Spherical Along Track Distance

spherical along track distance calculator online

Use spherical along track distance online for start to point km, point bearing deg, path bearing deg. Spherical Earth radius 6371.0088 km unless another radius is displayed. Not an ellipsoidal survey or real-time navigation service.

How to use it

Enter start to point km. Set point bearing deg, path bearing deg. Select Calculate and check the labeled output. Copy or download the JSON result.

Options and example settings

Calculation method

along_track_km = atan2(sin(start_to_point_km/6371.0088)*cosd(point_bearing_deg-path_bearing_deg),cos(start_to_point_km/6371.0088))*6371.0088 (^ means exponentiation; trig functions ending in d use degrees).

Worked examples

Apply spherical along track distance to the case below, keeping the displayed units and assumptions. Spherical Earth radius 6371.0088 km unless another radius is displayed. Not an ellipsoidal survey or real-time navigation service.

Spherical Along Track Distance — worked case

Settings: point bearing deg: 40; path bearing deg: 30

Input:

100

Calculated result for these inputs:

Output:

{
  "along_track_km": 98.48101915797605
}

Choose the right tool

Choose great-circle tools for shortest spherical paths and rhumb tools for constant bearings. Spherical models differ from ellipsoidal survey calculations. Web-map tiles have latitude limits and grid bearings require a stated convergence convention.

Limitations and common mistakes

• Spherical Earth radius 6371.0088 km unless another radius is displayed. Not an ellipsoidal survey or real-time navigation service.
• Use the displayed unit in every field. Ratios and percentages are different inputs; percent fields use values such as 25 rather than 0.25.

Frequently asked questions

How can I use spherical along track distance calculator online?

Enter start to point km. Set point bearing deg, path bearing deg. Select Calculate and check the labeled output. Copy or download the JSON result.

Technical references

• USGS: map and compass concepts

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.

Useful next tools

• Earth Chord from Surface Arc Length
• Spherical Triangle Area from Angles
• Naismith Walking Duration Scenario