  A recent study has introduced a procedure to quantify the survivability of a
team of armoured fighting vehicles when it is subjected to a single missile
attack. In particular this study investigated the concept of collaborative
active protection systems, focusing on the case where vehicle defence is
provided by high power radio frequency directed energy weapons. The purpose of
the current paper is to demonstrate how this analysis can be extended to
account for more than one missile threat. This is achieved by introducing a
jump stochastic process whose states represent the number of missiles defeated
at a given time instant. Analysis proceeds through consideration of the sojourn
times of this stochastic process, and it is shown how consideration of these
jump times can be related to transition probabilities of the auxiliary
stochastic process. The latter probabilities are then related to the
probabilities of detection and disruption of missile threats. The sum of these
sojourn times can then be used to quantify the survivability of the team at any
given time instant. Due to the fact that there is much interest in the
application of high energy lasers in the context of this paper, the numerical
examples will thus focus on such directed energy weapons for armoured fighting
vehicle team defence.
