EASA issues Certification Memorandum in support of 25.1309. The purpose of this CM is to provide an approach to the demonstration of compliance to certain CS 23 and CS 27 specifications that is in line with reference standard guidance as adapted to installation of system/ equipment that provide operational safety benefit. This is achieved by introducing credits for systems or equipment that provide operational safety benefits in the determination of the Development Assurance Level (DAL)1.
The intent of the Net Safety Benefit policy is to facilitate the introduction of new, safety enhancing technologies in the current, fleets that have been shown to provide operational safety benefits to improve the overall safety performance of the operation.
See https://www.easa.europa.eu/sites/default/files/dfu/certification_memorandum_cm-sa-001_-_net_safety_benefit_-_issue_1.1.pdf