GTF grounding: non-CO2 exposure supplement

Fleet context, emissions exposure, certified excess NOx, and non-CO2 model uncertainty. Companion to the GTF grounding tracker.

Fleet context

Not a modelled figure, reported fleet status.

Grounded share of A320neo-family GTF fleet

37.7%

720 of 1,912 PW1100G-powered A320neo-family aircraft, ~May 2026 (down from a late-2025 peak, per Pratt & Whitney/Cirium reporting)

Raw certified comparison: one aircraft, one LTO cycle

PW1127G-JM (neo, GTF, the grounded engine) vs two certified ceo engine options. Per aircraft (2 engines), ICAO EEDB. No fleet or excess-flying assumptions, this is what the certificates say for one aircraft, once.

Percent change from the neo baseline. Two scenarios shown side by side because the answer genuinely depends on which ceo engine picks up the replacement flying, not resolved to a single number. Colour shows direction: orange is more than the neo baseline, teal is less.

Per aircraft, per LTO cycle	Neo (GTF)	Scenario A: CFM56-5B	Scenario B: V2500

Fuel burn and NOx increase under either scenario, that holds regardless of which ceo fleet absorbs the flying. HC and CO move in opposite directions depending on scenario: not ambiguous data, a genuine engine-specific difference. nvPM is only certified for the CFM56-5B scenario, V2527-A5 predates the nvPM certification requirement, so no comparable figure exists for that engine.

Non-CO2 multiplier: why we show a range, not a number

Evidence for model uncertainty. Not used to derive any figure on this page.

Fleet share and CO2 exposure are scenario ceilings, not measured outcomes. NOx is certification-grade at climb-out; cruise correction via the Boeing Fuel Flow Method is the documented next step. The multiplier range exists to show why non-CO2 effects aren't collapsed into a single figure here, not to produce one.