This article reports a validation exercise regarding a novel, Total Aviation System (TAS) method for the certification of aeronautical products, systems, and services that constitute a change to the aviation system. The method promotes the development of a TAS-level safety argument that can potentially support performance based and compliance based certification. The validation exercise consisted of a 1.5 day workshop session with nine selected certification and safety experts, in which feedback was collected by means of questionnaires and focus group discussions on a set of certification specific Key Performance Areas. The method evaluated can clarify the interfaces and dependencies between domains and improve the management of cross-domain hazards throughout certification (including earlier identification). At the same time it requires: (i) more management, coordination and training efforts compared to current practice for both the certifier and the applicant; (ii) the open sharing of safety information between the relevant TAS stakeholders, which may require regulations to make this mandatory. Future evaluations will benefit from applying the approach to novel projects, and from comparative studies that apply the approach retrospectively to and compare it with past certification cases.