The expeditionary nature of the U.S. armed forces has been demonstrated in more ways than perhaps initially imagined when the doctrine was first espoused. In practical terms, it means that U.S. forces are deploying to more forward and less developed installations than ever before. Smarter and better equipped than ever, the deployed forces are usually fewer in number than would have been considered in the past. What facility and airfield security now may lack in numbers, they are making up for in technology. Instead of walking a perimeter, sensors are now prowling the landscape for unwanted intruders.

Sensing the Enemy

Lieutenant Colonel David Woods, deputy director and chief of security forces for the Force Protection Command and Control Special Program Office at Electronic Systems Center, Hanscom AFB, is delivering state-of-the-art sensor technology to defend air assets. "For delivery, we have had the Tactical Automated Security System (TASS) contact in place for the last five years. This year [2003], we awarded the Integrated Base Defense Security System (IBDSS) contract. Both are indefinite delivery/indefinite quantity contracts that have given us the stability and flexibility to provide the most current solutions to meet the warfighter's needs very quickly," he said.

Roy Higgins, of the Force Protection Command and Control Special Program Office, added, "The biggest change has been in the area of base access control. There is much more scrutiny of who is coming and going from our bases. At Air Force bases, perimeter security has always been of paramount concern. What changes as time goes by is the technology we employ."

Rapid movement of air assets to equally rapidly constructed airfields-part of the effort to take the global war on terrorism (GWOT) to the terrorists in their home bases-has posed significant military challenges. "A big challenge," said Woods, "is protecting aircraft in remote locations where there is no protection in the parking areas. We are developing a ‘suitcase' sized system that can easily be transported with the aircraft. The system consists of a few small radars and a couple of handheld annunciators. The system will detect and track all targets that come within 100 meters of the aircraft."

Woods agreed that early detection is the key. "A significant capability improvement is the ability to detect and track targets over an area. Up to recently, most sensors only told you if someone crossed the perimeter. Now we can detect targets beyond the perimeter, watch them approach and see where they go after crossing the perimeter. This capability change is due to advancements and increased procurement of ground-based radars." Looking ahead, Woods said, "We believe the next significant area of technology improvement will be in explosive detection. The most important integration advancement will be delivering a common operating picture to see first, understand first and act first."

Sensing the Danger

Shlomo Nir, general director for CONTROP Precision Technologies LTD, sees more incidents of terrorists targeting air assets. As a lieutenant colonel in the Israeli Air Force reserves, Nir has both a military and a private sector perspective to bring to sensor technology and its defenses applications. "The terrorists we're dealing with don't care particularly that they are being monitored when they are on a suicide mission. So the most important thing when it comes to protecting air assets is early acquisition-to give ground force defenses time to react to a threat," he explained. "Surveillance reduces the number of people you need to monitor a given area, but once the threat is identified, you need people on the scene in advance of a successful infiltration. So our sensors are designed to get target acquisition far out from defended assets." CONTROP produces the Stabilized Automatic Intruder Detection and Recognition System (SPIDER) and the Compact Electro-Optical Intruder Detection System (CEDAR).

"Before 9/11, we were developing perimeter security around secure installations like oil, nuclear, power and similar facilities," commented Nir. "We're still doing that and focusing on the airbase systems because we know that without early detection, airbases are particularly vulnerable to terrorist strikes. We know that incorporating thermal detection to augment or optic prescription is the best total solution for day-and-night surveillance. Since airfields are more vulnerable to attack at night because of their configurations and locations, the move to thermal technology is very strong. All important is range-detecting threats as far out as possible to give airfield defenders the chance to respond."

Perimeter surveillance systems from Sensor Technologies & Systems Inc. (STS), Scottsdale, AZ, use microwave sensors. Collaboration remains important when it comes to the technology in use. STS provides the U.S. Air Force with perimeter surveillance radar system (PSRS), which detects, alerts and tracks compromises to perimeter security around airfields in remote, difficult to protect landing sites within 300 meters. Other systems include the Air Force's Tactical Automated Security System (Northrop Grumman is one of the three prime contractors for this system), Qual-Tron Inc.'s Enhanced Mini Intrusion Detection System (EMIDS) and L3 Communications' Remotely Monitored Battlefield Sensor System II (REMBASS-II).

Glenn Herosian, manager, Integrated Security Systems, FLIR Systems Inc., added, "Thermal detection is an important advance because it ensures detection of bodies radiating heat.

"[The ideal system ensures] maximum pixels-on-target, [and] is the way we describe the best way to quickly classify a threat to get sufficient tracking to see if the subject in view is a suicide bomber or just a stray dog. The human element is always there; system operators must be able to process quickly what they are seeing and identify the threat."

A Terrorist-Deterrent Fence

Use of fences to deter terrorists doesn't provide the early warning or, in instances, the necessary dissuasion. Herosian posited that fences no longer make good neighbors when the neighborhood is teeming with terrorists. "Detection capability beyond the fence line, and building in the time to react-stand-off detection is the key to good airfield defense," he said.

Use of microwave technology and automatic detection sensors have changed the name of the detection game and given responders an edge they never had with mere optical technology that demanded a monitor to make an analysis of the threat as soon as it is seen. Now the threat can be assessed as soon as it was electronically detected.

Evolution from fences has not escaped wider notice by the military and its industrial partners. Walker Butler, president of STS, has been working with the U.S. Air Force, Army and Navy since 1998 to develop, test and deliver two wide-area sensors designed for perimeter protection of airfields, border, power plants, etc. "Since 9/11, and a few years before for STS, the need has changed from a fence line approach to a wide-area technology, from a straight line beam breaker approach to wide-area surveillance. This has several benefits: projecting surveillance beyond the fence line increases response time; wide-area [360 degree] coverage allows continuous tracking of intruders; while the inside of a base is typically masked off to reduce distraction alarms, this mask can be easily removed to allow tracking of any intruder that crosses the line. This promotes safety and reduces the time it takes to apprehend intruders. We finally know where the intruder is going," Butler explained.

Nir indicated that the human element hasn't become dispensable in the defense of aircraft and troops on airfields. Rather, sensors hone the abilities of the human defenders to respond quickly to the scene of an incursion and help determine quickly the nature of that intrusion. "Our equipment is designed to zoom in on an area in which an occurrence is detected," said Nir. "Systems have to have automatic detection because the alternative is scanning manually. Operators using these older methods are susceptible to fatigue and missing an area that a machine is programmed to cover." He added that detection alone is not a total solution for airfield monitoring planners.

"For most perimeter applications, the time of the line sensor is past. We need more situational awareness than just a relay closure can give us. We need a real time picture of what's happening both outside the perimeter and, if necessary, inside. The breakthrough is that this technology is now affordable and simple to operate," explained Butler.

Asked about the fencing systems Israel is building, Nir explained that terrorists often don't care if and when they are detected. "People planning for this kind of defense have to understand that they are dealing with suicide attackers, with people unconcerned about their own lives, interested only in mass destruction and killing," he emphasized. "Sometimes you have to build fences if you don't have much time to respond because attackers will plow right through without concern for detection. So you have to catch that early to respond accordingly. We see uses by the Air Force of our systems in Central Asia and whenever there is a need for monitoring an entire area. Sometimes it is practically or politically impossible to put up a fence, but you still need sophisticated monitoring systems to protect aircraft and personnel."

Similarly, Butler described the more important attributes of a good detection system. "They have to have sensitive detection of even the lowest/slowest intruders, very low false alarm rates, ease of operation and interpretation of the data, and costs that are affordable," he said.

"The Air Force is looking for a mixed technology system. That is, a good detection system with a robust assessment component. This capability is provided by using radar for detection, since radar responds to motion better than all other technologies, and then to use the radar to point a camera to allow assessment of what it is that moved. Cameras are great for assessment, but not good for wide-area surveillance. A look at the camera-only system on our Southwest border and its lack of utility is a good example of this concept. PSRS is deployed at Homestead ANGB in Florida specifically to protect aircraft. It is planned for installation at Offutt AFB [NE] next. The Remote Detection and Tracking Sensor [RDTS] is several months away from deployment at this time," said Butler. RDTS is developed by STS and can detect personnel out to 5 kilometers and vehicles out to 10 kilometers.

"The ideal system would be able to automatically distinguish between a good guy and a threat," said Woods. "With today's technology, it is relatively easy to detect someone, but it is not so easy to determine who is a threat. With the increase in available information, ease of disseminating and displaying that information in a way to ensure understanding of the information is becoming more and more important."

Butler was optimistic about the infusion of technology. "STS is forcing technology changes in the areas of millimeter-wave radars, low cost transceivers with low noise and great linearity, detection algorithms for non-standard targets and advanced manufacturing techniques to make these sensors available at affordable prices. The Air Force has just ordered 660 PSRS units for a mobile application, after several months of testing and evaluation at their security test site.

"There has not been a defeat of the radar technology to date. There probably will be after a number of years of deployment, and then we'll have to react. But that's what technology advance is all about, action and reaction. We're trying to maximize the number of years it takes to find whatever vulnerabilities there may be in this new technology," Butler said.

On that score, the Air Force attempts to defeat sensors in exercises, anticipating the methods of saboteurs. "When we develop and test a product or system, we bring in skilled ‘intruders' to try to defeat that product or system. That guides improvements to our existing systems and the next generation of security products," explained Woods.

Sensitive to the Future

"Airbases and naval vessels face a similar threat," Nir added, of suicide swimmers and speedboaters, the latter particularly deadly, as was found to be the case in the Gulf of Aden when the U.S.S. Cole was attacked by suicide bombers. He attributed the most important advances in thermal imaging to computer memory miniaturization. "Sensors allow you to utilize personnel to defend an airfield rather than just monitor the perimeter. But you always have to be looking ahead because terrorists adjust, even to sensors."

As important is the combination of thermal and low-light sensor capabilities. Sensor fusion-combining sensing technologies in a single device to thermal, infrared, and low-light-produced images-is clearly where the technology is heading.

Today's security challenges require continual technology enhancement. Events like the Force Protection Equipment Demonstration (FPED, Quantico, VA) have revealed new and existing ideas on airfield monitoring to a wide audience of security professionals. Likewise, groups that develop physical security technology, like the Physical Security Equipment Action Group (PSEAG), are becoming more and more critical for providing the technology for tomorrow's solutions.

Industry and military officials agree-no matter how advanced the detection system or how close to full-blown "sensor fusion" it becomes, there has to be sufficient time for humans to react to identified threats. As the military continues to establish "bare bones bases" and create airstrips rapidly, sensors to warn about threats will be an increasingly important component for success in the GWOT. Sensors are expensive, but still a small fraction of the cost of a destroyed KC-135 or C-130 on an isolated runway or the troops inside. Look for increasing, higher-level concern for promoting airfield sensor technology and use in the field in the near future.