A nav log that does the arithmetic
A VFR navigation log turns a line on the chart into headings and times you can fly. For each leg the log works through the heading chain and the time-speed-distance math:
- Wind correction from the true course, true airspeed and wind: the wind triangle.
- Headings: true heading, then magnetic with the variation, then compass with the deviation.
- Ground speed and time for the leg's distance, plus any extra minutes (such as the climb on the first leg).
- Fuel for the leg at the planned burn, with a running total and the fuel remaining.
The totals line shows the distance, time en route and fuel burned. If the fuel remaining falls below the reserve you chose, it turns red.
The worked example
The log opens with the flight from the Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C, chapter 16): Chickasha to Guthrie, Oklahoma, in a Cessna 150. True course 031°, 53 nautical miles in five legs, true airspeed 115 knots, the wind from 360° at 10 knots, 7° east variation and 2° deviation. The handbook works out a 3° left correction, headings of 028° true, 021° magnetic and 023° compass, and a ground speed of 106 knots. Its legs take 6, 6, 6, 7 and 5 minutes, 35 minutes in all with 5 minutes for the climb, burning about 4.7 gallons. The log reproduces every one of those numbers.
Printing
Print nav log prints the table on a clean light page, landscape works best. Two blank columns, ATE (actual time en route) and ATA (actual time of arrival), are there to fill in by hand as you pass each checkpoint. Keep the printed log with the chart; a pencil still works when the battery does not.
What it does not do
The log has no airport, airspace or obstacle database, and it does not draw your route. Measure true courses and distances on a current chart, check airspace and terrain along the route, and get a weather briefing. Magnetic variation comes from the chart's isogonic lines and compass deviation from the card in the airplane.
Plan a VFR cross-country with the nav log
- Draw the course on the sectional chart, pick checkpoints and measure each leg's true course and distance.
- Enter the true airspeed, fuel burn, magnetic variation, the forecast wind and the fuel on board.
- Add one leg per checkpoint with its true course and distance; add the compass deviation from the aircraft's card and any extra minutes for the climb.
- Check the headings, ground speeds, leg times and fuel remaining, then print the log and fill in actual times in flight.
Questions pilots ask
What goes on a VFR navigation log?
Checkpoints, altitude, wind, true course, wind correction angle, true heading, variation, magnetic heading, deviation, compass heading, distance, ground speed, estimated time en route, fuel, and blank columns for actual times. This log computes everything except the actual times.
What is the heading formula on a nav log?
TC ± WCA = TH ± V = MH ± D = CH: true course plus or minus wind correction angle gives true heading; subtract east or add west variation for magnetic heading; apply deviation from the compass card for compass heading.
Can the nav log use different winds for each leg?
Yes. Leave a leg's wind blank to use the planned wind, or enter a direction and speed for that leg, for example after climbing into a different wind at cruise altitude.
Is my nav log saved?
It is kept automatically in this browser's local storage so it survives a reload. It is not uploaded or synced. Choose Start a new log to clear it.