find_route {himach}

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,
  ...
)

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.

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.

Value

Dataframe with details of the route

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.

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
## Not run: 
routes <- find_route(aircraft[4,],
                    ap2,
                    fat_map = NZ_buffer30,
                    route_grid = NZ_grid,
                    ap_loc = airports)

## End(Not run)