E6B Calculator is a training and flight-planning aid. It is not FAA-approved equipment, it cannot be used during an FAA knowledge test, and nothing on it replaces your aircraft's POH/AFM, its weight and balance record, or an official weather briefing.
References
- Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C (2023): the wind-triangle and flight-planning examples (chapter 16), the standard-atmosphere and altimeter-correction tables and the density altitude and crosswind sample problems (chapter 11), the humidity example (chapter 4) and the cloud-base rule (chapter 12).
- Aircraft Weight and Balance Handbook, FAA-H-8083-1B: the sample airplane and loading problem (Figures 5-1 and 5-3) and the standard fuel weights (Figure 3-4).
- FAA Type Certificate Data Sheet 3A12, Revision 80: the Cessna 172S CG envelope, maximum weights and station positions in the weight-and-balance template.
- FAA Order 8080.6H, Conduct of Airman Knowledge Tests: what applicants may bring into the testing room. It holds the rules formerly in AC 60-11C, cancelled on August 22, 2025.
- AC 25-11B, Electronic Flight Displays: the color meanings the interface follows (Tables 5-1 and 5-2).
- U.S. Standard Atmosphere 1976 / ICAO standard atmosphere: the defining constants for pressure altitude, density altitude and true airspeed.
- National Weather Service density-altitude and vapor-pressure formulas for humidity.
- 14 CFR 91.151: the VFR fuel reserves offered in the fuel calculator.
- Aviation Weather Center Data API (aviationweather.gov): current METARs and TAFs by station. Reports are U.S. government data; the site caches each station for five minutes and identifies itself in its requests.
Methods
- Atmosphere. Pressure altitude is the field elevation plus the standard-atmosphere altitude of the altimeter setting, which is how an altimeter's Kollsman scale works. Density altitude inverts the standard atmosphere for the actual air density, with humidity through virtual temperature when a dewpoint is entered. Both layers of the model to 65,617 feet are included.
- Airspeed. True airspeed and Mach number use the subsonic compressible pitot relations; the E6B's density-only value is shown alongside.
- Wind. The wind triangle is solved exactly; the reverse problem finds the wind from heading, airspeed, track and ground speed.
- Rules of thumb (1,000 feet per inch of mercury, 120 feet per degree, 3 miles per 1,000 feet) are always labeled as estimates.
- Weather decoding runs in your browser. Unrecognized groups are highlighted, never guessed.
- The virtual E6B is drawn from the same logarithms and window geometry a mechanical E6B uses; it is our own face design, not a copy of any manufacturer's.
How it is tested
Automated tests run on every build:
- the PHAK examples and tables listed above, the FAA weight-and-balance example, the TCDS 3A12 envelope and the PHAK nav-log example;
- 1,500 real METARs and 400 real TAFs from the Aviation Weather Center's public cache (September 26, 2026), compared field by field with its own parser;
- every guided reading on the virtual E6B against the calculators.
The tests cover these references; they do not certify every possible input. If you find a result that disagrees with an authoritative source, please report it to hello@e6bcalculator.com with the inputs.
Typeface and design
Text is set in B612, a typeface designed for aircraft cockpit displays and released under the SIL Open Font License 1.1. The dark Instrument theme follows cockpit display conventions; the Paper theme and printouts use a light page.