Flight Computer (Digital)
A complete electronic flight computer with organised categories, fast numeric entry, clear units, validation and explanations; shares its validated math with the analog E6B.
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Pick a category on the rail (Time · Speed · Distance, Fuel, Conversions, Altitude & Airspeed, Gradient & Off-course, Wind, Reference) and a function in it — every calculation of the E6-B flight computer is here: 28 slide-rule-side functions, 9 wind-side and slide-front functions and the three printed reference panels. Type into the fields (Tab moves on, Enter keeps the result in the history, Esc restores the function's defaults, − / + nudge); on a phone the Keypad button opens thumb-sized keys. Unit selectors (NM / SM / km, kt / mph / km/h, ft / m, °C / °F, US gal / Imp gal / L, lb / kg, inHg / hPa, mm / in) stay as you set them for the whole session, whatever the category.
The display shows the primary result large, tagged Verified (procedure and example read in the manual), Assumption (the inventory's reasoning, e.g. a scale-reading resolution) or Rule of thumb (the 60-in-1 off-course rule, the 120 ft per °C density-altitude rule). Below it an original schematic shows what the physical computer does for the same problem — the outer and turned middle scales with the index arrow and the read pair, the altitude or airspeed window, the wind-side grid with grommet, TAS arc and wind dot, the component grid, the crosswind table, the temperature scale, the chart ruler — and the readout lists the setup step by step. The analog E6-B flight computer performs these same setups on the instrument.
Where the inventory documents a difference between the device and the exact relation, the Exact / E6-B reading switch shows both values and their difference: the airspeed window's single ratio CAS ÷ √σ against the compressible exact TAS, scale readings to the printed graduation, the 60-in-1 rule against the exact angle, table cells in whole knots. Scenario steps through the manual's worked examples of the current category with their page numbers; Practice poses the manual's sample problems and checks your answer against the printed answers (pp. 37–38) within a stated tolerance. Send-to links open the dedicated calculators with the values filled in.
Assumption: the positions of the unit arrows, the SECONDS and Mach indexes on the schematic are computed from their conversion ratios, not traced from the device; graduation resolution (0.1 / 0.2 / 0.5 / 1 at 15 / 30 / 60) is from the manual's description. True altitude uses the aircraft OAT for the whole column (the manual's p. 22 caution applies). The equipment-suffix panel reproduces the slide's printed codes as data and names current FAA Form 7233-4 Item 10 letters from AIM Appendix 4 as read on 2026-10-13 — re-check the current AIM before relying on it. The manual's inconsistent examples (listed under Method) are not used as oracles.
Every number comes from the platform’s shared calculations — the same ones the Wind Triangle, Crosswind, Time–Speed–Distance, Fuel Planning and TAS / CAS / EAS tools use (checked to give identical results for identical inputs). Time–speed–distance and fuel: t = d ÷ v, d = v × t, Q = q̇ × t (PHAK ch. 16). Conversions: NIST SP 811 factors (1 NM = 1,852 m, 1 SM = 1,609.344 m, 1 US gal = 3.785 411 784 L, 1 Imp gal = 4.546 09 L, 1 lb = 0.453 592 37 kg, 1 ft = 0.3048 m); fuel 6.0 lb/US gal avgas, 6.7 Jet A, oil 7.5 (PHAK ch. 10). Airspeed: exact subsonic TAS = a(OAT) × M(CAS, PA) (NACA Report 837, US Standard Atmosphere 1976); the E6-B window shown as CAS ÷ √σ. Density altitude: ISA inversion of the actual density; the 120 ft/°C rule labelled. True altitude: (calibrated − station) × T_OAT ÷ T_ISA(PA) + station (E6-B instruction manual pp. 21–22). Gradient: ft/min = ft/NM × GS ÷ 60. Off course: 60 × off ÷ along (rule) and atan (exact). Wind: the vector triangle (PHAK ch. 16); components HW = W cos α, XW = W sin α (AFH ch. 9); unknown wind = ground − air; variation east positive (east is least, west is best). Slide-rule geometry: position = 360° × (log10 v mod 1); the middle scale turned by the angle of the ratio multiplies every pair.
Verified: every function of the E6-B inventory against the E6-B instruction manual's worked examples and printed answers (pp. 8–35, answers pp. 37–38), the slide-front grid example and table cells, the NIST factors and the atmosphere values; identical results to the TAS / CAS / EAS, Wind Triangle, Crosswind / Headwind, Time-Speed-Distance and Fuel Planning tools; the “send to” links open the target tool with the same values; every category was exercised in a real browser at desktop and phone width.
Device readings on the Exact / E6-B switch are what a careful reading of the physical scales gives (rounded to the printed graduation, or the window ratio, or the rule the device embodies); they are labelled Assumption or Rule of thumb because the exact artwork positions were not traced. The manual's own reading errors (p. 8–9 "564", p. 17 "901 kg", p. 25 "2.4°", p. 28 "9.5 / 11.5") are recorded by the site and excluded from the scenarios and practice problems.
- E6-B flight computer instruction manual pp. 5–35, answers pp. 37–38 — every function, worked example and printed answer
- PHAK FAA-H-8083-25C ch. 11 (standard atmosphere, altimeter settings) and ch. 16 (wind triangle, magnetic variation)
- AFH FAA-H-8083-3C ch. 9 Figure 9-19 (crosswind components)
- NACA Report 837 (compressibility; TAS from CAS) and U.S. Standard Atmosphere 1976
- NIST SP 811 (unit conversion factors); PHAK ch. 10 fuel and oil planning densities
- AIM 5-1-5, 5-1-6 and Appendix 4 — FAA Form 7233-4 and Item 10 equipment letters (read 2026-10-13)