Navlog

POST /v1/planning/navlog

A navigation log for a flight: each leg with its course and heading, true and magnetic, wind, ground speed, time, fuel and ETA, and the fuel plan, from the aircraft performance in the request and the winds aloft along the flight (see Winds aloft; United States, still air elsewhere). BravoEcho holds no aircraft performance models: the times and fuel are only as right as the figures you send. Check them against the aircraft flight manual.

Request: the flight object (see Flight object) and:

• performance (required): cruise (tas_kt, fuel_per_hour) and, when they differ, climb and descent (tas_kt, fuel_per_hour, rate_fpm). A route string climbs and descends at the aircraft's own rates: its top of climb and top of descent are placed from rate_fpm and tas_kt (otherwise at 250 ft a NM up and a 3 degree path down). Waypoints are flown as given: a leg that climbs is flown at the climb figures, one that descends at the descent figures, the rest at the cruise figures.
• taxi_fuel, reserve (minutes at the cruise fuel flow, or fuel), fuel_on_board, and fuel_unit (gal, L, lb or kg: a label for your figures).
• step_nm (default 10, 5 to 50): how often the wind is sampled along the track.
• departure picks the wind forecasts and gives the ETAs; the legs' times come from the performance, not from speed_kt.

{
  "route": "KMSP DCT KMKE",
  "departure": "2026-10-14T15:00:00Z",
  "cruise_fl": 65,
  "performance": {
    "climb": { "tas_kt": 80, "fuel_per_hour": 12, "rate_fpm": 700 },
    "cruise": { "tas_kt": 120, "fuel_per_hour": 9 },
    "descent": { "tas_kt": 130, "fuel_per_hour": 7, "rate_fpm": 500 }
  },
  "taxi_fuel": 1.4,
  "reserve": { "minutes": 45 },
  "fuel_on_board": 48,
  "fuel_unit": "gal"
}

Each leg: from, to, phase (climb, cruise, descent), distance_nm, level_from_ft and level_to_ft, true_course_deg, magnetic_variation_deg (east positive) and magnetic_course_deg, the average wind (dir_deg, kt) and headwind_kt (positive a headwind), wind_correction_deg (positive to the right), true_heading_deg and magnetic_heading_deg, tas_kt, ground_speed_kt, time_min, fuel, the running elapsed_min and fuel_used, eta, and still_air_nm where no forecast reached. Ground speed holds the heading that makes good the track: the square root of the true airspeed squared less the crosswind squared, less the headwind; a wind that leaves no ground speed is 422.

The magnetic variation is the declination of the World Magnetic Model 2025 (WMM2025, developed by NOAA and the British Geological Survey) at the leg's great-circle midpoint and mid time, to a tenth of a degree. The magnetic course and heading are the true ones as shown minus the variation, rounded, with 360 for north; compass deviation is not applied. WMM2025 is valid from 2025.0 to 2030.0 (1 January 2025 to 31 December 2029), and a leg flown outside that has no magnetic fields. Near the magnetic poles the horizontal field is weak and a compass unreliable: a leg in the blackout zone (horizontal field under 2000 nT) has no magnetic fields, and one in the caution zone (2000 to 6000 nT) keeps them with a caution. meta.notes names the legs in each case. The model holds the field of the Earth's core only, not local anomalies.

totals: distance_nm, time_min, arrival, trip_fuel, taxi_fuel, reserve_fuel, required_fuel and, with fuel_on_board, fuel_at_destination and reserve_met; avg_headwind_kt. summary says it in one sentence. Live for the request above on 14 Oct: "KMSP to KMKE: 258 NM in 1 h 55 min, trip fuel 17.3 gal (taxi 1.4, reserve 6.8, required 25.4). With 48.0 on board, 29.3 left at the destination: reserve met. Average tailwind 17 kt." Its cruise leg: {"from": "TOC", "to": "TOD", "phase": "cruise", "distance_nm": 222, "true_course_deg": 115, "magnetic_variation_deg": -2.1, "magnetic_course_deg": 117, "wind": {"dir_deg": 307, "kt": 18}, "headwind_kt": -17.3, "wind_correction_deg": -1.5, "true_heading_deg": 113, "magnetic_heading_deg": 115, "tas_kt": 120, "ground_speed_kt": 137, "time_min": 97.1, "fuel": 14.6}. meta.winds names the forecasts used; meta.notes: courses and headings are given true and magnetic, the legs without magnetic fields and why, and where the winds come from.