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SAFETY & SECURITY Last modified on July 18, 2012

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A multi-layered approach is the best way to secure the airport perimeter, writes Alec Owen.
While airports have unique characteristics and requirements for perimeter security, they still follow the fundamental protection rules known as the Five Ds – define, deter, detect, delay and detain. 

An effective perimeter security system consistently prevents intruders from reaching their target.

Like any perimeter security application, the key to effective  airport perimeter security is to develop a multi-layered intrusion detection package.

And by taking a holistic approach to site security, the individual elements, or layers, complement each other, working together to provide a strong security regime to protect against both known and perceived threats. 

There is no single ‘quick-fix’ technology in the market to take care of this. Each element plays a critical role in securing a perimeter.

The first step is risk profiling the site to be protected. For example, is this an international or a domestic airport? Are there buildings (potential hiding spots) on or near the perimeter? Is the area  open and flat or undulating? Is it subject to weather extremes  like strong winds or snow? 

Next, profile the types of intruder you may encounter – vandals, petty thieves, trespassers, or professional ‘special forces’  type intruders? 

Next, assess the ‘attractiveness’ or potential targets contained within the site – are there goods of high value or worth on site,  or are aircraft the target?

Once you have profiled and documented the site, the first layer  to examine is the perimeter fence. Is the fence suitable for the application and potential or expected risks and will it provide a suitable deterrent for intruders?  

If vandals and trespassers are the major threat, then a chain-link fence topped with barbed wire is probably adequate, whereas if you are expecting a professional intruder trained to a higher level, then you may want to consider a razor wire topped anti-climb fence.  

There is no point spending more money than you need to on a fence, but conversely, the fence must match the profiled security risk.

It should not only define the boundary of the site, but also provide enough of a deterrent and delay to give security staff time to swing a CCTV camera around and visually verify the intrusion attempt or activity and respond accordingly.   

An important point here is the delay element. The perimeter fence should be situated a reasonable distance away from the buildings, hangars, or items to be protected so time is needed by an intruder to cross this ground. 

If fences are close to these buildings, they need to be more difficult to scale or penetrate in order to provide enough delay for security staff to respond.

A perimeter intrusion detection system (PIDS) attached to the fence is the first line of warning of an intrusion on the perimeter and identifies the location of an attempted entry. There are a multitude of systems and technologies on the market for detecting intruders climbing fences and airports have unique requirements to consider.

As airport perimeters are typically in the 12 to 16 kilometre range with some as large as 25 kilometres, a traditional zoned-based system may not be as cost effective as it would be for smaller sites.

It’s not simply the cost of the controllers installed on the  perimeter fence, but the cost of providing the power and communications infrastructure to support these controllers  around an entire airport perimeter. 

These infrastructures and their associated installation costs can often be significantly more than the cost of the intrusion detection system itself.

Of course, if the airport you are securing has a section of radio-transparent fence near an ILS or radar system, then you will need a non-metallic type of sensor on the fence in that area.  

On occasion, airports have one or more sides open to the  ocean. In these environments, avoid systems containing copper or steel as they will corrode and have much higher ongoing  maintenance requirements.  

As airports are typically large, flat, open areas and subject to winds, you will need a technology that can not only compensate for the wind without generating a nuisance alarm but still maintain sensitivity so it can continue to detect intruders.  

The newer PIDS technologies employ some fairly advanced  signal processing to achieve this, whereas the older technologies struggle to cope.

The next layer will involve the detection and tracking of an  intruder once they have penetrated the perimeter. This can be  done using a variety of technologies, but commonly comes down  to CCTV, microwave, ground based radar systems or similar open  area technologies.

CCTV with video analytics uses computers to automatically identify, track, and record intruders as they move away from the fence breach to other areas within the airport, without the operator having to constantly monitor the video.   

Linked to a digital video recorder (DVR), CCTV systems also provide forensic video documentation of an intrusion event and the intruder.

There have been many advances in video analytics and  intelligent video in recent years. Higher quality systems now  include an image-tracking feature, which allows monitoring of a number of separate intruders simultaneously by drawing a different coloured line around each of them and creating a trail line of where they have been.

Determine where and how many cameras you will need, and also the power and communications infrastructure required. Should you have a number of perimeter cameras, or just a few good quality centrally located PTZ cameras?  Can you share the power infrastructure with other devices? 

Cameras mounted on buildings tend to be easier to install and more stable than cameras set on the perimeter on poles.

Microwave sensors are volumetric motion detection devices that flood an area with a high-frequency field. Any movement within this area disturbs this field and sets off an alarm.  

Microwave sensors can be used to monitor an open area or along the inside of a perimeter fence line. As with CCTV, determine the area to be covered and where to position the microwave sensors to pick up power and communications.

Like microwaves, ground-based radars continuously scan  large open areas, detecting movements within a defined perimeter. Rarely used as a stand-alone intrusion detection system,  ground-based radar is more often used in conjunction with  intelligent tracking cameras, with the radar used as the  detection device and the CCTV camera as the verification and  tracking device.  

Combined ground-based radar/CCTV systems can provide an effective intrusion detection system for large flat open spaces – especially those difficult areas where you don’t  want a physical barrier, or cannot install one, such as over water or on a coastline.   These combined systems have a maximum detection range of typically 200 to 1,000 metres.

Next will be the physical security information management system or PSIM.  This is where all of the information from the detectors in the field, the CCTV and/or ground based radar is analysed and prioritised to identify situations that need urgent attention. 

A good system presents the entire intrusion scenario to the security staff in a simple to understand manner with clear instructions and procedures to handle them.

Lastly, you need to have enough suitably trained and equipped security response staff, as well as a clearly documented response and escalation procedure to handle intrusion events. 

This needs to specify what situations can be handled by the  security staff on-site, and what situations require the assistance and back-up of police.

The aim of a comprehensive package such as this is to provide a warning that someone has breached the airport perimeter, track them as they move around within the grounds, and delay them long enough for the appropriate security response to take place – before the intruder can reach their target.

About the author
Alec Owen is international client manager for Future Fibre Technologies and author of The Boundaries of Security –  Global Trends in Perimeter Security, a resource book for  the security industry.

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