Airside manoeuvre simulation
The science of airside motion.
Tractrix simulates how aircraft and ground vehicles really move on an apron or taxiway — swept paths, pushback, turning, jet blast, stands and fillets — and checks every result against ICAO, FAA and EASA clearances. The algorithms are open and every number can be traced to its source.
01 The product family
One engine, wherever you draw.
Every Tractrix product sends the same request to the same engine through the open tractrix/1 protocol. A swept path computed in AutoCAD is identical to one computed in QGIS or in the browser.
Web platform
Tractrix Cloud
Accounts, organisations and projects. Upload GeoJSON or DXF, run simulations in the browser, export results, automate with API tokens.
Explore Cloud →CAD add-in
Tractrix for AutoCAD
TXPATH, TXPUSHBACK, TXTURN and more. Results land on TX-* layers of your DWG, ready for sheets.
Explore AutoCAD →BIM add-in
Tractrix for Revit
The same commands inside the building model, so terminal, stand and apron design share one set of swept paths.
Explore Revit →Desktop GIS · Community
Tractrix for QGIS
The complete toolset as QGIS Processing algorithms, including stand design, taxiway fillets and envelope separation. Animated footprints play in the Temporal Controller. Free and open source.
Explore QGIS →Powered by
OpenAirside engine
Pure Python kinematics, aircraft library, standards and jet blast model under GPL-2.0-or-later. Run it headless with tractrix-engine run, audit it, extend it.
02 Capabilities
Each check tied to the clause it implements.
Clearance envelopes are the simulated swept envelope plus the distance the selected standard requires. Values are listed with their source on the standards reference.
| Capability | Standard basis | QGIS | Cloud | AutoCAD | Revit |
|---|---|---|---|---|---|
| Aircraft path and group path nose-gear, cockpit or custom tracking | ICAO Doc 9157 Pt 2 App. 1 | ● | ● | ● | ● |
| Pushback and towing towbar and towbarless tugs | Nose-wheel tow limit | ● | ● | ● | ● |
| Turning radii R1–R6 and 180° turn | Manufacturer APM method | ● | ● | ● | ● |
| Jet blast contours and intake hazard | ICAO Doc 9157 Table A2-1 | ● | ● | ● | ● |
| GSE and trailer trains | Steering lock, jack-knife > 90° | ● | ● | ● | ● |
| Wingtip and edge clearances | Annex 14 Table 3-1 · AC 150/5300-13B | ● | ● | ● | ● |
| Stand design and conflicts | Annex 14 §3.13.6 | ● | ○ | ○ | ○ |
| Taxiway fillet / required pavement | Doc 9157 Table 1-1 · FAA TESM | ● | ○ | ○ | ○ |
| Envelope separation check | User-defined separation | ● | — | — | — |
03 Open science
Evidence before assertion.
Commercial swept-path tools ask you to trust a black box. Tractrix publishes the model, the data and the tests, so a reviewer can reproduce any figure you put in a report.
- Every algorithm is in the open-source OpenAirside engine, with the equations on the methodology page.
- Aircraft dimensions come from the public-domain FAA Aircraft Characteristics Database; steering limits cite the manufacturer document.
- Every output carries a note of what was estimated rather than published.
- No vendor library, data file or software was used or reverse-engineered.
| Check | Result | Expected |
|---|---|---|
| A320 minimum edge margin, 45 m turns | 4.39 m | ≥ 3 m |
| B777-300ER, same turns | 6.6 m off, 2 breaches | Needs fillets |
| Fillet track-in, A320 | 2.63 m | 2.7 m by hand |
| Fillet track-in, B777-300ER | 11.6 m | — |
| Pushback nose-wheel angle | 17.8° | 17.5° analytic |
| Stand conflict S2/S3 | 0.18 m | 4.5 m required |
| A320 breakaway 56 km/h contour | 48 m | ICAO: 48 m |
04 Workflow
Draw. Simulate. Verify. Report.
The same four steps in every product. Your drawing stays the source of truth; Tractrix adds analysis layers and never edits your geometry.
-
Draw
Draw the centreline, lead-in or pushback route as a line in the direction of travel, on your own drawing or GIS layer.
in: polyline · pavement · obstacles
-
Simulate
Pick aircraft or vehicles from the library. The engine integrates the no-slip kinematics in 5 cm steps.
engine: tractrix/1 request
-
Verify
Steering-limit exceedances, pavement-edge breaches, obstacle and stand conflicts are flagged where they occur.
out: issues with value, limit, position
-
Report
Envelopes, tracks and time-stamped footprints for animation, plus an HTML report and a JSON summary.
out: GeoJSON · layers · HTML · JSON
05 The name
Named after the curve at the heart of the engine.
When a nose gear is steered along a line, the main gear does not follow the line. It cuts inside, tracing a curve that mathematicians have called the tractrix since the seventeenth century — the path of a load dragged on a rope of fixed length.
ICAO Doc 9157, Part 2, Appendix 1 describes aircraft ground manoeuvres with exactly this mathematics. Tractrix integrates it directly, rather than approximating it with circular arcs.
Start with the free QGIS plugin today.
The Community edition is the full engine with every tool. Cloud, AutoCAD and Revit are in preview; register interest and we will tell you when they open.