And the current monitoring systems... Do they work to detect the presence of explosives in the physiological duct?
No, not at all. There were a few articles on that grim subject pretty recently. Bottom line: There is no technology available today that would work in a practical way to do this. They are working on some things that could do it, but they will all be slow and expensive and they may expose passengers to X-rays or neutrons or something in order to work. One side "benefit" of these things is they will also be effective against drug smuggling. The risk is very real; a woman could carry several pounds of explosives. "They" are aware of this but there isn't much they can do right now. The way I see it, there are currently three risks to air travel which are simply inherent in the current reality of the system. One is explosives or other weapons smuggled in the body. Two is the risk of the plane being taken down from an external weapon, like a missile or even a big machinegun on the ground. Three is the risk of pilot suicide. I don't see that there is a technological solution to any of these attacks, and they are all real. Weapons smuggled in the body: I'm not sure if this has ever happened yet, but tons of drugs make their way around the world at a steady 98.6, so this is a real possibility. A missile from the ground: Many shoulder-launched missiles go "missing" every year, including ones from the US military. Many have been given to the Mujahadeen in Afghanistan while they were fighting the Soviets. Certainly the Pakistani ISI, and the Iraqis and Lybians and North Koreans have easy access to these things. Even if a terrorist can't get a missile, I would imagine that a plain old 50 cal machinegun, somewhere in the approach path of the planes, would probably be able to do the job. Pilot suicide: It is accepted by everyone but the Egyptians that pilot suicide was the cause of the Egypt Air crash in 1999. It is accepted by everyone that the cause of the Silk Air crash in December of 1997 was pilot suicide. How common is pilot suicide? Those are the only two that I know of. We will end up doing many expensive and harmful things to achieve a goal (perfect air safety) which is impossible to achieve. Taking away nail clippers is not the answer.