The topic of testability in equipment appears to generate as many different views as people asked to express an opinion. Certainly, a manufacturer's perceptive of testability appears to vary from the equipment user view. Both will agree that testability is an essential characteristic of equipment but its need is driven by different requirements. This paper presents a view of testability as seen by the users of complex military equipment in the three services. The general thesis is that the testability needs of the Royal Navy, Army and Royal Air Force must receive greater attention than at present given and that each element of the Armed Forces is faced with maintaining equipment for 20 years or more whereas industry has a much shorter period of interest.

In developing this thesis the paper starts by discussing the military requirements for testability and outlining the maintenance philosophies adopted by the three services. Procedures for establishing an effective testability programme, as part of the overall design effort, are then considered and a possible technique for the numerical assessment of testability is mentioned. Finally the paper emphasises the importance the three Services attach to the transportability of test software.