Operations#

Implementation status: Partial (coverage matrix row Operations — LF wired per DL-010/017; additive ARM/FAO/ATM present; per-route resolution absent from the production wedge). The page’s printed forms — three separate linear efficiency ramps, the multiplicative \(e^* = (1-\Delta\eta)\,e_{in}\), and the eq. 5 RPTK flight-count recomputation — are implemented standalone in src/engine/operations-full.ts (DL-137, Stage-1 shadow; the three end-values are named in the RST but never valued anywhere in the corpus, so they are required caller arguments). The production wedge remains subtractive on an S-curve with a fixed 0.35/0.35/0.30 split — a documented divergence from the printed linear ramps. Source: src/engine/cascade.ts:computeLCA (ops wedge, lfAt, lfFactorAt), src/engine/constants.ts:OPS_AMBITION, src/engine/operations-full.ts Test evidence: tests/load-factor.spec.ts, tests/suite-m-operations-fuelburn.spec.ts

Efficiency levers: ARM + FAO + ATM#

Operational fuel-burn improvement is the sum of three categories (cf. CASCADE Operations):

\[\Delta\eta_{ops} = \Delta\eta_{ARM} + \Delta\eta_{FAO} + \Delta\eta_{ATM}\]

  • ARM — Aircraft Retrofit & Maintenance (ambition table 0.4–2.0 %)

  • FAO — Fleet & Airport Operations (0.8–4.0 %)

  • ATM — Air Traffic Management (1.0–5.0 %)

The scenario may set each component explicitly (fb_arm, fb_fao, fb_atm) or a single total fb, which is split by the fixed category shares 35 % / 35 % / 30 % (OPS_CATEGORIES). The ops wedge in the time series is \(\Delta_{ops} = G_{gross} \cdot (\Delta\eta_{ops}/100) \cdot s(t)\), where \(s(t)\) is the normalised adoption curve over the model window.

Load factor#

Raising passenger load factor conserves revenue-passenger traffic, so fewer flights deliver the same payload; energy and emissions scale with the flight count (cf. CASCADE Operations, load-factor equations, RPTK conservation; DL-010/DL-017). Freighters are exempt. The aggregate energy multiplier at year \(y\):

\[F_{LF}(y) = (1 - f_{freight})\,\frac{LF_{in}}{LF(y)} + f_{freight}\]

with \(LF_{in}\) the baseline load factor (lf_entry_value, default 85 % — neutral for the frozen baseline; set 82.6 %, the IATA 2019 global passenger value [IATA, 2024], for CASCADE-reproduction scenarios) and \(f_{freight}\) the freighter share of fuel burn (lf_freight_share, default 10 %, literature range 8–12 %). The load factor itself ramps on an S-curve from lf_entry_year (default 2024) to 2050:

\[LF(y) = LF_{in} + (LF_{target} - LF_{in})\, s\!\left( \frac{y - y_{entry}}{2050 - y_{entry}}\right)\]

The lever enters the ops wedge as \(G_{gross}\cdot(1 - F_{LF}(y))\) (negative when the target load factor is below baseline — more flights) and applies in both offset modes; it is exactly zero at defaults so the frozen baseline is unaffected.

Test evidence (8 tests) pins: neutrality at defaults, frozen-baseline invariance, monotonicity in both directions, the RPTK-conservation identity (wedge = gross × pax share × (1 − LF_in/LF)), freighter exemption, ramp behaviour, and whole-engine conservation.

Contrail avoidance#

Implementation status: Extended — CASCADE application parity. The RST set publishes no contrail formulation (verified by full-text grep of the RST set, 2026-07-18); the CASCADE app exposes the strategy with exactly the inputs modelled here Source: src/engine/contrails.ts (pure module — not imported by cascade.ts), UI in src/components/modals/OperationsModal.tsx (Contrails tab) Test evidence: tests/contrails.spec.ts (20 tests)

Avoidance ramps from 0 at ca_start_year (default 2025) to the target share of contrail forcing at ca_target_year (default 2050), then holds — the same hold-not-stretch convention as the other levers. Any CurveShape may be selected via curve_ca; the default 'linear' matches the RST default for operations improvements:

\[r(y) = s\!\left(\frac{y - y_{start}}{y_{target} - y_{start}}\right) \in [0, 1], \qquad r = 1 \text{ held beyond } y_{target}\]

Prediction-success (knowledge) quality scales effectiveness — none / partial / perfect = ×0.0 / ×0.6 / ×1.0. These factors are documented HyFlux fallback assumptions: the RST set publishes no numeric effectiveness factors for the app’s knowledge modes (grep-verified):

\[X_{avoided}(y) = \operatorname{clamp}_{[0,1]}\!\Big( \frac{X_{target}}{100}\; r(y)\; k_{knowledge}\Big)\]

Rerouted flights burn ca_fuel_penalty % more fuel; the fleet-average extra burn is the per-flight penalty times the avoided fraction (conservative — in reality ~10 % of flights cause ~80 % of contrail warming, so the true rerouted share is smaller), and is netted against the avoided forcing as a CO₂ cost (fuel-burn % ≈ CO₂ % for the same fuel):

\[\Delta_{net}\ [\text{frac. of fleet CO}_2] = X_{avoided}\cdot R_{CO_2eq} - \frac{X_{avoided}\cdot p_{fuel}}{100}, \qquad R_{CO_2eq} = \tfrac{2}{3}\]

CONTRAIL_CO2EQ_RATIO (\(R_{CO_2eq}\)) expresses contrail-cirrus forcing as a fraction of aviation CO₂ forcing, anchored to the nonco2.ts envelope: Jet-A central ERF multiplier 2.0 ⇒ non-CO₂ ≈ 1.0×CO₂, of which contrail-cirrus is ~2/3 (Lee et al. 2021 ordering [Lee et al., 2021]). Conceptual, literature-approximate, editable — same status as nonco2.ts. The net fraction is signed and can go negative when the fuel penalty dominates.

Defaults are lever OFF (ca_target_share = 0 ⇒ all outputs exactly zero), so every existing scenario result is bit-identical. The module is deliberately pure and is not yet wired into the aggregate sweep — a future integration multiplies the net fraction by fleet CO₂ to obtain GtCO₂e; the OperationsModal tab (knowledge picker, start/target years, target share, fuel penalty, curve shape) exposes the parameters and URL-persists them today.

Known deviations / limitations#

  • Per-route operations resolution (fleet-assignment deltas, direct-routing and taxi savings per route) is not modelled; all levers are aggregate.

  • The contrail lever is an aggregate, display-level quantity: it is not wired into the aggregate sweep, and both the knowledge factors (0 / 0.6 / 1.0) and \(R_{CO_2eq} = 2/3\) are documented fallback/conceptual assumptions, not CASCADE-published values.

  • The ambition-table AMBITION.ops (3–21 %) is treated as ARM+FAO+ATM only; load factor is a separate multiplicative lever.

  • Curve-shape parameters for the individual ARM/FAO/ATM levers (curve_arm etc.) are URL-persisted but the engine currently applies one shared adoption curve to the summed total.

  • The custom pulse curve (CASCADE Operations, Custom Curves → Pulse) is implemented exactly as curves.ts:pulseAt and documented under HyFlux Extensions; UI exposure remains deferred because the CurveEditor param model does not map onto the pulse parameter set (see Aircraft — Fleet Renewal & Future Aircraft).