Final answer:
When taxiing, pilots or ground control must receive clearance from the tower to cross a runway, ensuring safety and avoiding conflicting traffic.
Step-by-step explanation:
When taxiing, in order to cross a runway (active or inactive), aircraft pilots or ground control receive clearance from the tower to proceed. This clearance ensures that there is no conflicting traffic on the runway and guarantees safe crossing.
The tower controller may communicate with the pilot using radio transmission or light signals to indicate when it is safe to cross the runway. The pilot must follow the instructions and only proceed once authorized.
It is important to note that pilots and ground control must always be vigilant and follow established standard operating procedures (SOPs) to ensure the safety of everyone involved.