himach (version 0.3.2)

find_route: Find best route between 2 airports

Description

find_route finds the quickest route between two airports, refuelling if necessary

Usage

find_route(
  ac,
  ap2,
  fat_map,
  avoid = NA,
  route_grid,
  cf_subsonic = NA,
  refuel = NA,
  refuel_h = 1,
  refuel_only_if = TRUE,
  refuel_topN = 1,
  max_circuity = 2,
  ap_loc,
  margin_km = 200,
  ...
)

Value

Dataframe with details of the route

Arguments

ac

One aircraft, as from make_aircraft

ap2

One airport pair, as from make_AP2

fat_map

sf::MULTIPOLYGON map of land, including buffer

avoid

sf::MULTIPOLYGON map of areas not to fly over

route_grid

GridLat routing grid as from make_route_grid

cf_subsonic

Further aircraft to use as comparator, default NA. (use is not recommended)

refuel

Airports available for refuelling, dataframe with APICAO, long, lat

refuel_h

Duration of refuelling stop, in hours

refuel_only_if

If TRUE (default) only test refuel options if necessary because the great circle distance is too far for the aircraft range

refuel_topN

Return the best N (default 1) refuelling options

max_circuity

Threshold for excluding refuelling stops (default 2.0)

ap_loc

Airport locations as from make_airports

margin_km

Great circle distance between airports must be less than aircraft range minus this operating margin (default 200km), to give a margin for arrival and departure.

...

Other parameters, passed to find_leg and thence to to make_route_envelope.

Refuelling

If either necessary, because the great circle distance is greater than the aircraft range, or because refuel_only_if is FALSE, find_route searches through a list of refuelling airports and chooses the quickest one (or refuel_topN).

Circuitous refuelling is avoided, tested against total distance < max_circuity * great circle distance. This is separate to the limits placed on circuity of individual legs in find_leg.

If no refuel option is found, a message is displayed. The route with `NA` for `time_h` is returned.

Each refuelling stop costs refuel_h in addition to the time to descend to the airport and then to climb out again.

Details

This function finds the quickest route between two airports. A 'route' is made up of one or two 'legs' (airport to airport without intermediate stop). find_route makes one or more calls to find_leg as required.

It assumes that the routing grid, route_grid, has already been classified as land or sea using the map fat_map. The map is further used when converting the grid-based route to one of great circles segments.

Examples

# need to load some of the built-in data
aircraft <- make_aircraft(warn = FALSE)
# get test datasets
NZ_buffer30 <- hm_get_test("buffer")
NZ_grid <- hm_get_test("grid")
airports <- make_airports(crs = sf::st_crs(NZ_buffer30))

options("quiet" = 4) #for heavy reporting
# from Auckland to Christchurch
ap2 <- make_AP2("NZAA","NZCH",airports)
# on some CRAN machines even this takes too long, so not run
if (FALSE) {
routes <- find_route(aircraft[4,],
                    ap2,
                    fat_map = NZ_buffer30,
                    route_grid = NZ_grid,
                    ap_loc = airports)
}