Whenever we think of Runway Incursions, the first picture that comes to our mind is 2 aircraft at the same place at the same time. But, this is far from truth! A Runway Incursion could involve 2 or more aircraft, or even an aircraft and a fuel truck, or even a golf cart or maybe just even a simple pedestrian. Here is the official FAA and ICAO accepted definition of Runway Incursion –
A Runway Incursion is any unauthorized intrusion onto a runway, regardless of whether an aircraft presents a potential conflict.
As pilots and flight instructors it is our responsibility to always be on the defense, and remain aware of our surroundings, and use communication tools and other resources available to our best advantage. As flight instructors, it is our duty to make sure that we have instilled this sense of Runway Incursion Avoidance into each one of our students, to the point that it has become their second nature.
Runway Incursions are categorized as D through A, and Accident. The escalation of categories continue, of course. Beyond a category A runway incursion is an event that results in a collision. That occurrence is officially defined as an accident.