Cropdusters fondly call their craft the back-and-forth business. Or at least “aerial application,” hoping to dust off their perception as noxious tumbleweeds. In the days following September’s terrorist attacks, aerial applicators operating under FAR Part 137, except those in firefighting, were more down-and-out than back-and-forth.

Cropdusters were grounded along with all U.S. civil aircraft on September 11. They then returned to the National Airspace System on September 14. On Sunday, September 16, James Callan, executive director of the National Agricultural Aviation Association (NAAA), got a call from the FAA at 8 a.m. ordering another ground stop for agplanes.

“The FAA said [the second grounding order] was a national security issue,” said Callan. Attorney General John Ashcroft, via the FBI and then the FAA, ordered the grounding of Part 137 operations. FBI investigations had revealed that up to 15 of the suspected terrorists had toured and tried to videotape cropduster aircraft, obtained flight manuals and performance charts at USDA’s own field office and by Internet and researched chemical and fuel capacity.

Agricultural aircraft were returned to service September 17, so long as they stayed clear of Class B airspace. But they were grounded again on September 23 following new revelations. The ban was to last one day but was extended on September 24. Cropdusters finally returned in force on Tuesday, September 25, effective at 12:05 a.m. in each local time zone.

In the course of the 12-day cycle, tiedowns had become secure compounds. Owner-operators, many of whom live near their personal landing strip, tried a range of measures at the call of the NAAA. Some removed batteries, anchored props with cable locks or chains, blocked taxiways with farm trucks or front-end loaders or removed crucial engine parts at night. Others installed electronic alarms, new lighting and reinforcements to hangar locks.

In stages, each FBI discovery clouded the industry. Terrorist research had included eight weekends of visits in groups of two or three men, up to an hour each visit, to South Florida Crop Care at Belle Glade Municipal Airport, as recently as the Saturday before the attack. Belle Glade Municipal lies on land reclaimed from the Everglades, 40 mi inland of Delray Beach, where alleged hijackers attended flight school.

In April last year one suspect visited the USDA’s Florida Farm Service Agency and was referred to a community bank in Homestead to ask about loans. Used cropdusters sell for less than $100,000, and new models go from $250,000 to about $1.2 million with full avionics. No loan application was filed.

The FBI asked the NAAA to post the following message on its Web site: “Members of the agricultural aviation industry should continue to be vigilant to any suspicious activity relative to the use, training in or acquisition of dangerous chemicals or airborne application of same, including threats, unusual purchases, suspicious behavior by employees or customers and unusual contacts with the public. Members should report any suspicious circumstances or information to local FBI offices.”

Florida has since required agricultural pilots to submit their certificates and to register their N numbers so that every flight can be tracked and reported to the FBI.

Under FAR 137.3, agricultural aircraft are defined as those dispensing any substance for plant nourishment, soil treatment, pest control and “economic poison,” meaning any substance or mixture intended for preventing, destroying, repelling or mitigating any insects, rodents, nematodes, fungi, weeds and other forms of plant, animal life or viruses.

Part 137 operators have struggled for years as environmental groups protested the danger of drifting chemicals. Farmers switched to ground-based delivery systems and to new formulas requiring smaller amounts and time to apply, all equating to less billable time for pilots. Crop prices have also fallen for three years, forcing cuts. Genetically engineered crops with built-in pest resistance have additionally reduced the need for aerial treatment.

For 1999, the last year for which complete figures are available, GAMA reported that 4,254 aerial application aircraft were registered in the U.S., 603 of which were rotorcraft. Of the fixed-wing fleet, there were 3,146 pistons, 337 turboprops, 106 jets and 63 classified as experimental, all of which logged 1.415 million hours that year. The industry is barebones and independent; NAAA lists 1,250 members.
Air Tractor of Olney, Texas, produced a yearly high of about 100 airplanes in the mid-1990s, but since 1998 this rate has declined to fewer than 50. The company is working on an amphibious 10-seat turboprop for the Department of the Interior. Last year its chief competitor, Albany, Ga.-based Ayres, filed for bankruptcy protection following its damaging venture in passenger aircraft with Czech-run Let.

‘Grounding was Economic Poison’
It was the figurative “economic poison” that rallied the NAAA. President Pat Kornegay cited at risk California cotton, Midwest corn, North Carolina soybean, Texas sunflowers and Arizona produce. “The agricultural production of this nation will wilt on the vine, the forest fires will consume our wilderness and an industry that has always been essential to the production of food and fiber will be destroyed,” warned Kornegay.

In the no-fly zone circling JFK, helicopter applicators halted their battle with the West Nile and Eastern equine encephalitis viruses, both borne by mosquito. In Georgia, the groundings left cotton unpicked, since the crop requires aerial defoliant before harvest. Michigan’s 93 aerial application pilots canceled their seed dispersal and gypsy moth treatments.

Industry supply chains were cut. The FBI warned the American Trucking Association to watch for suspicious hauls to cropdusters. One hijacking suspect had obtained a Michigan license to truck dynamite, gases and toxic and radioactive waste, and as many as 18 others believed to have had some involvement in the terrorist attacks were found to hold false licenses for hazardous material and commercial trucking.

Yet in televised reports, cropdusters in California’s Sacramento Valley and other regions shrugged off the economic effects, saying that September is the industry’s slowest time. Many operators agreed, though the 500-member California Agricultural Aviation Association repeated that the Golden State’s $29 billion crop industry was at grave risk.

Michael Osterholm directs infectious disease research at the University of Minnesota. “Even if one of these [supposedly planned terrorist] events [using an agplane] is just halfway successful,” Osterholm told TV networks, “it’s going to be catastrophic beyond anything we’ve ever seen.” Osterholm offered as backup Living Terrors, a book he co-authored with John Schwartz. In the fictional book, a cropduster sprays anthrax over a football stadium, infecting 30,000 people within 10 days.

Repro-Med Systems of Chester, N.Y., saw the agplane scare as a backdrop for sales. As cropdusters returned to the air September 25, company president Andrew Sealfon vividly described a possible airborne release of organophosphate nerve gas, which causes a death much like drowning. “One lesson should be that we must have Repro-Med’s Res-Q-Vac Airway Suction System at all levels of government, and throughout our medical infrastructure,” he concluded. Sealfon, a flight instructor, figured the Ayres Bull Thrush cropduster could dispense 510 gal of nerve agent at 110 mph.

NAAA’s Pat Kornegay countered, “Agricultural aircraft have never, since the inception of their use as an indispensable tool of production agriculture in the 1920s, been a threat to the security of the U.S. or its citizens.” He called the worry “far flung theoretical assumptions,” and said of the aerial application industry, “we are again victims of media misinformation.”

Still, public sentiment turned against operators, whether from sensational reporting or accurate reporting of sensational remarks. Willie Lee, who manages the South Florida Crop Care firm visited by the terrorists, operates an Air Tractor 502, which holds 500 gal of agent and 200 gal of fuel. “That’s a bomb itself right there,” Lester helpfully offered, among more colorful remarks to the media, including the New York Post. “A bomb itself right there! Ready to explode,” he reiterated.

Technically Difficult
Producing chemicals in volumes and concentration to be lethal by air would be technically difficult and expensive. The cult group Aum Shinrikyo, which killed 12 people in a 1995 attack in the Tokyo subway, reportedly spent $10 million to produce small amounts of sarin, and experts said that an airborne sarin attack would require multiple passes and more than one ton of agent.

“There are a lot of variables to get right, such as particle size, meteorological conditions and spray pressure, as well as the right dosage to kill or incapacitate people,” said Leslie-Anne Levy of the Washington think tank Henry L. Stimson Center. “It’s not as simple as brewing something in your bathroom and spraying and killing thousands.”

In fact, NAAA has conducted research since 1997 to limit misdirected chemicals via its spray drift task force. Test pilots varied such factors as the width of spray boom or application “swath,” application and nozzle height, application airspeed, droplet size, wind speed and direction relative to the application line.

Field and wind-tunnel tests considered wind shear as it differs by fixed-wing aircraft and rotorcraft shape in concert with the other variables. The typical test model consists of a 1,200-ft-wide field, medium droplet size, a 60-foot-wide swath, nozzles eight feet above ground level and a 10-mph crosswind.

Ray Newcomb, president of JBI Helicopter Services of Pembroke, N.H., said that 90 percent of spray nozzles have since been replaced by a raindrop nozzle, which delivers a precise stream in a 70-ft swath.

One Osama bin Laden follower was arrested in 1999 crossing the Canadian border with explosives, allegedly plotting to attack Los Angeles International Airport. In Afghanistan he had reportedly practiced the dispensing of cyanide gas for possible use in airborne attack. Callan of NAAA responded to questions of anthrax or mustard gas released over congested areas: “Our view is that it would be difficult. Certainly, we can’t spray any gas.”

Fleetwide, Part 137 fixed-wing aircraft range from about a 75-gal capacity to as large as 800 gal held in a composite hopper capable of liquid, seed, granular or mixed-flow delivery, depending on the filter and nozzle system. Most are single-seat and at full load have a range topping out at 200 mi. The great majority are tail-draggers, which require above-average deftness on the flight controls on takeoff and landing. The center of gravity can shift continuously during release, making the types difficult to master.

An average liquid application is about two gallons per acre, but in an emergency a dump handle can disperse the entire load within seconds. Terrorists might choose the emergency release.

In recent weeks, anthrax poisoning attempts have been made by U.S. mail. Some of these attacks included a fine grind of “military grade” anthrax, which could be toxic if released by cropdusters, though experts deemed it unlikely that the substance was available in sufficient volume.

At press time the NAAA still planned to hold its 35th Annual Convention & Exposition from December 3 to 6 at the Tropicana Hotel in Las Vegas.