GridLat-class           A grid and lattice combination
crs_120E                Asia-centred coordinate reference system
crs_Atlantic            Atlantic-centred coordinate reference system
crs_N                   Arctic-centred coordinate reference system
crs_Pacific             Pacific-centred coordinate reference system
crs_S                   Antarctic-centred coordinate reference system
crs_longlat             Lat-long coordinate reference system
find_leg                Find best non-stop route between 2 airports
find_route              Find best route between 2 airports
find_routes             Find best routes between airport-pair &
                        aircraft combinations
hm_clean_cache          Clean the route and SID-STAR cache.
hm_get_test             Get test data
hm_load_cache           Load route and SID/STAR cache
hm_save_cache           Save route and SID/STAR cache to file
mach_kph                Speed of sound, for Mach to km conversion
make_AP2                Make airport-pair dataset
make_aircraft           Make aircraft data from minimum dataset
make_airports           Make or load airport data
make_route_envelope     Make range-constrained envelope between 2
                        airports
make_route_grid         Make lat-long grid for route finding
map_routes              Map a set of routes
profile_routes          Profile a set of routes
st_window               Version of 'st_transform' with view window to
                        avoid dateline
summarise_routes        Summarise a set of routes
