Improving Airport Security, Security-net - the shape of things to come?

Today’s point solutions for security are the best they have ever been and their integration into a facility-wide security network holds the promise of providing security screeners with comprehensive ‘views’ of the passengers being screened. Such views could combine the results of the latest security screening with previous checks and also information about the passengers.

Furthermore, a facility-wide security net would allow security equipment and its operators to operate as a single system, as opposed to separate, and separately managed, security checkpoints. It would also be possible to provide the facility manager with a top-level view of the airport’s security. However, before discussing such a ‘security net’ it is worth exemplifying how good the point solutions have become.

Having the vision
Take, for example, the x-ray inspection (using an automatic explosive detection system - EDS) of baggage for the hold. Historically, it has been necessary to trade throughput against detection capabilities. Today, with systems like Smiths Detection’s HI-SCAN 10080 EDtS meeting all of the requirements for a 100% screening environment, throughput can be up to 0.5 metres per second (conveyor belt speed).

Specifically, the most recent development, the EDtS (Explosive Detection tomography System), uses five fan-shaped beams to scan every piece of luggage. Most current systems use only two or three beams to scan baggage, but current thinking is that five is the optimum number of beams: enabling better volume calculations and more accurate material classification.

Material classification is typically done through analysis of the so-called Z-effective (Z-eff) – which relates to the atomic number of the material’s molecules and structure, and is established through plotting high energy signal results against low energy signal results:

However, whilst such ‘banana’ plots are ideal for distinguishing an explosive (say Semtex) against a metal (say steel) a number of common compounds are so close to explosives, on the plot, that false alarms may result. Above, see how similar the Z-eff of chocolate is to that of Semtex.

Fortunately, the compounds, which confuse instruments that employ only Z-eff for material classification, have different densities. Density is mass divided by volume. An object’s mass can be estimated from the absorption of the x-ray energy and the Z-eff, and, thanks to the five beam system, its volume can be estimated from the tomography.

The EDtS, in combining Z-eff and density analyses, achieves high throughput (up to 1,800 bags per hour) and very high detection rates: and when the (automated) detection capabilities are as good as those of the EDtS it is then easy to a) integrate the instruments together and b) refine how they fit in with the airport’s procedures and processes. For example, EDtS allows an airport to adopt a fully automated multi-level screening concept:

• Level 1 – the EDtS would screen all baggage automatically for explosives. The majority of bags would clear at this level and directly transported to the sorting system and then to the aircraft. Suspicious bags would be forwarded to Level 2.
  
  
• Level 2 – A HI-SCAN 10065 HDX, which employs x-ray diffraction to determine if an object is non-hazardous, dangerous or still suspicious, would be used for the automatic inspection of baggage deemed suspicious at level 1. [Note: during peak hours, images of suspicious bags could be presented to security screeners at workstations. To support image interpretation, the suspicious items in question would be highlighted within a red frame].
  
  
• Level 3 – Those bags still deemed suspicious would be analysed in further detail. An instrument that may be used for such analysis is the HI-SCAN 8380-3D, designed specifically for baggage rechecks. This machine rotates the baggage whilst it is scanned – so building a precise 3D model. Furthermore, Ionscan trace detectors (see later) could be used to establish whether there are traces of explosives on the baggage.

The interconnection of multiple EDtS units, and the detection equipment used by the security screeners at levels 2 and 3, form the basis of an advanced hold baggage security net - a net which itself is capable of being part of a much wider network.

Checkpoint
Let us now consider another important aspect of airport security, the checkpoint, and look at not only the technology employed but also the procedures, processes and personnel involved in screening.

The walkthrough metal detector is of course looking for metallic threats, such as knives and guns, and raises an alarm when any metal object is detected. The operator’s role is to respond to the alarm.

Similarly, the desktop trace detector (for example an Ionscan 400B unit – see later) is present to detect particles of explosives on baggage and notify the operator. A walkthrough trace detector (for example Ionscan Sentinel – see later) may also be present at the checkpoint to detect particles of explosives on a passenger’s skin and/or clothing.

The carry-on baggage x-ray system, through which are passed bags, coats/jackets, mobile phones, laptop computers and so on, is responsible for presenting, to the operator, an image of the object. The operator, responsible for raising the alarm, is arguably therefore the ‘detector’ in this part of the checkpoint. The checkpoint may also include a member of staff overseeing ‘the proceedings’ and making assessments based on the appearance and behaviour of passengers. It is also possible that he/she or another member of staff may be rechecking boarding passes and identifications.

Whilst located at a single checkpoint, the above technologies, personnel and procedures are generally working independently of each other. Data is seldom shared between the detectors and the individual operators have little knowledge of what the others may have observed. True, operators can communicate with each other, but they generally have no ‘view’ of the activities occurring at other areas in the overall screening process. In addition, the checkpoint is only ever checking a passenger at that point in time. Whilst passports and boarding passes can be checked, there is little intelligence (history) of the passenger’s background or how they came to be at the checkpoint.

The lack of shared data (and passenger history) is, on the whole, preventing airports from maximising the strengths of their security solutions and keeping them from making best use of their equipment and personnel. So what needs to change?

Technology
Employing a proven solution/technology in a new role is always a good starting point, and developments are currently underway to adapt EDtS’s technology (the five beams and combined Z-eff and density analyses) into an ‘advanced Threat identification X-ray’ (aTiX) system for use at checkpoints. In much the same way that EDtS automatically detects suspicious objects, an aTiX will draw a checkpoint’s operator’s attention to objects within a carry-on bag/case.

As for metal detectors used to check passengers, they are producing too many false-alarms (particularly following the sensitivity hikes in 2001) and the technology has evolved little since their introduction. Little seems to be going on to address this limitation, other than the aggressive divestiture policies adopted by most airports.

Perhaps the most significant technology change to the checkpoint is the introduction of trace detection. It is the replacement for ‘sniffer’ technology, which was, limited to the detection of only high volatility (high vapour pressure) explosives such as Nitro-glycerine (NG) and Ethylene Glycol DiNitrate (EGDN). However, plastic explosives such as C-4 and Semtex exhibit low volatility and sniffer technology alone will not suffice.

Ion mobility spectrometry (IMS)-based trace detection technology forms the basis of Smiths Detection’s Ionscan 400B units. These are about the size of a laser-jet printer, can detect more than 40 explosives and take only six seconds to analyse a sample. At present, there are more than 6000 Ionscan 400B units operating in hundreds of airports around the world.

IMS technology also forms the basis of Smiths Detection’s Ionscan Sentinel (pictured below), arguably the industry’s first high reliability walk-through trace detection portal. Ionscan Sentinel uses jets of air to dislodge particles and vapours from a passenger’s clothing, skin and hair.

The sampling air is pulsed to dislodge particles from the passenger’s clothing and body and runs for approximately 4 seconds. Aided by gravity, the air is collected, at a rate of about 20,000 litres per minute, through vents at the base of the portal and is pre-concentrated before presentation to the IMS detector. Sentinel’s detection capabilities include: RDX, PETN, TNT and Semtex.

Another implementation of IMS-based trace detection can be found in Centurion – worthy of a mention in this article as the detector is now widely regarded as an invaluable aid to building and perimeter security.

Centurion affords fixed site continuous ambient air monitoring for chemical warfare agents and toxic industrial chemicals (TICs): either of which, if released in an airport, would have devastating effects. Multiple detectors can be wired back to a central command centre, where PC based monitoring software displays each Centurion detector location and provides real time monitoring views, and they can also be integrated with Sentinel units and x-ray screening systems.

Humans, machines and knowledge
For tomorrow’s airport security checkpoints to be effective it is essential that checkpoint personnel be freed of performing repetitive tasks – for example studying all x-ray images – so that they can truly exercise their judgements and experience under the EDtS multilevel screening of hold baggage concept discussed above, only those images of bags, which cannot be automatically cleared, would be presented to an operator. In short, the machines are left to do what they do best (the repetitive clearing of 'clean' bags) and humans to do what they do best (form opinions and use their insight).

As for the checking of passengers, many improvements need to be made. Whilst the Yes/No responses of the metal and walk-through trace detectors, as well as a number of other detection methods/systems currently under development, are serving the checkpoint well, they could contribute so much more by helping the checkpoint perform as an ‘entity’.

Hence, as well as maintaining existing and introducing new Yes/No-type detectors, we need to move away from unconnected discrete security steps/stages and start sharing data. For example, should Sentinel raise an alarm then it would be very easy to request, automatically, a closer inspection (by x-ray or a search) of the passenger’s hand luggage and probably use an Ionscan 400B to screen for explosives.

There is also the need for the ‘injection of information’ into the checkpoint. Currently when a person walks through, somebody compares the name on the boarding pass with an ID and then compares the ID with the person. There is nothing done to prove that the ID is genuine, and no background search is done.

There is though, a wealth of information which, if made available, would help a) identify the risk levels and b) rapidly clear all non-suspicious passengers (hopefully the majority). For example, just knowing how a passenger purchased his/her ticket, or knowing whether they changed flights close to the day/time of departure, can help the screeners assess the level of security which needs to be applied.

To CAPP it all
In January 2003 the USA’s Transportation Security Administration (TSA) proposed to establish a new system of records under the Privacy Act, known as Passenger and Aviation Security Screening Records (PASSR). PASSR would be established primarily to support the development of a new version of the Computer Assisted Passenger Pre-screening System (CAPPS II), which was piloted in 2002 in the US. CAPPS carries a great deal of publicly available information about passengers and pulls in information, about their ticket purchasing history, from the airline.

CAPPS assigns a threat level/ranking, of red, yellow or green, against each passenger. Based on their ranking, passengers could be steered towards either a standard or a high-level screening check. Of equal concern is the tracking of passengers once in the airport. Currently, due to limited passenger and luggage tracking capabilities, all passengers are checked and rechecked against their passports and boarding passes. In the ideal world, check-in should be the only time that the passengers need verify who they are and present their travel documents. It is at this stage that CAPPS information would be used, perhaps in conjunction with biometric technologies such as fingerprint/iris scanning or facial recognition. In addition, a digital photograph of the passenger at check-in may be taken – so that it can be viewed elsewhere in the airport.

Entering ‘the system’ could also see passengers’ baggage tagged, for the hold and carry-on, with either traditional barcode or radio frequency ID (RFID) tags. At subsequent security checks within the airport, passengers would need only to re-verify, with perhaps a fingerprint, that they have a right to be where they are. Furthermore, with tagged hand baggage, it would be possible to present, to the security screener, the image of the person who carried the bag during check in.

Conclusion
As mentioned at the beginning of this article, today’s point solutions for airport security are the best they have ever been: particularly with the union of x-ray and trace detection for screening carry-on and hold baggage. Add to this the screening of passengers for trace levels of explosives and today’s checkpoint becomes a high tech’ barrier: to detect (and deter) those who would try to carry explosives or weapons on to an aircraft.

Now is the time therefore to integrate the point solutions, enhance the airport checkpoints’ procedures and processes and to bring, to the checkpoints, intelligence of the passengers. Now is also the time to improve, through CAPPS and biometric technologies, passenger check-in, so that subsequent checks on passengers can be reduced to (possibly automated) simple re-verification measures.

Any airport would benefit from the above changes as they all maximise the use of key resources (both equipment and personnel) and simplify operational procedures. Passengers would benefit from the above changes too. Having gone through the enhanced check-in procedure, the passenger’s journey through the airport would not be hindered by repetitive documentation checks.

Above all, a (security) networked airport provides the facility’s management with a top-level view of the airport as a system. Hence, in addition to having a high reliability security ‘net’ the airport also has a means of monitoring, and therefore maximising, passenger throughput.