from the local Flight 

Standards District Office (FSDO). For 

the nearest FSDO office, check the FAA 

listing in the United States Government 

section of the local telephone directory.

The Pre-Application 

Process

Pre-application involves an 

informal meeting to provide you with 

an overview of the certification process 

and identify the necessary resources 

helpful to you as you go through the 

certification process. If you are familiar 

with all of the requirements of the agricultural aircraft operation’s certification 

process and the required documentation 

(e.g., if you have previous experience as 

an agricultural aircraft operator), you 

may not need a pre-application meeting. 

During the meeting, an official 

from the FSDO will determine if you 

meet the eligibility requirements for 

obtaining an operator certificate by 

asking you about the following: 

•  Your area of operation.

•  Location of your home base of

operations.

•  Location of probable satellite sites

for your operation.

•  Type of operation—private or

commercial.

•  Your experience with dispensing

pesticides or other agricultural 

materials.

•  Whether you are operating as an

individual, a corporation, or a 

partnership.

•  Your previous experience as an

agricultural aircraft operator.

•  Category and class of aircraft you

are operating (rotary- or fixedwing).

•  Qualifications and experience of

your chief supervisor.

•  Applicability of parts 91 and 137 to

the proposed type of work.

•  Any previous o r pending

enforcement action pertaining to 

you, your management personnel, 

or chief supervisor.

Depending on the size and scope 

of your proposed operation, you may 

need to prepare a letter of intent as part 

of the required documentation for your 

application. When required, the letter 

of intent must include:

•  The specific type of agricultural

aircraft operator certificate for 

which you are applying (commercial or private).

•  The legal company name of your

company and any “doing business 

as...” names.

•  Address of your home base of

operations.

•  Primary airport address, mailing

address, and telephone numbers.
102 APPENDIX 2

•  Type of aircraft proposed for the

operation.

•  The estimated date when operations or services will begin.

•  The names and addresses of all

management personnel or chief 

supervisor.

•  Names of three people you designate to provide certificate letters, 

in order of preference.

•  A copy of the articles of incorporation if the operation is a 

corporation.

Formal Application

The next step is to fill out and 

submit three copies of FAA Form 

8710-3—Agricultural Aircraft Operator 

Certificate Application, along with your 

Letter of Intent (if applicable) and other 

requested documents to the appropriate 

FAA Flight Standards District Office. 

You may obtain this form from the local 

FSDO or download it from the FAA web 

site (http://www.faa.gov) by typing in 

“FAA Form 8710-3” in the search box.

Document Compliance

A certification team assigned to you 

will review your application and associated documents within 30 business 

days of receiving it. They will notify 

you in writing whether the formal 

application is accepted or rejected. If 

the application is inaccurate, not completed properly, or does not include all 

the required documentation, the team 

returns the application to you with a 

letter outlining unsatisfactory items. 

You must correct these items before 

your certification process continues.

Demonstration and 

Inspection

This phase includes inspection of 

your facilities and aircraft. The team 

inspects your home base of operations 

for compliance with applicable operating 

procedures. The size and complexity of 

your operation determines the extent 

of the inspection required at your base. 

You must demonstrate to inspectors 

that you can conduct operations to the 

highest degree of safety.

You must provide for inspection 

at least one certificated and airworthy 

aircraft that is equipped for aerial agricultural work that you will use in your or 

your employer’s pest control operation. 

An Airworthiness Inspector verifies 

that the aircraft is properly certificated 

and airworthy, its inspection status is 

current, and it is safe for operation.

Inspectors look at five areas during 

this inspection:

•  The commercial applicator record

keeping system being used.

•  Methods used for informing

personnel of their duties and 

responsibilities.

•  Aircraft condition and airworthiness.

•  Facilities (if applicable).

•  Your knowledge and skills.

If you work as a pilot-in-command 

for an agricultural operator, then the 

operator or a person designated by that 

operator determines your knowledge 

and skills. Once you successfully demonstrate that you have the necessary 

knowledge and skills, the operator provides you with an endorsement letter.

Application Record Keeping

You must show examples of a 

record keeping system you have in 

place for your aerial application operation. The law requires you to keep 

these operation records for at least 12 

months or longer. Since record keeping 

requirements vary by state, check the 

requirements in the state where you 

are conducting business. These records 

should include the:

•  Name and address of each person

for whom agricultural aircraft services were provided.

•  Date of the service.

•  Name and quantity of the pesticides and other agricultural 

material dispensed for each operation conducted.

•  Name, address, and certificate

number of each pilot used in agricultural aircraft operations and the 
APPENDIX 2 103

date that pilot met the knowledge 

and skills requirements of 14 CFR 

§ 137.19(e).

•  Additional information depending

on state requirements.

Informing Personnel of Their 

Duties and Responsibilities

You must provide inspectors with 

documentation that shows how you 

have informed each person employed in 

your agricultural aircraft operation of 

their duties and responsibilities for the 

operation. The EPA Worker Protection 

Standard mandate for documenting 

pesticide handler training in agricultural operations satisfies some of these 

requirements. 

Aircraft

A n A irworthiness Inspector 

inspects the aircraft, aircraft records, 

and dispensing equipment. The 

inspector verifies the following to 

determine the aircraft is safe to conduct 

the proposed operation:

•  You have up-to-date and complete

aircraft maintenance records.

•  The aircraft complies with all

applicable airworthiness directives.

•  The aircraft meets certification

and airworthiness requirements.

•  The aircraft inspection is up-todate.

•  The aircraft has approved and

properly labeled seat belts and 

shoulder harnesses installed for 

each pilot station.

•  The aircraft is appropriately

equipped for agricultural operations.

•  If the aircraft is equipped to release

the tank or hopper as a unit, it is 

equipped to prevent inadvertent 

release by the pilot or other crewmember.

•  The aircraft is in a condition for

safe operation.

Should questions arise concerning 

the load jettisoning capability of the 

aircraft used in congested-area operations, you must present jettisoning test 

data that show the aircraft is equipped 

with a device capable of jettisoning at 

least one-half of the aircraft’s maximum 

authorized load of agricultural materials 

within 45 seconds. Jettisoning does not 

apply to rotary-wing aircraft.

Facilities

FAA regulations do not specify 

the type of facilities you must have as 

an agricultural operator. State and local 

regulations and, to some extent, EPA 

regulations address requirements for 

facilities. The FAA facilities inspection 

verifies that the practices and procedures at the base of operations conform 

to FAA regulations. 

Knowledge Test

The Operations Inspector conducts a knowledge and skills test during 

initial certification. As required by § 

137.19(e), you or your designated chief 

supervisor will be the testing candidate. 

This requirement applies to applicants 

who seek either a private or a commercial operating certificate. 

The objective of the knowledge 

and skills test is to evaluate the pilots 

in an operation and to assure that they 

are qualified to act as pilot-in-command 

of an agricultural aircraft. A pilot who 

was previously qualified under part 137 

may not have to take the knowledge and 

skills test if proper documentation is 

available. 

The pilot must have adequate 

knowledge of the aircraft’s operating 

limitations to be used under the applicable requirements contained in 14 

CFR part 91, § 91.9. Weight and balance 

information receives special emphasis. 

Knowledge of the aircraft’s performance capability is required and 

includes: 

•  Stall speeds at maximum certificated gross weight, straight ahead, 

power off, and flaps up.

•  Best rate and best angle of climb

speed.

•  Maneuvering speeds.

•  Density altitude and its effect on

performance.
104 APPENDIX 2

•  Performance capabilities and operating limitations of the aircraft to 

be used.

•  Takeoff distance required to clear

a 50-foot obstacle at maximum 

certificated gross weight with zero 

wind.

In addition, you must demonstrate 

your knowledge of the following limitations and restrictions applicable to 

agricultural aircraft operations: 

•  Passenger carrying.

•  Weight and balance.

•  Operating without position lights.

•  Dispensing in congested areas.

•  Not observing standard airport

traffic patterns.

•  Altitude during ferrying to and

from dispensing sites.

Before an applicator credential 

is awarded for dispensing pesticides, 

you must demonstrate a thorough 

knowledge of methods to protect a pilot 

against contamination and methods of 

safe pesticide use and handling. The 

knowledge test may be written or given 

orally, and consists of the following 

subject areas:

•  Steps to take before starting

operations, including surveying 

the area to be treated.

•  Handling pesticides and proper

disposal of used containers.

•  Pesticide hazards and precautions

when handling and applying 

pesticides.

•  Recognizing symptoms of pesticide

exposure, appropriate first aid, and 

how to contact a poison control 

center.

•  Safe flight and application procedures.

•  State-specific laws and regulations.

Skills Test

You perform the skills test with the 

aircraft’s tanks or hoppers loaded, using 

a suitable inert material such as water, 

lime, or sand. The examiner evaluates 

your piloting skills and operational 

judgment in the following areas: 

•  Ground crew coordination and

loading procedures.

•  Engine start, warm-up, and taxi

procedures.

•  Fixed-wing aircraft short-field

and soft-field takeoffs, directional 

control, liftoff, and climb.

•  Approaches to the working area.

•  Flareout.

•  Swath runs.

•  Pull ups and turnarounds.

•  Clean-up swath or trim passes.

•  Jettisoning of remainder of load

after swath runs in the event of 

in-flight emergency.

•  Rotary-wing aircraft rapid

deceleration or quick stops.

•  A pproach, touchdow n, a nd

directional control on landing.

•  Taxi, engine shutdown, and

securing of aircraft.

Certification

The FA A awards you t he 

Agricultural A ircraft Operator’s 

Certificate after the FSDO certification team concludes that you meet 

the qualifications listed above and you 

demonstrated that you have the necessary knowledge and skills or have a 

knowledge and skills endorsement from 

the operator of the firm for whom you 

are working. 
APPENDIX 3 105

Heat stress occurs when the body is 

subjected to a level of heat with which it 

cannot cope. With heat stress, the heat, 

not pesticide exposure, causes certain 

symptoms. Wearing personal protective 

equipment—clothing and devices that 

protect the body from contact with 

pesticides—can increase the risk of heat 

stress by limiting the body’s ability to 

cool down. 

Avoiding Heat Stress

Several factors work together to 

cause heat stress. Before beginning a 

pesticide-handling task, think about 

whether any of the following conditions 

are likely to be a problem that might 

lead to heat stress: 

•  Heat fac tors— temperat u re,

humidity, air movement, and 

sunlight.

•  Workload—the amount of effort

a task takes.

•  Personal protective equipment

(PPE).

•  Drinking water intake.

•  Scheduling.

Heat and Workload

High temperatures, high humidity, 

and sunlight increase the likelihood of 

heat stress, although air movement from 

wind or from fans may provide cooling. 

Because hard work causes the body to 

produce heat, a person is more likely 

to develop heat stress while working 

on foot than while driving a vehicle. 

Lifting or carrying heavy containers or 

equipment also increases the likelihood 

of overheating.

Signs and Symptoms of Heat Stress

Heat stress, even in mild forms, 

makes a person feel ill and impairs his or 

her ability to do a good job. They may 

get tired quickly, feel weak, be less alert, 

and be less able to use good judgment. 

Severe heat stress (heat stroke) is a 

serious illness. Unless you cool a heat 

stress victim quickly, he or she can die. 

Severe heat stress is fatal to more than 

10 percent of its victims, even young, 

healthy adults. Victims may remain sensitive to heat for months and be unable 

to return to the same type of work.

Learn the signs and symptoms of 

heat stress and take immediate action 

to cool yourself or another person down 

if these symptoms appear. Signs and 

symptoms may include:

•  Fatigue (exhaustion, muscle

weakness).

•  Headache, nausea, and chills.

•  Dizziness and fainting.

•  Loss of coordination.

•  Severe thirst and dry mouth.

•  Altered behavior (confusion,

slurred speech, quarrelsome or 

irrational attitude).

Heat cramps are another type of 

heat stress. These are painful muscle 

spasms in the legs, arms, or stomach 

caused by loss of body salts through 

heavy sweating. To relieve cramps, 

drink cool water. Stretching or 

kneading the muscles may temporarily 

relieve the cramps. If there is a chance 

that stomach cramps are pesticiderelated rather than caused from salt 

loss, get medical help right away.

First Aid for Heat Stress

It is not always easy to tell the difference between heat stress illness and 

pesticide poisoning because many signs 

and symptoms are similar. Get medical 

help right away rather than wasting 

time trying to decide what is causing 

the illness. First aid for heat stress 

includes:

•  Get the victim into a shaded or

cool area.

HEAT stress

appendix 3
106 APPENDIX 3

•  Cool the victim as rapidly as possible by sponging or splashing 

the skin, especially around the 

face, neck, hands, and forearms, 

with cool water or, when possible, 

immersing in cool water.

•  Carefully remove all PPE and any

other clothing that may be making 

the victim hot.

•  If conscious, have the victim drink

as much cool water as possible.

•  Keep the victim quiet until help

arrives.

Severe heat stress (heat stroke) is a 

medical emergency. Unless you cool the 

victim immediately, brain damage and 

death may result.
APPENDIX 4 107

Steps to Follow in Cleaning Up

a Pesticide Spill

appendix 4

The following steps should be taken 

whenever a pesticide spill takes place. 

For large spills, contact local authorities 

for assistance in management, prevention of injuries, and protection of 

the environment.

•  Refer to the pesticide label to

determine the PPE required for 

cleaning up a spill.

•  Clear the area and keep unprotected people from coming near 

the spill.

•  Administer first aid and obtain

medical care for anyone who 

received, or possibly received, a 

pesticide exposure.

•  Prevent fires by extinguishing

sources of ignition and providing 

adequate ventilation.

•  Control the release. Use any

strtegy available to stop the flow of 

the spill.

•  Contain the release. Use sand or

other absorbent to keep the pesticide confined. Patch the leaking 

container or transfer its contents 

to a sound container.

•  Clean up the spilled pesticide and

absorbent and any contaminated 

objects. Place these materials into 

a sealable and suitable holding 

container.

•  Clearly label containers holding

spilled pesticide and contaminated 

soil and other objects. Include the 

pesticide name, signal word, and 

name of responsible party.

•  Manage the contaminated area.

Consult the product label and 

Material Safet y Data Sheet 

(MSDS) for the particular product. 

Consult with the state regulatory 

agency on how to properly manage 

the release and how to properly 

dispose of recovered product and 

other items such as contaminated 

soil and absorbents.
108 APPENDIX 5

GLOBAL POSITIONING SYSTEMS

appendix 5

A global positioning system (GPS) provides one of the most accurate meth-ods 

of navigation for aerial pesticide applications. A receiver installed in the aircraft 

picks up satellite signals that let you 

know the speed of the aircraft, direction 

of travel, and its altitude and location. 

Because of the usefulness of this information, GPS equipment, in most cases, 

is an essential tool for precision aerial 

application. Recent studies indicate that 

at least 92 percent of agricultural pilots 

in the U.S. use GPS equipment.

A GPS receiver uses satellitetransmitted data to calculate its own 

current location. In order to find its 

exact location, the receiver must simultaneously detect identification signals 

from four different GPS satellites. The 

time it takes signals to travel from three 

of the GPS satellites form the basis for 

the calculations performed by the GPS 

receiver to determine its three-dimensional spatial location. Signals from the 

fourth satellite verify time signals from 

the three other satellites. 

The U.S. Department of Defense 

created the Global Positioning System 

program in 1973. The original intent of 

this program was to provide a satellitebased navigational system for military 

purposes. Although various aspects of 

GPS technology are now readily accessible to the public, the U.S. Department 

of Defense continues to fund and 

manage the GPS program.

The Global Positioning System can 

rapidly reference any specific location 

on Earth. Functionally, the GPS system 

consists of three major components or 

segments:

•  Space Segment—a constellation of

24 Earth-orbiting satellites.

•  Control Segment—five Earthbased satellite monitoring stations.

•  User Segment—individual GPS

signal receivers owned and 

operated by users.

Space Segment

The Department of Defense began 

launching Earth-orbiting GPS satellites in February 1989 and completed 

this task in June 1993 with 24 satellites in orbit. Each satellite completes 

one orbit around the Earth every 12 

hours, remaining in one of six orbital 

paths. Relative to the Earth’s surface, 

the six orbital paths are equidistantly 

spaced at 60-degree intervals and each 

orbital path is inclined approximately 

55 degrees relative to the Earth’s equatorial plane. This satellite arrangement 

enables a GPS user to access between 

five and eight satellites at any one time.

Control Segment

The control segment consists of 

five Earth-based tracking stations. 

Stations are located in Hawaii, on 

Ascension Island in the middle of the 

South Atlantic Ocean, on the island of 

Diego Garcia in the middle of the Indian 

Ocean, on Kwajalein Atoll (2,100 miles 

southwest of Hawaii and 1,400 miles 

east of Guam) in the Pacific Ocean, and 

in Colorado Springs, Colorado.

The Colorado Springs location 

is the master station. All the tracking 

stations monitor the satellites and 

determine precise orbit location data. 

The Colorado Springs master station 

sends corrections for orbital location 

and clock data to all satellites in the 

system. This information enables a 

satellite to send an up-to-date subset 

of satellite location and time data to a 

user’s GPS receiver.

User Segment

The user segment is the worldwide 

total of all GPS receivers currently in 

service. This includes government, 

military, and civilian users. Seagoing 

vessels, trains, trucks, mass transit 

busses, cars, farm equipment, motorcycles, commercial airliners, general 

aviation aircraft, and agricultural air-
APPENDIX 5 109

craft use GPS signals for navigation. In 

addition, GPS units provide useful data 

for many purposes other than navigation, such as:

•  A universal and instantly available

global time reference having 

atomic clock accuracy.

•  A basis for precision map construction.

•  A way to precisely measure movements of geological formations.

•  The ability to track all of the individual vehicles within an entire 

fleet, such as with taxicabs or fire 

trucks.

•  The guidance needed for an aircraft to execute an accurate and 

safe landing under local zero visibility conditions.

•  The ability to provide aircraft

speed and location in real time for 

agricultural aircraft to automatically and continuously regulate 

spray output as a function of the 

actual travel speed and position of 

the aircraft.

Differential GPS

Each GPS satellite broadcasts 

signals over two microwave frequency 

channels. One channel carries a strong 

signal that only the military uses. The 

signal of the second channel, known 

as the coarse acquisition (C/A) signal, 

is less robust. This signal is available 

for nonmilitary GPS use, although 

calculations based on it do not provide 

pinpoint precision of the GPS receiver 

location. C/A signals typically provide 

location precision in a range of ± 100 

feet horizontal accuracy. This level of 

precision is not accurate enough for 

aerial pesticide application.

To improve accuracy of the 

C/A signal, a technology known as 

Differential GPS (DGPS) provides 

greater precision. DGPS technology 

with a strong differential correction 

signal reduces the horizontal error 

range down to between less than three 

feet and rarely more than ten feet. Aerial 

applicators use DGPS systems.

Regular GPS relies on a single 

receiver, but DGPS technology requires 

two. One receiver remains fixed at an 

accurately surveyed location, and serves 

as a reference point. Aircraft have the 

second receivers installed in them. Both 

of these receivers detect the same C/Asignals from orbiting satellites, but the 

stationary receiver transmits data to 

refine the mobile receiver’s positioning 

information. Although the stationary 

receiver cannot determine which particular GPS satellites a mobile receiver 

uses, it detects all accessible satellites, 

computes the timing signal correction 

factor for each, and transmits the correction data to the aircraft’s mobile 

receiver, which sorts out the satellite 

data.

DGPS providers transmit the correction signals from stationary GPS 

receivers to mobile receivers over a widerange communication network. Two 

transmission methods predominate:

•  FM radio tower beacon (e.g., U.S.

Coast Guard Differential GPS 

Navigation Service; Nationwide 

Differential GPS Service).

•  Communication satellite relay (e.g.,

Wide Area Augmentation System 

(WAAS) and various commercial 

DGPS services).

Wide Area Augmentation System

Because GPS alone did not meet 

navigation requirements of the Federal 

Aviation Administration for accuracy, 

integrity, and availability, the FAA 

and the Department of Transportation 

(DOT) developed the Wide Area 

Augmentation System (WAAS) for use 

in precision flight approaches. WAAS 

corrects for GPS signal errors caused 

by ionospheric disturbances, timing, 

and satellite orbit errors, and it provides 

vital integrity information regarding 

the status of each GPS satellite.

WAAS consists of approximately 

25 ground reference stations positioned 

across the United States, covering a 

very large service area. These stations 

link together and form the U.S. WAAS 

network. Two master stations, one 

located on the East Coast and the other 

on the West Coast, collect data from 

the reference stations and create a correction message that they transmit to a 
110 APPENDIX 5

geostationary communication satellite 

(GEO). The satellite broadcasts the 

message on the same GPS frequency 

to receivers onboard aircraft that are 

within the broadcast coverage area of 

the WAAS.

The WAAS improves basic GPS 

accuracy to approximately 28 feet vertically and horizontally, improves the 

availability of the signals using geostationary communication satellites, 

and provides necessary integrity information about the entire GPS system.

For some users in the U.S., the 

position of the geostationary satellites 

over the equator makes it difficult to 

receive their signals if trees or mountains obstruct the view of the southern 

horizon. WAAS signal reception is 

ideal for open land areas and for marine 

applications.

U.S. Coast Guard Maritime 

Differential GPS Navigation Service

The U.S. Coast Guard provides 

a Maritime DGPS service for the 

Harbor and Harbor Approach phase 

of marine navigation. The Maritime 

DGPS service coverage area includes 

the coastal United States, Great Lakes, 

Puerto Rico, and most of Alaska and 

Hawaii. It consists of two DGPS control 

centers and about 65 DGPS reference 

stations. The reference stations transmit 

correction signals on U.S. Coast Guard 

radio beacon frequencies, and this 

service is available to the public.

Many GPS receivers are equipped 

with built-in radio receivers that accept 

and process GPS-satellite correction 

signal data. The position accuracy of 

the Maritime DGPS Service is within 

approximately 33 feet. If an aircraft is 

equipped with suitable DGPS receiving 

equipment, and is less than 100 miles 

from a reference station, its pilot may 

typically expect positioning accuracy 

of about 2.5 feet. For aircraft operating 

more than 100 miles away from the 

Maritime DGPS reference station, 

positioning accuracy decays at a rate 

of approximately 3 feet per 90 miles. 

Because of this distance-related decay 

in accuracy, you should obtain GPS satellite signal corrections from the closest 

Maritime DGPS reference station for 

the most accurate positioning data. The 

Nationwide DGPS program is incorporating the Maritime DGPS program 

into its system.

Nationwide DGPS Service

A 1997 federal law directed the U.S. 

Department of Transportation to work 

with several other government entities 

to develop and operate a standardized 

Nationwide DGPS Service. The goal of 

this service is to provide reliable localarea GPS-satellite signal correction 

data to the public without charge. This 

program involves the U.S. Air Force, 

U.S. Coast Guard, U.S. Army Corps of 

Engineers, the National Oceanic and 

Atmospheric Administration, the Federal 

Highway Administration, and the Federal 

Railroad Administration. When completed, the Nationwide DGPS Service 

expects to have approximately 80 DGPS 

radio beacon sites in place throughout 

the continental United States. The plan 

will provide every area in the continental 

United States with double coverage 

DGPS correction data from two landbased radio beacon towers. The program 

will ultimately include all U.S. Coast 

Guard-operated DGPS reference stations. Each Nationwide DGPS System 

radio beacon site has a 300-foot tower 

antenna that substantially increases 

the effective range available for mobile 

DGPS user reception. The signal from 

each site covers a range of 250 miles with 

enough signal strength to provide positional accuracy of about 3 feet or less.

Commercial DGPS Services

Commercial DGPS ser vices 

provide additional options for pilots 

making aerial applications in remote 

locations. These services fill in areas 

missed by the government systems. 

Most mobile DGPS equipment is compatible with the commercial DGPS 

services. Subscribing to one of these 

services provides pilots with a high 

degree of location accuracy suitable for 

precise aerial pesticide application. 
GLOSSARY 111

adjuvant. A material added to a pesticide 

mixture to improve or alter the deposition, toxic effects, mixing ability, persistence, or other qualities of the active 

ingredient.

agitation device (agitator). A mechanical 

or hydraulic device that stirs the liquid in 

a spray tank to prevent the mixture from 

separating or settling.

agricultural aircraft operations. The Federal Aviation Administration Regulation 

Part 137 of the Code of Federal Regulations Title 14 (14 CFR 137) prescribes 

rules governing agricultural aircraft operations within the United States and the 

requirements for commercial and private 

Agricultural Aircraft Operator certificates 

for those operations.

agricultural aircraft operator certificate. 

Certificate issued by the Federal Aviation Administration under provision of 

14 CFR 137 to pilots who meet specific 

requirements as provided in Part 137.

anti-drip device. A spring-loaded mechanism built into an aircraft spray nozzle 

that closes off the nozzle when the fluid 

pressure drops below a certain level. This 

prevents nozzles from dripping when the 

spray is shut off.

application pattern. The course the pilot 

follows above the area being treated 

with a pesticide. See also back and forth 

application pattern and racetrack application pattern.

application swath. See swath and swath 

width.

area of a circle.

Area = 3.14 × radius × radius (A = πr2)

area of a square or rectangle.

Area = length × width

area of a triangle.

Area = base × height divided by 2

back and forth application pattern.

Also known as a back and forth flight 

pattern. Making application swaths in a 

sequential manner by flying a swath in 

one direction and the adjacent swath in 

the opposite direction.

baffle. A structure built into an aircraftmounted spray tank that suppresses the 

sloshing of liquid in the tank, reducing the 

effect of load shift on the aircraft.

boom. A structure attached to an aircraft to 

which spray nozzles are attached.

buffer area (or zone). A part of a pestinfested area that is not treated with a 

pesticide to protect adjoining areas from 

pesticide hazards.

buffer strip. An area of a field left unsprayed 

for protecting nearby structures or sensitive areas from drift. The minimum 

buffer strip is usually one swath width.

carrier. The liquid or powdered inert substance that is combined with the active 

ingredient in a pesticide formulation. 

May also apply to the water, oil, or other 

substance that a pesticide is mixed with 

prior to application.

Code of Federal Regulations (CFR). Regulations used to enforce federal laws. The 

CFR contain sections that address aerial 

application of pesticides as well as training 

and certification of pesticide handlers.

co-distillation. A phenomenon where pesticide molecules are picked up in water 

vapor and can move off site.

Commercial Agricultural Aircraft Operator. 

A category of the FAA certification process applying to pilots for hire who make 

pesticide applications by air.

Glossary
112 GLOSSARY

commercial applicator. A person who, 

for hire, uses or supervises the use of a 

restricted-use pesticide and this definition varies among states.

conflict with labeling. Any deviation 

from instructions, requirements, or 

prohibitions of pesticide product labeling concerning storage, handling, or use, 

except: a decrease in dosage rate per unit 

treated; a decrease in the concentration 

of the mixture applied; application at a 

frequency less than specified; use to control a target pest not listed, provided the 

application is to a commodity/site that is 

listed and the use of the product against 

an unnamed pest is not expressly prohibited; employing a method of application 

not expressly prohibited, provided other 

directions are followed; mixing with another pesticide or with a fertilizer, unless 

such mixing is expressly prohibited; and 

an increase in the concentration of the 

mixture applied.

congested area. A populated area where 

personal injury or property damage 

might occur if an aircraft crashes or if the 

pesticide load must be dumped.

conventional application volume. For 

aircraft, the conventional application 

volume ranges between 5 to 15 or more 

gallons of spray per acre.

corrosive materials. Certain chemicals 

that react with metals or other materials. 

Some pesticides are corrosive, and special 

handling requirements are needed when 

using these.

coverage. The degree to which a pesticide 

is distributed over a target surface.

decontaminate. The most important 

step in reducing potential injury when 

someone has been exposed to a pesticide. 

Decontamination involves thoroughly 

washing the exposed skin with soap and 

water or flushing the exposed eye with a 

gentle stream of running water.

dehydration. The process of a plant or 

animal losing water or drying up. Dehydration is a major contributor to heat 

related illnesses in people.

density altitude. A condition where air molecules spread out or become less dense as 

altitude increases and/or as temperatures 

rise. Density altitude has an effect on the 

operational performance of an aircraft.

differential GPS (DGPS). A global positioning navigation system that relies on a mobile receiver mounted in an aircraft and a 

fixed ground-based receiver, providing a 

higher degree of positional accuracy than 

a mobile receiver used alone.

directions for use. The instructions found 

on pesticide labels indicating the proper 

procedures for mixing and application.

drift (spray). (from National Coalition on 

Drift Minimization) “The movement of 

pesticide through the air at the time of 

pesticide application or soon thereafter 

from the target site to any non- or offtarget site, excluding pesticide movements by erosion, migration, volatility, or windblown soil particles after 

application.”

driftable fine. Spray droplets that are 200 

microns in diameter or smaller.

droplet spectra. A classification of spray 

droplets into eight categories based on 

the volume median diameters of spray 

droplets. The eight categories are extra 

fine, very fine, fine, medium, coarse, very 

coarse, extra coarse, and ultra coarse.

dynamic surface tension. Variation or 

changes in the surface tension of a liquid based on the position of molecules 

of substances within droplets that alter 

surface tension.

economic poison. (1) Any substance or 

mixture of substances intended for preventing, destroying, repelling, or mitigating any insects, rodents, nematodes, 

fungi, weeds, and other forms of plant or 

animal life or viruses, except viruses on 

or in people or other animals, which the 

Secretary of Agriculture shall declare to 

be a pest, and (2) any substance or mixture of substances intended for use as a 

plant regulator, defoliant, or desiccant.

effective swath width. A swath that includes overlaps made with each pass to 

achieve a more even application.

environmental contamination. Spread of 

pesticides away from the application site 

into the environment, usually with the 

potential for causing harm to organisms.

evaporate. The process of a liquid turning 

into a gas or vapor.
GLOSSARY 113

exposure. The unwanted contact with pesticides or pesticide residues by people, 

other organisms, or the environment.

extensional viscosity. The amount of 

stretching or stringiness required for a 

droplet to break off from a stream or 

flow of liquid.

Federal Aviation Administration (FAA).

The federal agency responsible for enforcing rules affecting aircraft operations.

ferrying. The process of flying an aircraft 

from its home base to a pesticide application site and returning to its home base 

or location where the material loading 

takes place.

field worker. Any person who, for any kind 

of compensation, performs cultural activities in a field. A field worker does not 

include individuals performing tasks as 

a crop advisor, including field checking 

or scouting, making observations of the 

well being of the plants, or taking samples, nor does it include local, state, or 

federal officials performing inspection, 

sampling, or other similar official duties.

filter screen. Fine screens placed in key 

locations in a spraying system to catch 

foreign materials that would otherwise 

clog the spray nozzles.

fine. A spray droplet that is 200 microns in 

diameter or smaller.

first aid. The immediate assistance provided 

to someone who has received an exposure to a pesticide. First aid for pesticide 

exposure usually involves removal of 

contaminated clothing and washing the 

affected area of the body to remove as 

much of the pesticide material as possible. First aid is not a substitute for 

competent medical treatment.

flow rate. The amount of pesticide being 

expelled by a pesticide spray or granule 

applicator per unit of time.

general-use pesticide. Pesticides that have 

been designed for use by the general 

public as well as by licensed or certified 

applicators. General-use pesticides usually have minimal hazards and do not 

require a permit for purchase or use.

geostationary communication satellite. 

A satellite whose orbit speed exactly 

matches the rotation of the earth, and 

thus remains stationary in relation to 

the earth; used for communication and 

global positioning.

global positioning system. A navigational device that uses signals from satellites 

to determine the receiver’s position.

granule. A dry formulation of pesticide active ingredient and inert materials compressed into small, pebble-like shapes.

handle. Mixing, loading, transferring, 

applying (including chemigation), or 

assisting with the application (including flagging) of pesticides; maintaining, 

servicing, repairing, cleaning, or handling equipment used in these activities 

that may contain residues; working 

with opened (including emptied but not 

rinsed) containers of pesticides; adjusting, repairing, or removing treatment 

site coverings; incorporating (mechanical or watered-in) pesticides into the 

soil; entering a treated area during 

any application or before the inhalation exposure level listed on pesticide 

product labeling has been reached or 

greenhouse ventilation criteria have 

been met; performing the duties of a 

crop advisor, including field checking 

or scouting, making observations of 

the well being of the plants, or taking 

samples during an application or any 

restricted entry interval listed on pesticide product labeling. Handle does not 

include local, state, or federal officials 

performing inspection, sampling, or 

other similar official duties.

handler. A person involved with mixing, 

loading, transferring, applying (including chemigation), or assisting with 

the application (including flagging) 

of pesticides; maintaining, servicing, 

repairing, cleaning, or handling equipment used in these activities that may 

contain residues; working with opened 

(including emptied but not rinsed) 

containers of pesticides; adjusting, 

repairing, or removing treatment site 

coverings; incorporating (mechanical 

or watered-in) pesticides into the soil; 

entering a treated area during any application or before the inhalation exposure 

level listed on pesticide product labeling has been reached or greenhouse 

ventilation criteria have been met; and 
114 GLOSSARY

performing the duties of a crop advisor, 

including field checking or scouting, 

making observations of the well being 

of the plants, or taking samples during 

an application or any restricted entry 

interval listed on pesticide product labeling. The handler definition does not 

include local, state, or federal officials 

performing inspection, sampling, or 

other similar official duties.

heat-related illness. Potentially lifethreatening overheating of the body under working conditions that lack proper 

preventive measures, such as drinking 

plenty of water, taking frequent breaks in 

the shade to cool down, and removing or 

loosening personal protective equipment 

during breaks. 

human flagger. An individual who assists 

in an aerial application by positioning 

and waving marking flags to indicate to 

the pilot the location of swaths. Flaggers 

must receive pesticide handler training.

intentional misapplication. The deliberate improper use of a pesticide, such as 

exceeding the label rate or applying the 

material to a site not listed on the label.

inversion. A weather phenomenon in which 

cool air near the ground is trapped by 

a layer of warmer air above. Vapors of 

pesticides applied during an inversion 

can become trapped and concentrated 

and move away from the treatment area 

with the potential to cause damage or 

injury at some other location.

labeling. The pesticide product label and all 

other written, printed, or graphic matter 

accompanying the pesticide. Labeling 

may not necessarily be attached to or 

part of the container.

light bar. An accessory to the aircraft 

mounted global position system that 

enables the pilot to locate the center of 

each spray swath through the use of an 

array of lights.

low volume (LV) application volume.

Application of liquid pesticides at the 

rate of 0.5 to 5 gallons of liquid per acre.

Material Safety Data Sheet (MSDS). An 

information sheet provided by a pesticide manufacturer describing chemical 

qualities, hazards, safety precautions, and 

emergency procedures to be followed in 

case of a spill, fire, or other emergency.

mesh. The number of wires per inch in a 

screen, such as a screen used to filter 

foreign particles out of spray solutions 

to keep nozzles from becoming clogged. 

Mesh is also used to describe the size of 

pesticide granules, pellets, and dusts.

micron. A very small unit of measure: 1/1,000,000 of a meter; represented by 

the greek symbol μ.

MSDS. See material safety data sheet.

non-target organism. Animals or plants 

within a pesticide-treated area that are 

not intended to be controlled by the 

pesticide application.

off-target pesticide drift. Pesticide drift 

that moves outside of the application 

area during or immediately following a 

pesticide application.

off-target pesticide movement. Any 

movement of a pesticide from the location where it was applied. Off-target 

movement occurs through drift, volatilization, percolation, water runoff, crop 

harvest, blowing dust, and by being carried away on organisms or equipment.

output volume. The amount of a pesticide 

mixture discharged by an aircraft over a 

measure period of time. The usual output volume for aircraft liquid sprayers is 

measure in gallons per minute or gallons 

per mile.

pattern testing. The process used to 

determine the spray swath or granule 

swath pattern by flying test passes and 

visualizing the droplet array or granule 

distribution across the swath.

personal protective equipment (PPE).

Apparel and devices worn to minimize 

human body contact with pesticides or 

pesticide residues. PPE must be provided 

by an employer and is separate from, or 

in addition to, work clothing. PPE may 

include chemical resistant suits, chemical resistant gloves, chemical resistant 

footwear, respiratory protection devices, 

chemical resistant aprons, chemical resistant headgear, protective eye wear, or 

a coverall (one- or two-piece garment).
GLOSSARY 115

pesticide drift. Any movement of pesticide 

material from its intended swath during application. Movement of pesticide 

material becomes problematic when it 

moves from the application site.

pesticide handler. See handler.

phytotoxic. Injurious to plants.

pilot-in-command. The Journeymen Pest 

Control Aircraft Pilot supervising or 

conducting a pesticide application.

precautionary statement. The section on 

pesticide labels where human and environmental hazards are listed; personal 

protective equipment requirements are 

listed here as well as first aid instructions 

and information for physicians.

private agricultural aircraft operator.

A category of the FAA certification 

process applying to pilots who make 

pesticide applications by air on their 

own property or property of which they 

control.

private applicator. An individual who uses 

or supervises the use of a pesticide for 

the purpose of producing an agricultural 

commodity on property owned, leased, 

or rented by him or her or his or her 

employer. 

prop wash. The displacement of air and 

spray droplets caused by the propeller of the aircraft. The spray pattern is 

displaced to the left of the centerline of 

the aircraft.

racetrack application pattern. The application pattern that involves making 

successive overlapping loops across a 

field rather than a back and forth pattern. 

regulations. The guidelines or working 

rules that a regulatory agency uses to 

carry out and enforce laws.

residual effectiveness. The pesticidal action of material after it has been applied. 

Most pesticide compounds will remain 

active several hours to several weeks or 

even months after being applied.

restricted-entry interval (REI). The period of time after a field is treated with 

a pesticide during which restrictions on 

entry are in effect to protect people from 

potential exposure to hazardous levels of 

residues.

restricted-use pesticide. Highly hazardous 

pesticides that can only be possessed or 

used by certified commercial or private 

applicators.

rotor distortion. Similar to prop wash of 

a fixed wing aircraft, but involving the 

displacement of air and entrapped spray 

droplets as a result of the rotation of the 

rotary wing aircraft rotor.

service container. Any container designed 

to hold concentrate or diluted pesticide 

mixtures, including the sprayer tank, but 

not the original pesticide container.

shear viscosity. The resistance of a liquid 

to flow.

smoke generator. A device mounted on an 

aircraft that produces smoke by injecting 

oil into the exhaust system. This smoke 

trail is used by the pilot to visualize air 

movement.

statement of practical treatment. A section of the pesticide label that provides 

information on treating people who have 

been exposed to the pesticide. This includes emergency first aid information.

supplemental label. Additional instructions and information not found on the 

pesticide label because the label is too 

small but legally considered to be part 

of the pesticide labeling.

swath (or swath width). The area covered 

by one pass of the pesticide application 

equipment.

temperature inversion. See inversion.

ultra low volume (ULV) application 

volume. Applications of less than 0.5 

gallons of spray per acre.

volume median diameter (VMD). Half of 

the total spray volume of a nozzle consists 

of spray droplets that are smaller than the 

VMD numerical value, while the other 

half is made up of droplets that are larger 

than the VMD numerical value.

wide area augmentation system (WAAS). 

A highly accurate GPS navigational system used for precision flight positional 

determination. 

wing tip vortex. The circular or spiral 

swirling of air caused by the wing tips of 

an aircraft, and resulting in entrapment 

of spray droplets affecting the dispersal 
116 CHAPTER 7

pattern. Keeping the fixed wing aircraft 

boom length at approximately 75 percentage of the wingspan eliminates spray 

droplets becoming entrapped.

Worker Protection Standard. The 1992 

amendment to the Federal Insecticide, 

Fungicide, and Rodenticide Act (FIFRA) 

that makes significant changes to pesticide labeling and mandates specific training of pesticide handlers and workers 

in production agriculture, commercial 

greenhouses and nurseries, and forests.
INDEX 117

A

access, unauthorized 11, 17, 18, 19, 21, 31, 84

acres per minute treated, determining 68, 69, 70, 

additional labeling 12, 13

additional restrictions

pesticide label 12, 13, 22, 24, 25-26

on application 13, 22, 26, 84

adjacent

crops 25, 30, 82, 83, 84

fields 25

non-target areas 24, 25, 82, 84

swath 57, 88

adjuvant 28, 36-37, 40

drift control 37, 40

aerial application

equipment, calibrating 12, 40, 58, 63-78, 87

equipment, cleaning 26-27

operation security, evaluating 18

making 81-93, 95

aerial pest control operator 1, 9-13, 25

laws and regulations for 93, 94

aerial pesticide applicator pilot 1, 9

detailed content outline for 3-5

laws and regulations for 9-13

agitation 44, 45, 46, 52

hydraulic 46, 52

mechanical 46

tank 46

agricultural aircraft operation 101-104

FAA requirements for 10, 29, 101-104

operator certificate 101, 104

air shear 39, 40, 51, 57, 75

aircraft

crash, plans and emergency response in case of 29

factors influencing 90-92

features and limitations of 23-24

securing 18

airspeed, application 24, 27, 39-40, 47-51, 65, 69, 

 71-75, 87, 92

alcohol and drugs, avoiding use of 18, 21-22

using before or during operation 22

altitude

application 10, 64, 66, 71, 75, 83, 87

ferrying 82

American Society of Agricultural and Biological 

 Engineers 36, 37

amount of pesticide to put into the tank, 

 determining 64, 69-71

answers, review questions 96

antenna, GPS 53

anti-drip device nozzle 45, 52

application

airspeed 24, 27, 39-40, 47-51, 65-69, 71, 75, 87, 92

altitude 10, 64, 66, 71, 75, 83, 87

avoiding obstructions during 83, 87-88, 89

documenting 27-28, 54

equipment, aerial, calibrating 12, 40, 58, 63-78, 87

equipment malfunction 23, 29, 48, 49

equipment, types of 12, 43-62

height 22, 24, 28, 38, 40, 65, 68, 75, 87, 90

instructions 11, 12-13, 26

low volume 45, 47, 49-50, 51

pattern, back and forth 88-89

pattern, racetrack 88-89

pattern, turnaround 89-90

reviewing and documenting 27-28

safety 22-28

site, adjacent crops 25, 30, 82, 83, 84

site, checking 19, 25, 26, 82-83

speed 24, 27, 28, 39-40, 43, 44, 47-51, 54, 57, 64, 

 65-69, 71, 75, 87, 88, 89, 90, 92

speed, changing 71-75

swath 28, 40, 45, 51, 53, 55, 56, 57, 58, 59, 60, 65, 

 66, 67-68, 70, 75, 76-77

Index
118 INDEX

techniques 12, 40

volume 44, 49, 50, 51, 54, 55, 63, 64, 65, 66, 69, 

 71, 75, 87

what to watch for during 83-86

applying granules 57-59, 69, 75-78, 81, 86, 90, 92

area of a circle, calculating 73

area of a rectangle, calculating 71

area of a square, calculating 71

area of a triangle, calculating 72

ASABE 13, 36, 37

ASABE S-572.1 13, 36, 37

as-applied map 28, 54

associated labeling 12

atomization 39, 44, 75

avoiding heat stress 22, 105

avoiding obstructions during application 83, 87-88, 

 89

avoiding use of alcohol and drugs 21

B

back and forth application pattern 88, 89

baffle 45

boom, spray 47-48, 49, 51, 52, 53, 54-56

length of 24-25, 39, 49, 55

booms and nozzles, positioning 54-57

buffer area or zone 13, 22, 26, 40, 84, 88

buffer strip 88

C

calculating area of 

a circular application site 73

a rectangular or square application site 71

a triangular application site 72

an irregularly-shaped application site 74

calibrate equipment, why needed 64-65

calibrating

aerial application equipment 63-78

granule applicators 75-78

liquid spraying equipment 65-75

calibration

methods, equipment 65-78

reasons for 64-65

capacity, spray tank 65-66, 70

carrier, pesticide spray 37, 38, 50

catastrophic event 29

categories, standard droplet size 13, 35, 36, 37, 

 38, 39

centrifugal

spray pump 45, 46

spreader 58, 60

certificate, agricultural aircraft operator 65, 

 101-103

certification, pesticide applicator 1, 2, 10-12, 27

certified commercial applicators, general 

 standards for 11-12

changing

application speed 71

nozzle orifice size 75

output pressure 75

sprayer output 71

check valve 29, 45, 46, 47, 49, 52, 56

checking the application site 82-83

checklist

ground crew 86

pilot 85

Class II Medical Certificate 10

classification of droplet size 35-37

cleanup

kit, spill 28, 29, 107

pesticide spill 20, 107

clothing and equipment, protective 11

Code of Federal Regulations 10, 12

co-distillation 38

commercial

agricultural aircraft operator 10, 101

applicator 1, 11

DGPS services 110

pesticide applicator pilots 1

communication 18, 24, 27, 30, 81, 82, 84

communication satellite, geostationary 110

compatibility 26

competency, determination of 11

components, liquid dispersal system 44-57

conflict with labeling 27

conflicts, resolving 27

congested area 23, 103, 104

contact information, pesticide regulatory agency

 98-100

container, service 10

contamination, environmental 29, 30

content outline, detailed 3-8

controller, flow volume 49, 52, 53, 54, 57, 66, 67

conventional application volume 49
INDEX 119

corrosive pesticide materials 44

coverage, pesticide 24, 36, 39, 40, 45, 65, 75, 86, 

 87, 89

crash, aircraft, plans in case of 29

crops adjacent to the application site 25, 30, 82, 

 83, 84

cultural practices 25, 27

D

decontaminate 44

dehydration, preventing 22

density altitude 89-92

detailed content outline 3-8

determination of competency 10, 11

determining

acres per minute treated 68, 69

amount of pesticide to put into the tank 69, 70

application volume per acre 69, 70

DGPS 52, 53, 56, 64, 81, 83, 86, 90, 108, 110

service, commercial 110

differential global positioning systems 52, 109, 

 110, 112

differential GPS 52, 53, 56, 64, 81, 83, 86, 90, 108-110

diluting pesticide concentrates, knowing 

 procedures for 12

dispersal

equipment 23, 43-60

system requirements 43-60

displacement, prop wash 54, 55

distortion, rotor 55, 56

documenting

application 27-28, 54

handler training 103

drift 12, 13, 20, 23, 24, 25, 29, 33-40

control adjuvant 37, 40

factors that contribute to 34-39

minimizing off target 13, 24, 33-40, 75, 81, 86, 87

driftable fine 34, 35, 50

droplet

size and drift, external factors affecting 37

size categories, standard 37

size, classification of 35-37

size, effects of evaporation on 37-38

spectra 13, 35-37, 112

spectra, nozzle classification by 36-37

drugs, avoiding use of 18, 21-22

dry material spreaders 57-60

dynamic surface tension 36

E

economic poison 10

effective swath width 28, 40, 45, 51, 53, 55, 56, 57, 58, 

 59, 60, 65, 66, 67-68, 70, 75, 76-77

effects of evaporation on droplet size 37-38

electronics 49, 52-54, 57

emergencies

ground crew 28-29

planning for 28-30

emergency

information 28

maneuvers 23, 24

response plan 28-30

employee

habits 19, 21-22

training 19-21

endangered species area protection map 12

environmental

concerns 65

contamination 29, 30

fate of pesticides 11

Environmental Protection Agency 10

registration number 27, 28

requirements for certification 10-12

environmentally sensitive areas 25, 26

equipment

calibration methods 63-78

securing 17-19

estimating density altitude 89-92

evaporate 35, 37-38

extensional viscosity 36

external factors affecting droplet size 

and drift 37-39

F

FAA requirements for agricultural aircraft 

operators 101

facilities, securing 18

factors

influencing the aircraft 90-92

contributing to drift 34-39

fan-driven pump 44, 45, 51, 66

fan-pattern nozzles 40, 49, 50

FBI 18, 19

features and limitations of the aircraft 23-24

Federal Aviation Administration 10, 29, 52, 101
120 INDEX

federal aviation regulations 10, 29, 52, 101

Federal Bureau of Investigation 18, 19

feed rate, granule spreader 58, 60

ferrying 10, 28, 46, 81, 82

filter screen 46, 49, 56

filters and screens 46, 49, 51, 56

fines (pesticide droplet) 35, 50, 75

first aid 11, 18, 20, 24, 26, 29

and decontamination requirements 18, 20, 26

for heat stress 20, 21, 22, 113

measures 26

first and last runs of the day 82

flagger, human 29, 40, 53, 85

flight hazards 25, 28, 29, 54, 81, 83

flight pattern 24, 28, 29, 53, 58, 81, 87, 88-90

application record 27

back and forth 88-89

racetrack 88, 89

Flight Standards District Office 28, 101

flow meters, valves, and pressure gauges 48-49

flow volume 66-67

flow volume controllers 49, 53, 54

FSDO 28, 101

fuel and oil check, preflight 22

G

gallons per minute, determining 67-70

general standards for certified commercial 

 applicators 11

general types of pesticides 11

general-use pesticide 11, 13

generator, smoke 40

global positioning system 52, 53, 54, 108

differential 52, 53, 54, 108

GPS 52, 53, 54, 108

antenna 53

light bar 53

systems 53

granule 57-60

applying 57-60

calibrating applicators for 69, 75-78

spreader 57-60

ground crew

checklist 86

emergencies 28-29

member 18, 19, 21, 22, 23, 24, 25, 27, 28, 29, 30, 

 43, 56, 60, 82, 84-86

onsite, importance of during an application 84-86

ground equipment 17, 22, 23

H

habits, employee 19, 21-22

handler, pesticide 19, 20-22, 26, 29, 65

harvested crops, residues on 64

hazards, flight 25, 28, 29, 54, 81, 83, 87-88

hazards, health 11, 12, 17, 19, 20, 26, 27, 30, 84

health, human 20, 64

heat and heat stress 20, 21, 22, 113

height, application 22, 24, 28, 38, 40, 65, 68, 75, 

 87, 90

hollow-cone pattern nozzles 49, 50, 51-52

hopper, pesticide 43, 45-46, 58-60, 64, 75

human exposure, preventing 29

human flagger 29, 40, 53, 85

human health concerns 20, 64

humidity 28, 37-38, 54, 68, 92

effect on granule flow 75

pesticide label restrictions 84

hydraulic agitation 46, 52

I

illness, heat-related 20, 21, 22, 113

importance of onsite ground crew during an 

 application 84-86

interior baffles 45

inversion, temperature 34, 37, 38-39, 40, 84, 92

L

label and labeling

comprehension 11

conflict with 27

instructions 10, 11, 12, 13, 24, 25-26, 29, 30, 36, 

 43, 63, 64, 65, 68, 69, 75, 83, 84, 86

pesticide 12-13, 20, 22, 23, 24, 25-26, 29, 36, 63,

 64, 65, 68, 69, 75, 83, 84, 86

precautionary statement 13, 29

laws and regulations 9-12

local 10

leaching 33

length, spray boom 24-25, 39, 49, 55
INDEX 121

light bar, GPS 53

limitations, personal, pilot 24-25

line screens 46, 49, 56

liquid dispersal system components 43-54

liquid spraying equipment, calibrating 65-75

local laws and regulations 10

local weather conditions 25, 82, 90

low volume 45, 47, 49

LV 49, 50

M

making an aerial pesticide application 81-94

malfunction, application equipment 23, 29, 48, 49

maneuvers, emergency 23, 24

map

as-applied 28, 54

endangered species area protection 12

mapping systems 52, 53, 54

mechanical agitation 46

Medical Certificate, Class II 10

medications, over-the-counter and prescription 21

mesh 46, 51

micron 34, 35, 36

minimizing off-target drift 39-40

mixing equipment, types of 12

N

NAAA 13, 93-94

National Aerial Pesticide Applicator Pilot 

 Certification Examination 1

National Agricultural Aviation Association 13, 

93-94

National Coalition on Drift Minimization 34

National Weather Service 38

NCODM 34

negative pressure, system 46, 47

non-target organism 10, 11, 19, 21, 22, 24

notification and posting requirements 26

notification requirements 26

nozzle

anti-drip device 45, 52

classification by droplet spectra 35-37

orientation 24, 28, 35, 39-40

hollow-cone pattern 49, 50, 51-52

orifice size, changing 46, 57, 75

positioning 48, 54-60

rotary atomizer 50, 51

screen 46

straight stream 49, 50

variable flow rate 49, 50

variable orifice flood 49, 50, 51

wind shear 39, 51, 57, 75

O

obstructions, avoiding during application 83, 

 87–88, 89

off-target

drift, minimizing 33-40, 75, 81, 86, 87

pesticide drift, preventing 13, 24, 33-40, 75, 

 81-86, 87

pesticide movement 27, 29, 34, 40, 68, 87, 90

onsite ground crew, importance of during an 

 application 84-86

operating pressure, spraying system 24, 28, 36, 39, 

 40, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 57

Operation S.A.F.E. 93-94

operation, agricultural aircraft 101-104

operator, aerial pest control 1, 9-13, 25

laws and regulations for 9-13

output

changing 75

rate, spray 76

sprayer, changing 71

volume, spray 115

overcompensation, prop wash 55

overspray, drift, and other misapplication 29-30

over-the-counter and prescription medications 21

P

PAASS 13

pattern testing a spray boom 54, 55-57, 68

pattern, application

back and forth 88-89

racetrack 88-89

per acre application volume, determining 69-70

personal limitations, pilot 24-25

personal protective equipment 20, 21, 22, 26, 30

pest control operator, aerial 1, 9-13, 25

laws and regulations for 9-13

pesticide

amount to put into the tank, determining 64, 69-71

applicator certification 1, 2, 10-12, 27
122 INDEX

applicator pilot, aerial 1, 9

drift 12, 13, 20, 23, 24, 25, 29, 33-40

environmental fate 11

exposure routes 11, 20

general types of 11

handler 19, 20-22, 26, 29, 65

label 12-13, 20, 22, 23, 24, 25-26, 29, 36, 63, 64, 

 65, 68, 69, 75, 83, 84, 86

label directions 24

label restrictions, understanding 25-27

laws and regulations 9-13

poisoning symptoms 11

regulatory agency 1, 10, 11, 13, 21, 22, 39, 63

regulatory agency contact information 98

restricted-use 1, 11, 13, 27

spill, steps to follow when cleaning up 20, 107

tanks and hoppers 45

toxicity 11

uses, selective 10

pilot

aerial pesticide applicator 1, 9

checklist 85

in command 10, 101

qualifications and limitations 24-25

pipes, hoses, and fittings 46-47

piping 46, 47

planning for emergencies 28-30

plans in case of aircraft crash 29

poison, economic 10

positioning booms and nozzles 48, 54-57

positive shut-off valve 24, 47, 52

post-application volatilization 33, 34

posting requirements 26

PPE 20, 21, 22, 26, 30

preflight fuel and oil check 22

pressure gauge 48, 49

pressure

system operating 24, 28, 36, 39, 40, 44, 45, 46, 

 47, 48, 49, 50, 51, 52, 53, 54, 55, 57

system, negative 46, 47

preventing

dehydration and heat related illness 22

human exposure 29

off-target pesticide drift 13, 24, 33-40, 75, 81, 86, 87

procedures

for diluting pesticide concentrates 12

Professional Aerial Applicator’s Support System 13

prop wash 54, 55

displacement 54

overcompensation 55

protective clothing and equipment 20, 21, 22, 26, 30

pump

centrifugal 45, 46

fan-driven 44, 45, 51, 66

Q

qualifications and limitations, pilot 24-25

R

racetrack application pattern 88-89

rainfall or irrigation water 34

ram-air spreader 58-60

reasons for calibration 64, 65

record keeping 27-28

registration number, EPA 27

regulations, federal aviation 10

regulatory requirements 9-11

requirements

for certification, EPA 10-12

personal protective equipment 26

regulatory 9

residues on harvested crops 64

resolving conflicts 27

response plan, emergency 28-30

rest break 23

restricted-use pesticide 1, 11, 13, 27

review question answers 97

rotary atomizer 50, 51

rotor

distortion 55

vortex 25, 39, 55

routes of exposure, pesticide 11, 20

RUP 1, 11, 13, 27

S

S.A.F.E. 93-94

safety hazards 11, 12, 17, 19, 20, 26, 27, 30, 84

safety program, well-developed 19

scouting the target site 22, 25, 30

screen, nozzle 46
INDEX 123

securing

facilities, storage areas, and surrounding 

 property 17-19

pesticide application aircraft, vehicles, 

 and equipment 17-19

security, aerial application operation 17-19

selective pesticide uses 10

Self Regulating Application and Flight Efficiency 93

sensitive area, environmental 25, 26

service container 10

shear

viscosity 36, 37

air 39, 40, 51, 57, 75

shut-off valve, positive 24, 47, 52

smoke generator 40

soil contamination, reason for calibration 65

SOP 30

spectra, droplet, nozzle classification by 35-37

speed

application 24, 27, 28, 39-40, 43, 44, 47-51, 54, 

 57, 64, 65-69, 71, 75, 87, 88, 89, 90, 92

application, changing 71, 75

spill

cleaning up 107

cleanup kit 28, 29, 107

spray

boom 47-48, 49, 51, 52, 53, 54-56

boom length 24-25, 39, 49, 55

boom pattern testing 54, 55-57, 68

nozzle classification by droplet spectra 13, 35, 

 36, 37, 38, 39

output volume 53, 54, 57, 65, 66, 67-71, 75

pump, centrifugal 45, 46

pump, fan-driven 44, 45, 51, 66

tank vent 45

tank volume 69

volume and dilution restrictions 13

sprayer output, changing 71

spraying system operating pressure 7, 36, 57

spreader

mounting 59-60

dry material 57-60

granule 58-60

ram-air 58-60

vanes 58-59

standard droplet size categories 24, 28, 36, 39, 40,

 44, 45, 46, 47, 48, 49 50, 51, 52, 53, 54, 55, 57

standard operating procedures 30

standard S-572.1, ASABE 36-37

staying alert 22

steps to follow in cleaning up a pesticide spill 107

storage areas, securing 18

straight stream nozzle 50

suck-back 40, 43, 46, 47, 52

surface tension, dynamic 36, 37

swath

application 28, 40, 45, 51, 53, 55, 56, 57, 58, 59, 60, 

 65, 66, 67-68, 70, 75, 76-77

width, effective 55, 56, 57, 60, 66, 67-68, 69, 76, 87

symptoms of pesticide poisoning 11

synergism 11

T

tank

agitation 46

capacity 65-66, 70

pesticide 45-46

vent 45

volume 69

target site, scouting 22, 25, 30

technique, application 12, 40

temperature inversion 34, 37, 38-39, 40, 84, 92

toxicity, pesticide 11

training

handler 20-21

turnaround, application pattern 89-90

types of application and mixing equipment 12, 44-60

U

U.S. Department of Homeland Security 19

U.S. Environmental Protection Agency 10-13, 19

U.S. Federal Aviation Administration 10

ultra low volume 45, 49, 50

ULV 45, 49, 50

unauthorized access 11, 17, 18, 19, 21, 31, 84

understanding

pesticide label restrictions 25-26

the work order 23-25

using the GPS light bar 53

V

valve, positive shut-off 24, 47, 52

vanes, spreader 58-59

variable flow rate flat fan nozzle 50-51
124 INDEX

variable orifice flood nozzle 51

vent, spray tank 45

viscosity, extensional 36

viscosity, shear 37

VMD 35, 36

volatilization, post-application 33, 34

volume

application 45, 49, 50, 51, 54, 55, 63, 64, 65, 66, 

 69, 71, 75, 87

spray tank 69

volume median diameter 35, 36

vortex

rotor 25, 39, 55

wing tip 25, 39, 48, 54, 55

W

weather

conditions, local 25, 82, 90

factors 24

well-developed safety program 19

what to watch for during an application 83-86

why you need to calibrate equipment 64-65

wind shear on nozzles 39, 40, 51, 57, 75

wingtip and rotor vortex 54, 55

work crews 25

work order, understanding 23

Worker Protection Standard (WPS) 12, 20, 26