TABLE OF CONTENTS The product selected by, or provided to, an owner or organization must meet its intended use or purpose. As has been discussed in previous chapters, the product must have the performance and supportability characteristics necessary for it to achieve a predetermined need. From the viewpoint of the owner, the goodness of the product is ultimately measured in two ways: being available to be used when the need arises, and being cost effective to purchase, operate, and maintain. This chapter focuses on availability and Chap. 11 discusses cost of ownership. Before starting a detailed investigation of availability, a definition of each term is necessary.
Availability. The probability that an item is in an operable and committable state when called for at an unknown (random) time.
Having a system for the sheer act of possessing it gives no value to the owner. Value in possessing a system comes through the ability to actually use the system. Therefore, the ability for use of a system becomes the final gauge of value to the owner. The most common term for this value of a system is availability, or the ability to use a system when required. This concept can be compared to owning an automobile. Just having an automobile does not give sufficient value to the owner unless the automobile provides some form of transportation upon demand. For example, if a person owns an automobile, but the automobile is inoperative due to some failure, then the owner cannot use...
