Integrity gaps in certification and MRV across aviation mitigation policies

The mitigation of aviation’s climate impacts hinges on upstream emission reductions via sustainable aviation fuels and on out‑of‑sector solutions such as carbon offsetting and removals. Their credibility relies on climate claims that are substantiated by certification and monitoring, reporting and verification (MRV) architectures, yet no systematic comparison of how existing policies and standards operationalise certification requirements has been attempted. We assess MRV and certification provisions in ten policies and standards relevant to aviation, spanning sustainable aviation fuels and carbon credits. We use a novel 40‑criterion evaluation framework developed through literature review, expert consultation and natural language processing. We find that the comprehensiveness of certification requirements is driven less by policy type (compliance versus voluntary) or technology family (fuels versus offsets and removals) than by how stand‑alone and prescriptive the policy or standard is. The Paris Agreement Article 6.4 mechanism, which sets detailed rules for its methodologies, covers the broadest range of criteria but still exhibits selective blind spots. Instruments that delegate implementation of certification rules to third‑party programmes with heterogeneous methodologies, such as CORSIA‑eligible emission units and Paris Agreement Article 6.2, systematically show gaps in core integrity dimensions. Within CORSIA, certification requirements are substantially more stringent for alternative fuels than for eligible emission units, despite both being compliance options, resulting in uneven integrity standards for ostensibly equivalent mitigation. Overall, current policies and standards governing aviation mitigation claims are neither comprehensive nor internally consistent enough to guarantee integrity across and fungibility between different net‑zero aviation pathways.