Can Security Scans Replace Metal Detectors?

Amsterdam Schiphol has been testing millimetre-wave portals since 2006. (All images via author)

Marijn Ornstein, Manager of Security Policy for Amsterdam Schiphol Airport, asks if there is now a viable business case for airports to completely replace metal detectors with Security Scans.

 

Amsterdam Schiphol has been testing millimetre-wave portals since 2006. (All images via author)

Since 2006 Amsterdam Airport Schiphol has been testing millimetre-wave portals, known as Security Scans that form part of the security checks for passengers and staff.
What is a security scan and how does it work?
The Security Scan is a machine that makes a scan of the body contours using millimetre wave reflection technology.  The scans they produce immediately show security staff whether a passenger is carrying any prohibited items on his or her body.
Until October 2009, the scans we used at Amsterdam produced images that were being analyzed by security agents.  The security agent (an image analyst) remotely viewed the images and was therefore unable to actually see the person that was the subject of the scan; only the scan itself.  As an extra privacy precaution, the passenger’s face was blurred and the image was deleted after assessment.  Using a radiophone, the image analyst would tell the security agent at the screening point whether a partial hand search was required and, if so, on which part of the body.
Notwithstanding these privacy precautions, privacy issues were being raised by parliamentarians and governments throughout the world.  This inspired Amsterdam Airport Schiphol to unfold its Privacy by Design approach, which led to the development of an automated detection module.  The classifier automatically detects anomalies on a person being scanned by using intricate algorithms.  The operation of the scanner itself is quite easy and hardly any staff training is required before they can use it operationally.
After the scan is made there are only three potential screens the security agent at the check point sees:
1)  A red screen with a ‘stick man’.  Here, yellow spots indicate potential threat items on the body.  Only the areas with potential threat items are checked by hand.
2)  A green screen with OK, which shows that no anomalies have been detected.
3)  A yellow screen with an exclamation mark.  This means an error has occurred and another scan must be made.
With this automated detection an image analyst is no longer needed and there are no more privacy issues.  Another advantage of using the automated detection system is that it also resolves some other issues, such as communication and image quality.
The airport’s security team worked closely together with the Dutch and US Governments to develop the scanner and we are grateful to the EU for granting us the opportunity to use the Security Scan on the basis of the new technology clauses in the EU legislation.
Since the incident on December 25, 2009, when a Nigerian national allegedly boarded a flight carrying explosives in his underwear, Amsterdam Airport Schiphol has started deploying the security scan machines equipped with automated detection throughout its terminal.  A frequently asked question in this respect is whether a Security Scan machine would have detected any explosives on that Christmas Day.  Of course, even with hindsight this question can never be established with 100% certainty, but one thing we know for sure: a walk-through metal detector would have never detected explosive in underwear, since it is only capable of detecting metal.
 
The Security Scan business case
By the end of 2010, Amsterdam/Schiphol will have 60 Security Scans in operation, so the airport already has enough experience to assess the new technology’s performance.  And this leads to the question: Is there now a viable business case for airports to completely replace metal detectors with Security Scans?
I don’t think this question can be answered with a definitive yes or no, or at least not yet.  For Amsterdam Airport Schiphol though, the answer is unequivocally yes.
To assess a business case, the airport’s security department defines innovation requirements which are based upon Schiphol’s Security Values.  Schiphol’s Security Mission Statement calls for the organization, control and continuous improvement of its security processes, while conforming to legislation at a competitive cost level, in co-operation with our stakeholders in a way that is compatible with the future.  This is to ensure an efficient, effective and high quality operation.  In short we call them the seven Cs:
Fig 1: The ‘Cs’ in the triangle show the goals, whereas the Cs in the circle represent the way Amsterdam Airport Schiphol would like to achieve these goals.

 
Fig 2: Based on this ambition we have defined innovation requirements into seven ‘Ss’ that are:

 
Security: Security Scan compared to metal detectors
We have recorded a higher level of detection performance when using the security scan simply because the scan detects a broader range of prohibited items, such as explosives and ceramic knives, whereas the metal detector only detects metal objects.  This does not imply that we aim to withdraw the metal detectors from operation completely; it remains a fall-back system while the Security Scan continues to be developed and improved in terms of speed and cost.
We spent a lot of time and energy on developing the Security Scan technology but we believe that scanning times and performances can be further improved.  Ways of potentially streamlining the security process that are being studied at the moment include; the usefulness of having security staff make parallel observations, the body segmentation of images and how to improve the screening of certain clothing.
Speed: Security Scan and its improving throughput
When our airport installed its first machines, the average throughput was approx 2 to 2.5 passengers per minute; not enough for an efficient operation.  After having installed three quarters of our machines, our security staff are getting used to working with the scanner and the overall throughput is now up to an average of three passengers per minute.
Now the staff have experienced the learning curve, we believe we are seeing the benefits of using the system, as some security agents working as a team are able to achieve an average throughput of 4.5 passengers per minute.  Of course, once passengers are familiar with how the Security Scans work, they will know which items to divest, thereby streamlining the whole process.
Our target is to reach a stable average of 3.5 passengers per minute by May 2011.  This increase in throughput depends on further technical developments, optimizing processes and the positive attitude of our security staff.
Space: Security Scan needs a larger footprint
The Security Scan’s ‘footprint’ is remarkably different compared to that of a walk-through metal detector.  The total lay-out of the new security lane with two Security Scans is almost 1.5 times larger than a traditional security lane which has just one metal detector.  Fitting this new footprint into the current interior design has proved to be a real ‘brain-twister’ for us, especially due to the current security gate layout in our Non-Schengen area.
Staff: Finding the right occupation for Security Scans
With this automated detection an image analyst is no longer needed and there are no more privacy issues.

In the traditional layout where one walk-through metal detector is used alongside two x-ray machines, we have eight to ten security agents.  In the new configuration, using two Security Scans alongside two x-ray machines, we require ten security staff to man the checkpoints.  This number may change in the future but more testing and evaluation is required first, because we don’t want to do anything that would have a negative influence on security levels or processing times.
Spending: Investments and exploitation costs Security Scans
Innovations cost money, especially when you are becoming the worldwide trendsetter.  Obviously the Security Scan machines cost more than a walk-through metal detector but we believe that when they are in wider use the initial investment cost will drop.  To date we have not reduced the number of operating staff because this is only possible if and when throughput times have improved.




Satisfaction: Increasing perception when using Security Scan
The Security Scan has not only confronted passengers with a new screening experience, it has also forced security staff and airlines to fit this new technology into their processes.
We believe it is very important to co-operate with our stakeholders, so we will engage in some customer research to study passenger, staff and airline perceptions and attitudes towards the new process.  What we already know is that, the passengers – due to the fact that the scan reduces the need for full hand searches considerably – appreciate the new system.
Sustainability: Security Scan means being compatible with the future
Future laws and regulations and incidents may require more detection through hand or machine searches.  Therefore we at Amsterdam Airport Schiphol doubt the metal detector’s sustainability.  No one can foresee what our future threats will be.  Of course we aim to remain compliant with any future requirements and believe that the real threat to aviation does not come from passengers carrying metal items, but those who may carry explosives.  Having the Christmas 2009 incident in mind, this is a real possibility, but in the end we believe that aviation security would benefit if the main focus would shift away from identifying dangerous items and move towards identifying who the terrorists are.
Conclusion
"We believe that aviation security would benefit if the main focus would shift away from identifying dangerous items and move towardsidentifying who the terrorists are" - Marijn Ornstein.

When weighing up the seven ‘S’ innovation requirements, we believe that we have been quite successful so far with meeting the needs of Security, Satisfaction and Sustainability.  However for Spending, Space, Speed and Staff, there is still more room for improvement.
We strongly believe in the Security Scan’s potential for combating terrorism.  With our mission statement in mind, we will continue to improve our technology; its acceptance and its process, until there are no undesirable restraints in replacing walk-through metal detectors with security scanners.
 
 
 
The Agents’ View
After the scan is made there are only three potential screens the security agent at the check point sees: 1) A red screen with a ‘stick man’.  Here, yellow spots indicate potential threat items on the body.  Only the areas with potential threat items are checked by hand.  2) A green screen with OK, which shows that no anomalies have been detected.  3) A yellow screen with an exclamation mark means an error has occurred and another scan must be made