flight-ops-calculators

Flight Ops Calculators

Ten deterministic command-line tools in scripts/. All JSON-by-default, all with --pretty for humans, all pure Python stdlib (no deps, no network, no API keys). Run any with --help for usage.

scripts/
├── gradient.py          climb/descent geometry solver
├── fuel_uplift.py       Jet A-1 uplift reconciliation (3% rule)
├── wind_components.py   crosswind / headwind
├── altitude.py          PA / DA / ISA-dev
├── airspeed.py          CAS / TAS / Mach
├── pet_psr.py           Point of Equal Time & Point of Safe Return
├── descent.py           Top-of-Descent (3× rule + tax)
├── weight_balance.py    W&B + CG + %MAC
├── etops.py             EDTO / ETOPS diversion radius
└── holding.py           direct / parallel / teardrop entry
tests/
└── test_all.py          34 zero-dep assertions; `python3 tests/test_all.py`

See references/formulas.md for derivations, constants, and edge cases. Run the test suite any time you edit a script: python3 tests/test_all.py.

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1. gradient.py — climb/descent solver

Eight variables — distance_nm, time_min, gs_kt, altitude_ft, rate_fpm, angle_deg, gradient_pct, gradient_ft_per_nm — and six relationships. Supply any sufficient subset (typically 3 values), solves for the rest. Sign convention: + climb, − descent for altitude, rate, angle, and gradient.

Triggers: "climb gradient", "ROC required", "3-to-1 descent", "TOD distance", "angle vs %", "ft/NM", obstacle clearance, any 3 of the variables above.

# Required gradient to clear 1500 ft in 5 NM at 140 kt
python3 scripts/gradient.py --distance-nm 5 --altitude-ft 1500 --gs-kt 140 --pretty

# 3° descent from FL100 at GS 250 — how far out is TOD, what's the ROD?
python3 scripts/gradient.py --altitude-ft -10000 --angle-deg -3 --gs-kt 250 --pretty

# ROC for 5% gradient at GS 180
python3 scripts/gradient.py --gradient-pct 5 --gs-kt 180 --pretty

2. fuel_uplift.py — Jet A-1 uplift reconciliation

Compares mass ordered vs mass actually delivered (volume × SG × temp correction), flags >3% deltas (the Jet A-1 SG-band rule).