INCOSE Systems Engineering Handbook, 5th Edition

3 LIFE CYCLE ANALYSES AND METHODS

3.1 QUALITY CHARACTERISTICS AND APPROACHES

3.1.1 Introduction to Quality Characteristics

ISO/IEC/IEEE 15288 (2023), Section 3.36 defines Quality Characteristic (QC) as: inherent characteristic of a product, process, or system related to a requirement. QCs are how the stakeholders will judge the quality of the system. Approaches exist that help ensure these characteristics are present in the SoI and its broader context or environment.

The objective of the following sections is to give enough information to a Systems Engineering (SE) practitioner to appreciate the significance of various QC approaches, even if they are not an expert in the subject. In previous editions of the handbook, the QC approaches were known as Specialty Engineering or the Engineering Specialties. These approaches are also known as Design for X (DFX) and Through-Life Considerations. The QCs are informally known as the -ilities since many, but not all, end in “ility” in the English language.

QC approaches, as used in this handbook, are life cycle perspectives that need to be considered to ensure the system is developed and its ecosystem cultivated so that QCs are present when the system is produced, utilized, supported, and ultimately retired. QC approaches often generate non-functional requirements. Some QC approaches, such as safety, security, and resilience may also generate functional requirements. These QC approaches are applied throughout the system’s life cycle, ...