How EasyNavLog builds a navlog

Every number on the log comes from the same E6B arithmetic you learned for the written test, applied to real data. The app's "How it's done" page shows this math worked for a leg of your own flight; this page explains the method.

1. Course and distance

Each checkpoint has a latitude and longitude (from FAA data, or from where you clicked on the chart). Distance and true course between consecutive checkpoints come from the great-circle formulas, so a 30 nm leg is accurate to a few hundredths of a mile.

2. Winds aloft

The NWS FB winds aloft forecast (06, 12 or 24 hour period) for the station nearest each leg is read, and the wind at your cruise altitude is interpolated between the forecast levels, exactly as you would do by hand between 3,000 and 6,000 ft. You can override the forecast with a manual wind.

3. Wind correction angle and ground speed

WCA = asin( WS × sin(WD − TC) / TAS ) GS = sqrt( TAS² − (WS × sin(WD − TC))² ) − WS × cos(WD − TC) TH = TC + WCA

WD is the true wind direction, WS the wind speed, TC the true course and TAS your cruise true airspeed. This is the wind triangle the E6B solves graphically.

4. Magnetic heading and compass heading

MH = TH − VAR (east variation is positive, so "east is least") CH = MH + DEV (from your compass deviation card)

Variation comes from the World Magnetic Model for the day you plan, so it matches what current charts show rather than a stale value stored with a navaid. VOR radials use the station's own slaved variation, as the FAA defines them.

5. Time and fuel

Each leg's time is distance divided by ground speed. Climb and descent portions are folded into the first and last legs at climb and descent speeds and fuel flows, taxi fuel is added, and fuel remaining counts down from fuel on board. The alternate or reserve column is filled from your alternate airport, or from the reserve time you choose.

6. Everything else on the page

Frequencies come from the FAA frequency file (ATIS, tower, ground, clearance, UNICOM/CTAF, approach and departure). Airport diagrams are drawn to scale from runway, taxiway and apron geometry. METARs, TAFs, convective SIGMETs, SIGMETs, G-AIRMETs, PIREPs and TFRs touching the route are gathered at build time and written onto page 2 and the map. The ICAO flight plan block is filled from the plan and can be edited before printing.

The app also runs a set of self-checks against textbook examples every time it loads. You can see them at the bottom of the "How it's done" page. If a number ever looks wrong, use the Feedback button so we can look into it.

Try it with your own route