One of the most important tasks of aircraft vulnerability assessment is to rank vulnerable components so that proper actionscan beappliedtotheweaker componentstoimprovesurvivability.Currently, whencomparingthe contributions ofcomponentstothe overall aircraft vulnerabilityina military context, existingmethodsfocusedonthe aircraftkillstate without considering the intermediate states that are related to performance degradations. This work aims to investigate how performance-related importance measures in the field of reliability can be modified to rank the vulnerable components.Component vulnerability importance measures consideringperformance degradationsare proposed. Two applications, one with eight critical components and one consisting of 84 noncritical components and 28 critical components dealing with aircraft being hit by metallic fragments detonated from a missile, are provided. The analysis shows that the proposed method is useful for engineers to determine which components are more likely to cause aircraft performance degradations in the combat environment from the standpoint of vulnerability.@en