This paper describes a decision tree analysis to assess the cost-effectiveness of MANPADS (Man-Portable Air Defense Systems) countermeasures. These countermeasures are electronic devices that can be installed on commercial airplanes to detect and deflect surface-to-air missiles (SAMs) fired by terrorists. The model considers a terrorist attempt to shoot down a commercial airplane with a heat-seeking SAM, and it evaluates the decision to install countermeasures, taking into account alternative modes of attack, probabilities of success, and consequences to the economy. All model variables were fully parameterized, using reasonable ranges based on open-source literature. Not surprisingly, the probability of an attack, the consequences of an attack to the economy, and the cost of countermeasures are the most important parameters. Surprisingly, some of the hotly disputed parameters, such as the probability of an airplane surviving a successful hit or the probability of a false alarm, have very little impact on the results. The analysis suggests that MANPADS countermeasures installed on planes can be cost-effective if the probability of such an attack is large (greater than about 0.40 in ten years), the economic losses are large (greater than about $75 billion), and the countermeasures are relatively inexpensive (smaller than about $15 billion). An economic analysis conducted as part of this analysis showed that the economic impacts can be as large as $250 billion, thus making countermeasures a possibly cost-effective option. More research is needed to determine the real costs of MANPADS countermeasures and how terrorists may shift their tactics, once countermeasures are installed.

Should We Protect Commercial Airplanes Against Surface-to-Air Missile Attacks by Terrorists?

A study on the energy dissipation of several different CFRP-based targets completely penetrated by a high velocity projectile

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Electronic warfare self-protection of battlefield helicopters : a holistic view

The infrared (IR) signature of a jet aircraft engine in altitude operation is a key component for the design of effective IR countermeasures and low-emission engines. Predicting the signature with radiometric models is widely accomplished, but measurements in situ are crucial for model verification. The altitude test cell provides a venue for measuring the IR signature in a simulated altitude environment, but the facility is designed for testing engines, not IR imaging. As a result, the imaging in the test cell is laden with measurement uncertainty due to stray radiation from the facility structure, hot exhaust gases, and the measurement equipment itself. Post-processing using correction factors is necessary to extract the engine signal from the stray radiation. This research investigated the uncertainties in measuring the IR signature of a turbofan engine inside an altitude test cell. The engine is measured by an IR camera immersed in the hot exhaust gases 35 feet downstream from the on-engine axis view. A protective enclosure and zinc selenide (ZnSe) window shield the camera from the heat and vibrations of the plume. The requirements for the IR measurement system include the apparent intensity and radiance of the visible engine surfaces in three bands of operation, two Medium Wave IR (MWIR) bands and one Long Wave IR (LWIR), with a spatial resolution of 1 in. To explore the extent of the measurement uncertainties, a radiometric model of the altitude test cell is formulated to quantify the engine and stray flux. To increase the fidelity of the model, the ZnSe window, a source of stray radiation, is characterized through measurements and experimentation. The resulting data is employed in the radiometric model. Specific measurement conditions at which the stray radiation is 5% or less of the total radiation are then derived, thereby decreasing the necessity for post-processing correction factors. These conditions are derived for the 3–4-, 4.5–5-, 8–9- and 8–12-μm bands using a parametric analysis. Two LWIR bands are considered to provide insight into specific previous measurements made with a quantum-well IR photo-detector (QWIP, roughly 8–9 μm), as well as potential future measurements made using broader band imagers (e.g., HgCdTe at 8–12 μm). A sensitivity analysis in the style of a Monte Carlo simulation is also performed to gauge the uncertainty in the radiometric model calculations.

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Analysis of Uncertainties in Infrared Camera Measurements of a Turbofan Engine in an Altitude Test Cell

Measured and computedmean and fluctuating radiation intensities are reported for a subsonic exhaust plume and used to characterize the influence of turbulent fluctuations on mean radiation properties. Narrowband radiation intensity measurements were acquired using an infrared camera fitted with a narrowband filter (4:34 0:1 m). Unsteady three-dimensional calculations were used to estimate both time-dependent and mean temperature and partial pressure values of the exhaust species in the flow. From these scalar values the mean and root mean square of the radiation intensity were calculated using a narrowband radiation model. Axial distributions of the calculated intensities based on the time-dependent quantities show trends similar to thosemeasured, but consistently overpredict the intensity by 40%. Intensity distributions based on mean scalars were in better quantitative agreement, but decay more rapidly downstream than experimental data. Turbulent fluctuations have little effect on the mean radiation intensity near the nozzle exit, but they become increasingly more important downstream in the flow. The influence of turbulent fluctuations on mean intensity values increases with radial distance from the centerline. This trend correlates to increases in normalized fluctuations in the temperature and radiation intensity.

Influence of Turbulent Fluctuations on the Radiation Intensity Emitted from Exhaust Plumes

Recent events have focused attention on the threat that terrorists with shoulder fired surface-to-air missiles (SAMs), referred to as Man-Portable Air Defense Systems (MANPADS), pose to commercial airliners. This report discusses SAMs and examines options for mitigating missile threats.

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Homeland Security: Protecting Airliners from Terrorist Missiles

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Bartholomew Elias

Papers

Homeland Security: Protecting Airliners from Terrorist Missiles

Homeland Security: Protecting Airliners from Terrorist Missiles [Updated October 22, 2004]