Aircraft single-hit vulnerability/survivability is usually expressed as the probability of kill or the vulnerable area in case of being given a random threat （e.g. a fragment） hit on the aircraft. In this paper, introducing the ＂equivalent target method＂ in lethality field into the aircraft vulnerability assessment, a generic vulnerability calculation model is proposed. In order for a good representation of reality, the model considers the threat change of state-of-motion during the threat penetrating into the components successively. Application shows that the proposed generic model has solved the Pk/h （probability of kill given by a hit on the component） calculation problem in aircraft vulnerability assessment, and is easier to be computerized than other commonly used models.
A new method is proposed for calculating the aircraft equivalent single vulnerable area using Monte-Carlo simulation technique. The method simulates the kill events of single vulnerable components and multiply vulnerable components or redundant components to ＇Model of Filling Boxes with Balls＇, in which the area of each box is equal to the component＇s vulnerable area. By randomly and uniformly sampling the threat hit locations, the expected number of hits required to kill an aircraft can be given and the aircraft equivalent singly vulnerable area can be attained. Examples demonstrate the correctness and feasibility of the proposed method. Analysis show that the developed method overcomes two shortcomings of currently used methods. （1） It can calculate the equivalent single vulnerable area of aircraft with several sets of multiply vulnerable components, and （2） When the components of each multiple set have different vulnerable areas, the method also applies.
