A great deal of money (over $40 billion) has been spent by federal and state governments on many wasteful anti-terrorism projects, like focusing on bio-terrorism and dirty bomb defenses that suggest such an attack is inevitably imminent. It isn't. And the reason it has not happened already is that the terrorists are a lot smarter than we give them credit for. They know that both terror scenarios are not as apocalyptic as the public believes, and to make either weapon anywhere nearly effective results in too much danger to the builder and the perpetrator. In other words, each is an unreliable, inefficient weapon.

In reality, instead of thwarting terrorist tactics, Homeland Security and other agencies are actually assisting terrorists by concentrating on expensive, exotic and complex schemes while ignoring the more basic terrorist threat. Terrorists' weapon of choice remains the conventional bomb, proof of that is demonstrated daily in Iraq and various other volatile nations. Conventional bombs achieve their purpose, injuring and killing masses of people in a horrible manner. They are relatively safe to use, are easy to assemble and are cheap, which earns them the status of favored instrument of terror.

Suicide bombers are a real and present danger. The threat is well known to everyone and many precautions are now taken to avert and uncover them, among them are: pat downs, behavior profiling, sniffer dogs, explosive screening machines and video analytics software. And new devices are being tested with promising results such as backscatter and millimeter wave systems that "see" through clothing. These type of defenses against suicide bombers are rather effective in the field where it is possible to individually screen people. But there is a dimension and an approach where such tools are ineffective.

Security personnel tend to look around them for trouble, they look behind, in front of them and to the sides but hardly ever up. And the next terrorist threat could be airborne.  A small aircraft is a discrete form of transport, thousands fly overhead daily and most of the time one hardly takes any notice of them. A single engine aircraft modified for parachute jumping can hold nine people and carry them up to quite an altitude - 4000 meters without difficulty. Imagine if the plane held 9 terrorists fitted out with parachutes and they were all strapped with high explosives.

With modern parachutes they could navigate several kilometers toward their target, after having been dropped by a plane out of sight of the eventual landing zone. Using a parapente chute they could travel even further. In view of the fact that they are suicide bombers, they could elect not to use a parachute and simply skydive down at a terminal velocity of 200 kph onto their target. With the use of wind suits they could glide an even longer distance, depending on the altitude of the plane. Using oxygen masks they could be free to climb to higher altitudes beyond 4500 meters, which would increase their glide distance accordingly. This added distance could mean the use of a larger plane with even more terrorists aboard, as nobody would see the drop plane from the target area. The target could be a crowded stadium, an open-air concert, a large political demonstration, an inauguration or a downtown section of a city during rush hour - wherever there are many people congregating.

All this may read like some chapter from a thriller, but when you think about it, the scenario is feasible, economical and an efficient terrorist strategy. Such a spectacular strike could take place in daylight or at night and would be very hard to defeat. The resulting scene of carnage from this type of assault would create chaos and fear and immense attention from the mass media; all are determining factors in a terrorist's selection of an act of violence. It is worth taking such a development into consideration and acting to prevent it from ever happening.