How many crewmembers must communicate with the ground personnel using the interphone system when the aircraft is on the ground?

The requirement for at least one of the two flight crewmembers to communicate with the ground personnel using the interphone system when the aircraft is on the ground is grounded in safety protocols and operational efficiency. This arrangement ensures that there is a designated crew member available to relay important information between the ground crew and the flight team, which is critical for coordination during ground operations.

Having at least one crewmember engaged in this communication allows for the effective exchange of vital information such as safety checks, operational updates, and responses to any ground activities that may affect the aircraft or its preparations for flight. This system not only enhances safety by ensuring that crucial messages are conveyed promptly but also aids in the decision-making process regarding taxiing, fueling, and other necessary ground operations.

While it is preferable for all flight crewmembers to be aware of ground communications, the regulatory and practical focus is on ensuring that at least one representative from the cockpit is actively engaged in this process. This maintains a clear line of communication that can be crucial in ensuring a safe and efficient operation while the aircraft is on the ground.