This International Standard describes early reliability assessment methods for items based onfield data and test data for components and modules. It is applicable to mission, safety andbusiness critical, high integrity and complex items. It contains information on why earlyreliability estimates are required and how and where the assessment would be used. Finally,it details methods for reliability assessment and the data required to support the assessment.To estimate durability (life time or wear-out), the physics-of-failure method is used.Three types of assessment are discussed in detail:– the similarity approach;– models for durability analysis;– handbook methods.Clause 6 provides an introduction to reliability assessment and Clause 7 the management ofthe process. Clause 8 describes the data needs, sources and types for assessments andClause 9 provides details of the assessment methods.Annexes A and B provide additional information to aid understanding of the similarity analysisand durability analysis.This standard is applicable to making reliability estimates for specifications, design, designmodification and support engineering.