An old and uninformed theory about using crop dusters to disperse weapons of mass destruction has resurfaced in a new report a bipartisan commission released Oct. 21 criticizing the government for insufficiently preparing for a bioterrorism attack.

In a report titled “The Clock is Ticking,” the Commission on the Prevention of Weapons of Mass Destruction Proliferation and Terrorism admonishes that the consequences of ignoring warnings about the threat of bioterrorism “could be dire.”

The next sentence is the part that troubles NAAA: “For example, one recent study from the intelligence community projected that a one- to two-kilogram release of anthrax spores from a crop duster plane could kill more Americans than died in World War II. Clean-up and other economic costs could exceed $1.8 trillion.”

For the record, a crop duster has never been involved in any terrorist activity, and the chances are extremely remote that an ag plane ever could be weaponized to disperse a chemical or biological weapon. Many security experts in government and in the private sector are in agreement with NAAA’s position that ag aviation aircraft represent a poor option as potential vehicles for terrorist attacks.

There are several reasons for this, including the fact that chemical agents are very susceptible to the wind. Dr. Amy Smithson, a bioterrorism expert at the Monterey Institute’s James Martin Center for Nonproliferation Studies, has stated: “To infect the human lung, the required particle size of a biological warfare agent is 1 to 10 microns, ideally 1 to 5. Yet, the sprayers on the average crop duster aim to disperse in 100 micron particle sizes or greater, a heavier weight that improves the chances of the materials settling on the target area. These sprayers cannot be ‘dialed down,’ so to speak, to consistently disperse the payload in the necessary micron size.”

According to experts at USDA’s Agricultural Research Service:

• Most biological materials are not dermally active; therefore, materials must be atomized into respirable droplets.

• Living organisms (i.e., bacteria) can be destroyed with the high pressures required to generate small droplets.

• Spray clouds or concentrations of aerosols are quickly diluted by wind, which makes it very difficult to deliver biological agents in concentrations sufficient enough to be “effective.”

The complexity and sophistication of aerial application aircraft, combined with the level of skill required to operate these planes make it unlikely they could be used in attacks by terrorists. From excessive weight to tail-configured steering, an ag plane is a unique aircraft to fly. Furthermore, nearly all crop dusters have single-seat cockpits, a fact that all but eliminates the possibility of hijacking.

Aerial Application Security Procedures
Even thought the chances of weaponizing an ag plane with a chemical or biological weapon are extremely unlikely, NAAA and its members take chemical and aviation security matters very seriously. After 9/11, NAAA and its membership responded by aggressively promoting a set of enhanced security procedures. These security measures include:

• Storing aircraft and crop protection products in locked hangars with electronic security systems when not in use.

• Parking and disabling loader trucks, forklifts or other heavy equipment to block aircraft.

• Using propeller locks, propeller chains or tie-downs on aircraft in cases where the aircraft must be left outdoors.

• Removing batteries from planes and disassembling engines from unused aircraft.

• Installing hidden security switches to prevent unauthorized startup of the aircraft.

• Securely storing and monitoring crop protection products in buildings with steel doors and electronic security systems with tampering tape.

• Establishing contact with federal and local law enforcement agencies to coordinate responses to security breaches at ag aviation facilities.

The aerial application industry and NAAA are committed to remaining vigilant about agricultural aviation security issues. For example, NAAA educates aerial applicators about security issues year-round in the Professional Aerial Application Support System (PAASS) program. PAASS’s goals are to educate pilots on security issues, minimize drift and promote aviation safety.

The idea that terrorists might weaponize an agricultural airplane to disperse a chemical or biological weapon is neither plausible nor probable. NAAA would like to dispel this notion once and for all now that some of the vagaries of agricultural aviation are better understood.

Posted Oct. 23, 2009