Under what condition must vehicles and aircraft not cross runway holding markings?

The correct answer is about the requirement for vehicles and aircraft to wait until departure aircraft have passed the point of crossing. This condition is essential for maintaining safety in airport operations, particularly in preventing potential collisions or incidents on the runway.

Runway holding markings indicate areas where vehicles and aircraft must stop to ensure that the runway is clear for departing or arriving aircraft. It is crucial for ground personnel and vehicles to wait until any aircraft that is taking off has completely left the runway area before proceeding across the marking. This practice helps to ensure safe separation between ground operations and airborne movements, maintaining the integrity of the runway environment.

Understanding this requirement is vital for anyone operating on or near runways since it plays a critical role in preventing runway incursions, which can lead to serious accidents. The focus on the precise timing of when to cross ensures that all personnel are aware of the active flight operations and can act accordingly to minimize risk.