Compute the along-track distances of a body, `b` (for example a ground level projection position of an aircraft), from two geographical coordinates, `a1` and `a2` (for example an airport's runway thresholds), of a great circle arc.

along_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 along-track distances from `b`'s cross-track intersection to `a1` - `a2`

See also

Examples

if (FALSE) { b <- c(8.086135, 49.973942, 6401) # EDDF: 07R (longitude, latitude, altitude) a1 <- c(8.53417, 50.0275, 328) # EDDF: 25L a2 <- c(8.58653, 50.0401, 362) along_track_distance(b, a1, a2) }