To qualify as a runway incursion, which of the following conditions must be met?

To qualify as a runway incursion, the key condition is that at least one aircraft must be on the runway. This is because a runway incursion is defined as any occurrence at an airport involving the incorrect presence of an aircraft, vehicle, or person on the protected area of a runway. Therefore, having at least one aircraft on the runway creates a potential for conflict, making it a critical component of identifying a runway incursion.

While it might also be true that a vehicle could be on the runway, the fundamental aspect that makes an event a runway incursion is the presence of an aircraft. The concept of a collision hazard is more related to the potential consequences of an incursion rather than the definition itself. Thus, the correct identification revolves around the presence of an aircraft, which establishes the context for evaluating the safety of the operational area.