Survivability is composed of two components: susceptibility and vulnerability. Susceptibility is “the inability of
the aircraft to avoid the elements that make up the hostile man-made environment,” and vulnerability is “the
inability of the aircraft to withstand the hostile man-made environment.” That is, vulnerability has to do with the
ability of the aircraft structure and critical components to survive a hit by a threat weapon, and susceptibility has to
do with the ability of the aircraft to avoid being hit in the first place.