Let’s be clear: Doc 9811 is not a regulation. It doesn’t carry the legally binding weight of an Annex to the Chicago Convention. But to dismiss it as a mere "guideline" would be a fatal misunderstanding.
When an ICAO auditor visits a country, they do not simply ask, "Do you have training?" They pull from Doc 9811’s checklist: icao doc 9811
The manual dedicates significant space to the deadly "yellow vs. blue" conflict—the battle between ground service vehicles and the aircraft itself. It defines safe following distances, no-go zones (the danger area around engines and pitot tubes), and mandatory chocking procedures. A key rule: No vehicle moves within the safety zone unless the aircraft’s engines are shut down or the crew has explicitly signaled. Let’s be clear: Doc 9811 is not a regulation
Furthermore, because it is non-binding, enforcement relies on national regulators. Some countries adopt it wholesale; others cherry-pick. The result is a global patchwork of safety standards. When an ICAO auditor visits a country, they