Airport Security: Explosives Detection Systems - Assignment Example

Aviation security holds a significant part in preventing smuggling and terrorism. This is why explosives and illegal materials detection is very important. The methods are mainly based on 3 principles: 1) Reasonable efforts must be exhausted to prevent terrorist access to airports; 2) Terrorists who can penetrate the initial security screening will still go through weapons detection procedures and explosives detection systems, and; 3) Aircraft systems and structure should be built in a way that minimizes any damage that could result from blasts and raises the chances of passenger survival (Marshall & Oxley 2009, p. 18). Of these principles, the second appears to be the most critical.

Serious breaches of security in the past resulted in extensive efforts to solve this security issue by technology (Marshall & Oxley 2009, p. 20). One of the main concerns is early or real-time detection of explosives in checked luggage. However, as technology becomes more advanced, means of disguising explosive materials also became smarter (Cremers & Chinni 2009, p 505). Explosives Detection Systems Screening passengers and their baggage require sophisticated systems. Such tools should be both publicly accepted and accurate.

There are policies and procedures set by aviation security that determine what needs to be reported by these detection tools (Marshall & Oxley 2009, p. 23). Specifically, these systems should be able to perform the following: 1) Report the type of illegal materials; 2) Detect the minimum mass or quantity; 3) Determine the shape of the material, and; 4) Report the location of the material in the luggage. The most popular detection systems are those that can: 1) Provide immediate and accurate reports to avoid the inconvenience of passengers; 2) Have a low percentage of false alarms; 3) Low-cost of the detection tool, and; 4) Provide ways to alert human operators whenever necessary (Marshall & Oxley 2009, p. 25-6). Explosive Detection Canines Minimizing associations of a target substance to a non-target substance is a common issue in this method.

For example, kerosene, acetone, toluene, or hexane usually exist in non-target substances, but the same materials are found in the vapor headspace of some explosives (Marshall & Oxley 2009, p. 30). To avoid this, dog trainers should do some optional conditioning like the use of a secondary negative reinforcer that is proven to provide good results in explosive-sniffing canines. Yet, due to the wide variety of chemical components, false alarms can never be eradicated in this detection method (Marshall & Oxley 2009, p. 34-5). Trace Explosives Detection Devices (TEDD) This includes 'ion-mobility spectrometry', 'gas chromatography', 'chemiluminescence', and 'atmospheric pressure electron ionization'.

In these methods, detecting trace explosives is first done by wiping the suspected material with a sampler (Cremers & Chinni 2009, p. 459). For example, the operator might wipe the handle of the luggage with the sampler and then place the sampler into the TEDD. However, not all explosives can be detected by this technique, as optimal sampling is different from one explosive to another (Cremers & Chinni 2009, p. 460). First, research shows that explosive materials created under a controlled environment still have the chance to avoid contaminating the surface of the container, although admittedly very hard to do.

Using C4 explosives as a model, even a 10% left material is enough for TEDDs to detect the existence of a substance. However, this 10% sampling yield is also based on the surface being tested, the material being detected, and the specific technique being used (Marshall & Oxley 2009, p. 233). Several factors could affect the removal of the explosive materials on surfaces, like the duration of the contact, roughness of the surface, state of accumulation, shape, and size of the particles, surface assimilation, electrostatic and molecular attraction between the surface, and the explosive material, and even the quantity of the explosive particles (Marshall & Oxley 2009, p. 234-5). Therefore, to maximize the effectiveness of TEDDs, adequate sampling is required, and only within specific chemical selectivity and boundaries of detection. 

Bulk Explosives Detection Devices This includes tools that remotely detect the chemical, physical, or a combination of both properties of a thing to evaluate the possible presence of explosive materials. Techniques such as millimeter waves, electromagnetic fields, gamma rays, and x-rays have been utilized to detect explosives and weapons. High oxygen or nitrogen content in high bulk density is the common target. There will always be non-threatening objects that will meet these targets, like sausages, while there will be explosive materials that will not, like triacetone triperoxide (Marshall & Oxley 2009, p. 145-7). In comparison, trace detection presents lower chances for false alarms compared to bulk detection, because the latter is usually based on genetic characteristics.

However, positive trace detection is limited to the explosives provided in the library, and can often be misleading (Cremers & Chinni 2009, p. 475). It is then not an accident that certified detection tools are both under the bulk explosives detection category (Marshall & Oxley 2009, p. 167). Trace explosives detection requires the presence of the explosive material on the surface --- again another drawback for TEDDs.