Comparative Analysis of GHG Calculation Methodologies in Aviation

The aviation sector faces mounting pressure to deliver transparent, comparable greenhouse-gas (GHG) disclosures under European Sustainability Reporting Standards (ESRS). We provide a comparison of aviation GHG methodologies spanning simple factor tools and flight-specific, lifecycle-inclusive approaches. Our approach combines a structured documentation review (retaining calculators that publish or allow derivation of emission intensity per passenger-kilometre), controlled computations for standardized short-, medium-, and long-haul profiles under each method’s native assumptions (energy scope, class/cargo allocation, distance modelling, non-CO₂ handling), and a documentation-based multi-criteria analysis (0–3 rubric) on boundary clarity, non-CO₂ treatment, data granularity, documentation/auditability, and reporting alignment; we also record standards applicability with a binary (0/1) screen and test sensitivity to weights and thresholds. Results show modest dispersion at short haul but pronounced divergence at long haul, driven chiefly by inclusion of radiative forcing indices (RFIs) and well-to-wake (WTW) factors; methods applying RFI+WTW report systematically higher CO₂e than tank-to-wake calculators. High-scoring, well-documented frameworks and European factor sets emphasizing WTW and transparent assumptions are best positioned for ESRS-style disclosures, while some tools remain useful for screening if omissions are made explicit. We find no universal monotonic link between score and emissions; the long-haul association is mechanistic (scope completeness and non-CO₂ inclusion). We propose a minimum-viable ESRS-ready approach: explicit energy scope declaration, documented non-CO₂ treatment with RFI sensitivity, versioned/traceable factors and allocation rules, and reproducible calculations. Limitations include partial “black-box” implementations, scope heterogeneity, and residual judgment in scoring.