Tractrix for QGIS manual

Version 0.2.0QGIS 3.34 – 4.xAvailable

Tractrix for QGIS — the OpenAirside plugin — adds ten Processing algorithms that simulate aircraft and ground-vehicle manoeuvres on your map layers and check them against ICAO, FAA or EASA clearances.

Installation

Requirements

• QGIS 3.34 LTR or later, including QGIS 4.x, built with Qt5 or Qt6.
• Windows, macOS or Linux. No additional Python packages are required: the engine is pure Python.

Install from ZIP

1. Download the plugin ZIP from the download centre or Downloads (account required).
2. In QGIS choose Plugins → Manage and Install Plugins → Install from ZIP.
3. Select the ZIP and press Install Plugin. QGIS may warn that the plugin is experimental; that flag stays until version 1.0.

If you build the ZIP yourself from a source checkout, zip the openairside/ folder on its own so that the archive contains openairside/metadata.txt at its top level.

Install with the script (macOS)

With QGIS closed, run tools/install.sh from a checkout of the repository. It copies openairside/ into the QGIS 4 default profile and enables the plugin. Set QGIS_PROFILE to install into another profile.

Where the tools appear

• Processing → Toolbox → Tractrix, in the groups Aircraft, Airside design, Stands and aprons, Ground vehicles and Libraries. (The provider ID stays openairside.)
• The Tractrix menu under Plugins, with every tool.
• The Tractrix toolbar, with the first five tools.

Update and uninstall

Install a newer ZIP over the old one to update. To remove the plugin, use Plugins → Manage and Install Plugins → Installed → Tractrix for QGIS (OpenAirside) → Uninstall Plugin.

Concepts

Direction of travel

Draw every path line in the direction the aircraft or vehicle moves. For pushback, draw from the parked position in the direction the aircraft moves backwards.

Working CRS

Calculations are done in metres. If the input layer is in a projected CRS with metre units it is used as is; otherwise (for example EPSG:4326) the tool works in the local UTM zone and writes outputs in that CRS.

Tracking point

The point of the aircraft that follows the line: the nose gear, the cockpit (pilot's eye, the ICAO and FAA design assumption), or a custom point ahead of the main gear. The main gear follows the tractrix of the line.

Standard and context

The clearance added around the swept envelope depends on the standard (ICAO, FAA, EASA or none) and the context (taxiway, taxilane or stand). See the standards reference.

Clearance versus edge margin

The clearance is a buffer around the whole aircraft envelope, for wingtip-to-object checks. The edge margin is the distance from each outer main-gear tyre to the pavement edge, checked against the wheel-to-edge clearance when you give a pavement layer.

Run

One aircraft on one line part. Every output feature carries a run label such as A320 / path 3, so group paths can be told apart and separation can be checked between runs.

Common outputs

The manoeuvre tools — aircraft path, pushback / towing and GSE path — write the same five optional layers, plus an optional HTML report and a JSON summary. Untick an output in the dialog to skip it; Poses is off by default.

Element values

Envelopes use element = swept_envelope, clearance_envelope, main_gear_swept, nose_gear_swept, engine_swept, tug_swept or vehicle_swept. Tracks use the key-point name: nose, cockpit, nose_gear, main_gear_centre, main_gear_left_outer, main_gear_right_outer, wingtip_left, wingtip_right, tail, tailplane_tip_left/_right and engine_N_exhaust.

Issue kinds

The dialog log prints one line per run with the maximum steering angle, exceedances, minimum edge margin, contacts and clearance infringements.

Tools reference

Each tool is listed with its Processing ID, for use in scripts and models. Parameter IDs are shown in capitals.

Demo project walkthrough

Open sample_data/demo_airport.qgz from a checkout of the repository. It contains a taxiway with two 45 m turns and no fillets, an apron with four stands (S2 and S3 deliberately too close for code C), a pushback route and a baggage-train route, and the outputs of every tool in sample_data/demo_outputs/.

1. Taxi an A320. Run Aircraft path simulation on the taxiway centreline with cockpit tracking and the pavement layer. The minimum edge margin is 4.39 m, above the 3 m required: no issues.
2. Taxi a B777-300ER on the same line. The outer main gear leaves the unfilleted pavement by 6.6 m and two edge-margin breaches are flagged. The turns need fillets.
3. Design the fillets. Run Taxiway fillet / required pavement with both aircraft. The maximum track-in is 2.63 m for the A320 (2.7 m by hand) and 11.6 m for the B777-300ER; the fillet polygons show the pavement to add.
4. Check the stands. Run Stand design on the lead-in lines. S2 and S3 are 0.18 m apart where code C requires 4.5 m: a conflict is written.
5. Push back. Run Pushback / towing on the pushback route. The maximum nose-wheel angle is 17.8°, against 17.5° from the analytic solution.
6. Jet blast. Run Jet blast contours on the Parked positions output, breakaway thrust. The A320's 56 km/h contour reaches 48 m behind the tail, as in ICAO Doc 9157.
7. Baggage train. Run GSE / vehicle path on the baggage route with the tractor and four dollies, and inspect the articulation angles.

Animating with the Temporal Controller

Footprint layers are temporal: each footprint has a time timestamp computed from the distance travelled and the speed you entered. The layer is configured automatically (single field, instantaneous, not accumulated).

1. Open View → Panels → Temporal Controller.
2. Choose Animated temporal navigation (the play icon).
3. Press the refresh button next to the range to fit it to the layers, set the step (for example 1 second), and press play.
4. To export frames for a video, use Export animation in the same panel.

Simulated times start at 2026-01-01 00:00 UTC. Use a lower FOOTPRINT_SPACING for a smoother animation. For a 3D view, extrude the footprints in QGIS 3D by the height_m field.

Styling

On load, outputs are given a categorised style: envelopes and stands by element, footprints by unit, issues and stand conflicts by kind, jet blast by velocity_kmh. Layer opacity is set between 45 % and 100 % so the base map stays visible.

Change the style as you would for any layer, then save it with Style → Save as default or as a .qml file to reuse it across projects.

Reports

Set HTML report to a file path to write a report with one section per run: aircraft or unit, travel, maximum steering angle against the limit, steering exceedances, minimum outer-tyre to pavement-edge margin and breaches (when a pavement layer is given), swept area, clearance applied, obstacle contacts and clearance infringements, and every note — including what geometry was estimated and where the steering limit came from. The same figures are returned as JSON in the SUMMARY output, for models and scripts.

Scripting and models

Every tool can be used in the graphical modeller and from the Python console:

import processing

result = processing.run("openairside:aircraft_path", {
    "PATH": "centrelines",          # layer name, id or path
    "AIRCRAFT": [0],                # index into the aircraft list
    "TRACKING": 1,                  # 0 nose gear, 1 cockpit, 2 custom
    "STANDARD": 0,                  # 0 ICAO, 1 FAA, 2 EASA, 3 none
    "CONTEXT": 0,                   # 0 taxiway, 1 taxilane, 2 stand
    "PAVEMENT": "pavement",
    "ENVELOPES": "TEMPORARY_OUTPUT",
    "ISSUES": "TEMPORARY_OUTPUT",
})
print(result["SUMMARY"])

Enum parameters such as AIRCRAFT take indexes into the list shown in the dialog; to choose aircraft by type in a script, put the ICAO type in a field of the path layer and pass it as AIRCRAFT_FIELD. For use outside QGIS, see the command-line engine.