cross_track_distance: Compute the cross-track distance from a great circle arc
Description
Compute the cross-track distance of a body, `b` (for example a ground level projection
position of an aircraft), from a great circle arc determined by two geographical coordinates,
`a1` and `a2` (for example an airport's runway thresholds).
Usage
cross_track_distance(b, a1, a2)
Arguments
b
the geographical coordinates (WGS84) of a body:
a vector of longitude, latitude (in decimal degrees) and
eventually altitude (in meters)
a1
the geographical coordinates (WGS84) of one end of a great circle arc:
a vector of longitude, latitude (in decimal degrees) and
eventually altitude (in meters)
a2
the geographical coordinates (WGS84) of the other end of a great circle arc:
a vector of longitude, latitude (in decimal degrees) and
eventually altitude (in meters)
Value
the surface cross-track distance from `b` to the arc `a1` - `a2`