navlog calculator

What is a navlog calculator?

A navlog calculator is a flight planning tool that helps pilots estimate heading, groundspeed, estimated time enroute (ETE), and fuel for each leg of a trip. Instead of manually working through every wind triangle and time/fuel equation, this calculator does the math quickly and consistently.

For VFR and IFR planning, a clean navigation log reduces cockpit workload. You can brief the route on the ground, verify assumptions, and make better in-flight decisions when actual wind and groundspeed differ from plan.

What this calculator computes

• Wind correction angle (WCA): how many degrees left or right to steer to stay on course.
• True heading (TH): true course adjusted by wind correction.
• Magnetic heading (MH): true heading adjusted for magnetic variation.
• Headwind/tailwind and crosswind components: wind impact on speed and tracking.
• Groundspeed (GS): expected speed over the ground.
• Leg time: ETE in minutes and hours:minutes format.
• Fuel required: trip fuel plus optional reserve fuel.

How to use it correctly

1) Enter route and aircraft data

Use a realistic true course and true airspeed for your planned altitude and cruise configuration. Enter leg distance in nautical miles.

2) Enter wind data in true direction

Wind direction must be the direction the wind is from, referenced to true north. For example, “wind 210 at 15” means direction 210 and speed 15 knots.

3) Add magnetic variation and fuel numbers

Variation is entered as East positive and West negative. Fuel burn should be your realistic cruise burn, not a best-case brochure number.

4) Review and apply judgment

The output is planning guidance. Always compare with current weather, performance charts, NOTAMs, route constraints, and your approved procedures.

Core formulas behind the navlog

These are the same concepts used in classic E6B planning:

• Crosswind component: Wind Speed × sin(WindDir − Course)
• Headwind component: Wind Speed × cos(WindDir − Course)
• Wind correction angle: asin(Crosswind ÷ TAS)
• Groundspeed: TAS − Headwind
• ETE (hours): Distance ÷ Groundspeed
• Fuel (gallons): Fuel Burn × Time

If groundspeed becomes very low or non-positive, your assumptions may be unrealistic for that leg/altitude and should be re-evaluated.

Practical planning tips

• Round headings and time values to a practical level for in-cockpit use.
• Break long routes into manageable legs so updates are easier in flight.
• Add conservative fuel margins; do not rely on exact-perfect winds.
• Recompute when altitude changes, because winds and TAS can shift materially.
• Cross-check this result with your avionics/FMS flight plan and official briefing products.

Limitations and safety note

This tool provides planning estimates only and does not replace approved flight planning software, aircraft POH/AFM data, dispatch requirements, or pilot judgment. Always comply with regulations, operating limitations, and your organization’s procedures.