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Revision as of 05:39, 22 July 2017 by Mickybadia (talk | contribs) (v1.3.2)
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ATC-pie logo
ATC-pie at the KSFO mess
ATC-pie at the KSFO mess
Developed by Michael Filhol
Initial release February 1, 2015
Latest release 1.3.2 (July 22, 2017)
Written in Python3
OS Any
Platform Qt5
Development status Active
Type ATC client
License GNU GPL v3

ATC-pie is an air traffic control simulation program allowing to play solo games, connect to FlightGear multi-player networks and set up tutorial sessions for teacher supervision of an ATC student. It features en-route centre control (CTR) as well as airport-based service (TWR, APP, GND...) where 3d tower viewing is possible. It is essentially designed for realism and simulates many tasks and situations of real-life ATC such as:

  • strip rack and sequence management;
  • transponder identification;
  • handovers to/from neighbouring controllers;
  • ATIS recording;
  • flight plan filing and editing;
  • routing and conflict anticipation.

The program is free and open source, and programmed in Python3 for Qt5 hence system-independant. Only Python3 and its Qt5 bindings must be installed. That done, it is meant to work straight away, with no make/compile command to run or external resource to install. The whole world is immediately available on radar. Tower viewing requires a running FlightGear installation and the appropriate aircraft and scenery.


Visit the ATC-pie screenshot wiki category for more

Working principles


You are the air traffic controller, working with or without a tower window or radar scope, depending on your position and local facility. Players will connect to the network (multi-player), AI traffic be simulated (solo), or teacher traffic generated (tutorial session), with different types of aircraft and transponder equipment.

As in real life, your main radar technology is SSR, hence unless you cheat or activate the primary radar, will show you only what you pick up from on-board transponders in its range. This means:

  • if a transponder is off, you will not see the aircraft on your radar screen;
  • if a transponder is on, you will at least be able to see its position and read the transponder code, possibly its altitude and even its type and callsign, depending on the mode set by the pilot.


The ATC-pie strip detail sheet

Your basic traffic flow and sequence working unit is the strip, each representing a controlled (or soon expected) aircraft. Strips are created, filled with details and moved along and across racks until handed over to a different controller or discarded. Strip details include:

  • most importantly, the aircraft's callsign, to be used on the radio;
  • information like aircraft type, airspeed, route... that can be specified by the pilots themselves when filing flight plans;
  • transponder code and flight parameter assignments (or vectors: heading, altitude/FL, speed).

Linking strips

Strip details can be manually edited, but every strip can also be linked to a flight plan and/or a visible radar contact on the scope screen. Linking to a strip will automatically:

  • make the strip display the missing elements available from the linked aircraft transponder or flight plan;
  • inform the radar contact label with useful details provided on the strip, e.g. assigned altitude.

Any detail mismatch between a strip and its linked flight plan or radar contact will be reported for you to resolve.

Radar identification

Radar identification: both matched strip and radar contact marked in blue

To identify an aircraft and link the right radar contact to a strip, an ATC can rely on different things. He can read an aircraft's callsign straight away if its transponder has mode S turned on, tell from reported positions and altitudes, or use a transponder code.

For instance, say a VFR traffic makes an initial radio contact giving his callsign and approximate position, with no mode S transponder. ATC will typically pull out a new blank strip and give the pilot a unique transponder code to squawk, writing it on the strip alongside the announced callsign, then wait for it to appear on the radar. This allows for radar identification of aircraft–strip pairs such that:

  • the strip is assigned a transponder code;
  • no other strip is assigned the same code;
  • the aircraft is the only unidentified traffic squawking that code in radar range.

ATC-pie identifies such pairs automatically and reports them to you so you can properly link the two and get back to the pilot: "radar identified".

Program features

The features listed below have been tested on various Linux versions, Mac and Windows.


Available modes and sessions:

  • FlightGear multi-player connections (FGMS)
  • Solo games with simulated IFR traffic
  • Teacher–student tutoring sessions
  • For all session types: en-route centre or airport control mode
  • For all airport sessions: 3d tower view available

Common data sources:

  • Airport and navigation data retrieved from X-Plane file sets (whole world base set included, customisation possible)
  • Radar background images and hand drawings (integrated OpenStreetMap tile retrieval helper, script to import drawings from EuroScope/VATSIM/IVAO .sct sector files)
  • Ground elevation maps (can be generated automatically with a provided script)
  • Editable aircraft data base (ICAO designators, cruise speeds, WTC, etc.)
  • Online real world declination lookup for true/magnetic distinction

FlightGear multi-player games:

  • Weather: real world METAR retrieval
  • Strip exchange: handovers with other ATC-pie and OpenRadar instances in range
  • Flight plans: interface with Lenny64's data base (the de facto FG standard), incl. in-game retrieval, filing and editing (work on local copies and manage sync with online status), opening and closing
  • In-app announcement of ATC sessions on Lenny64's popular event page

Solo sessions (AI traffic):

  • CTR control mode, or configurable combination of TWR, GND, APP and DEP positions in airport mode
  • Voice instruction recognition (with Sphinx)
  • Pilot read-back speech synthesis (with pyttsx)
  • Weather: randomised
  • Strip exchange: handovers to/from virtual ATCs
  • Airline choice and custom aircraft appearence
  • Configurable airspace rules and entry/exit/routing points
  • Adjustable difficulty (traffic density)

Tutorial sessions (teaching/learning):

  • Teacher spawns and manipulates traffic visible to student (flight and transponder settings)
  • Weather: wind control by teacher
  • Strip exchange: configurable ATC neighbours and handover supervision by teacher
  • Traffic snapshots and recall to repeat situations with the student


  • Floatable/dockable panels and toolbars (see screenshot), save/restore window layout
  • Customisable colours
  • Notification system combining selectable sounds, status bar messages and time-tagged history
  • Notes, general and location-specific settings saved on close and restored on restart

ATC surveillance

Radar and transponders:

  • Full transponder support and mode-dependant radar behaviour (off, A, C, S, GND)
  • Radar identification assistant (detects unique matches between strip info and radar contacts)
  • Primary radar activation (see targets without XPDR signals)
  • Runway occupation/incursion detection
  • Route/vector conflict anticipation and separation incident alarm
  • Open multiple radar screens

Tower viewing (airport mode, requires FlightGear):

  • Internally started or through connection to an external instance
  • Controller pane to orient/zoom view or follow aircraft
  • Additional views can be connected (for multiple camera angles)

Traffic management

Strips, racks, flight plans:

  • User-defined racks with configurable colours for linked radar contacts and ATCs to collect strips from
  • Runway boxes with automatic WTC timers when freed
  • Loose strip bays with customisable backgrounds
  • Approach spacing hints for inbound sequences

Routes, vectors, conflicts:

  • Convenient mouse input for vectors, taxi instructions and route/waypoint changes
  • Route presets, analysis, drawing and world map view
  • Current leg and next waypoint display with geodesic calculations of headings and distances
  • Visible mismatches between assigned vectors and picked up positions (see all-in-one graphics)

Misc. tools:

  • Multiple weather station monitor
  • Quick point-to-point heading and distance measuring tool and access to Earth coordinates
  • Direct text annotation of radar screen with mouse
  • Custom alarm clocks with quick two-key timer set-up
  • AD/nav/parking point browser and indicator



  • FGCom integration, incl. echo test and possible use of externally running client
  • ATIS recording with pre-filled preparation notepad (see feature dialog)
  • Multiple frequency transmissions and monitoring, frequency-specific sound level selection

Text chat:

  • Preset message list manager
  • Predefined and custom aliases for context-sensitive replacements (general, location- and ACFT-specific)
  • Sender blacklist management (filter out trolls)

Using ATC-pie

To download the program and learn more about how to use it, read the ATC-pie installation and user guides. If you have a question, check the FAQ for help or try the forum.