Chris Collins

Tools · aviation

E6B pilot calculators

The flight computer on your phone: wind triangle and wind finding, runway crosswind, pressure and density altitude, true airspeed and Mach, time/speed/distance and fuel with reserves, climb and descent planning, weight and balance with a CG envelope chart, glide range, and unit conversions. Not for navigation.

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How to use it

Not for navigation. A training and planning aid: check every number against your aircraft’s POH/AFM, the charts and an official briefing. The weight-and-balance profiles are examples only.

How to use it

Pick a tab; every field is remembered in this browser. Units (speed, altitude, temperature, pressure, weight, fuel, distance) are under Display units; directions are degrees.

  • Wind triangle — true course, true airspeed and the wind give the true heading, wind correction angle and ground speed, with a vector diagram. Find the wind works backwards from your heading and TAS and the track and ground speed your GPS shows.

  • Crosswind — runway (27, 09L, or a heading such as 274) and the wind give the headwind or tailwind and crosswind components, in gusts too, against your own crosswind limit.

  • Density altitude — field elevation, altimeter setting and outside air temperature give the pressure altitude and density altitude, exact and by rule of thumb; plus an ISA table at any altitude.

  • TAS & Mach — IAS (plus the position error from your POH’s calibration table) or CAS, pressure altitude and OAT give the true airspeed, Mach number and equivalent airspeed; and the reverse.

  • Time & fuel — any two of ground speed, distance and time give the third; fuel burn, usable fuel, taxi allowance and a 30- or 45-minute reserve give the endurance, fuel needed and what is spare.

  • Climb & descent — top of descent at your descent rate, the rate for a 3° (or any) path, the rate needed to lose height in a given distance, and time, distance and gradient for a climb.

  • Weight & balance — the loading table, take-off, landing (after the fuel you will burn) and zero-fuel weight and CG, plotted on the CG envelope. Two example profiles (Cessna 172S, Piper PA-28-181) show the shape; choose My aircraft to enter your own empty weight and arm, stations and envelope, and export or import it as JSON.

  • Glide — still-air glide range from height and glide ratio, adjusted for a head- or tailwind.

  • Convert — speed, length, distance, pressure, temperature, fuel volume, weight and vertical speed.

Formulas and sources

  • Wind triangle: WCA = asin(W·sin(ω − TC) / TAS), heading = TC + WCA, GS = TAS·cos(WCA) − W·cos(ω − TC), where ω is the direction the wind blows from.

  • Runway components: crosswind = W·sin(θ), headwind = W·cos(θ), θ the angle between wind and runway. ATIS and tower winds are magnetic, like runway numbers; METAR and TAF winds are true.

  • ISA (ICAO Doc 7488): 15 °C and 1013.25 hPa at sea level, −1.98 °C per 1,000 ft to 36,089 ft, then −56.5 °C; for example 10,000 ft is −4.8 °C and 696.8 hPa.

  • Pressure altitude from QNH by the ISA relation; rule of thumb elevation + 1,000 ft per inHg below 29.92. Density altitude from the air density (dry air), equivalent to the NWS formula; rule of thumb PA + 118.8 × (OAT − ISA) (FAA Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25).

  • TAS from CAS for compressible, subsonic flow: impact pressure qc = p₀[(1 + 0.2(CAS/a₀)²)^3.5 − 1], Mach = √(5[(qc/p + 1)^(2/7) − 1]), TAS = Mach × a, with a = 661.48 kt × √(T/288.15) (Ed Williams, Aviation Formulary). CAS 150 kt at 10,000 ft in the ISA is 174 kt TAS (Mach 0.273).

  • Descent: a 3° path is about 3 nm per 1,000 ft and ground speed × 5 ft/min (exact: GS × 101.27 × tan 3°).

  • Reserves: US 14 CFR 91.151 (30 min day VFR, 45 min night VFR) and 91.167 (IFR: to the alternate plus 45 min). Avgas weighs about 6.0 lb per US gallon.

  • Weight and balance: CG = Σ(weight × arm) / Σ weight, checked against the envelope polygon and the maximum weight.

Limits

  • Not for navigation, and not a substitute for your aircraft’s POH/AFM performance and loading data. The example profiles use typical figures in the shape of those types' manuals — your aircraft’s empty weight, arms and limits will differ.

  • IAS → CAS needs your aircraft’s calibration table; the tool takes that correction as one number.

  • Density altitude here ignores humidity (the aviation-weather tool includes it); on a humid day the real value is a few hundred feet higher.

  • The ISA model stops at 65,617 ft; airspeeds are subsonic.

  • Weight and balance arms are in inches; a utility-category envelope or a lateral CG is not modelled.

Related: Aviation weather (METAR/TAF), Great-circle routes, Flight tracker, Unit converter.

Linking to an example

Each setting has a short parameter (values in knots, feet, °C, hPa, pounds, US gallons and nautical miles, whatever units you display), and the tab comes from the # part of the address, for example /tools/e6b/?tc=90&tas=110&wd=45&ws=25#wind.

Tab Parameters Meaning Example

#wind

tc, tas, wd, ws; fh, ftas, ftrk, fgs

course, TAS, wind from, wind speed; find-the-wind inputs

tc=360&tas=120&wd=330&ws=20

#runway

rwy, xwd, xws, xg, xlim

runway, wind direction, speed, gust, your limit

rwy=18&xwd=210&xws=25

#altitude

elev, qnh (hPa), oat, isaalt

field elevation, altimeter setting, OAT, ISA table altitude

elev=5434&qnh=1020&oat=34

#airspeed

cas, iascorr, pa, tat, tasin

CAS, position error, pressure altitude, OAT, TAS to convert

cas=150&pa=10000&tat=-4.8

#fuel

spd, dist, mins, burn, fob, taxi, res

ground speed, distance, minutes, burn/h, fuel on board, taxi fuel, reserve minutes

burn=8.5&fob=40&mins=150&res=30

#descent

dfrom, dto, dgs, drate, dang, ddist; cfrom, cto, crate, cgs

descent and climb planning

dfrom=9500&dto=1500&dgs=140&dang=3

#wb

prof, burnwb

profile (c172s, pa28, custom), fuel burned before landing

prof=pa28

#glide

gh, gr, gtas, gw

height AGL, glide ratio, best-glide TAS, wind (+ tail)

gh=6000&gr=9

u_spd, u_alt, u_tmp, u_prs, u_wt, u_vol, u_dist

display units (kt/mph/km/h, ft/m, °C/°F, inHg/hPa, lb/kg, US gal/L, nm/sm/km)

u_prs=hPa

example

one of the presets below (it also picks the tab); other parameters override it

example=wind-330-20

A custom aircraft profile and the loading travel only in Share link's compressed ?s=.

Presets:

  • wind-330-20 — course 360° at 120 kt TAS, wind 330° at 20 kt: heading 355°, GS 102 kt

  • crosswind-rwy18 — runway 18, wind 210° at 25 kt: 12.5 kt crosswind, 21.7 kt headwind

  • density-denver — Denver (5,434 ft), 30.12 inHg, 34 °C: density altitude ≈ 8,600 ft

  • tas-fl100 — CAS 150 kt at 10,000 ft in the ISA: TAS ≈ 174 kt

  • fuel-c172 — a 2 h 30 min leg at 8.5 gal/h with 40 gal and a 30-minute reserve

  • descent-3deg — descend from 9,500 to 1,500 ft at 140 kt on a 3° path

  • wb-c172 — Cessna 172S example loading (use your POH)

  • glide-9to1 — 9:1 glide from 6,000 ft AGL with a 15 kt headwind

Runs entirely in your browser; nothing you type leaves this page.