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traffic
In BlueSky, the Traffic object is a global singleton (only one instance exists) that contains all of the data related to the actual simulation of the traffic. This data can be aircraft-related (e.g., aircraft positions, velocities, etc.), but can also include other simulated aspects affecting the aircraft such as weather (a wind model, turbulence) or aircraft performance models.
The Traffic object offers a number of methods to help with managing all aircraft at once. However, inside the object the various parameters are represented by numpy vectors that contain the value of that parameter for all existing aircraft. This enables the use of fast numpy vector calculations wherever these traffic parameters are used. (To find out more about this, look here.)
The number of aircraft that exist in the simulation at any given time is represented in the Traffic object by the variable ntraf. In the simulation each aircraft has a unique identifier which is shown in the aircraft label on the radar screen (and which can be used to send commands to the aircraft). For an aircraft with identifier AC123, the index of this aircraft in all parameter vectors can be found using the Traffic object member function id2idx("AC123").
The Traffic object is accessible as a top-level import from the bluesky package:
from bluesky import traf
# Get number of aircraft
num_ac = traf.ntraf
# Get the index of the aircraft with identifier KL204 and print its latitude
idx = traf.id2idx("KL204")
print(traf.lat[idx])
...Part of the Traffic object are also system simulations like the Airborne Separation Assurance System (ASAS, in traf.asas), the autopilot (in traf.ap) and the flight management system (FMS, in traf.ap.route and traf.actwp for the active waypoint data).
The variables are available as part of the traffic object:
Basic aircraft information
| Name | Unit | Description |
|---|---|---|
| id | string | Aircraft identifier / callsign |
| type | string | Aircraft type |
Aircraft location and orientation
| Name | Unit | Description |
|---|---|---|
| lat | deg | Aircraft latitude |
| lon | deg | Aircraft longitude |
| alt | m | Aircraft altitude |
| hdg | deg | Aircraft heading |
| trk | deg | Aircraft track angle |
| distflown | m | Aircraft distance flown |
Aircraft velocities
| Name | Unit | Description |
|---|---|---|
| tas | m/s | Aircraft true airspeed |
| gs | m/s | Aircraft ground speed |
| gsnorth | m/s | Aircraft ground speed north component |
| gseast | m/s | Aircraft ground speed east component |
| cas | m/s | Aircraft calibrated airspeed |
| M | - | Aircraft mach number |
| vs | m/s | Aircraft vertical speed |
Atmospheric properties per aircraft
| Name | Unit | Description |
|---|---|---|
| p | N/m^2 | Air pressure |
| rho | kg/m^3 | Air density |
| Temp | K | Air temperature |
| dtemp | K | Delta-t for non-ISA conditions |
Aircraft autopilot settings
| Name | Unit | Description |
|---|---|---|
| selspd | m/s or - | Aircraft selected speed (CAS or Mach) |
| selalt | m | Aircraft selected altitude |
| selvs | m/s | Aircraft selected vertical speed |
Aircraft navigation settings
| Name | Unit | Description |
|---|---|---|
| swlnav | boolean | Lateral navigation (LNAV) guidance mode is on/off |
| swvnav | boolean | Vertical navigation (VNAV) guidance is on/off |
| swvnavspd | boolean | Vertical navigation speed guidance is on/off |
Child objects The traffic object has several child objects with specific functionality: