Engineering and professional-use disclaimer

Version 1.0-draftLast updated [LAST UPDATED DATE]Effective [EFFECTIVE DATE]Draft prepared 30 September 2026

Tractrix and OpenAirside compute how aircraft and ground vehicles move on the airside, and check the resulting envelopes against clearances. They are built to be transparent and reproducible, and every limitation we know of is documented. They are nevertheless planning aids: this disclaimer explains what that means for you. It applies to all Tractrix products — Tractrix Cloud, the AutoCAD and Revit add-ins, Tractrix for QGIS, the OpenAirside engine and the tractrix-engine binary — and to every report and export they produce.

1. A planning aid, not a certified design tool

Results are intended to support feasibility studies, concept and preliminary design, option comparison and review by qualified professionals. They are not certified, have not been approved by any civil aviation authority, and are not endorsed by any aircraft or vehicle manufacturer. They do not replace:

• the manufacturer's airport planning documents (for example the Airplane Characteristics for Airport Planning or Aircraft Characteristics — Airport and Maintenance Planning manuals);
• the standards and regulations that apply to the aerodrome (for example ICAO Annex 14, Volume I and the Aerodrome Design Manual, FAA Advisory Circular 150/5300-13, EASA CS-ADR-DSN, or national regulations);
• aeronautical studies, safety assessments or approvals required by the competent authority; or
• the judgement of qualified and responsible engineers.

2. Model and data limitations

• Kinematic model. Motion is computed geometrically: the model does not represent tyre scrub or slip, differential thrust, differential braking, wind, pavement friction or slope, gear deflection, or pilot and driver technique. Real manoeuvres can differ.
• Aircraft data. Dimensions come from the FAA Aircraft Characteristics Database, a public-domain dataset. Where a dimension needed by the model is not in the source (for example some gear positions or nose-to-gear distances), it is estimated and marked as estimated in the library and on outputs. Steering limits are taken from manufacturers' published documents where cited.
• Jet blast. Jet-blast contours are indicative empirical estimates based on published velocity profiles. They do not account for terrain, structures, wind or specific engine and thrust settings, and are not a substitute for the manufacturer's jet-blast data or a site-specific study.
• Standards values. Clearance values are transcribed by us from ICAO, FAA and EASA publications and cited by clause. Transcription errors are possible and publications are amended; always check against the current official text. We do not warrant that any output complies with any standard.
• Inputs. Results are only as good as their inputs. Check units, coordinate systems (drawings must be in planar metres), path geometry, aircraft or vehicle type and parameters.
• Engine versions. Each result records the engine version that produced it. Updates can change results; re-run and review analyses after an update.

The methodology documents the model, its validation and its limitations in detail.

3. Validation

The engine is tested against analytical cases and against published manufacturer turning data where available, as described in the methodology. Validation is limited to the cases documented; it does not demonstrate accuracy for every aircraft, vehicle, manoeuvre or geometry.

4. No operational use

Tractrix must not be used for real-time or operational purposes, including air traffic control, apron or stand management, surface movement guidance and control, marshalling, aircraft or vehicle guidance, pilot or driver instruction or training, or in any situation where a failure or inaccuracy could directly cause death, personal injury, or damage to aircraft, vehicles or property.

5. Your responsibility

If you use Tractrix results, you are responsible for:

• ensuring that the people who use and interpret the results are suitably qualified and experienced;
• verifying results that matter for a decision against the manufacturer's documents and the applicable standards, and by independent calculation or review where appropriate;
• applying appropriate safety margins and professional judgement;
• all designs, approvals, submissions to authorities, construction and operational decisions; and
• telling your clients and reviewers that results are produced by a planning aid with the limitations described here — the reports produced by the products include a statement to that effect, which should not be removed.

6. No warranty and limitation of liability

For the open-source products, the GNU General Public License disclaims all warranties and limits liability (sections 11 and 12 of GPL version 2; sections 15 and 16 of version 3); see the desktop software licence. For Tractrix Cloud, the warranties and limitations of the Cloud Terms apply. In both cases, and to the fullest extent permitted by law, REAT Global and the contributors to OpenAirside are not liable for any loss arising from reliance on results that were not verified as described above. Nothing in this disclaimer limits liability that cannot be limited by law.

7. Report a problem

If you find a result that looks wrong, please report it with the input and the aircraft type through Downloads (account required). Corrections to aircraft data and standards values are especially welcome.