In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

The second part of the V-cycle involves a series of evaluation activities to ensurethe suitability of the final product. These activities are known as ‘verification’ and‘validation’. Verification is the process of ensuring that the final product meets therequirements (that is, the product was built correctly). Validation is the process ofensuring that the requirements are sufficiently correct and complete (that is, theright product has been built).Figure 34: Simplistic representation of aircraft development processVerification and validation activities include testing the individual items ofequipment (and software), and then progressively integrating the equipment intosystems for more sophisticated testing activities, until the aircraft is evaluated as acomplete entity. Verification and validation also include methods such as peerreviews, modelling and other analyses. The V-cycle is an iterative rather than afixed process as the verification and validation activities can lead to design changesthroughout the cycle.As indicated in Figure 34, safety assessment activities are a key part of a goodsystem development process. Initial safety assessment activities help evaluate theinitial design and derive requirements, and a final system safety assessmentprovides assurance that the resulting system meets the safety requirements.It is generally accepted that, for all but the simplest systems, it is impossible toguarantee the correctness of all the system requirements and associatedassumptions. In order to reduce the potential effect of errors in the requirements orsubsequent design implementation, systems are designed with fault-tolerant featuresin their architecture, such as redundancy and dissimilarity.- 89 -