About SimNavLog
Who makes it
One developer, in their spare time, because they wanted it to exist. A flight simulation enthusiast — not a pilot, not an instructor, and not anyone with an aviation qualification of any kind. What is implemented here was learned from textbooks and public material, and it is implemented well enough to be interesting in a simulator and nowhere near well enough to be trusted anywhere else.
It is free to use, and it will stay free to use for planning a flight. There is no advertising, no analytics and no tracking cookies — the only cookies it sets are the ones that keep you signed in and keep the forms safe. Nothing you type here is sold, shared or handed to anyone for their own purposes, and you can delete all of it from your account settings whenever you like; the privacy policy says the same at length.
If you want the longer version of what an account adds, that is on the Free & Supporter page.
The sources that make it possible
Almost every number in a nav log comes from somewhere else. The airspace, the charts, the weather, the terrain, the airfields, the magnetic variation — all of it is collected, maintained and given away by people and organisations with no connection to this project. SimNavLog is mostly a way of arranging their work on a sheet of paper.
openAIP, in particular
The airspace layer exists because of openAIP. Airspace volumes, their vertical limits and their frequencies are published for the whole world by a volunteer community, and there is no free alternative that covers the globe. Without openAIP, SimNavLog would have no airspace to show you anywhere.
Asked in September 2026 how a project like this could support them, they said there is currently no way to pay — and asked instead that we spread the word and contribute data back. This page is the first half of that. The second half is the section below, and it is open to you as much as to us.
Aeronautical and weather data
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openAIP
CC BY-NC 4.0
Airspace volumes, their vertical limits and ATC frequencies, and VFR reporting points — worldwide. There is no free global alternative to openAIP: without it there is no airspace layer, anywhere.
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Aviation Weather Center
public domain
The METARs behind the weather cards: reported wind, visibility, cloud, temperature and pressure at the airfields along the route.
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NOAA / NCEP GFS
a US Government work not subject to copyright
Forecast wind and temperature at cruising altitude — the numbers the wind correction angle, true heading and ground speed are computed from. The Global Forecast System, run four times a day.
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U.S. Geological Survey
public domain
Ground elevation along the route, behind the terrain profile and the minimum safe altitude it suggests for each leg.
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OurAirports
public domain
Airports, runways, navaids and radio frequencies — the lookup behind every waypoint you type an identifier for.
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NOAA NCEI / BGS
a US Government work not subject to copyright
The magnetic model SimNavLog computes variation from, locally, for every point on the route — the step from true course to magnetic.
Maps and charts
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OpenStreetMap
ODbL
The default base map under the route — roads, towns, coastlines, lakes — drawn by a global volunteer community.
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OpenTopoMap
CC-BY-SA
The shaded-relief base map, for seeing the shape of the ground a route crosses before the terrain profile confirms it.
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Open Flightmaps
OFMA General Users' License
The European VFR chart layer — a real aeronautical chart to draw the route on, produced for the whole of Europe by volunteers and given away.
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FAA
public domain
The US VFR sectional chart layer, published by the FAA.
Software running in your browser
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Leaflet
BSD-2-Clause
The map itself. Every layer, marker, route line and drag in the browser is Leaflet doing the work.
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Open-Meteo
AGPL-3.0 (server), CC BY 4.0 (data)
The weather server SimNavLog runs alongside itself: it ingests NOAA's GFS forecasts and answers the wind and temperature queries behind every leg. Run unmodified — the link is its complete source.
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HeroIcons
MIT
The interface icons throughout the application.
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Astigmatic
Apache-2.0
The handwriting face the nav log is filled in with, and the reason a printed sheet looks like a sheet somebody wrote on.
Help improve the data
Several of these sources are edited by the people who use them, which means a report is a fix rather than a ticket: correct it once and everyone reading that data gets the correction, whatever application they use it in. If SimNavLog shows you something wrong, this is where it actually gets better.
OpenStreetMap
A wrong road, town or coastline on the base map is OpenStreetMap's to fix, and anyone may fix it. Dropping a note on the map takes a moment and needs no account.
Open Flightmaps
Report a chart error by email. The open flightmaps licence asks every user to report errors as they find them, and asks applications built on the data to offer their users a way to do the same — this is ours.
openAIP
openAIP is crowd-sourced. With a free account you can find the airspace or airfield and file a change request against the record itself, and the fix reaches everyone using openAIP rather than only SimNavLog.
OurAirports
Community-edited. A free account lets you correct an airport record directly, and every airport page carries a problem-report form if you would rather just say what looks wrong.
Please check the official publication for the country concerned before reporting something as wrong. These are volunteer projects, and a mistaken report costs somebody an evening.