Why the TSA Can't Eliminate the Threat from Bombs

In the wake of last month's attempted bombing of a Northwest Airlines A330, the US government has taken several steps which were intended to reduce the risk of someone else getting on an airplane with a bomb. While steps like these will reduce the risk, it will not eliminate the risk.

How Safe is Safe Enough?
When it comes to bombs on an airplane, the average passenger would consider the situation safe enough if the probability of a bomb on board an airplane were zero, but the reality of the situation is that as long as people have a desire to blow up airplanes full of passengers, steps can be taken to make flying safer by reducing that probability, but as long as there are airliners flying, the probability can't be eliminated.

Risk Management and Airline Security
Risk can be defined as the probability of some undesirable event like a bomb exploding on an airplane. Risk management is the process of reducing risk by either reducing the probability of an event or reducing the severity of the event. The steps taken by the US government are risk management steps that may reduce the likelihood that a bomb will be exploded on an airplane, but none of these steps are 100% effective.

How Airline Security Works
The short story is that there are multiple things that can be done to stop bombings, hijackings, sabotage, and other mayhem out of the skies. Passenger screening at the airport is one of the things that everyone can see, and there is much more that is not so visible, from bomb-sniffing dogs to terrorists watch lists. There are many procedures and systems in place because no one system or procedure can prevent every attempt to bring down an airplane. For an example, you can look at one part of the US government's response to the Christmas day bombing event, placing advanced screening systems in US airports.

Advanced Imaging Units Deployed to US Airports
Last week, the Department of Homeland Security announced that it would was adding at least 300 advanced imaging units throughout the United States by the end of 2010. This technology produces a full body scan that would show a graphic image of a person's body underneath his or her clothes. Had one of these devices been used to screen the alleged bomber, it would have presumably detected the the explosive device hidden under his clothes.

Sample Image from a Full Body Scan Device

How the Technology Was Used in 2009
While these detection systems may be useful, the way that they have been deployed in the past and the way that they will be deployed in the near future guarantee that not all passengers will be screened using these systems. The Transportation Security Administration provided a detailed overview of how 40 of these units were used in they were deployed in 2009 at 19 US airports. They were used as a primary screening method at only six airports, and as a secondary screening method at the 13 other airports. TSA plans to install hundreds more this year, but not all US airports will have this option available.

Why this Method Can't Be 100% Effective
In addition and plans to deploy at least 300 additional units in 2010. Even if the TSA meets its goal and adds 300 units to the 40 currently in use, not every airport will have them, since the TSA provides screening at about 450 airports. This means that for some airports passengers will have to be screened with systems or methods that don't have the advantages or capabilities of these advanced detection units.

Even if an airport has these devices in available, they may not be used. The TSA emphasized that these technologies were optional, and any passenger that did not want to use them could be screened with another method.

Why a Less than Perfect System Is Acceptable
While some passengers may wonder why TSA would place these advanced devices only in some airports, and would not require that all passengers be screened in this way, keep in mind that this kind of technology is only one kind of protective system, designed to protect airliners against individuals who try to sneak weapons, bombs, and other banned items into the secure area of an airport. Even a partial implementation of these security measures may find some banned items, and may deter some potential terrorists from attempting to bring bombs and guns on board aircraft.

Why Extra Security Is not Enough
The threat from those who want to disrupt the air transportation system is one that constantly evolves. For every system or procedure that is put into place, those who intend to bring harm to the system will take steps to either avoid those measures or find a way to defeat them. While extra measures will not make air travel perfectly safe, they will likely make travel less risky.

Resources
TSA imaging technology background information
Bomb related deaths on US and Canadian airliners since 1949

Poll Question of the Day
The USA Today newspaper and the Gallup polling organization recently released a poll that says 78% of air travelers who have taken at least one trip in the last 12 months approve of US airports' using full body scan imaging on airline passengers. AirSafe.com would like to know how you feel about this technology:

The survey is now closed. The survey asked the following questions:

• Do you approve of full body scans at US airports?
  
  
• Should children be scanned in this way?
  
  
• Have you flown on airliner at least once in the past 12 months?
  
  
• What do you think about the increased security?

The results of the survey are available here.