What should be avoided when using a loudhailer?

Pointing a loudhailer at the fuselage should be avoided because it can create excessive noise levels that may not only disturb the structural integrity of the aircraft but also impact the communication among crew members and between the crew and passengers. The fuselage is designed to contain sounds and vibrations, and directing loud sounds at it can lead to unintended consequences, including confusion or distraction during critical phases of flight.

Using a loudhailer indoors, during takeoff, or when the plane is landing has specific contexts where it is important to ensure communication does not interfere with operational capacities or safety protocols. However, the act of pointing a loudhailer at the fuselage can lead to direct, adverse effects on the aircraft's systems and personnel, making it essential to avoid this practice.