SimConnect MCP docs

AI Traffic & ATC

SimConnect MCP can fill the airport you’re flying from with traffic of its own and control it the way a tower and approach controller would. You ask in plain language, for example “run the airline schedule at Prague”. The server then puts aircraft into the simulator and flies them from stand to runway and from their origin to the stand, clearing and spacing them as it goes.

It runs the traffic engine of the mrlm-net/simconnect Go library, pkg/traffic/world, the same engine as the library’s airport map. Every tool mentioned here is described in full in the SimConnect Mode reference.

Beta. The traffic tools change the simulator: they add and remove aircraft. They’re new and still changing between releases.

What you need

• Windows with MSFS 2020 or 2024 running, and the server in simconnect or both mode (see Getting Started).
• Your aircraft at or near the airport. The simulator only serves an airport’s stands, taxiways and procedures once it has loaded the airport around the user aircraft.
• AI aircraft models. Each flight uses an installed aircraft of its type, in its airline’s livery where one is installed. The more airline liveries you have, for example from an AI traffic package, the more the traffic looks like the real thing. list_aircraft_models shows what’s installed.
• Ground vehicles. Tugs, fuel trucks, stairs and GPUs use GSX’s models when GSX is installed, else MSFS’s own.

The engine starts with the first traffic tool you use. If the simulator restarts, it starts again by itself and sets your schedule, real traffic and corridor again.

Ways to add traffic

By hand, one aircraft at a time. spawn_departure puts an aircraft on a stand and spawn_arrival puts one on its arrival route (STAR). The runway, stand, SID or STAR and model are chosen for you unless you name them. By default each flight waits for your clearances: pushback, taxi, cross, line up, take off. You give them with atc_clearance, so you can play the controller yourself. Spawn with hold_for_clearances: false, or give atc_clearance manual with on: false, to let the engine’s controllers handle it.

By schedule. start_schedule runs a realistic airline day at your airports, with light aircraft in the circuit by day, and the flights go by themselves. It uses the same generator as generate_schedule. get_schedule shows the departure and arrival boards, and stop_schedule ends the run.

At chosen times. add_flights adds flights to the schedule at the times you want: an arrival a few minutes before your ETA, a departure just after your off-block. Start the schedule with generator: false to fly only those.

Real-world traffic. set_real_traffic switches an airport from the timetable to the aircraft a feed such as ADS-B sees, which you pass with observe_traffic. Parked aircraft go on a stand near where they’re seen and wait until their departure is seen. Departures push, and arrivals appear on their track and join a STAR. Unknown origins and destinations stay unknown.

Around you in cruise. set_traffic_corridor takes your route ahead, level and speed, and keeps a few airliners around you. One flies ahead the same way, one comes the other way and one crosses, each 1,000 or 2,000 ft above or below. They’re replaced once they’re far behind.

What each flight gets

Each airport has a fleet of tugs, fuel trucks, stairs and GPUs sized by its stands. A departure waits for a free tug. Fuelling, stairs and the GPU are left out when it’s too late for them.

The tower and the approach controller

At each airport it works, the engine runs:

• A tower per runway, which clears line-ups, take-offs and runway crossings, and sends an arrival around when the runway won’t be free.
• A landing sequence per runway end, which orders the arrivals on the final by wake, keeps at least the minimum spacing (more in low visibility), and has them lose delays with speed, vectors and holds.
• Separation, with conflicts predicted and resolved for ours, and TCAS II on each of ours (get_tcas).
• The radio: every instruction and readback, by position and frequency.

You can watch them with get_landing_sequence, get_conflicts and get_atc_log, and step in with approach_instruction. With it you can move an arrival up or down the order, slow it or set its speed, hold it (at its STAR fix or at a point), release it, send it direct, have it join the final at a point, or send it around. get_traffic_airport_info shows the runways in use and the ATIS the engine’s controllers work with.

Your own flight. The engine never controls or calls your aircraft. When your ATC clears you onto a runway, set_player_clearance tells the engine, and while you line up, take off or land there, none of its traffic is cleared onto it. Landing, you’re put in the landing sequence and the traffic fits around you.

Filming it

In MSFS 2024 the engine can take the camera. set_camera with auto lets a director film our traffic, cutting to whoever matters. follow stays on one aircraft, and view holds a chase, cockpit, wing, front, top or tower view, of ours or of your own aircraft. scene plays a scripted film at an airport, spawning its own cast (a departure, an arrival, or both). off gives the camera back to the simulator, and the server gives it back when it stops.

Things to ask

• “Run the airline schedule at LKPR, at most 8 aircraft at once.”
• “What’s on the departure board? Who’s delayed, and why?”
• “Show me the landing sequence for runway 24 and the last radio calls.”
• “Put a Smartwings 737 on stand C22 departing runway 24, and let me give the clearances.”
• “Clear TVS1860 to push back.” … “Taxi.” … “Line up and wait.” … “Cleared for take-off.”
• “Slow down AFR1094 and move it behind KLM1008.”
• “Add an arrival from Munich 20 minutes from now.”
• “I’m cruising at FL360 along this route: put some traffic around me.”
• “Film the traffic at Prague.” … “Follow CSA7.” … “Give me the camera back.”
• “Stop the schedule and let the aircraft finish their flights.” (stop_schedule)
• “Stop the schedule and remove everything now.” (stop_schedule with remove: true)

Limits

• The airport must be loaded around your aircraft. Traffic at an airport far from you can’t be spawned.
• En route aircraft the schedule created aren’t on the engine’s list of ours. When the server stops they stay until its connection closes.
• observe_traffic takes sightings you pass to it. The server doesn’t fetch an ADS-B feed itself.

The tools

For a worked example, see Scenario 4 in Examples.