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Infrared missiles pose a significant threat to civilian and military aviation. ManPADS missiles are especially
dangerous in the hands of rogue and undisciplined forces. Yet, not all the launched missiles hit their targets;
the miss being either attributable to misuse of the weapon or to missile performance restrictions. This paper
analyses some of the factors affecting aircraft vulnerability and demonstrates a structured analysis of the risk
and aircraft vulnerability problem.
The aircraft-missile engagement is a complex series of events, many of which are only partially understood.
Aircraft and missile designers focus on the optimal design and performance of their respective systems, often
testing only in a limited set of scenarios. Most missiles react to the contrast intensity, but the variability of the
background is rarely considered. Finally, the vulnerability of the aircraft depends jointly on the missile’s performance
and the doctrine governing the missile’s launch. These factors are considered in a holistic investigation.
The view direction, altitude, time of day, sun position, latitude/longitude and terrain determine the background
against which the aircraft is observed. Especially high gradients in sky radiance occur around the sun
and on the horizon. This paper considers uncluttered background scenes (uniform terrain and clear sky) and
presents examples of background radiance at all view angles across a sphere around the sensor.
A detailed geometrical and spatially distributed radiometric model is used to model the aircraft. This
model provides the signature at all possible view angles across the sphere around the aircraft. The signature is
determined in absolute terms (no background) and in contrast terms (with background). It is shown that the
background significantly affects the contrast signature as observed by the missile sensor. A simplified missile
model is constructed by defining the thrust and mass profiles, maximum seeker tracking rate, maximum guidance
acceleration and seeker sensitivity. For the purpose of this investigation the aircraft is equipped with conventional
pyrotechnic decoy flares and the missile has no counter-countermeasure means (security restrictions on open
publication). This complete simulation is used to calculate the missile miss distance, when the missile is launched
from different locations around the aircraft. The miss distance data is then graphically presented showing miss
distance (aircraft vulnerability) as a function of launch direction and range.
The aircraft vulnerability graph accounts for aircraft and missile characteristics, but does not account for
missile deployment doctrine. A Bayesian network is constructed to fuse the doctrinal rules with the aircraft
vulnerability data. The Bayesian network now provides the capability to evaluate the combined risk of missile
launch and aircraft vulnerability.
It is shown in this paper that it is indeed possible to predict the aircraft vulnerability to missile attack in a
comprehensive modelling and a holistic process. By using the appropriate real-world models, this approach is
used to evaluate the effectiveness of specific countermeasure techniques against specific missile threats. The use
of a Bayesian network provides the means to fuse simulated performance data with more abstract doctrinal rules
to provide a realistic assessment of the aircraft vulnerability.
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