Route
Routes, legs, and the geometry around them.
These tools work with routes and moving objects: legs and totals for a route, cross-track error, the closest point on a route, range rings, fly-by turns, closest point of approach, intercepts, and time, speed, and distance. Pilots, drone operators, and mariners use them for planning. Start with route legs. A pitfall is mixing true and magnetic courses between legs; the legs tool lists both.
Planning and education aid. Not for primary navigation. Full disclaimer
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I want to find where two courses cross
- Where two courses cross
The point where two courses from two positions meet, on geodesics or rhumb lines, and how far each has to run to get there.
I want to work out the course to intercept a moving target
- Intercept a moving target
The course to steer, the time, and the meeting point for reaching a target that is moving on a steady course and speed, or why it cannot be reached.
I want to total up a route's legs
- Route legs, courses, and totals
Each leg's distance, true and magnetic course, and cumulative distance for a route of waypoints, with leg times and arrival times from a groundspeed and departure time.
- Time, speed, and distance
Solves for time, speed, or distance from the other two, and the arrival time from a departure time and UTC offset.
I want to know how far I am off a route
- Cross-track and along-track distance
How far a point is off the course line from A to B (right of course positive), how far along the course its closest point lies, and that point, on the ellipsoid to the millimeter.
- Closest point on a route
The point on a multi-leg route closest to a position: which leg, how far along the route, and how far off it (right of course positive).
I want to find when two moving craft pass closest
- Closest point of approach
When two moving objects come closest, how close, and the bearing and range then, in a local flat frame (for separations under 500 km), with climb rates and height for aircraft in 3D.
I want to anticipate a turn at a waypoint
- Fly-by turn anticipation
How early to start a fly-by turn at a waypoint: turn radius, lead distance, arc length, and time in the turn, from the inbound and outbound courses, speed, and bank angle or turn rate.
I want to draw range rings around a point
- Range rings
Geodesic circles at one or more distances around a point, drawn true on the ellipsoid, with their areas, and a GeoJSON file cut correctly at the antimeridian and around a pole.
Guides that use these tools
- VFR cross-country: Distance and true course between two airports, the heading to fly into the wind, the magnetic heading, and the time en route.