openscope

Spawn Patterns

As of version 3.3.0, we define how aircraft come into the system using Spawn Patterns. Spawn Patterns define how, how many, and what sorts of aircraft will spawn (appear) along a specifc route. Spawn Patterns are used for both arrivals and departures. The shape of the data is exactly the same for both, all keys are expected to be passed all the time.

Lets look at some examples before we continue:

// Departures
{
     "origin": "KLAS",
     "destination": "",
     "category": "departure",
     "route": "KLAS.BOACH6.HEC",
     "commands": {
        "19L": "fh 180",
        "1R": "fh 360"
     },
     "altitude": "",
     "speed": "",
     "method": "random",
     "rate": 5,
     "airlines": [
         ["aal", 10],
         ["ual", 10],
         ["ual/long", 3]
     ]
 }

// Arrivals
{
    "origin": "",
    "destination": "KLAS",
    "category": "arrival",
    "route": "BETHL.GRNPA1.KLAS",
    "commands": {
        "19L": "cross TOROO A100",
        "1R": "cross TOROO A100"
    },
    "altitude": [30000, 40000],
    "speed": 320,
    "method": "cyclic",
    "rate": 17.5,
    "period": 75,
    "offset": 25,
    "airlines": [
        ["aal", 10],
        ["ual", 10],
        ["ual/long", 3]
    ]
}

// Overflights
{
    "origin": "",
    "destination": "",
    "category": "overflight",
    "route": "DAG.V21.MLF",
    "altitude": 9000,
    "speed": 320,
    "method": "random",
    "rate": 8,
    "airlines": [
        ["aal", 10],
        ["ual", 10],
        ["ual/long", 3]
    ]
}

Key descriptions

• (*) denotes a required field
• All keys are required to be present and can be left as an empty string when not used by a particular pattern. ex "destination": "" for an arrival pattern.

airlines*

List of airlines, and their spawn weight. A higher weight will increase the frequency that a particular airline is chosen. Airline selections are random based on weight. Typically, you should use the approximate number of flights that airline would have on that route in a given day.

• Should always be a two-dimensional array
• Should always have a shape of either:
  • [AIRLINE_ID, FREQUENCY_WEIGHT]
  • [AIRLINE_ID/AIRLINE_FLEET, FREQUENCY_WEIGHT]

origin (* for departures only)

• ICAO identifier of the origin airport

destination (* for arrivals only)

• ICAO identifier of the destination airport

category*

• Must be arrival, departure, or overflight.

route*

• Should be in the shape of a routeString.
  • For direct routes: FIXXA..FIXXB..FIXXC..FIXXD
  • For complex routes: FIXXA..FIXXB..ENTRY.PROCEDURE_ID.EXIT
  • Prepend a fix name with @ to hold at that fix FIXXA..@FIXXB..FIXXC
  • Prepend a three digit heading with # to fly that heading until given further instructions

commands

Commands to pass to an aircraft when it spawns. This could be used for tower assigned departure headings, altitude crossings that might be assigned by another controller, etc.

• One entry per runway
• Command string can be any valid command as defined in the aircraft-command guide

altitude

For arrivals/overflights: Altitude an aircraft spawns at. For departures: Altitude the aircraft is requesting in their flight plan. —> Altitude may be omitted for departures; the a/c will then request the highest altitude their aircraft is capable of reaching.

You can specify either an exact altitude or an array of two altitudes (in which case an altitude will be randomly chosen within the specified range). Always enter altitudes as a number (eg. 18000), not as a string (eg "18000").

• Should be a number in MSL altitude.
• Should always have a shape of either:
  • a single number
  • an array of [MIN_ALTITUDE, MAX_ALTITUDE]

speed (* for arrivals)

Speed an aircraft spawns at, expressed in knots of indicated airspeed. This should be a number (eg. 320), not a string (eg "320").

method*

Defines the method used to calculate delay between aircraft spawns.

• Should always be one of: cyclic, random, surge, wave

See spawnPatternMethodReadme.md for more information

rate*

Rate at which aircraft spawn expressed in ACPH (aircraft per hour). This should be a number (eg. 15), not a string (eg "15").

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