What audible signal accompanies an emergency call from the flight deck?

The audible signal that accompanies an emergency call from the flight deck is characterized by a sequence of three hi/lo chimes. This specific pattern is designed to alert the cabin crew and ground personnel of an urgent situation, distinguishing it from standard communications and ensuring immediate attention. The hi/lo chimes are distinct enough to signal that the situation is critical and requires prompt action, making them an essential part of the aircraft's safety communication protocols.

Other signals, though they may be used for different forms of communication or alerts, do not indicate an emergency call. For instance, a continuous ringing sound or a single alert tone may signal other types of notifications, but they lack the specific urgency conveyed by the hi/lo chimes associated with emergency situations. Thus, understanding the meaning of these signals is vital for cabin crew and ground personnel to respond appropriately in an emergency.