Cropduster Terrorism

Technology Review Online ^ | March 11, 2002 | By Richard A. Muller

[Orion78]

What terrorist weapon is more destructive than TNT and more available than nukes? It's gasoline.

By Richard A. Muller

Technology for Presidents

from Technology Review Online

March 11, 2002

Before murdering thousands at the World Trade Center, Mohammad Atta made repeated trips to rural airports, trying to learn everything he could about crop dusters. Why? Most people think he was interested in spreading chemical or biological terror over a major city. But there is no evidence that al Qaeda had stores of such materials. Searches in Afghanistan turned up no major chemical or biological facilities—nor is there evidence the group somehow had access to stockpiles in the United States. New facts amplify the mystery. A crop duster manual was found in the possession of Zacarias Moussouai, who prosecutors think would have been the 20th suicide hijacker, if he hadn't been arrested first. A federal witness, Essam al Ridi, testified at U.S. trial of the four men accused in the 1998 U.S. embassy bombings in Kenya and Tanzania that Osama bin Laden wanted to buy a crop-dusting business.

Why? Maybe bin Laden just wanted to dust crops. (I know nobody takes that one seriously.) Maybe he actually did have stores of chemical or biological agents, and we'll uncover them soon. But I bet they don't exist. I have a totally different interpretation of al Qaeda's interest in crop dusters. Let me lead you to my conclusion by starting with a review of what happened on September 11—and more importantly, what didn't.

When Mohammad Atta boarded American Airlines flight 11 in Boston that morning, the only illegal things he carried were his intentions—no guns, no explosives, no long knives. Despite all the well-documented weaknesses of our airline inspectors, the risks of being caught with a weapon were too great for Atta et al. to take that chance.

The brilliance of the operation was its low risk. No purchases of explosives. No illegal weapons. Virtually no infrastructure needed. The danger of someone finding out was nil, since even most of the terrorists didn't have to know the mission. (And many of them may not have known right up to their deaths, despite bin Laden's subsequent assertion that they were told just before they boarded.) Atta's plan depended on the airline policy that directed pilots to cooperate with hijackers. Don't argue; don't threaten; just do what they ask. This approach had saved lives (and airplanes) in the past.

Atta and his co-conspirators took early flights, minimizing the risk that the flights would be behind schedule and making it easier to attack New York and Washington simultaneously. But even more importantly, they took transcontinental flights. That was to make sure the planes were fully loaded with fuel.

Gasoline, mixed with air, releases 15 times as much energy as an equal weight of TNT. That fact astonishes most people. The numbers are simple: one gram of TNT releases 0.65 kilocalories of energy; one gram of gasoline, mixed with air, releases 10 kilocalories. TNT is not valued for its high energy, but rather for its ability to deliver the material-shattering force that accompanies rapid energy delivery (high power). Even chocolate chip cookies have nine times the energy content of TNT. To tear down a building, if you're in no hurry, don't use TNT; hire some teenagers, give them sledgehammers, and feed them cookies.

The history of gasoline as a weapon dates at least to the Molotov cocktail of the 1930s. In World War II, what the flame throwers really threw was burning gasoline. Vietnam made gasoline-based Napalm famous. Recently, in Afghanistan, the U.S. killed and demoralized Taliban troops with "fuel-air" explosives. Why were these so dreadful? Because 7 tons of gasoline, mixed with air and detonated from a parachute, release the energy of over 100 tons of TNT. So don't drop TNT if you can drop gasoline. It gives 15 times the bang per ton.

Atta and his terrorists hijacked a Boeing 767 that carried 60 tons of fuel, equivalent to 900 tons of TNT, nearly a kiloton. When it hit the north tower of the World Trade Center, it didn't all explode, but it continued to burn for over an hour. A long slow burning can be more terrible than an explosion. The building's structure finally failed, the columns buckled, the upper floors fell like a pile-driver on the lower floors, and they collapsed in turn. A near-identical attack felled the south tower.

Atta knew that September 11 would be the last day on which an airplane could be hijacked with ease. After September 11, sky marshals are hardly necessary. No pilot ever again will willingly hand over the controls to a terrorist. Even if a hijacker kills the pilots, the courage and the fury of the passengers and crew will be unleashed.

An Air Tractor 502 Crop Duster airplane is far smaller than a 767, but it is also a flying tanker. It has fertilizer containers that hold roughly 1,200 liters of liquid, plus a 500-liter fuel tank. It flies close to the ground, where it cannot be seen by most radar technologies. Fill 'er up with 1,700 liters of gasoline, and you are carrying roughly 2.1 to 2.4 tons, the energy equivalent of 32 to 36 tons of TNT.

What could a single suicide pilot do with a full crop duster? Crash into Yankee Stadium during the World Series, or into the Superbowl, or the Olympics opening ceremony. The deaths, including trampling, might exceed those at the World Trade Center, with everything broadcast live on international TV. (I virtually held my breath during these recent events.) Or the pilot might target a petrochemical plant, or a nuclear waste facility near a large city. (Can we please move those radioactive wastes to the relative safety of Yucca Mountain in Nevada?)

Fortunately (for us), it turns out that the Air Tractor is notoriously difficult to fly, particularly when fully loaded, and even more so if kept at very low (radar-avoiding) altitude. Maneuvering a Boeing 767 is probably easier, as long as you don't have to land. Moreover, the crop duster community is very close, small, and wary. Even before September 11, they didn't let Atta photograph their planes or even sit in the cockpits. For the next few years, you can be assured that every suspicious visit to a crop duster facility will be reported immediately to the FBI.

But don't take too much comfort in the difficulty of obtaining and flying a crop duster. Other kinds of small planes can be used. At the World Trade Center, jet fuel, a kerosene-based equivalent to gasoline, killed more people and destroyed more property than bin Laden had dreamed possible. Gasoline is a low-risk explosive, and doesn't require any special license to buy. So beware. If any al Qaeda agents are left in the U.S. and they want to kill and terrorize, then their weapon of choice may well be one that you can buy at the corner station.

[Orion78]

PING!

[1066AD]

Interesting, but how does jet fuel compare to gasoline ?

[thegreatbeast]

The idea is that you disperse the gasoline in a atomized spray and somehow ignite it, right? Dispersing it over a small area like a stadium would require a serious goosing of the equipment in order to unload it quickly I would think. Otherwise it would pretty much be one of those spectacular fireballs that are so popular in movies.

[jetson]

What about the geneticaly altered virus's that Russian made in the late 80's. No one seems to know where 20 tons of altered virus went. A cup of the virus is enough to brew more. We need accountability of all this stuff before we makes claims like your making.

[Starrgaizr]

The biggest threat is foreign pilots. All those excited teenagers dancing for joy on 9-11 in the Arab world who are working their way up the aviation ladder towards the big 747 job for the Islamic country flagged airlines that still fly here all the time.

Crop dusters scare me when I compete for ramp space with them at rural airports. Their pilots are intimidating because they are unbelievably experienced and smirk at novices like me. The article ignores one thing: turn on the sprayers and create a dense mist of vaporizing gasoline in a pass over the crowd before crashing it in. That could hurt. The panic alone would crush many.

I love to fly but many of my fellow pilots are not doing themselves favors by arguing that G.A. is harmless and the FAA is out of line for suspending some foreign pilots' privileges without "due process." It will take just one attack for them to lose all credibility and hurt us more than facing those threats head on.

[Walkingfeather]

diesel=jetfuel

[jocon307]

"Moreover, the crop duster community is very close, small, and wary. Even before September 11, they didn't let Atta photograph their planes or even sit in the cockpits."

Yes, I've actually read and heard some interviews with these folks, they know those planes are tough to handle and I guess they are well aware that they exist in order to spread insectide POISON over large areas.

This was a very good post, I especially like the part about the teenagers, the sledgehammers, and the cookies. Ahhhh, if we could only bottle the energy of teenagers!

[Doctor Stochastic]

The Cropduster came off second best if you remember North by Northwest.

[Starrgaizr]

Think of the Indy 500 or the Kentucky Derby, perhaps -- a large open area filled with tens of thousands of spectators. A few passes would probably ignite even without crashing from ground sources. Could create havoc.

Then again, I have no idea if spraying avgas (or jet-A) from a crop sprayer would work.

[Iowa Granny]

marking for a later read

[Starrgaizr]

The AirTractor 502

For operators needing additional power for faster ferry speeds, short strip operation with big loads, or high altitude spraying, the AT-502A meets the performance requirement. The slow-turning 5-blade prop offers quieter operation in noise-sensitive communities. Aircraft is sold with customer-furnished used PT6A-45R engine.

Agricultural airplane complete with 2" spray system, streamlined booms with 38 nozzles, 2" bottom loading valve, Transland special 38" wide gate, 500 gallon fiberglass hopper, pump shut-off valve, 3-color polyurethane paint finish, 29 x I I high flotation tires & wheels with dual 3-piston brakes, electrically operated high-lift flaps with aileron droop, new 5-blade constant speed reversing Hartzell propeller, 250 amp starter-generator, 3 batteries, 216 gallon fuel tanks, strobe lights, turn windows, nose mounted landing lights, electric turn coordinator, air conditioned cockpit, windshield washer and wiper, fuel flowmeter, 5-blade ground adjustable spray pump fan, 18 gallon hopper rinse tank, Hoerner wing tips that increase wingspan to 52.0 feet, outside air temperature gauge, 8,000 pound FAA certificated gross weight.

The additional wing structure of the AT-502B allows installation of Hoerner wing tips that increase wingspan to 52 feet. Rate of climb is increased, speed at gross weight is increased, and swath width is increased for higher productivity. New hopper rinse system is standard equipment.

Agricultural airplane with 2" stainless spray system, streamlined booms with 38 nozzles, 2" bottom loading valve, Transland special 38" wide gate, 500 gallon fiberglass hopper, pump shut-off valve, 3-color polyurethane paint finish, 29 x 11 high-flotation tires & wheels with dual 3-piston brakes, electrically operated high-lift flaps with aileron droop, new Pratt & Whitney PT6A-15AG 680 SHP turboprop engine with 3-blade constantspeed reversing Hartzell propeller, 250 amp starter-generator, 170 gallon fuel tanks, strobe lights, turn windows, nose mounted landing light, electric turn coordinator, air conditioned cockpit, windshield washer and wiper, hopper rinse tank, fuel filter warn light, 5-blade ground adjustable spray pump fan, outside air temperature gauge, 8,000 pound FAA certificated gross weight.

Hopper capacity 500 U.S. gallons Engine type See Below Engine H.P. and R.P.M 680 @ 2200 Take-off weight 9700 lbs. Landing weight 8000 lbs. Empty weight w/ spray equip. installed 4297 lbs. Useful Load 5403 lbs. Fuel capacity 170 U.S. gallons (216 or 234 gal. opt.) Wing span 52 ft.

[Ford Fairlane]

actually, kerosene + additives = jetfuel

Diesel is a little thicker

[Fiddlstix]

BTTT

[Orion78]

Face to Face With Atta

JOHNELLE BRYANT: It, it wasn't actually a crop-duster in itself that he was wanting to finance. He wanted to finance a twin-engine, six-passenger aircraft, that he could use as both a charter flights, and remove the, the seats. And he said he was an engineer, and he wanted to build a chemical tank that would fit inside the aircraft, and take up every available square inch of the aircraft, except for where the pilot would be sitting. And run the spray nozzles along the wind span. And use it as both a crop-duster plane, and as a charter plane.

[Orion78]

"The brilliance of the operation was its low risk. No purchases of explosives. No illegal weapons. Virtually no infrastructure needed."

[IncPen]

In the days following 9.11 (certainly before that week was up), I recall a radio news report that the pentagon had calculated the force exerted by the planes used in the attacks, to include the fuel and velocity therein.

The stated purpose was to offer to a court in a subsequent trial proof that the planes were indeed weapons of mass destruction.

The force, as I recall, was compared favorably in terms of percentage to the bombs used against Japan in 1945

The report was, IIRC, on ABC or CBS radio...

[Smokin' Joe]

I saw one of these spraying crops in the river bottoms near Fairview, Montana just two days ago. The pilot seemed to be quite capable of putting the product on target, flying well under 25 feet. A couple of passes spraying gasoline over a crowd in a large open stadium, pop and drop a flare, and the result would be a horrorshow. Similarly, could be used in city streets, parking areas, anywhere people gather.

I for one, am glad this is a small, highly qualified, and close-knot community--which will have more effect policing the ranks than anything.

[eno_]

A truck bomb would be simpler to accomplish the goal of injusring many people in a large crowd.

If your objective is to kill thousands, VX is the ticket. Saddam made that stuff in industrial quantities. Get ANY on your skin and you are beyond help.

[The_Victor]

Thanks for the ping. This pretty much confirms my thoughts following 9/11.